Bump version numbers for 1.2.19 release.

Migrate BlogController and FeedController to ViewModel

Closes #1891 and #1866

See merge request briar/briar!1342

.gitlab-ci.yml

@@ -1,30 +1,52 @@
 image: briar/ci-image-android:latest
 
 stages:
-- test
-- optional_tests
-- check_reproducibility
+  - test
+  - optional_tests
+  - check_reproducibility
 
-test:
-  stage: test
+.base-test:
   before_script:
     - set -e
     - export GRADLE_USER_HOME=$PWD/.gradle
-
   cache:
+    key: "$CI_COMMIT_REF_SLUG"
     paths:
       - .gradle/wrapper
       - .gradle/caches
-
-  script:
-    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom animalSnifferMain animalSnifferTest
-    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom check compileOfficialDebugAndroidTestSources compileScreenshotDebugAndroidTestSources
-
   after_script:
-    # these file change every time but should not be cached
+    # these file change every time and should not be cached
     - rm -f $GRADLE_USER_HOME/caches/modules-2/modules-2.lock
     - rm -fr $GRADLE_USER_HOME/caches/*/plugin-resolution/
 
+test:
+  extends: .base-test
+  stage: test
+  script:
+    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom animalSnifferMain animalSnifferTest
+    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom check
+
+android test:
+  extends: .base-test
+  stage: optional_tests
+  image: briar/ci-image-android-emulator:latest
+  script:
+    # start emulator first, so it can fail early
+    - start-emulator.sh
+    # run normal and screenshot tests together (exclude Large tests)
+    - ./gradlew -Djava.security.egd=file:/dev/urandom connectedAndroidTest -Pandroid.testInstrumentationRunnerArguments.notAnnotation=androidx.test.filters.LargeTest
+  artifacts:
+    name: "${CI_PROJECT_PATH}_${CI_JOB_STAGE}_${CI_COMMIT_REF_NAME}_${CI_COMMIT_SHA}"
+    paths:
+      - kernel.log
+      - logcat.txt
+    expire_in: 3 days
+    when: on_failure
+  when: manual
+  except:
+    - tags
+  tags:
+    - kvm
 
 test_reproducible:
   stage: check_reproducibility
@@ -40,6 +62,7 @@ test_reproducible:
     - export GRADLE_USER_HOME=$PWD/.gradle
 
   cache:
+    key: "$CI_COMMIT_REF_SLUG"
     paths:
       - .gradle/wrapper
       - .gradle/caches

.idea/runConfigurations/Instrumentation_Tests__destroys_DB_.xml

@@ -0,0 +1,51 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="Instrumentation Tests (destroys DB)" type="AndroidTestRunConfigurationType" factoryName="Android Instrumented Tests">
+    <module name="briar.briar-android" />
+    <option name="TESTING_TYPE" value="1" />
+    <option name="METHOD_NAME" value="" />
+    <option name="CLASS_NAME" value="" />
+    <option name="PACKAGE_NAME" value="org.briarproject.briar.android" />
+    <option name="INSTRUMENTATION_RUNNER_CLASS" value="" />
+    <option name="EXTRA_OPTIONS" value="-e notAnnotation androidx.test.filters.LargeTest" />
+    <option name="INCLUDE_GRADLE_EXTRA_OPTIONS" value="true" />
+    <option name="CLEAR_LOGCAT" value="false" />
+    <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
+    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
+    <option name="FORCE_STOP_RUNNING_APP" value="true" />
+    <option name="TARGET_SELECTION_MODE" value="DEVICE_AND_SNAPSHOT_COMBO_BOX" />
+    <option name="DEBUGGER_TYPE" value="Auto" />
+    <Auto>
+      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
+      <option name="SHOW_STATIC_VARS" value="true" />
+      <option name="WORKING_DIR" value="" />
+      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
+      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
+    </Auto>
+    <Hybrid>
+      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
+      <option name="SHOW_STATIC_VARS" value="true" />
+      <option name="WORKING_DIR" value="" />
+      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
+      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
+    </Hybrid>
+    <Java />
+    <Native>
+      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
+      <option name="SHOW_STATIC_VARS" value="true" />
+      <option name="WORKING_DIR" value="" />
+      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
+      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
+    </Native>
+    <Profilers>
+      <option name="ADVANCED_PROFILING_ENABLED" value="false" />
+      <option name="STARTUP_PROFILING_ENABLED" value="false" />
+      <option name="STARTUP_CPU_PROFILING_ENABLED" value="false" />
+      <option name="STARTUP_CPU_PROFILING_CONFIGURATION_NAME" value="Sample Java Methods" />
+      <option name="STARTUP_NATIVE_MEMORY_PROFILING_ENABLED" value="false" />
+      <option name="NATIVE_MEMORY_SAMPLE_RATE_BYTES" value="2048" />
+    </Profilers>
+    <method v="2">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
+    </method>
+  </configuration>
+</component>

bramble-android/build.gradle

@@ -8,11 +8,15 @@ android {
 	compileSdkVersion 30
 	buildToolsVersion '30.0.2'
 
+	packagingOptions {
+		doNotStrip '**/*.so'
+	}
+
 	defaultConfig {
 		minSdkVersion 16
 		targetSdkVersion 29
-		versionCode 10214
-		versionName "1.2.14"
+		versionCode 10219
+		versionName "1.2.19"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
@@ -38,8 +42,8 @@ configurations {
 
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
-	tor 'org.briarproject:tor-android:0.3.5.12@zip'
-	tor 'org.briarproject:obfs4proxy-android:0.0.11-2@zip'
+	tor 'org.briarproject:tor-android:0.3.5.13@zip'
+	tor 'org.briarproject:obfs4proxy-android:0.0.12-dev-40245c4a@zip'
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'
 

bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPlugin.java

@@ -175,6 +175,11 @@ class AndroidBluetoothPlugin
 		} catch (IOException e) {
 			IoUtils.tryToClose(s, LOG, WARNING);
 			throw e;
+		} catch (NullPointerException e) {
+			// BluetoothSocket#connect() may throw an NPE under unknown
+			// circumstances
+			IoUtils.tryToClose(s, LOG, WARNING);
+			throw new IOException(e);
 		}
 	}
 

bramble-android/src/main/java/org/briarproject/bramble/util/AndroidUtils.java

@@ -114,12 +114,8 @@ public class AndroidUtils {
 
 	/**
 	 * Returns an array of supported content types for image attachments.
-	 * GIFs can't be compressed on API < 24 so they're not supported.
-	 * <p>
-	 * TODO: Remove this restriction when large message support is added
 	 */
 	public static String[] getSupportedImageContentTypes() {
-		if (SDK_INT < 24) return new String[] {"image/jpeg", "image/png"};
-		else return new String[] {"image/jpeg", "image/png", "image/gif"};
+		return new String[] {"image/jpeg", "image/png", "image/gif"};
 	}
 }

bramble-android/witness.gradle

@@ -75,8 +75,8 @@ dependencyVerification {
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         'org.bouncycastle:bcpkix-jdk15on:1.56:bcpkix-jdk15on-1.56.jar:7043dee4e9e7175e93e0b36f45b1ec1ecb893c5f755667e8b916eb8dd201c6ca',
         'org.bouncycastle:bcprov-jdk15on:1.56:bcprov-jdk15on-1.56.jar:963e1ee14f808ffb99897d848ddcdb28fa91ddda867eb18d303e82728f878349',
-        'org.briarproject:obfs4proxy-android:0.0.11-2:obfs4proxy-android-0.0.11-2.zip:57e55cbe87aa2aac210fdbb6cd8cdeafe15f825406a08ebf77a8b787aa2c6a8a',
-        'org.briarproject:tor-android:0.3.5.12:tor-android-0.3.5.12.zip:db71fb3290acff79d572af0752570eaf6aad7c4d88c9b9aa0b4d5afe2b9ead9c',
+        'org.briarproject:obfs4proxy-android:0.0.12-dev-40245c4a:obfs4proxy-android-0.0.12-dev-40245c4a.zip:8ab05a8f8391be2cb5ab2b665c281a06d9e3a756bd0f95a40a36ca927866ea82',
+        'org.briarproject:tor-android:0.3.5.13:tor-android-0.3.5.13.zip:e0978db136731dae07774b722970cdae1e462fb5adc82845dd80a7e2d87f356c',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
         'org.checkerframework:checker-qual:2.8.1:checker-qual-2.8.1.jar:9103499008bcecd4e948da29b17864abb64304e15706444ae209d17ebe0575df',

bramble-core/src/main/resources/bridges

@@ -2,12 +2,11 @@ Bridge obfs4 192.95.36.142:443 CDF2E852BF539B82BD10E27E9115A31734E378C2 cert=qUV
 Bridge obfs4 38.229.1.78:80 C8CBDB2464FC9804A69531437BCF2BE31FDD2EE4 cert=Hmyfd2ev46gGY7NoVxA9ngrPF2zCZtzskRTzoWXbxNkzeVnGFPWmrTtILRyqCTjHR+s9dg iat-mode=1
 Bridge obfs4 37.218.245.14:38224 D9A82D2F9C2F65A18407B1D2B764F130847F8B5D cert=bjRaMrr1BRiAW8IE9U5z27fQaYgOhX1UCmOpg2pFpoMvo6ZgQMzLsaTzzQNTlm7hNcb+Sg iat-mode=0
 Bridge obfs4 85.31.186.98:443 011F2599C0E9B27EE74B353155E244813763C3E5 cert=ayq0XzCwhpdysn5o0EyDUbmSOx3X/oTEbzDMvczHOdBJKlvIdHHLJGkZARtT4dcBFArPPg iat-mode=0
-Bridge obfs4 85.31.186.26:443 91A6354697E6B02A386312F68D82CF86824D3606 cert=PBwr+S8JTVZo6MPdHnkTwXJPILWADLqfMGoVvhZClMq/Urndyd42BwX9YFJHZnBB3H0XCw iat-mode=0
+Bridge obfs4 144.217.20.138:80 FB70B257C162BF1038CA669D568D76F5B7F0BABB cert=vYIV5MgrghGQvZPIi1tJwnzorMgqgmlKaB77Y3Z9Q/v94wZBOAXkW+fdx4aSxLVnKO+xNw iat-mode=0
 Bridge obfs4 193.11.166.194:27015 2D82C2E354D531A68469ADF7F878FA6060C6BACA cert=4TLQPJrTSaDffMK7Nbao6LC7G9OW/NHkUwIdjLSS3KYf0Nv4/nQiiI8dY2TcsQx01NniOg iat-mode=0
 Bridge obfs4 193.11.166.194:27020 86AC7B8D430DAC4117E9F42C9EAED18133863AAF cert=0LDeJH4JzMDtkJJrFphJCiPqKx7loozKN7VNfuukMGfHO0Z8OGdzHVkhVAOfo1mUdv9cMg iat-mode=0
 Bridge obfs4 193.11.166.194:27025 1AE2C08904527FEA90C4C4F8C1083EA59FBC6FAF cert=ItvYZzW5tn6v3G4UnQa6Qz04Npro6e81AP70YujmK/KXwDFPTs3aHXcHp4n8Vt6w/bv8cA iat-mode=0
 Bridge obfs4 209.148.46.65:443 74FAD13168806246602538555B5521A0383A1875 cert=ssH+9rP8dG2NLDN2XuFw63hIO/9MNNinLmxQDpVa+7kTOa9/m+tGWT1SmSYpQ9uTBGa6Hw iat-mode=0
-Bridge obfs4 146.57.248.225:22 10A6CD36A537FCE513A322361547444B393989F0 cert=K1gDtDAIcUfeLqbstggjIw2rtgIKqdIhUlHp82XRqNSq/mtAjp1BIC9vHKJ2FAEpGssTPw iat-mode=0
 Bridge obfs4 45.145.95.6:27015 C5B7CD6946FF10C5B3E89691A7D3F2C122D2117C cert=TD7PbUO0/0k6xYHMPW3vJxICfkMZNdkRrb63Zhl5j9dW3iRGiCx0A7mPhe5T2EDzQ35+Zw iat-mode=0
 Bridge obfs4 51.222.13.177:80 5EDAC3B810E12B01F6FD8050D2FD3E277B289A08 cert=2uplIpLQ0q9+0qMFrK5pkaYRDOe460LL9WHBvatgkuRr/SL31wBOEupaMMJ6koRE6Ld0ew iat-mode=0
 Bridge obfs4 78.46.188.239:37356 5A2D2F4158D0453E00C7C176978D3F41D69C45DB cert=3c0SwxpOisbohNxEc4tb875RVW8eOu1opRTVXJhafaKA/PNNtI7ElQIVOVZg1AdL5bxGCw iat-mode=0

bramble-java/build.gradle

@@ -16,8 +16,8 @@ dependencies {
 	implementation fileTree(dir: 'libs', include: '*.jar')
 	implementation 'net.java.dev.jna:jna:4.5.2'
 	implementation 'net.java.dev.jna:jna-platform:4.5.2'
-	tor 'org.briarproject:tor:0.3.5.12@zip'
-	tor 'org.briarproject:obfs4proxy:0.0.7@zip'
+	tor 'org.briarproject:tor:0.3.5.13-1@zip'
+	tor 'org.briarproject:obfs4proxy:0.0.12-dev-40245c4a@zip'
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'
 

bramble-java/src/main/java/org/briarproject/bramble/plugin/tor/UnixTorPluginFactory.java

@@ -25,6 +25,7 @@ import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 import javax.net.SocketFactory;
 
+import static java.util.logging.Level.INFO;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.OsUtils.isLinux;
 
@@ -96,8 +97,15 @@ public class UnixTorPluginFactory implements DuplexPluginFactory {
 		String architecture = null;
 		if (isLinux()) {
 			String arch = System.getProperty("os.arch");
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("System's os.arch is " + arch);
+			}
 			if (arch.equals("amd64")) {
 				architecture = "linux-x86_64";
+			} else if (arch.equals("aarch64")) {
+				architecture = "linux-aarch64";
+			} else if (arch.equals("arm")) {
+				architecture = "linux-armhf";
 			}
 		}
 		if (architecture == null) {
@@ -105,6 +113,10 @@ public class UnixTorPluginFactory implements DuplexPluginFactory {
 			return null;
 		}
 
+		if (LOG.isLoggable(INFO)) {
+			LOG.info("The selected architecture for Tor is " + architecture);
+		}
+
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		TorRendezvousCrypto torRendezvousCrypto = new TorRendezvousCryptoImpl();

bramble-java/witness.gradle

@@ -23,8 +23,8 @@ dependencyVerification {
         'org.apache.ant:ant-launcher:1.9.4:ant-launcher-1.9.4.jar:7bccea20b41801ca17bcbc909a78c835d0f443f12d639c77bd6ae3d05861608d',
         'org.apache.ant:ant:1.9.4:ant-1.9.4.jar:649ae0730251de07b8913f49286d46bba7b92d47c5f332610aa426c4f02161d8',
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
-        'org.briarproject:obfs4proxy:0.0.7:obfs4proxy-0.0.7.zip:5b2f693262ce43a7e130f7cc7d5d1617925330640a2eb6d71085e95df8ee0642',
-        'org.briarproject:tor:0.3.5.12:tor-0.3.5.12.zip:2f542c4befd216f2226bf7c76e3b8b2d99af6f146a8cb28bf727f42014587006',
+        'org.briarproject:obfs4proxy:0.0.12-dev-40245c4a:obfs4proxy-0.0.12-dev-40245c4a.zip:172029e7058b3a83ac93ac4991a44bf76e16ce8d46f558f5836d57da3cb3a766',
+        'org.briarproject:tor:0.3.5.13-1:tor-0.3.5.13-1.zip:ef35c16bf8dc1f4c75ed71d9f55e4514f383d124ec96b859aca647c990927c99',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
         'org.codehaus.mojo:animal-sniffer-annotations:1.17:animal-sniffer-annotations-1.17.jar:92654f493ecfec52082e76354f0ebf87648dc3d5cec2e3c3cdb947c016747a53',

briar-android/build.gradle

@@ -19,11 +19,15 @@ android {
 	compileSdkVersion 30
 	buildToolsVersion '30.0.2'
 
+	packagingOptions {
+		doNotStrip '**/*.so'
+	}
+
 	defaultConfig {
 		minSdkVersion 16
 		targetSdkVersion 29
-		versionCode 10214
-		versionName "1.2.14"
+		versionCode 10219
+		versionName "1.2.19"
 		applicationId "org.briarproject.briar.android"
 
 		vectorDrawables.useSupportLibrary = true
@@ -95,6 +99,7 @@ dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
 	implementation project(':bramble-android')
 
+	implementation 'androidx.fragment:fragment:1.3.0'
 	implementation 'androidx.preference:preference:1.1.1'
 	implementation 'androidx.exifinterface:exifinterface:1.3.1'
 	implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'

briar-android/src/androidTest/java/org/briarproject/briar/android/UiTest.java

@@ -4,16 +4,20 @@ import android.app.Activity;
 import android.content.Intent;
 
 import org.briarproject.bramble.api.account.AccountManager;
+import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.api.settings.SettingsManager;
 import org.briarproject.briar.R;
 
-import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.test.espresso.intent.rule.IntentsTestRule;
 
 import static androidx.test.core.app.ApplicationProvider.getApplicationContext;
+import static org.briarproject.briar.android.controller.BriarControllerImpl.DOZE_ASK_AGAIN;
+import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_NAMESPACE;
 
 
 @SuppressWarnings("WeakerAccess")
@@ -27,6 +31,8 @@ public abstract class UiTest {
 	protected AccountManager accountManager;
 	@Inject
 	protected LifecycleManager lifecycleManager;
+	@Inject
+	protected SettingsManager settingsManager;
 
 	public UiTest() {
 		BriarTestComponentApplication app = getApplicationContext();
@@ -39,22 +45,8 @@ public abstract class UiTest {
 	protected class CleanAccountTestRule<A extends Activity>
 			extends IntentsTestRule<A> {
 
-		@Nullable
-		private final Runnable runnable;
-
 		public CleanAccountTestRule(Class<A> activityClass) {
 			super(activityClass);
-			this.runnable = null;
-		}
-
-		/**
-		 * Use this if you need to run code before launching the activity.
-		 * Note: You need to use {@link #launchActivity(Intent)} yourself
-		 * to start the activity.
-		 */
-		public CleanAccountTestRule(Class<A> activityClass, Runnable runnable) {
-			super(activityClass, false, false);
-			this.runnable = runnable;
 		}
 
 		@Override
@@ -62,16 +54,17 @@ public abstract class UiTest {
 			super.beforeActivityLaunched();
 			accountManager.deleteAccount();
 			accountManager.createAccount(USERNAME, PASSWORD);
-			if (runnable != null) {
-				Intent serviceIntent =
-						new Intent(getApplicationContext(), BriarService.class);
-				getApplicationContext().startService(serviceIntent);
-				try {
-					lifecycleManager.waitForStartup();
-				} catch (InterruptedException e) {
-					throw new AssertionError(e);
-				}
-				runnable.run();
+			Intent serviceIntent =
+					new Intent(getApplicationContext(), BriarService.class);
+			getApplicationContext().startService(serviceIntent);
+			try {
+				lifecycleManager.waitForStartup();
+				// do not show doze white-listing dialog
+				Settings settings = new Settings();
+				settings.putBoolean(DOZE_ASK_AGAIN, false);
+				settingsManager.mergeSettings(settings, SETTINGS_NAMESPACE);
+			} catch (InterruptedException | DbException e) {
+				throw new AssertionError(e);
 			}
 		}
 	}

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/media/PngSuiteImageCompressorTest.java

@@ -10,12 +10,15 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.logging.Logger;
 
+import androidx.test.filters.LargeTest;
+
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.bramble.test.TestUtils.isOptionalTestEnabled;
 import static org.junit.Assert.fail;
 import static org.junit.Assume.assumeTrue;
 
+@LargeTest
 @RunWith(Parameterized.class)
 public class PngSuiteImageCompressorTest
 		extends AbstractImageCompressorTest {

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/media/PngSuiteImageSizeCalculatorTest.java

@@ -12,11 +12,14 @@ import java.util.List;
 import java.util.Map;
 import java.util.logging.Logger;
 
+import androidx.test.filters.LargeTest;
+
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.bramble.test.TestUtils.isOptionalTestEnabled;
 import static org.junit.Assume.assumeTrue;
 
+@LargeTest
 @RunWith(Parameterized.class)
 public class PngSuiteImageSizeCalculatorTest
 		extends AbstractImageSizeCalculatorTest {

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/conversation/ConversationActivityNotSignedInTest.java

@@ -1,39 +0,0 @@
-package org.briarproject.briar.android.conversation;
-
-import android.content.Context;
-import android.content.Intent;
-
-import org.briarproject.briar.R;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-
-import androidx.test.ext.junit.runners.AndroidJUnit4;
-import androidx.test.rule.ActivityTestRule;
-
-import static androidx.test.espresso.Espresso.onView;
-import static androidx.test.espresso.matcher.ViewMatchers.isDisplayed;
-import static androidx.test.espresso.matcher.ViewMatchers.withText;
-import static androidx.test.platform.app.InstrumentationRegistry.getInstrumentation;
-import static org.briarproject.briar.android.ViewActions.waitUntilMatches;
-import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
-
-@RunWith(AndroidJUnit4.class)
-public class ConversationActivityNotSignedInTest {
-
-	@Rule
-	public ActivityTestRule<ConversationActivity> testRule =
-			new ActivityTestRule<>(ConversationActivity.class, false, false);
-
-	@Test
-	public void openWithoutSignedIn() {
-		Context targetContext = getInstrumentation().getTargetContext();
-		Intent intent = new Intent(targetContext, ConversationActivity.class);
-		intent.putExtra(CONTACT_ID, 1);
-		testRule.launchActivity(intent);
-
-		onView(withText(R.string.sign_in_button))
-				.perform(waitUntilMatches(isDisplayed()));
-	}
-
-}

briar-android/src/androidTestScreenshot/java/org/briarproject/briar/android/settings/SettingsActivityScreenshotTest.java

@@ -16,6 +16,7 @@ import androidx.test.espresso.contrib.DrawerActions;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import androidx.test.rule.ActivityTestRule;
 
+import static androidx.test.core.app.ApplicationProvider.getApplicationContext;
 import static androidx.test.espresso.Espresso.onView;
 import static androidx.test.espresso.action.ViewActions.click;
 import static androidx.test.espresso.assertion.ViewAssertions.matches;
@@ -29,7 +30,9 @@ import static androidx.test.espresso.matcher.ViewMatchers.withClassName;
 import static androidx.test.espresso.matcher.ViewMatchers.withId;
 import static androidx.test.espresso.matcher.ViewMatchers.withText;
 import static org.briarproject.briar.android.ViewActions.waitUntilMatches;
+import static org.briarproject.briar.android.util.UiUtils.hasScreenLock;
 import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assume.assumeTrue;
 
 @RunWith(AndroidJUnit4.class)
 public class SettingsActivityScreenshotTest extends ScreenshotTest {
@@ -76,6 +79,8 @@ public class SettingsActivityScreenshotTest extends ScreenshotTest {
 
 	@Test
 	public void appLock() {
+		assumeTrue("device has no screen lock",
+				hasScreenLock(getApplicationContext()));
 		// scroll down
 		onView(withClassName(is(RecyclerView.class.getName())))
 				.perform(scrollTo(hasDescendant(

briar-android/src/main/AndroidManifest.xml

@@ -27,7 +27,10 @@
 	<uses-permission android:name="android.permission.USE_FINGERPRINT" />
 	<uses-permission android:name="android.permission.VIBRATE" />
 	<uses-permission android:name="android.permission.WAKE_LOCK" />
-	<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
+	<uses-permission
+		android:name="android.permission.WRITE_EXTERNAL_STORAGE"
+		android:maxSdkVersion="18"
+		tools:ignore="ScopedStorage" />
 
 	<uses-permission-sdk-23 android:name="android.permission.ACCESS_FINE_LOCATION" />
 	<uses-permission-sdk-23 android:name="android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS" />
@@ -38,6 +41,7 @@
 		android:name="org.briarproject.briar.android.BriarApplicationImpl"
 		android:allowBackup="false"
 		android:banner="@mipmap/tv_banner"
+		android:fullBackupContent="@xml/backup_rules"
 		android:icon="@mipmap/ic_launcher_round"
 		android:label="@string/app_name"
 		android:logo="@mipmap/ic_launcher_round"

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -30,8 +30,10 @@ import org.briarproject.bramble.util.StringUtils;
 import org.briarproject.briar.android.account.DozeHelperModule;
 import org.briarproject.briar.android.account.LockManagerImpl;
 import org.briarproject.briar.android.account.SetupModule;
+import org.briarproject.briar.android.blog.BlogModule;
 import org.briarproject.briar.android.contact.ContactListModule;
 import org.briarproject.briar.android.forum.ForumModule;
+import org.briarproject.briar.android.introduction.IntroductionModule;
 import org.briarproject.briar.android.keyagreement.ContactExchangeModule;
 import org.briarproject.briar.android.logging.LoggingModule;
 import org.briarproject.briar.android.login.LoginModule;
@@ -82,7 +84,9 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 		SettingsModule.class,
 		DevReportModule.class,
 		ContactListModule.class,
+		IntroductionModule.class,
 		// below need to be within same scope as ViewModelProvider.Factory
+		BlogModule.class,
 		ForumModule.class,
 		GroupListModule.class,
 		GroupConversationModule.class,

briar-android/src/main/java/org/briarproject/briar/android/BriarApplicationImpl.java

@@ -51,6 +51,7 @@ public class BriarApplicationImpl extends Application
 		Localizer.initialize(prefs);
 		super.attachBaseContext(
 				Localizer.getInstance().setLocale(base));
+		Localizer.getInstance().setLocale(this);
 		setTheme(base, prefs);
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/BriarService.java

@@ -37,7 +37,7 @@ import javax.inject.Inject;
 import androidx.core.app.NotificationCompat;
 
 import static android.app.NotificationManager.IMPORTANCE_DEFAULT;
-import static android.app.NotificationManager.IMPORTANCE_NONE;
+import static android.app.NotificationManager.IMPORTANCE_LOW;
 import static android.app.PendingIntent.FLAG_UPDATE_CURRENT;
 import static android.content.Intent.ACTION_SHUTDOWN;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TASK;
@@ -46,6 +46,7 @@ import static android.content.Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS;
 import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
 import static android.content.Intent.FLAG_ACTIVITY_NO_ANIMATION;
 import static android.os.Build.VERSION.SDK_INT;
+import static android.os.Process.myPid;
 import static androidx.core.app.NotificationCompat.VISIBILITY_SECRET;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
@@ -56,8 +57,10 @@ import static org.briarproject.briar.android.BriarApplication.ENTRY_ACTIVITY;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.FAILURE_CHANNEL_ID;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.FAILURE_NOTIFICATION_ID;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.ONGOING_CHANNEL_ID;
+import static org.briarproject.briar.api.android.AndroidNotificationManager.ONGOING_CHANNEL_OLD_ID;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.ONGOING_NOTIFICATION_ID;
 import static org.briarproject.briar.api.android.LockManager.ACTION_LOCK;
+import static org.briarproject.briar.api.android.LockManager.EXTRA_PID;
 
 public class BriarService extends Service {
 
@@ -120,11 +123,17 @@ public class BriarService extends Service {
 			if (SDK_INT >= 26) {
 				NotificationManager nm = (NotificationManager)
 						requireNonNull(getSystemService(NOTIFICATION_SERVICE));
+				// Delete the old notification channel, which had
+				// IMPORTANCE_NONE and showed a badge
+				nm.deleteNotificationChannel(ONGOING_CHANNEL_OLD_ID);
+				// Use IMPORTANCE_LOW so the system doesn't show its own
+				// notification on API 26-27
 				NotificationChannel ongoingChannel = new NotificationChannel(
 						ONGOING_CHANNEL_ID,
 						getString(R.string.ongoing_notification_title),
-						IMPORTANCE_NONE);
+						IMPORTANCE_LOW);
 				ongoingChannel.setLockscreenVisibility(VISIBILITY_SECRET);
+				ongoingChannel.setShowBadge(false);
 				nm.createNotificationChannel(ongoingChannel);
 				NotificationChannel failureChannel = new NotificationChannel(
 						FAILURE_CHANNEL_ID,
@@ -170,6 +179,7 @@ public class BriarService extends Service {
 	@Override
 	protected void attachBaseContext(Context base) {
 		super.attachBaseContext(Localizer.getInstance().setLocale(base));
+		Localizer.getInstance().setLocale(this);
 	}
 
 	private void showStartupFailureNotification(StartResult result) {
@@ -202,7 +212,12 @@ public class BriarService extends Service {
 	@Override
 	public int onStartCommand(Intent intent, int flags, int startId) {
 		if (ACTION_LOCK.equals(intent.getAction())) {
-			lockManager.setLocked(true);
+			int pid = intent.getIntExtra(EXTRA_PID, -1);
+			if (pid == myPid()) lockManager.setLocked(true);
+			else if (LOG.isLoggable(WARNING)) {
+				LOG.warning("Tried to lock process " + pid + " but this is " +
+						myPid());
+			}
 		}
 		return START_NOT_STICKY; // Don't restart automatically if killed
 	}

briar-android/src/main/java/org/briarproject/briar/android/Localizer.java

@@ -68,7 +68,21 @@ public class Localizer {
 			return new Locale(tag);
 	}
 
-	// Returns the localized version of context
+	/*
+	 * Apply localization to the specified context.
+	 *
+	 * It updates the configuration of the context's resources object but can
+	 * also return a new context derived from the context parameter. Hence
+	 * make sure to work with the return value of this method instead of
+	 * the context you passed as a parameter.
+	 *
+	 * This method also has side-effects as it calls Locale#setDefault().
+	 *
+	 * When using this in attachBaseContext() of Application, Service or
+	 * Activity subclasses, it is important to not only apply this method to the
+	 * base Context parameter received in that method, but also apply it on the
+	 * class itself which also extends Context.
+	 */
 	public Context setLocale(Context context) {
 		Resources res = context.getResources();
 		Configuration conf = res.getConfiguration();
@@ -82,7 +96,7 @@ public class Localizer {
 		Locale.setDefault(locale);
 		if (SDK_INT >= 17) {
 			conf.setLocale(locale);
-			context.createConfigurationContext(conf);
+			context = context.createConfigurationContext(conf);
 		} else
 			conf.locale = locale;
 		//noinspection deprecation

briar-android/src/main/java/org/briarproject/briar/android/account/DozeFragment.java

@@ -33,7 +33,6 @@ public class DozeFragment extends SetupFragment
 	private DozeView dozeView;
 	private HuaweiView huaweiView;
 	private Button next;
-	private ProgressBar progressBar;
 	private boolean secondAttempt = false;
 
 	public static DozeFragment newInstance() {
@@ -58,11 +57,19 @@ public class DozeFragment extends SetupFragment
 		huaweiView = v.findViewById(R.id.huaweiView);
 		huaweiView.setOnCheckedChangedListener(this);
 		next = v.findViewById(R.id.next);
-		progressBar = v.findViewById(R.id.progress);
+		ProgressBar progressBar = v.findViewById(R.id.progress);
 
 		dozeView.setOnButtonClickListener(this::askForDozeWhitelisting);
 		next.setOnClickListener(this);
 
+		viewModel.getIsCreatingAccount()
+				.observe(getViewLifecycleOwner(), isCreatingAccount -> {
+					if (isCreatingAccount) {
+						next.setVisibility(INVISIBLE);
+						progressBar.setVisibility(VISIBLE);
+					}
+				});
+
 		return v;
 	}
 
@@ -104,15 +111,6 @@ public class DozeFragment extends SetupFragment
 
 	@Override
 	public void onClick(View view) {
-		setNextClicked();
 		viewModel.dozeExceptionConfirmed();
 	}
-
-	@Override
-	void setNextClicked() {
-		super.setNextClicked();
-
-		next.setVisibility(INVISIBLE);
-		progressBar.setVisibility(VISIBLE);
-	}
 }

briar-android/src/main/java/org/briarproject/briar/android/account/LockManagerImpl.java

@@ -32,8 +32,10 @@ import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
 import static android.app.AlarmManager.ELAPSED_REALTIME;
+import static android.app.PendingIntent.FLAG_UPDATE_CURRENT;
 import static android.app.PendingIntent.getService;
 import static android.content.Context.ALARM_SERVICE;
+import static android.os.Process.myPid;
 import static android.os.SystemClock.elapsedRealtime;
 import static java.util.concurrent.TimeUnit.MINUTES;
 import static java.util.logging.Level.WARNING;
@@ -75,23 +77,25 @@ public class LockManagerImpl implements LockManager, Service, EventListener {
 	LockManagerImpl(Application app, SettingsManager settingsManager,
 			AndroidNotificationManager notificationManager,
 			@DatabaseExecutor Executor dbExecutor) {
-		this.appContext = app.getApplicationContext();
+		appContext = app.getApplicationContext();
 		this.settingsManager = settingsManager;
 		this.notificationManager = notificationManager;
 		this.dbExecutor = dbExecutor;
-		this.alarmManager =
+		alarmManager =
 				(AlarmManager) appContext.getSystemService(ALARM_SERVICE);
 		Intent i =
 				new Intent(ACTION_LOCK, null, appContext, BriarService.class);
-		this.lockIntent = getService(appContext, 0, i, 0);
-		this.timeoutNever = Integer.valueOf(
+		i.putExtra(EXTRA_PID, myPid());
+		// When not using FLAG_UPDATE_CURRENT, the intent might have no extras
+		lockIntent = getService(appContext, 0, i, FLAG_UPDATE_CURRENT);
+		timeoutNever = Integer.parseInt(
 				appContext.getString(R.string.pref_lock_timeout_value_never));
-		this.timeoutDefault = Integer.valueOf(
+		timeoutDefault = Integer.parseInt(
 				appContext.getString(R.string.pref_lock_timeout_value_default));
-		this.timeoutMinutes = timeoutNever;
+		timeoutMinutes = timeoutNever;
 
 		// setting this in the constructor makes #getValue() @NonNull
-		this.lockable.setValue(false);
+		lockable.setValue(false);
 	}
 
 	@Override
@@ -148,7 +152,7 @@ public class LockManagerImpl implements LockManager, Service, EventListener {
 		boolean oldValue = lockable.getValue();
 		boolean newValue = hasScreenLock(appContext) && lockableSetting;
 		if (oldValue != newValue) {
-			this.lockable.setValue(newValue);
+			lockable.setValue(newValue);
 		}
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/account/SetPasswordFragment.java

@@ -38,7 +38,6 @@ public class SetPasswordFragment extends SetupFragment {
 	private TextInputEditText passwordConfirmation;
 	private StrengthMeter strengthMeter;
 	private Button nextButton;
-	private ProgressBar progressBar;
 
 	public static SetPasswordFragment newInstance() {
 		return new SetPasswordFragment();
@@ -64,7 +63,7 @@ public class SetPasswordFragment extends SetupFragment {
 				v.findViewById(R.id.password_confirm_wrapper);
 		passwordConfirmation = v.findViewById(R.id.password_confirm);
 		nextButton = v.findViewById(R.id.next);
-		progressBar = v.findViewById(R.id.progress);
+		ProgressBar progressBar = v.findViewById(R.id.progress);
 
 		passwordEntry.addTextChangedListener(this);
 		passwordConfirmation.addTextChangedListener(this);
@@ -75,6 +74,17 @@ public class SetPasswordFragment extends SetupFragment {
 			passwordConfirmation.setImeOptions(IME_ACTION_DONE);
 		}
 
+		viewModel.getIsCreatingAccount()
+				.observe(getViewLifecycleOwner(), isCreatingAccount -> {
+					if (isCreatingAccount) {
+						nextButton.setVisibility(INVISIBLE);
+						progressBar.setVisibility(VISIBLE);
+						// this also avoids the keyboard popping up
+						passwordEntry.setFocusable(false);
+						passwordConfirmation.setFocusable(false);
+					}
+				});
+
 		return v;
 	}
 
@@ -116,20 +126,6 @@ public class SetPasswordFragment extends SetupFragment {
 		IBinder token = passwordEntry.getWindowToken();
 		Object o = getContext().getSystemService(INPUT_METHOD_SERVICE);
 		((InputMethodManager) o).hideSoftInputFromWindow(token, 0);
-
-		setNextClicked();
 		viewModel.setPassword(passwordEntry.getText().toString());
 	}
-
-	@Override
-	void setNextClicked() {
-		super.setNextClicked();
-
-		passwordEntry.setFocusable(false);
-		passwordConfirmation.setFocusable(false);
-		if (!viewModel.needToShowDozeFragment()) {
-			nextButton.setVisibility(INVISIBLE);
-			progressBar.setVisibility(VISIBLE);
-		}
-	}
 }

briar-android/src/main/java/org/briarproject/briar/android/account/SetupFragment.java

@@ -7,7 +7,6 @@ import android.view.KeyEvent;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
-import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.TextView;
 import android.widget.TextView.OnEditorActionListener;
@@ -19,8 +18,6 @@ import org.briarproject.briar.android.fragment.BaseFragment;
 
 import javax.inject.Inject;
 
-import androidx.annotation.CallSuper;
-import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.lifecycle.ViewModelProvider;
 
@@ -35,7 +32,6 @@ abstract class SetupFragment extends BaseFragment implements TextWatcher,
 		OnEditorActionListener, OnClickListener {
 
 	private final static String STATE_KEY_CLICKED = "setupFragmentClicked";
-	private boolean clicked = false;
 
 	@Inject
 	ViewModelProvider.Factory viewModelFactory;
@@ -48,27 +44,6 @@ abstract class SetupFragment extends BaseFragment implements TextWatcher,
 				.get(SetupViewModel.class);
 	}
 
-	@Override
-	public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
-		if (savedInstanceState != null) {
-			clicked = savedInstanceState.getBoolean(STATE_KEY_CLICKED);
-		}
-		if (clicked) {
-			setNextClicked();
-		}
-	}
-
-	@Override
-	public void onSaveInstanceState(@NonNull Bundle outState) {
-		super.onSaveInstanceState(outState);
-		outState.putBoolean(STATE_KEY_CLICKED, clicked);
-	}
-
-	@CallSuper
-	void setNextClicked() {
-		this.clicked = true;
-	}
-
 	@Override
 	public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
 		inflater.inflate(R.menu.help_action, menu);
@@ -114,5 +89,4 @@ abstract class SetupFragment extends BaseFragment implements TextWatcher,
 	public void afterTextChanged(Editable editable) {
 		// noop
 	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/account/SetupViewModel.java

@@ -17,6 +17,8 @@ import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
 import androidx.lifecycle.AndroidViewModel;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
 
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.briar.android.account.SetupViewModel.State.AUTHOR_NAME;
@@ -36,6 +38,8 @@ class SetupViewModel extends AndroidViewModel {
 	@Nullable
 	private String authorName, password;
 	private final MutableLiveEvent<State> state = new MutableLiveEvent<>();
+	private final MutableLiveData<Boolean> isCreatingAccount =
+			new MutableLiveData<>(false);
 
 	private final AccountManager accountManager;
 	private final Executor ioExecutor;
@@ -67,6 +71,10 @@ class SetupViewModel extends AndroidViewModel {
 		return state;
 	}
 
+	LiveData<Boolean> getIsCreatingAccount() {
+		return isCreatingAccount;
+	}
+
 	void setAuthorName(String authorName) {
 		this.authorName = authorName;
 		state.setEvent(SET_PASSWORD);
@@ -97,6 +105,7 @@ class SetupViewModel extends AndroidViewModel {
 	private void createAccount() {
 		if (authorName == null) throw new IllegalStateException();
 		if (password == null) throw new IllegalStateException();
+		isCreatingAccount.setValue(true);
 		ioExecutor.execute(() -> {
 			if (accountManager.createAccount(authorName, password)) {
 				LOG.info("Created account");

briar-android/src/main/java/org/briarproject/briar/android/account/UnlockActivity.java

@@ -77,7 +77,7 @@ public class UnlockActivity extends BaseActivity {
 
 	@Override
 	protected void onActivityResult(int requestCode, int resultCode,
-			Intent data) {
+			@Nullable Intent data) {
 		super.onActivityResult(requestCode, resultCode, data);
 		if (requestCode == REQUEST_KEYGUARD_UNLOCK) {
 			if (resultCode == RESULT_OK) unlock();

briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityComponent.java

@@ -11,10 +11,8 @@ import org.briarproject.briar.android.account.SetupActivity;
 import org.briarproject.briar.android.account.UnlockActivity;
 import org.briarproject.briar.android.blog.BlogActivity;
 import org.briarproject.briar.android.blog.BlogFragment;
-import org.briarproject.briar.android.blog.BlogModule;
 import org.briarproject.briar.android.blog.BlogPostFragment;
 import org.briarproject.briar.android.blog.FeedFragment;
-import org.briarproject.briar.android.blog.FeedPostFragment;
 import org.briarproject.briar.android.blog.ReblogActivity;
 import org.briarproject.briar.android.blog.ReblogFragment;
 import org.briarproject.briar.android.blog.RssFeedImportActivity;
@@ -85,7 +83,6 @@ import dagger.Component;
 @ActivityScope
 @Component(modules = {
 		ActivityModule.class,
-		BlogModule.class,
 		CreateGroupModule.class,
 		GroupInvitationModule.class,
 		GroupMemberModule.class,
@@ -152,8 +149,6 @@ public interface ActivityComponent {
 
 	void inject(BlogPostFragment fragment);
 
-	void inject(FeedPostFragment fragment);
-
 	void inject(ReblogFragment fragment);
 
 	void inject(ReblogActivity activity);

briar-android/src/main/java/org/briarproject/briar/android/activity/BaseActivity.java

@@ -109,6 +109,7 @@ public abstract class BaseActivity extends AppCompatActivity
 	protected void attachBaseContext(Context base) {
 		super.attachBaseContext(
 				Localizer.getInstance().setLocale(base));
+		Localizer.getInstance().setLocale(this);
 	}
 
 	public ActivityComponent getActivityComponent() {

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentRetrieverImpl.java

@@ -28,9 +28,12 @@ import javax.inject.Inject;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
+import static java.util.Arrays.asList;
 import static java.util.Objects.requireNonNull;
+import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.AndroidUtils.getSupportedImageContentTypes;
 import static org.briarproject.bramble.util.IoUtils.tryToClose;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.android.attachment.AttachmentItem.State.AVAILABLE;
@@ -86,7 +89,17 @@ class AttachmentRetrieverImpl implements AttachmentRetriever {
 		List<AttachmentHeader> headers = messageHeader.getAttachmentHeaders();
 		List<LiveData<AttachmentItem>> items = new ArrayList<>(headers.size());
 		boolean needsSize = headers.size() == 1;
+		List<String> supported = asList(getSupportedImageContentTypes());
 		for (AttachmentHeader h : headers) {
+			// Fail early if we don't support the content type
+			if (!supported.contains(h.getContentType())) {
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("Unsupported content type " + h.getContentType());
+				}
+				AttachmentItem item = new AttachmentItem(h, "", ERROR);
+				items.add(new MutableLiveData<>(item));
+				continue;
+			}
 			// try cache for existing item live data
 			MutableLiveData<AttachmentItem> liveData =
 					itemsWithSize.get(h.getMessageId());

briar-android/src/main/java/org/briarproject/briar/android/blog/BaseController.java

@@ -1,48 +0,0 @@
-package org.briarproject.briar.android.blog;
-
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.android.controller.handler.ExceptionHandler;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.api.blog.BlogPostHeader;
-
-import java.util.Collection;
-
-import javax.annotation.Nullable;
-
-import androidx.annotation.UiThread;
-
-@NotNullByDefault
-interface BaseController {
-
-	@UiThread
-	void onStart();
-
-	@UiThread
-	void onStop();
-
-	void loadBlogPosts(GroupId g,
-			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);
-
-	void loadBlogPost(BlogPostHeader header,
-			ResultExceptionHandler<BlogPostItem, DbException> handler);
-
-	void loadBlogPost(GroupId g, MessageId m,
-			ResultExceptionHandler<BlogPostItem, DbException> handler);
-
-	void repeatPost(BlogPostItem item, @Nullable String comment,
-			ExceptionHandler<DbException> handler);
-
-	@NotNullByDefault
-	interface BlogListener {
-
-		@UiThread
-		void onBlogPostAdded(BlogPostHeader header, boolean local);
-
-		@UiThread
-		void onBlogRemoved();
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/blog/BaseControllerImpl.java

@@ -1,209 +0,0 @@
-package org.briarproject.briar.android.blog;
-
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.event.EventListener;
-import org.briarproject.bramble.api.identity.IdentityManager;
-import org.briarproject.bramble.api.identity.LocalAuthor;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.android.controller.DbControllerImpl;
-import org.briarproject.briar.android.controller.handler.ExceptionHandler;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.blog.Blog;
-import org.briarproject.briar.api.blog.BlogCommentHeader;
-import org.briarproject.briar.api.blog.BlogManager;
-import org.briarproject.briar.api.blog.BlogPostHeader;
-import org.briarproject.briar.util.HtmlUtils;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-
-import androidx.annotation.CallSuper;
-
-import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logDuration;
-import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.bramble.util.LogUtils.now;
-import static org.briarproject.briar.util.HtmlUtils.ARTICLE;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-abstract class BaseControllerImpl extends DbControllerImpl
-		implements BaseController, EventListener {
-
-	private static final Logger LOG =
-			Logger.getLogger(BaseControllerImpl.class.getName());
-
-	protected final EventBus eventBus;
-	protected final AndroidNotificationManager notificationManager;
-	protected final IdentityManager identityManager;
-	protected final BlogManager blogManager;
-
-	private final Map<MessageId, String> textCache = new ConcurrentHashMap<>();
-	private final Map<MessageId, BlogPostHeader> headerCache =
-			new ConcurrentHashMap<>();
-
-	BaseControllerImpl(@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager, EventBus eventBus,
-			AndroidNotificationManager notificationManager,
-			IdentityManager identityManager, BlogManager blogManager) {
-		super(dbExecutor, lifecycleManager);
-		this.eventBus = eventBus;
-		this.notificationManager = notificationManager;
-		this.identityManager = identityManager;
-		this.blogManager = blogManager;
-	}
-
-	@Override
-	@CallSuper
-	public void onStart() {
-		eventBus.addListener(this);
-	}
-
-	@Override
-	@CallSuper
-	public void onStop() {
-		eventBus.removeListener(this);
-	}
-
-	@Override
-	public void loadBlogPosts(GroupId groupId,
-			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				Collection<BlogPostItem> items = loadItems(groupId);
-				handler.onResult(items);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	Collection<BlogPostItem> loadItems(GroupId groupId) throws DbException {
-		long start = now();
-		Collection<BlogPostHeader> headers =
-				blogManager.getPostHeaders(groupId);
-		logDuration(LOG, "Loading headers", start);
-		Collection<BlogPostItem> items = new ArrayList<>(headers.size());
-		start = now();
-		for (BlogPostHeader h : headers) {
-			headerCache.put(h.getId(), h);
-			BlogPostItem item = getItem(h);
-			items.add(item);
-		}
-		logDuration(LOG, "Loading bodies", start);
-		return items;
-	}
-
-	@Override
-	public void loadBlogPost(BlogPostHeader header,
-			ResultExceptionHandler<BlogPostItem, DbException> handler) {
-
-		String text = textCache.get(header.getId());
-		if (text != null) {
-			LOG.info("Loaded text from cache");
-			handler.onResult(new BlogPostItem(header, text));
-			return;
-		}
-		runOnDbThread(() -> {
-			try {
-				long start = now();
-				BlogPostItem item = getItem(header);
-				logDuration(LOG, "Loading text", start);
-				handler.onResult(item);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	@Override
-	public void loadBlogPost(GroupId g, MessageId m,
-			ResultExceptionHandler<BlogPostItem, DbException> handler) {
-
-		BlogPostHeader header = headerCache.get(m);
-		if (header != null) {
-			LOG.info("Loaded header from cache");
-			loadBlogPost(header, handler);
-			return;
-		}
-		runOnDbThread(() -> {
-			try {
-				long start = now();
-				BlogPostHeader header1 = getPostHeader(g, m);
-				BlogPostItem item = getItem(header1);
-				logDuration(LOG, "Loading post", start);
-				handler.onResult(item);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	@Override
-	public void repeatPost(BlogPostItem item, @Nullable String comment,
-			ExceptionHandler<DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				LocalAuthor a = identityManager.getLocalAuthor();
-				Blog b = blogManager.getPersonalBlog(a);
-				BlogPostHeader h = item.getHeader();
-				blogManager.addLocalComment(a, b.getId(), comment, h);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	private BlogPostHeader getPostHeader(GroupId g, MessageId m)
-			throws DbException {
-		BlogPostHeader header = headerCache.get(m);
-		if (header == null) {
-			header = blogManager.getPostHeader(g, m);
-			headerCache.put(m, header);
-		}
-		return header;
-	}
-
-	@DatabaseExecutor
-	private BlogPostItem getItem(BlogPostHeader h) throws DbException {
-		String text;
-		if (h instanceof BlogCommentHeader) {
-			BlogCommentHeader c = (BlogCommentHeader) h;
-			BlogCommentItem item = new BlogCommentItem(c);
-			text = getPostText(item.getPostHeader().getId());
-			item.setText(text);
-			return item;
-		} else {
-			text = getPostText(h.getId());
-			return new BlogPostItem(h, text);
-		}
-	}
-
-	@DatabaseExecutor
-	private String getPostText(MessageId m) throws DbException {
-		String text = textCache.get(m);
-		if (text == null) {
-			text = HtmlUtils.clean(blogManager.getPostText(m), ARTICLE);
-			textCache.put(m, text);
-		}
-		return text;
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/blog/BasePostFragment.java

@@ -1,121 +0,0 @@
-package org.briarproject.briar.android.blog;
-
-import android.content.Intent;
-import android.os.Bundle;
-import android.os.Handler;
-import android.os.Looper;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.ProgressBar;
-
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.R;
-import org.briarproject.briar.android.fragment.BaseFragment;
-
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-
-import androidx.annotation.CallSuper;
-import androidx.annotation.UiThread;
-
-import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
-import static android.view.View.INVISIBLE;
-import static android.view.View.VISIBLE;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.util.UiUtils.MIN_DATE_RESOLUTION;
-
-@UiThread
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-abstract class BasePostFragment extends BaseFragment {
-
-	static final String POST_ID = "briar.POST_ID";
-
-	private static final Logger LOG =
-			getLogger(BasePostFragment.class.getName());
-
-	private final Handler handler = new Handler(Looper.getMainLooper());
-
-	protected MessageId postId;
-	private ProgressBar progressBar;
-	private BlogPostViewHolder ui;
-	private BlogPostItem post;
-	private Runnable refresher;
-
-	@CallSuper
-	@Nullable
-	@Override
-	public View onCreateView(LayoutInflater inflater,
-			@Nullable ViewGroup container,
-			@Nullable Bundle savedInstanceState) {
-		// retrieve MessageId of blog post from arguments
-		byte[] p = requireArguments().getByteArray(POST_ID);
-		if (p == null) throw new IllegalStateException("No post ID in args");
-		postId = new MessageId(p);
-
-		View view = inflater.inflate(R.layout.fragment_blog_post, container,
-				false);
-		progressBar = view.findViewById(R.id.progressBar);
-		progressBar.setVisibility(VISIBLE);
-		ui = new BlogPostViewHolder(view, true, new OnBlogPostClickListener() {
-			@Override
-			public void onBlogPostClick(BlogPostItem post) {
-				// We're already there
-			}
-
-			@Override
-			public void onAuthorClick(BlogPostItem post) {
-				if (getContext() == null) return;
-				Intent i = new Intent(getContext(), BlogActivity.class);
-				i.putExtra(GROUP_ID, post.getGroupId().getBytes());
-				i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-				getContext().startActivity(i);
-			}
-		}, getFragmentManager());
-		return view;
-	}
-
-	@CallSuper
-	@Override
-	public void onStart() {
-		super.onStart();
-		startPeriodicUpdate();
-	}
-
-	@CallSuper
-	@Override
-	public void onStop() {
-		super.onStop();
-		stopPeriodicUpdate();
-	}
-
-	@UiThread
-	protected void onBlogPostLoaded(BlogPostItem post) {
-		progressBar.setVisibility(INVISIBLE);
-		this.post = post;
-		ui.bindItem(post);
-	}
-
-	private void startPeriodicUpdate() {
-		refresher = () -> {
-			LOG.info("Updating Content...");
-			ui.updateDate(post.getTimestamp());
-			handler.postDelayed(refresher, MIN_DATE_RESOLUTION);
-		};
-		LOG.info("Adding Handler Callback");
-		handler.postDelayed(refresher, MIN_DATE_RESOLUTION);
-	}
-
-	private void stopPeriodicUpdate() {
-		if (refresher != null) {
-			LOG.info("Removing Handler Callback");
-			handler.removeCallbacks(refresher);
-		}
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/blog/BaseViewModel.java

@@ -0,0 +1,204 @@
+package org.briarproject.briar.android.blog;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.identity.IdentityManager;
+import org.briarproject.bramble.api.identity.LocalAuthor;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
+import org.briarproject.briar.android.viewmodel.LiveResult;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.blog.Blog;
+import org.briarproject.briar.api.blog.BlogCommentHeader;
+import org.briarproject.briar.api.blog.BlogManager;
+import org.briarproject.briar.api.blog.BlogPostHeader;
+import org.briarproject.briar.util.HtmlUtils;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+import androidx.annotation.UiThread;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.LogUtils.now;
+import static org.briarproject.briar.util.HtmlUtils.ARTICLE;
+
+@NotNullByDefault
+abstract class BaseViewModel extends DbViewModel implements EventListener {
+
+	private static final Logger LOG = getLogger(BaseViewModel.class.getName());
+
+	private final EventBus eventBus;
+	protected final IdentityManager identityManager;
+	protected final AndroidNotificationManager notificationManager;
+	protected final BlogManager blogManager;
+
+	protected final MutableLiveData<LiveResult<ListUpdate>> blogPosts =
+			new MutableLiveData<>();
+
+	BaseViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			EventBus eventBus,
+			IdentityManager identityManager,
+			AndroidNotificationManager notificationManager,
+			BlogManager blogManager) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
+		this.eventBus = eventBus;
+		this.identityManager = identityManager;
+		this.notificationManager = notificationManager;
+		this.blogManager = blogManager;
+		eventBus.addListener(this);
+	}
+
+	@Override
+	protected void onCleared() {
+		super.onCleared();
+		eventBus.removeListener(this);
+	}
+
+	@DatabaseExecutor
+	protected List<BlogPostItem> loadBlogPosts(Transaction txn, GroupId groupId)
+			throws DbException {
+		long start = now();
+		List<BlogPostHeader> headers =
+				blogManager.getPostHeaders(txn, groupId);
+		logDuration(LOG, "Loading headers", start);
+		List<BlogPostItem> items = new ArrayList<>(headers.size());
+		start = now();
+		for (BlogPostHeader h : headers) {
+			BlogPostItem item = getItem(txn, h);
+			items.add(item);
+		}
+		logDuration(LOG, "Loading bodies", start);
+		return items;
+	}
+
+	@DatabaseExecutor
+	protected BlogPostItem getItem(Transaction txn, BlogPostHeader h)
+			throws DbException {
+		String text;
+		if (h instanceof BlogCommentHeader) {
+			BlogCommentHeader c = (BlogCommentHeader) h;
+			BlogCommentItem item = new BlogCommentItem(c);
+			text = getPostText(txn, item.getPostHeader().getId());
+			item.setText(text);
+			return item;
+		} else {
+			text = getPostText(txn, h.getId());
+			return new BlogPostItem(h, text);
+		}
+	}
+
+	@DatabaseExecutor
+	private String getPostText(Transaction txn, MessageId m)
+			throws DbException {
+		return HtmlUtils.clean(blogManager.getPostText(txn, m), ARTICLE);
+	}
+
+	LiveData<LiveResult<BlogPostItem>> loadBlogPost(GroupId g, MessageId m) {
+		MutableLiveData<LiveResult<BlogPostItem>> result =
+				new MutableLiveData<>();
+		runOnDbThread(true, txn -> {
+			long start = now();
+			BlogPostHeader header = blogManager.getPostHeader(txn, g, m);
+			BlogPostItem item = getItem(txn, header);
+			logDuration(LOG, "Loading post", start);
+			result.postValue(new LiveResult<>(item));
+		}, e -> {
+			logException(LOG, WARNING, e);
+			result.postValue(new LiveResult<>(e));
+		});
+		return result;
+	}
+
+	protected void onBlogPostAdded(BlogPostHeader header, boolean local) {
+		runOnDbThread(true, txn -> {
+			BlogPostItem item = getItem(txn, header);
+			txn.attach(() -> onBlogPostItemAdded(item, local));
+		}, this::handleException);
+	}
+
+	@UiThread
+	private void onBlogPostItemAdded(BlogPostItem item, boolean local) {
+		List<BlogPostItem> items = addListItem(getBlogPostItems(), item);
+		if (items != null) {
+			Collections.sort(items);
+			blogPosts.setValue(new LiveResult<>(new ListUpdate(local, items)));
+		}
+	}
+
+	void repeatPost(BlogPostItem item, @Nullable String comment) {
+		runOnDbThread(() -> {
+			try {
+				LocalAuthor a = identityManager.getLocalAuthor();
+				Blog b = blogManager.getPersonalBlog(a);
+				BlogPostHeader h = item.getHeader();
+				blogManager.addLocalComment(a, b.getId(), comment, h);
+			} catch (DbException e) {
+				handleException(e);
+			}
+		});
+	}
+
+	LiveData<LiveResult<ListUpdate>> getBlogPosts() {
+		return blogPosts;
+	}
+
+	@UiThread
+	@Nullable
+	protected List<BlogPostItem> getBlogPostItems() {
+		LiveResult<ListUpdate> value = blogPosts.getValue();
+		if (value == null) return null;
+		ListUpdate result = value.getResultOrNull();
+		return result == null ? null : result.getItems();
+	}
+
+	static class ListUpdate {
+
+		@Nullable
+		private final Boolean postAddedWasLocal;
+		private final List<BlogPostItem> items;
+
+		ListUpdate(@Nullable Boolean postAddedWasLocal,
+				List<BlogPostItem> items) {
+			this.postAddedWasLocal = postAddedWasLocal;
+			this.items = items;
+		}
+
+		/**
+		 * @return null when not a single post was added with this update.
+		 * true when a single post was added locally and false if remotely.
+		 */
+		@Nullable
+		public Boolean getPostAddedWasLocal() {
+			return postAddedWasLocal;
+		}
+
+		public List<BlogPostItem> getItems() {
+			return items;
+		}
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogActivity.java

@@ -16,6 +16,9 @@ import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.appcompat.widget.Toolbar;
+import androidx.lifecycle.ViewModelProvider;
+
+import static java.util.Objects.requireNonNull;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -23,7 +26,16 @@ public class BlogActivity extends BriarActivity
 		implements BaseFragmentListener {
 
 	@Inject
-	BlogController blogController;
+	ViewModelProvider.Factory viewModelFactory;
+
+	private BlogViewModel viewModel;
+
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(BlogViewModel.class);
+	}
 
 	@Override
 	public void onCreate(@Nullable Bundle state) {
@@ -31,32 +43,36 @@ public class BlogActivity extends BriarActivity
 
 		// GroupId from Intent
 		Intent i = getIntent();
-		byte[] b = i.getByteArrayExtra(GROUP_ID);
-		if (b == null) throw new IllegalStateException("No group ID in intent");
-		GroupId groupId = new GroupId(b);
-		blogController.setGroupId(groupId);
+		GroupId groupId =
+				new GroupId(requireNonNull(i.getByteArrayExtra(GROUP_ID)));
+		viewModel.setGroupId(groupId);
 
 		setContentView(R.layout.activity_fragment_container_toolbar);
 		Toolbar toolbar = setUpCustomToolbar(false);
 
 		// Open Sharing Status on Toolbar click
-		if (toolbar != null) {
-			toolbar.setOnClickListener(v -> {
-				Intent i1 = new Intent(BlogActivity.this,
-						BlogSharingStatusActivity.class);
-				i1.putExtra(GROUP_ID, groupId.getBytes());
-				startActivity(i1);
-			});
-		}
+		toolbar.setOnClickListener(v -> {
+			Intent i1 = new Intent(BlogActivity.this,
+					BlogSharingStatusActivity.class);
+			i1.putExtra(GROUP_ID, groupId.getBytes());
+			startActivity(i1);
+		});
+
+		viewModel.getBlog().observe(this, blog ->
+				setTitle(blog.getBlog().getAuthor().getName())
+		);
+		viewModel.getSharingInfo().observe(this, info ->
+				setToolbarSubTitle(info.total, info.online)
+		);
 
 		if (state == null) {
 			showInitialFragment(BlogFragment.newInstance(groupId));
 		}
 	}
 
-	@Override
-	public void injectActivity(ActivityComponent component) {
-		component.inject(this);
+	private void setToolbarSubTitle(int total, int online) {
+		requireNonNull(getSupportActionBar())
+				.setSubtitle(getString(R.string.shared_with, total, online));
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogCommentItem.java

@@ -8,7 +8,9 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 
-// This class is not thread-safe
+import javax.annotation.concurrent.NotThreadSafe;
+
+@NotThreadSafe
 class BlogCommentItem extends BlogPostItem {
 
 	private static final BlogCommentComparator COMPARATOR =

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogController.java

@@ -1,46 +0,0 @@
-package org.briarproject.briar.android.blog;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-
-import java.util.Collection;
-
-import androidx.annotation.UiThread;
-
-@NotNullByDefault
-public interface BlogController extends BaseController {
-
-	void setGroupId(GroupId g);
-
-	@UiThread
-	void setBlogSharingListener(BlogSharingListener listener);
-
-	@UiThread
-	void unsetBlogSharingListener(BlogSharingListener listener);
-
-	void loadBlogPosts(
-			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);
-
-	void loadBlogPost(MessageId m,
-			ResultExceptionHandler<BlogPostItem, DbException> handler);
-
-	void loadBlog(ResultExceptionHandler<BlogItem, DbException> handler);
-
-	void deleteBlog(ResultExceptionHandler<Void, DbException> handler);
-
-	void loadSharingContacts(
-			ResultExceptionHandler<Collection<ContactId>, DbException> handler);
-
-	interface BlogSharingListener extends BlogListener {
-		@UiThread
-		void onBlogInvitationAccepted(ContactId c);
-
-		@UiThread
-		void onBlogLeft(ContactId c);
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogFragment.java

@@ -1,9 +1,7 @@
 package org.briarproject.briar.android.blog;
 
-import android.content.DialogInterface;
 import android.content.Intent;
 import android.os.Bundle;
-import android.os.Parcelable;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -12,33 +10,25 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.Toast;
 
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.activity.BriarActivity;
-import org.briarproject.briar.android.blog.BlogController.BlogSharingListener;
-import org.briarproject.briar.android.controller.SharingController;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
+import org.briarproject.briar.android.blog.BaseViewModel.ListUpdate;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.sharing.BlogSharingStatusActivity;
 import org.briarproject.briar.android.sharing.ShareBlogActivity;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
-import org.briarproject.briar.api.blog.BlogPostHeader;
-
-import java.util.Collection;
+import org.briarproject.briar.android.widget.LinkDialogFragment;
 
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
-import androidx.appcompat.app.ActionBar;
 import androidx.appcompat.app.AlertDialog;
+import androidx.lifecycle.ViewModelProvider;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView.LayoutManager;
 
@@ -49,30 +39,22 @@ import static com.google.android.material.snackbar.Snackbar.LENGTH_LONG;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_SHARE_BLOG;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
-import static org.briarproject.briar.android.controller.SharingController.SharingListener;
 
 @UiThread
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class BlogFragment extends BaseFragment
-		implements BlogSharingListener, SharingListener,
-		OnBlogPostClickListener {
+		implements OnBlogPostClickListener {
 
 	private final static String TAG = BlogFragment.class.getName();
 
 	@Inject
-	BlogController blogController;
-	@Inject
-	SharingController sharingController;
-	@Nullable
-	private Parcelable layoutManagerState;
+	ViewModelProvider.Factory viewModelFactory;
 
 	private GroupId groupId;
-	private BlogPostAdapter adapter;
-	private LayoutManager layoutManager;
+	private BlogViewModel viewModel;
+	private final BlogPostAdapter adapter = new BlogPostAdapter(false, this);
 	private BriarRecyclerView list;
-	private MenuItem writeButton, deleteButton;
-	private boolean isMyBlog = false, canDeleteBlog = false;
 
 	static BlogFragment newInstance(GroupId groupId) {
 		BlogFragment f = new BlogFragment();
@@ -87,8 +69,8 @@ public class BlogFragment extends BaseFragment
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
-		blogController.setBlogSharingListener(this);
-		sharingController.setSharingListener(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(BlogViewModel.class);
 	}
 
 	@Nullable
@@ -103,95 +85,75 @@ public class BlogFragment extends BaseFragment
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
-		adapter = new BlogPostAdapter(requireActivity(), this,
-				getFragmentManager());
 		list = v.findViewById(R.id.postList);
-		layoutManager = new LinearLayoutManager(getActivity());
+		LayoutManager layoutManager = new LinearLayoutManager(getActivity());
 		list.setLayoutManager(layoutManager);
 		list.setAdapter(adapter);
 		list.showProgressBar();
 		list.setEmptyText(getString(R.string.blogs_other_blog_empty_state));
 
-		if (savedInstanceState != null) {
-			layoutManagerState =
-					savedInstanceState.getParcelable("layoutManager");
-		}
-
+		viewModel.getBlogPosts().observe(getViewLifecycleOwner(), result ->
+				result.onError(this::handleException)
+						.onSuccess(this::onBlogPostsLoaded)
+		);
+		viewModel.getBlogRemoved().observe(getViewLifecycleOwner(), removed -> {
+			if (removed) finish();
+		});
 		return v;
 	}
 
 	@Override
 	public void onStart() {
 		super.onStart();
-		sharingController.onStart();
-		loadBlog();
-		loadSharedContacts();
-		loadBlogPosts(false);
+		viewModel.blockAndClearNotifications();
 		list.startPeriodicUpdate();
 	}
 
 	@Override
 	public void onStop() {
 		super.onStop();
-		sharingController.onStop();
+		viewModel.unblockNotifications();
 		list.stopPeriodicUpdate();
 	}
 
-	@Override
-	public void onDestroy() {
-		super.onDestroy();
-		blogController.unsetBlogSharingListener(this);
-		sharingController.unsetSharingListener(this);
-	}
-
-	@Override
-	public void onSaveInstanceState(Bundle outState) {
-		super.onSaveInstanceState(outState);
-		if (layoutManager != null) {
-			layoutManagerState = layoutManager.onSaveInstanceState();
-			outState.putParcelable("layoutManager", layoutManagerState);
-		}
-	}
-
 	@Override
 	public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
 		inflater.inflate(R.menu.blogs_blog_actions, menu);
-		writeButton = menu.findItem(R.id.action_write_blog_post);
-		if (isMyBlog) writeButton.setVisible(true);
-		deleteButton = menu.findItem(R.id.action_blog_delete);
-		if (canDeleteBlog) deleteButton.setEnabled(true);
-
+		MenuItem writeButton = menu.findItem(R.id.action_write_blog_post);
+		MenuItem deleteButton = menu.findItem(R.id.action_blog_delete);
+		viewModel.getBlog().observe(getViewLifecycleOwner(), blog -> {
+			if (blog.isOurs()) writeButton.setVisible(true);
+			if (blog.canBeRemoved()) deleteButton.setEnabled(true);
+		});
 		super.onCreateOptionsMenu(menu, inflater);
 	}
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		switch (item.getItemId()) {
-			case R.id.action_write_blog_post:
-				Intent i = new Intent(getActivity(),
-						WriteBlogPostActivity.class);
-				i.putExtra(GROUP_ID, groupId.getBytes());
-				startActivityForResult(i, REQUEST_WRITE_BLOG_POST);
-				return true;
-			case R.id.action_blog_share:
-				Intent i2 = new Intent(getActivity(), ShareBlogActivity.class);
-				i2.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-				i2.putExtra(GROUP_ID, groupId.getBytes());
-				startActivityForResult(i2, REQUEST_SHARE_BLOG);
-				return true;
-			case R.id.action_blog_sharing_status:
-				Intent i3 = new Intent(getActivity(),
-						BlogSharingStatusActivity.class);
-				i3.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-				i3.putExtra(GROUP_ID, groupId.getBytes());
-				startActivity(i3);
-				return true;
-			case R.id.action_blog_delete:
-				showDeleteDialog();
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
+		int itemId = item.getItemId();
+		if (itemId == R.id.action_write_blog_post) {
+			Intent i = new Intent(getActivity(), WriteBlogPostActivity.class);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivityForResult(i, REQUEST_WRITE_BLOG_POST);
+			return true;
+		} else if (itemId == R.id.action_blog_share) {
+			Intent i = new Intent(getActivity(), ShareBlogActivity.class);
+			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivityForResult(i, REQUEST_SHARE_BLOG);
+			return true;
+		} else if (itemId == R.id.action_blog_sharing_status) {
+			Intent i =
+					new Intent(getActivity(), BlogSharingStatusActivity.class);
+			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivity(i);
+			return true;
+		} else if (itemId == R.id.action_blog_delete) {
+			showDeleteDialog();
+			return true;
 		}
+		return super.onOptionsItemSelected(item);
 	}
 
 	@Override
@@ -201,7 +163,6 @@ public class BlogFragment extends BaseFragment
 
 		if (request == REQUEST_WRITE_BLOG_POST && result == RESULT_OK) {
 			displaySnackbar(R.string.blogs_blog_post_created, true);
-			loadBlogPosts(true);
 		} else if (request == REQUEST_SHARE_BLOG && result == RESULT_OK) {
 			displaySnackbar(R.string.blogs_sharing_snackbar, false);
 		}
@@ -212,35 +173,25 @@ public class BlogFragment extends BaseFragment
 		return TAG;
 	}
 
-	@Override
-	public void onBlogPostAdded(BlogPostHeader header, boolean local) {
-		blogController.loadBlogPost(header,
-				new UiResultExceptionHandler<BlogPostItem, DbException>(
-						this) {
-					@Override
-					public void onResultUi(BlogPostItem post) {
-						adapter.add(post);
-						if (local) {
-							list.scrollToPosition(0);
-							displaySnackbar(R.string.blogs_blog_post_created,
-									false);
-						} else {
-							displaySnackbar(R.string.blogs_blog_post_received,
-									true);
-						}
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				}
-		);
+	private void onBlogPostsLoaded(ListUpdate update) {
+		adapter.submitList(update.getItems(), () -> {
+			Boolean wasLocal = update.getPostAddedWasLocal();
+			if (wasLocal != null && wasLocal) {
+				list.scrollToPosition(0);
+				displaySnackbar(R.string.blogs_blog_post_created,
+						false);
+			} else if (wasLocal != null) {
+				displaySnackbar(R.string.blogs_blog_post_received,
+						true);
+			}
+			list.showData();
+		});
 	}
 
 	@Override
 	public void onBlogPostClick(BlogPostItem post) {
-		BlogPostFragment f = BlogPostFragment.newInstance(post.getId());
+		BlogPostFragment f =
+				BlogPostFragment.newInstance(groupId, post.getId(), false);
 		showNextFragment(f);
 	}
 
@@ -256,111 +207,10 @@ public class BlogFragment extends BaseFragment
 		getContext().startActivity(i);
 	}
 
-	private void loadBlogPosts(boolean reload) {
-		blogController.loadBlogPosts(
-				new UiResultExceptionHandler<Collection<BlogPostItem>,
-						DbException>(this) {
-					@Override
-					public void onResultUi(Collection<BlogPostItem> posts) {
-						if (posts.isEmpty()) {
-							list.showData();
-						} else {
-							adapter.addAll(posts);
-							if (reload || layoutManagerState == null) {
-								list.scrollToPosition(0);
-							} else {
-								layoutManager.onRestoreInstanceState(
-										layoutManagerState);
-							}
-						}
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
-	private void loadBlog() {
-		blogController.loadBlog(
-				new UiResultExceptionHandler<BlogItem, DbException>(this) {
-					@Override
-					public void onResultUi(BlogItem blog) {
-						setToolbarTitle(blog.getBlog().getAuthor());
-						if (blog.isOurs())
-							showWriteButton();
-						if (blog.canBeRemoved())
-							enableDeleteButton();
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
-	private void setToolbarTitle(Author a) {
-		getActivity().setTitle(a.getName());
-	}
-
-	private void loadSharedContacts() {
-		blogController.loadSharingContacts(
-				new UiResultExceptionHandler<Collection<ContactId>,
-						DbException>(this) {
-					@Override
-					public void onResultUi(Collection<ContactId> contacts) {
-						sharingController.addAll(contacts);
-						int online = sharingController.getOnlineCount();
-						setToolbarSubTitle(contacts.size(), online);
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
 	@Override
-	public void onBlogInvitationAccepted(ContactId c) {
-		sharingController.add(c);
-		setToolbarSubTitle(sharingController.getTotalCount(),
-				sharingController.getOnlineCount());
-	}
-
-	@Override
-	public void onBlogLeft(ContactId c) {
-		sharingController.remove(c);
-		setToolbarSubTitle(sharingController.getTotalCount(),
-				sharingController.getOnlineCount());
-	}
-
-	@Override
-	public void onSharingInfoUpdated(int total, int online) {
-		setToolbarSubTitle(total, online);
-	}
-
-	private void setToolbarSubTitle(int total, int online) {
-		ActionBar actionBar =
-				((BriarActivity) getActivity()).getSupportActionBar();
-		if (actionBar != null) {
-			actionBar.setSubtitle(
-					getString(R.string.shared_with, total, online));
-		}
-	}
-
-	private void showWriteButton() {
-		isMyBlog = true;
-		if (writeButton != null)
-			writeButton.setVisible(true);
-	}
-
-	private void enableDeleteButton() {
-		canDeleteBlog = true;
-		if (deleteButton != null)
-			deleteButton.setEnabled(true);
+	public void onLinkClick(String url) {
+		LinkDialogFragment f = LinkDialogFragment.newInstance(url);
+		f.show(getParentFragmentManager(), f.getUniqueTag());
 	}
 
 	private void displaySnackbar(int stringId, boolean scroll) {
@@ -373,38 +223,21 @@ public class BlogFragment extends BaseFragment
 	}
 
 	private void showDeleteDialog() {
-		DialogInterface.OnClickListener okListener =
-				(dialog, which) -> deleteBlog();
-		AlertDialog.Builder builder = new AlertDialog.Builder(getActivity(),
+		AlertDialog.Builder builder = new AlertDialog.Builder(requireContext(),
 				R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.blogs_remove_blog));
 		builder.setMessage(
 				getString(R.string.blogs_remove_blog_dialog_message));
 		builder.setPositiveButton(R.string.cancel, null);
-		builder.setNegativeButton(R.string.blogs_remove_blog_ok, okListener);
+		builder.setNegativeButton(R.string.blogs_remove_blog_ok,
+				(dialog, which) -> deleteBlog());
 		builder.show();
 	}
 
 	private void deleteBlog() {
-		blogController.deleteBlog(
-				new UiResultExceptionHandler<Void, DbException>(this) {
-					@Override
-					public void onResultUi(Void result) {
-						Toast.makeText(getActivity(),
-								R.string.blogs_blog_removed, LENGTH_SHORT)
-								.show();
-						finish();
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
-	@Override
-	public void onBlogRemoved() {
+		viewModel.deleteBlog();
+		Toast.makeText(getActivity(), R.string.blogs_blog_removed, LENGTH_SHORT)
+				.show();
 		finish();
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogModule.java

@@ -1,35 +1,23 @@
 package org.briarproject.briar.android.blog;
 
-import org.briarproject.briar.android.activity.ActivityScope;
-import org.briarproject.briar.android.activity.BaseActivity;
-import org.briarproject.briar.android.controller.SharingController;
-import org.briarproject.briar.android.controller.SharingControllerImpl;
+import org.briarproject.briar.android.viewmodel.ViewModelKey;
 
+import androidx.lifecycle.ViewModel;
+import dagger.Binds;
 import dagger.Module;
-import dagger.Provides;
+import dagger.multibindings.IntoMap;
 
 @Module
-public class BlogModule {
+public interface BlogModule {
 
-	@ActivityScope
-	@Provides
-	BlogController provideBlogController(BaseActivity activity,
-			BlogControllerImpl blogController) {
-		activity.addLifecycleController(blogController);
-		return blogController;
-	}
+	@Binds
+	@IntoMap
+	@ViewModelKey(FeedViewModel.class)
+	ViewModel bindFeedViewModel(FeedViewModel feedViewModel);
 
-	@ActivityScope
-	@Provides
-	FeedController provideFeedController(FeedControllerImpl feedController) {
-		return feedController;
-	}
-
-	@ActivityScope
-	@Provides
-	SharingController provideSharingController(
-			SharingControllerImpl sharingController) {
-		return sharingController;
-	}
+	@Binds
+	@IntoMap
+	@ViewModelKey(BlogViewModel.class)
+	ViewModel bindBlogViewModel(BlogViewModel blogViewModel);
 
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostAdapter.java

@@ -1,6 +1,5 @@
 package org.briarproject.briar.android.blog;
 
-import android.content.Context;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -8,52 +7,44 @@ import android.view.ViewGroup;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.util.BriarAdapter;
 
-import androidx.annotation.Nullable;
-import androidx.fragment.app.FragmentManager;
+import androidx.recyclerview.widget.DiffUtil;
+import androidx.recyclerview.widget.ListAdapter;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class BlogPostAdapter extends BriarAdapter<BlogPostItem, BlogPostViewHolder> {
+class BlogPostAdapter extends ListAdapter<BlogPostItem, BlogPostViewHolder> {
 
+	private final boolean authorClickable;
 	private final OnBlogPostClickListener listener;
-	@Nullable
-	private final FragmentManager fragmentManager;
 
-	BlogPostAdapter(Context ctx, OnBlogPostClickListener listener,
-			@Nullable FragmentManager fragmentManager) {
-		super(ctx, BlogPostItem.class);
+	BlogPostAdapter(boolean authorClickable, OnBlogPostClickListener listener) {
+		super(new DiffUtil.ItemCallback<BlogPostItem>() {
+			@Override
+			public boolean areItemsTheSame(BlogPostItem a, BlogPostItem b) {
+				return a.getId().equals(b.getId());
+			}
+
+			@Override
+			public boolean areContentsTheSame(BlogPostItem a, BlogPostItem b) {
+				return a.isRead() == b.isRead();
+			}
+		});
+		this.authorClickable = authorClickable;
 		this.listener = listener;
-		this.fragmentManager = fragmentManager;
 	}
 
 	@Override
 	public BlogPostViewHolder onCreateViewHolder(ViewGroup parent,
 			int viewType) {
-		View v = LayoutInflater.from(ctx).inflate(
+		View v = LayoutInflater.from(parent.getContext()).inflate(
 				R.layout.list_item_blog_post, parent, false);
-		return new BlogPostViewHolder(v, false, listener, fragmentManager);
+		return new BlogPostViewHolder(v, false, listener, authorClickable);
 	}
 
 	@Override
 	public void onBindViewHolder(BlogPostViewHolder ui, int position) {
-		ui.bindItem(getItemAt(position));
-	}
-
-	@Override
-	public int compare(BlogPostItem a, BlogPostItem b) {
-		return a.compareTo(b);
-	}
-
-	@Override
-	public boolean areContentsTheSame(BlogPostItem a, BlogPostItem b) {
-		return a.isRead() == b.isRead();
-	}
-
-	@Override
-	public boolean areItemsTheSame(BlogPostItem a, BlogPostItem b) {
-		return a.getId().equals(b.getId());
+		ui.bindItem(getItem(position));
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostFragment.java

@@ -1,76 +1,163 @@
 package org.briarproject.briar.android.blog;
 
+import android.content.Intent;
 import android.os.Bundle;
+import android.os.Handler;
+import android.os.Looper;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ProgressBar;
 
-import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.blog.BaseController.BlogListener;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
-import org.briarproject.briar.api.blog.BlogPostHeader;
+import org.briarproject.briar.android.fragment.BaseFragment;
+import org.briarproject.briar.android.widget.LinkDialogFragment;
 
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.annotation.UiThread;
+import androidx.lifecycle.LifecycleOwner;
+import androidx.lifecycle.ViewModelProvider;
+
+import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
+import static android.view.View.INVISIBLE;
+import static android.view.View.VISIBLE;
+import static java.util.Objects.requireNonNull;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
+import static org.briarproject.briar.android.util.UiUtils.MIN_DATE_RESOLUTION;
 
-@UiThread
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class BlogPostFragment extends BasePostFragment implements BlogListener {
+public class BlogPostFragment extends BaseFragment
+		implements OnBlogPostClickListener {
 
 	private static final String TAG = BlogPostFragment.class.getName();
+	private static final Logger LOG = getLogger(TAG);
+
+	static final String POST_ID = "briar.POST_ID";
+	static final String IS_FEED = "briar.IS_FEED";
+
+	protected BlogViewModel viewModel;
+	private final Handler handler = new Handler(Looper.getMainLooper());
+
+	private ProgressBar progressBar;
+	private BlogPostViewHolder ui;
+	private BlogPostItem post;
+	private Runnable refresher;
 
 	@Inject
-	BlogController blogController;
+	ViewModelProvider.Factory viewModelFactory;
 
-	static BlogPostFragment newInstance(MessageId postId) {
+	static BlogPostFragment newInstance(GroupId blogId, MessageId postId,
+			boolean isFeed) {
 		BlogPostFragment f = new BlogPostFragment();
-
 		Bundle bundle = new Bundle();
+		bundle.putByteArray(GROUP_ID, blogId.getBytes());
 		bundle.putByteArray(POST_ID, postId.getBytes());
-
+		bundle.putBoolean(IS_FEED, isFeed);
 		f.setArguments(bundle);
 		return f;
 	}
 
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(BlogViewModel.class);
+	}
+
+	@Nullable
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		Bundle args = requireArguments();
+		GroupId groupId =
+				new GroupId(requireNonNull(args.getByteArray(GROUP_ID)));
+		MessageId postId =
+				new MessageId(requireNonNull(args.getByteArray(POST_ID)));
+		boolean isFeed = args.getBoolean(IS_FEED);
+
+		View view = inflater.inflate(R.layout.fragment_blog_post, container,
+				false);
+		progressBar = view.findViewById(R.id.progressBar);
+		progressBar.setVisibility(VISIBLE);
+		ui = new BlogPostViewHolder(view, true, this, isFeed);
+		LifecycleOwner owner = getViewLifecycleOwner();
+		viewModel.loadBlogPost(groupId, postId).observe(owner, result ->
+				result.onError(this::handleException)
+						.onSuccess(this::onBlogPostLoaded)
+		);
+		return view;
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		startPeriodicUpdate();
+	}
+
+	@Override
+	public void onStop() {
+		super.onStop();
+		stopPeriodicUpdate();
+	}
+
+	@UiThread
+	private void onBlogPostLoaded(BlogPostItem post) {
+		progressBar.setVisibility(INVISIBLE);
+		this.post = post;
+		ui.bindItem(post);
+	}
+
+	@Override
+	public void onBlogPostClick(BlogPostItem post) {
+		// We're already there
+	}
+
+	@Override
+	public void onAuthorClick(BlogPostItem post) {
+		Intent i = new Intent(requireContext(), BlogActivity.class);
+		i.putExtra(GROUP_ID, post.getGroupId().getBytes());
+		i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+		requireContext().startActivity(i);
+	}
+
+	@Override
+	public void onLinkClick(String url) {
+		LinkDialogFragment f = LinkDialogFragment.newInstance(url);
+		f.show(getParentFragmentManager(), f.getUniqueTag());
+	}
+
+	private void startPeriodicUpdate() {
+		refresher = () -> {
+			LOG.info("Updating Content...");
+			ui.updateDate(post.getTimestamp());
+			handler.postDelayed(refresher, MIN_DATE_RESOLUTION);
+		};
+		LOG.info("Adding Handler Callback");
+		handler.postDelayed(refresher, MIN_DATE_RESOLUTION);
+	}
+
+	private void stopPeriodicUpdate() {
+		if (refresher != null) {
+			LOG.info("Removing Handler Callback");
+			handler.removeCallbacks(refresher);
+		}
+	}
+
 	@Override
 	public String getUniqueTag() {
 		return TAG;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
-	@Override
-	public void onStart() {
-		super.onStart();
-		blogController.loadBlogPost(postId,
-				new UiResultExceptionHandler<BlogPostItem, DbException>(
-						this) {
-					@Override
-					public void onResultUi(BlogPostItem post) {
-						onBlogPostLoaded(post);
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
-	@Override
-	public void onBlogPostAdded(BlogPostHeader header, boolean local) {
-		// doesn't matter here
-	}
-
-	@Override
-	public void onBlogRemoved() {
-		finish();
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostItem.java

@@ -17,7 +17,7 @@ public class BlogPostItem implements Comparable<BlogPostItem> {
 	private final BlogPostHeader header;
 	@Nullable
 	protected String text;
-	private boolean read;
+	private final boolean read;
 
 	BlogPostItem(BlogPostHeader header, @Nullable String text) {
 		this.header = header;
@@ -74,9 +74,6 @@ public class BlogPostItem implements Comparable<BlogPostItem> {
 
 	protected static int compare(BlogPostHeader h1, BlogPostHeader h2) {
 		// The newest post comes first
-		long aTime = h1.getTimeReceived(), bTime = h2.getTimeReceived();
-		if (aTime > bTime) return -1;
-		if (aTime < bTime) return 1;
-		return 0;
+		return Long.compare(h2.getTimeReceived(), h1.getTimeReceived());
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostViewHolder.java

@@ -9,6 +9,7 @@ import android.view.ViewGroup;
 import android.widget.ImageButton;
 import android.widget.TextView;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.view.AuthorView;
@@ -17,23 +18,24 @@ import org.briarproject.briar.api.blog.BlogPostHeader;
 
 import javax.annotation.Nullable;
 
-import androidx.annotation.NonNull;
 import androidx.annotation.UiThread;
 import androidx.core.view.ViewCompat;
-import androidx.fragment.app.FragmentManager;
 import androidx.recyclerview.widget.RecyclerView;
 
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.blog.BasePostFragment.POST_ID;
+import static org.briarproject.briar.android.blog.BlogPostFragment.POST_ID;
 import static org.briarproject.briar.android.util.UiUtils.TEASER_LENGTH;
 import static org.briarproject.briar.android.util.UiUtils.getSpanned;
 import static org.briarproject.briar.android.util.UiUtils.getTeaser;
 import static org.briarproject.briar.android.util.UiUtils.makeLinksClickable;
-import static org.briarproject.briar.api.blog.MessageType.POST;
+import static org.briarproject.briar.android.view.AuthorView.COMMENTER;
+import static org.briarproject.briar.android.view.AuthorView.REBLOGGER;
+import static org.briarproject.briar.android.view.AuthorView.RSS_FEED_REBLOGGED;
 
 @UiThread
+@NotNullByDefault
 class BlogPostViewHolder extends RecyclerView.ViewHolder {
 
 	private final Context ctx;
@@ -43,20 +45,16 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 	private final ImageButton reblogButton;
 	private final TextView text;
 	private final ViewGroup commentContainer;
-	private final boolean fullText;
+	private final boolean fullText, authorClickable;
 
-	@NonNull
 	private final OnBlogPostClickListener listener;
-	@Nullable
-	private final FragmentManager fragmentManager;
 
 	BlogPostViewHolder(View v, boolean fullText,
-			@NonNull OnBlogPostClickListener listener,
-			@Nullable FragmentManager fragmentManager) {
+			OnBlogPostClickListener listener, boolean authorClickable) {
 		super(v);
 		this.fullText = fullText;
 		this.listener = listener;
-		this.fragmentManager = fragmentManager;
+		this.authorClickable = authorClickable;
 
 		ctx = v.getContext();
 		layout = v.findViewById(R.id.postLayout);
@@ -67,10 +65,6 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		commentContainer = v.findViewById(R.id.commentContainer);
 	}
 
-	void setVisibility(int visibility) {
-		layout.setVisibility(visibility);
-	}
-
 	void hideReblogButton() {
 		reblogButton.setVisibility(GONE);
 	}
@@ -103,7 +97,7 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		author.setPersona(
 				item.isRssFeed() ? AuthorView.RSS_FEED : AuthorView.NORMAL);
 		// TODO make author clickable more often #624
-		if (!fullText && item.getHeader().getType() == POST) {
+		if (authorClickable) {
 			author.setAuthorClickable(v -> listener.onAuthorClick(item));
 		} else {
 			author.setAuthorNotClickable();
@@ -114,7 +108,7 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		if (fullText) {
 			text.setText(postText);
 			text.setTextIsSelectable(true);
-			makeLinksClickable(text, fragmentManager);
+			makeLinksClickable(text, listener::onLinkClick);
 		} else {
 			text.setTextIsSelectable(false);
 			if (postText.length() > TEASER_LENGTH)
@@ -147,17 +141,16 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 			reblogger.setAuthorClickable(v -> listener.onAuthorClick(item));
 		}
 		reblogger.setVisibility(VISIBLE);
-		reblogger.setPersona(AuthorView.REBLOGGER);
+		reblogger.setPersona(REBLOGGER);
 
 		author.setPersona(item.getHeader().getRootPost().isRssFeed() ?
-				AuthorView.RSS_FEED_REBLOGGED :
-				AuthorView.COMMENTER);
+				RSS_FEED_REBLOGGED : COMMENTER);
 
 		// comments
+		// TODO use nested RecyclerView instead like we do for Image Attachments
 		for (BlogCommentHeader c : item.getComments()) {
-			View v = LayoutInflater.from(ctx)
-					.inflate(R.layout.list_item_blog_comment,
-							commentContainer, false);
+			View v = LayoutInflater.from(ctx).inflate(
+					R.layout.list_item_blog_comment, commentContainer, false);
 
 			AuthorView author = v.findViewById(R.id.authorView);
 			TextView text = v.findViewById(R.id.textView);

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogViewModel.java

@@ -1,24 +1,24 @@
 package org.briarproject.briar.android.blog;
 
-import android.app.Activity;
+import android.app.Application;
 
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
-import org.briarproject.briar.android.controller.ActivityLifecycleController;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.sharing.SharingController;
+import org.briarproject.briar.android.sharing.SharingController.SharingInfo;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.blog.Blog;
 import org.briarproject.briar.api.blog.BlogInvitationResponse;
@@ -35,85 +35,54 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import androidx.annotation.Nullable;
+import androidx.annotation.UiThread;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
 
-import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
-import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class BlogControllerImpl extends BaseControllerImpl
-		implements ActivityLifecycleController, BlogController, EventListener {
+class BlogViewModel extends BaseViewModel {
 
-	private static final Logger LOG =
-			Logger.getLogger(BlogControllerImpl.class.getName());
+	private static final Logger LOG = getLogger(BlogViewModel.class.getName());
 
 	private final BlogSharingManager blogSharingManager;
+	private final SharingController sharingController;
 
-	// UI thread
-	@Nullable
-	private BlogSharingListener listener;
+	private volatile GroupId groupId;
 
-	private volatile GroupId groupId = null;
+	private final MutableLiveData<BlogItem> blog = new MutableLiveData<>();
+	private final MutableLiveData<Boolean> blogRemoved =
+			new MutableLiveData<>();
 
 	@Inject
-	BlogControllerImpl(@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager, EventBus eventBus,
+	BlogViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			EventBus eventBus,
+			IdentityManager identityManager,
 			AndroidNotificationManager notificationManager,
-			IdentityManager identityManager, BlogManager blogManager,
-			BlogSharingManager blogSharingManager) {
-		super(dbExecutor, lifecycleManager, eventBus, notificationManager,
-				identityManager, blogManager);
+			BlogManager blogManager,
+			BlogSharingManager blogSharingManager,
+			SharingController sharingController) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
+				eventBus, identityManager, notificationManager, blogManager);
 		this.blogSharingManager = blogSharingManager;
-	}
-
-	@Override
-	public void onActivityCreate(Activity activity) {
-	}
-
-	@Override
-	public void onActivityStart() {
-		super.onStart();
-		notificationManager.blockNotification(groupId);
-		notificationManager.clearBlogPostNotification(groupId);
-	}
-
-	@Override
-	public void onActivityStop() {
-		super.onStop();
-		notificationManager.unblockNotification(groupId);
-	}
-
-	@Override
-	public void onActivityDestroy() {
-	}
-
-	@Override
-	public void setGroupId(GroupId g) {
-		groupId = g;
-	}
-
-	@Override
-	public void setBlogSharingListener(BlogSharingListener listener) {
-		this.listener = listener;
-	}
-
-	@Override
-	public void unsetBlogSharingListener(BlogSharingListener listener) {
-		if (this.listener == listener) this.listener = null;
+		this.sharingController = sharingController;
 	}
 
 	@Override
 	public void eventOccurred(Event e) {
-		if (groupId == null || listener == null)
-			throw new IllegalStateException();
 		if (e instanceof BlogPostAddedEvent) {
 			BlogPostAddedEvent b = (BlogPostAddedEvent) e;
 			if (b.getGroupId().equals(groupId)) {
 				LOG.info("Blog post added");
-				listener.onBlogPostAdded(b.getHeader(), b.isLocal());
+				onBlogPostAdded(b.getHeader(), b.isLocal());
 			}
 		} else if (e instanceof BlogInvitationResponseReceivedEvent) {
 			BlogInvitationResponseReceivedEvent b =
@@ -121,41 +90,36 @@ class BlogControllerImpl extends BaseControllerImpl
 			BlogInvitationResponse r = b.getMessageHeader();
 			if (r.getShareableId().equals(groupId) && r.wasAccepted()) {
 				LOG.info("Blog invitation accepted");
-				listener.onBlogInvitationAccepted(b.getContactId());
+				sharingController.add(b.getContactId());
 			}
 		} else if (e instanceof ContactLeftShareableEvent) {
 			ContactLeftShareableEvent s = (ContactLeftShareableEvent) e;
 			if (s.getGroupId().equals(groupId)) {
 				LOG.info("Blog left by contact");
-				listener.onBlogLeft(s.getContactId());
+				sharingController.remove(s.getContactId());
 			}
 		} else if (e instanceof GroupRemovedEvent) {
 			GroupRemovedEvent g = (GroupRemovedEvent) e;
 			if (g.getGroup().getId().equals(groupId)) {
 				LOG.info("Blog removed");
-				listener.onBlogRemoved();
+				blogRemoved.setValue(true);
 			}
 		}
 	}
 
-	@Override
-	public void loadBlogPosts(
-			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler) {
-		if (groupId == null) throw new IllegalStateException();
-		loadBlogPosts(groupId, handler);
+	/**
+	 * Set this before calling any other methods.
+	 */
+	@UiThread
+	public void setGroupId(GroupId groupId) {
+		if (this.groupId == groupId) return; // configuration change
+		this.groupId = groupId;
+		loadBlog(groupId);
+		loadBlogPosts(groupId);
+		loadSharingContacts(groupId);
 	}
 
-	@Override
-	public void loadBlogPost(MessageId m,
-			ResultExceptionHandler<BlogPostItem, DbException> handler) {
-		if (groupId == null) throw new IllegalStateException();
-		loadBlogPost(groupId, m, handler);
-	}
-
-	@Override
-	public void loadBlog(
-			ResultExceptionHandler<BlogItem, DbException> handler) {
-		if (groupId == null) throw new IllegalStateException();
+	private void loadBlog(GroupId groupId) {
 		runOnDbThread(() -> {
 			try {
 				long start = now();
@@ -163,50 +127,65 @@ class BlogControllerImpl extends BaseControllerImpl
 				Blog b = blogManager.getBlog(groupId);
 				boolean ours = a.getId().equals(b.getAuthor().getId());
 				boolean removable = blogManager.canBeRemoved(b);
-				BlogItem blog = new BlogItem(b, ours, removable);
+				blog.postValue(new BlogItem(b, ours, removable));
 				logDuration(LOG, "Loading blog", start);
-				handler.onResult(blog);
 			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
+				handleException(e);
 			}
 		});
 	}
 
-	@Override
-	public void deleteBlog(ResultExceptionHandler<Void, DbException> handler) {
-		if (groupId == null) throw new IllegalStateException();
+	void blockAndClearNotifications() {
+		notificationManager.blockNotification(groupId);
+		notificationManager.clearBlogPostNotification(groupId);
+	}
+
+	void unblockNotifications() {
+		notificationManager.unblockNotification(groupId);
+	}
+
+	private void loadBlogPosts(GroupId groupId) {
+		loadFromDb(txn -> new ListUpdate(null, loadBlogPosts(txn, groupId)),
+				blogPosts::setValue);
+	}
+
+	private void loadSharingContacts(GroupId groupId) {
+		runOnDbThread(true, txn -> {
+			Collection<Contact> contacts =
+					blogSharingManager.getSharedWith(txn, groupId);
+			txn.attach(() -> onSharingContactsLoaded(contacts));
+		}, this::handleException);
+	}
+
+	@UiThread
+	private void onSharingContactsLoaded(Collection<Contact> contacts) {
+		Collection<ContactId> contactIds = new ArrayList<>(contacts.size());
+		for (Contact c : contacts) contactIds.add(c.getId());
+		sharingController.addAll(contactIds);
+	}
+
+	void deleteBlog() {
 		runOnDbThread(() -> {
 			try {
 				long start = now();
 				Blog b = blogManager.getBlog(groupId);
 				blogManager.removeBlog(b);
 				logDuration(LOG, "Removing blog", start);
-				handler.onResult(null);
 			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
+				handleException(e);
 			}
 		});
 	}
 
-	@Override
-	public void loadSharingContacts(
-			ResultExceptionHandler<Collection<ContactId>, DbException> handler) {
-		if (groupId == null) throw new IllegalStateException();
-		runOnDbThread(() -> {
-			try {
-				Collection<Contact> contacts =
-						blogSharingManager.getSharedWith(groupId);
-				Collection<ContactId> contactIds =
-						new ArrayList<>(contacts.size());
-				for (Contact c : contacts) contactIds.add(c.getId());
-				handler.onResult(contactIds);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
+	LiveData<BlogItem> getBlog() {
+		return blog;
 	}
 
+	LiveData<Boolean> getBlogRemoved() {
+		return blogRemoved;
+	}
+
+	LiveData<SharingInfo> getSharingInfo() {
+		return sharingController.getSharingInfo();
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedController.java

@@ -1,32 +0,0 @@
-package org.briarproject.briar.android.blog;
-
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.api.blog.Blog;
-
-import java.util.Collection;
-
-import androidx.annotation.UiThread;
-
-@NotNullByDefault
-public interface FeedController extends BaseController {
-
-	void loadBlogPosts(
-			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);
-
-	void loadPersonalBlog(ResultExceptionHandler<Blog, DbException> handler);
-
-	@UiThread
-	void setFeedListener(FeedListener listener);
-
-	@UiThread
-	void unsetFeedListener(FeedListener listener);
-
-	@NotNullByDefault
-	interface FeedListener extends BlogListener {
-
-		@UiThread
-		void onBlogAdded();
-	}
-}

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedControllerImpl.java

@@ -1,143 +0,0 @@
-package org.briarproject.briar.android.blog;
-
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.NoSuchGroupException;
-import org.briarproject.bramble.api.db.NoSuchMessageException;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.identity.Author;
-import org.briarproject.bramble.api.identity.IdentityManager;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.event.GroupAddedEvent;
-import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.blog.Blog;
-import org.briarproject.briar.api.blog.BlogManager;
-import org.briarproject.briar.api.blog.event.BlogPostAddedEvent;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.inject.Inject;
-
-import androidx.annotation.Nullable;
-
-import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logDuration;
-import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.bramble.util.LogUtils.now;
-import static org.briarproject.briar.api.blog.BlogManager.CLIENT_ID;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-class FeedControllerImpl extends BaseControllerImpl implements FeedController {
-
-	private static final Logger LOG =
-			Logger.getLogger(FeedControllerImpl.class.getName());
-
-	// UI thread
-	@Nullable
-	private FeedListener listener;
-
-	@Inject
-	FeedControllerImpl(@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager, EventBus eventBus,
-			AndroidNotificationManager notificationManager,
-			IdentityManager identityManager, BlogManager blogManager) {
-		super(dbExecutor, lifecycleManager, eventBus, notificationManager,
-				identityManager, blogManager);
-	}
-
-	@Override
-	public void onStart() {
-		super.onStart();
-		if (listener == null) throw new IllegalStateException();
-		notificationManager.blockAllBlogPostNotifications();
-		notificationManager.clearAllBlogPostNotifications();
-	}
-
-	@Override
-	public void onStop() {
-		super.onStop();
-		notificationManager.unblockAllBlogPostNotifications();
-	}
-
-	@Override
-	public void setFeedListener(FeedListener listener) {
-		this.listener = listener;
-	}
-
-	@Override
-	public void unsetFeedListener(FeedListener listener) {
-		if (this.listener == listener) this.listener = null;
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (listener == null) throw new IllegalStateException();
-		if (e instanceof BlogPostAddedEvent) {
-			BlogPostAddedEvent b = (BlogPostAddedEvent) e;
-			LOG.info("Blog post added");
-			listener.onBlogPostAdded(b.getHeader(), b.isLocal());
-		} else if (e instanceof GroupAddedEvent) {
-			GroupAddedEvent g = (GroupAddedEvent) e;
-			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
-				LOG.info("Blog added");
-				listener.onBlogAdded();
-			}
-		} else if (e instanceof GroupRemovedEvent) {
-			GroupRemovedEvent g = (GroupRemovedEvent) e;
-			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
-				LOG.info("Blog removed");
-				listener.onBlogRemoved();
-			}
-		}
-	}
-
-	@Override
-	public void loadBlogPosts(
-			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				long start = now();
-				Collection<BlogPostItem> posts = new ArrayList<>();
-				for (Blog b : blogManager.getBlogs()) {
-					try {
-						posts.addAll(loadItems(b.getId()));
-					} catch (NoSuchGroupException | NoSuchMessageException e) {
-						logException(LOG, WARNING, e);
-					}
-				}
-				logDuration(LOG, "Loading all posts", start);
-				handler.onResult(posts);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	@Override
-	public void loadPersonalBlog(
-			ResultExceptionHandler<Blog, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				long start = now();
-				Author a = identityManager.getLocalAuthor();
-				Blog b = blogManager.getPersonalBlog(a);
-				logDuration(LOG, "Loading personal blog", start);
-				handler.onResult(b);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedFragment.java

@@ -2,7 +2,6 @@ package org.briarproject.briar.android.blog;
 
 import android.content.Intent;
 import android.os.Bundle;
-import android.os.Parcelable;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -10,53 +9,41 @@ import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
 
-import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.blog.FeedController.FeedListener;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
+import org.briarproject.briar.android.blog.BaseViewModel.ListUpdate;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
+import org.briarproject.briar.android.widget.LinkDialogFragment;
 import org.briarproject.briar.api.blog.Blog;
-import org.briarproject.briar.api.blog.BlogPostHeader;
-
-import java.util.Collection;
-import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
-import androidx.annotation.UiThread;
+import androidx.lifecycle.ViewModelProvider;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
-import static android.app.Activity.RESULT_OK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static com.google.android.material.snackbar.Snackbar.LENGTH_LONG;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
 
-@UiThread
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class FeedFragment extends BaseFragment implements
-		OnBlogPostClickListener, FeedListener {
+public class FeedFragment extends BaseFragment
+		implements OnBlogPostClickListener {
 
 	public final static String TAG = FeedFragment.class.getName();
-	private static final Logger LOG = Logger.getLogger(TAG);
 
 	@Inject
-	FeedController feedController;
+	ViewModelProvider.Factory viewModelFactory;
 
-	private BlogPostAdapter adapter;
+	private FeedViewModel viewModel;
+	private final BlogPostAdapter adapter = new BlogPostAdapter(true, this);
 	private LinearLayoutManager layoutManager;
 	private BriarRecyclerView list;
-	@Nullable
-	private Blog personalBlog;
-	@Nullable
-	private Parcelable layoutManagerState;
 
 	public static FeedFragment newInstance() {
 		FeedFragment f = new FeedFragment();
@@ -70,7 +57,8 @@ public class FeedFragment extends BaseFragment implements
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
-		feedController.setFeedListener(this);
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(FeedViewModel.class);
 	}
 
 	@Nullable
@@ -82,9 +70,6 @@ public class FeedFragment extends BaseFragment implements
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
-		adapter =
-				new BlogPostAdapter(getActivity(), this, getFragmentManager());
-
 		layoutManager = new LinearLayoutManager(getActivity());
 		list = v.findViewById(R.id.postList);
 		list.setLayoutManager(layoutManager);
@@ -93,103 +78,38 @@ public class FeedFragment extends BaseFragment implements
 		list.setEmptyText(R.string.blogs_feed_empty_state);
 		list.setEmptyAction(R.string.blogs_feed_empty_state_action);
 
-		if (savedInstanceState != null) {
-			layoutManagerState =
-					savedInstanceState.getParcelable("layoutManager");
-		}
+		viewModel.getBlogPosts().observe(getViewLifecycleOwner(), result ->
+				result.onError(this::handleException)
+						.onSuccess(this::onBlogPostsLoaded)
+		);
 
 		return v;
 	}
 
-	@Override
-	public void onActivityResult(int requestCode, int resultCode,
-			@Nullable Intent data) {
-		super.onActivityResult(requestCode, resultCode, data);
-
-		// The BlogPostAddedEvent arrives when the controller is not listening
-		if (requestCode == REQUEST_WRITE_BLOG_POST && resultCode == RESULT_OK) {
-			showSnackBar(R.string.blogs_blog_post_created);
-		}
-	}
-
 	@Override
 	public void onStart() {
 		super.onStart();
-		feedController.onStart();
+		viewModel.blockAndClearAllBlogPostNotifications();
 		list.startPeriodicUpdate();
-		loadPersonalBlog();
-		loadBlogPosts(false);
 	}
 
 	@Override
 	public void onStop() {
 		super.onStop();
-		feedController.onStop();
-		adapter.clear();
-		list.showProgressBar();
+		viewModel.unblockAllBlogPostNotifications();
 		list.stopPeriodicUpdate();
-		// TODO save list position in database/preferences?
 	}
 
-	@Override
-	public void onDestroy() {
-		super.onDestroy();
-		feedController.unsetFeedListener(this);
-	}
-
-	@Override
-	public void onSaveInstanceState(Bundle outState) {
-		super.onSaveInstanceState(outState);
-		if (layoutManager != null) {
-			layoutManagerState = layoutManager.onSaveInstanceState();
-			outState.putParcelable("layoutManager", layoutManagerState);
-		}
-	}
-
-	private void loadPersonalBlog() {
-		feedController.loadPersonalBlog(
-				new UiResultExceptionHandler<Blog, DbException>(this) {
-					@Override
-					public void onResultUi(Blog b) {
-						personalBlog = b;
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
-	private void loadBlogPosts(boolean clear) {
-		int revision = adapter.getRevision();
-		feedController.loadBlogPosts(
-				new UiResultExceptionHandler<Collection<BlogPostItem>, DbException>(
-						this) {
-					@Override
-					public void onResultUi(Collection<BlogPostItem> posts) {
-						if (revision == adapter.getRevision()) {
-							adapter.incrementRevision();
-							if (clear) adapter.setItems(posts);
-							else adapter.addAll(posts);
-							if (posts.isEmpty()) list.showData();
-							if (layoutManagerState == null) {
-								list.scrollToPosition(0);  // Scroll to the top
-							} else {
-								layoutManager.onRestoreInstanceState(
-										layoutManagerState);
-							}
-						} else {
-							LOG.info("Concurrent update, reloading");
-							loadBlogPosts(clear);
-						}
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
+	private void onBlogPostsLoaded(ListUpdate update) {
+		adapter.submitList(update.getItems(), () -> {
+			Boolean wasLocal = update.getPostAddedWasLocal();
+			if (wasLocal != null && wasLocal) {
+				showSnackBar(R.string.blogs_blog_post_created);
+			} else if (wasLocal != null) {
+				showSnackBar(R.string.blogs_blog_post_received);
+			}
+			list.showData();
+		});
 	}
 
 	@Override
@@ -200,67 +120,48 @@ public class FeedFragment extends BaseFragment implements
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		if (personalBlog == null) return false;
-		switch (item.getItemId()) {
-			case R.id.action_write_blog_post:
-				Intent i1 =
-						new Intent(getActivity(), WriteBlogPostActivity.class);
-				i1.putExtra(GROUP_ID, personalBlog.getId().getBytes());
-				startActivityForResult(i1, REQUEST_WRITE_BLOG_POST);
-				return true;
-			case R.id.action_rss_feeds_import:
-				Intent i2 =
-						new Intent(getActivity(), RssFeedImportActivity.class);
-				startActivity(i2);
-				return true;
-			case R.id.action_rss_feeds_manage:
-				Intent i3 =
-						new Intent(getActivity(), RssFeedManageActivity.class);
-				i3.putExtra(GROUP_ID, personalBlog.getId().getBytes());
-				startActivity(i3);
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
+		int itemId = item.getItemId();
+		if (itemId == R.id.action_write_blog_post) {
+			Blog personalBlog = viewModel.getPersonalBlog().getValue();
+			if (personalBlog == null) return false;
+			Intent i = new Intent(getActivity(), WriteBlogPostActivity.class);
+			i.putExtra(GROUP_ID, personalBlog.getId().getBytes());
+			startActivity(i);
+			return true;
+		} else if (itemId == R.id.action_rss_feeds_import) {
+			Intent i = new Intent(getActivity(), RssFeedImportActivity.class);
+			startActivity(i);
+			return true;
+		} else if (itemId == R.id.action_rss_feeds_manage) {
+			Blog personalBlog = viewModel.getPersonalBlog().getValue();
+			if (personalBlog == null) return false;
+			Intent i = new Intent(getActivity(), RssFeedManageActivity.class);
+			i.putExtra(GROUP_ID, personalBlog.getId().getBytes());
+			startActivity(i);
+			return true;
 		}
-	}
-
-	@Override
-	public void onBlogPostAdded(BlogPostHeader header, boolean local) {
-		feedController.loadBlogPost(header,
-				new UiResultExceptionHandler<BlogPostItem, DbException>(
-						this) {
-					@Override
-					public void onResultUi(BlogPostItem post) {
-						adapter.incrementRevision();
-						adapter.add(post);
-						if (local) {
-							showSnackBar(R.string.blogs_blog_post_created);
-						} else {
-							showSnackBar(R.string.blogs_blog_post_received);
-						}
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				}
-		);
+		return super.onOptionsItemSelected(item);
 	}
 
 	@Override
 	public void onBlogPostClick(BlogPostItem post) {
-		FeedPostFragment f =
-				FeedPostFragment.newInstance(post.getGroupId(), post.getId());
+		BaseFragment f = BlogPostFragment
+				.newInstance(post.getGroupId(), post.getId(), true);
 		showNextFragment(f);
 	}
 
 	@Override
 	public void onAuthorClick(BlogPostItem post) {
-		Intent i = new Intent(getContext(), BlogActivity.class);
+		Intent i = new Intent(requireContext(), BlogActivity.class);
 		i.putExtra(GROUP_ID, post.getGroupId().getBytes());
 		i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-		getContext().startActivity(i);
+		requireContext().startActivity(i);
+	}
+
+	@Override
+	public void onLinkClick(String url) {
+		LinkDialogFragment f = LinkDialogFragment.newInstance(url);
+		f.show(getParentFragmentManager(), f.getUniqueTag());
 	}
 
 	@Override
@@ -283,14 +184,4 @@ public class FeedFragment extends BaseFragment implements
 		sb.make(list, stringRes, LENGTH_LONG).show();
 	}
 
-	@Override
-	public void onBlogAdded() {
-		loadBlogPosts(false);
-	}
-
-	@Override
-	public void onBlogRemoved() {
-		loadBlogPosts(true);
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedPostFragment.java

@@ -1,87 +0,0 @@
-package org.briarproject.briar.android.blog;
-
-import android.os.Bundle;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
-
-import javax.annotation.Nullable;
-import javax.inject.Inject;
-
-import androidx.annotation.UiThread;
-
-import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-
-@UiThread
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-public class FeedPostFragment extends BasePostFragment {
-
-	private static final String TAG = FeedPostFragment.class.getName();
-
-	private GroupId blogId;
-
-	@Inject
-	FeedController feedController;
-
-	static FeedPostFragment newInstance(GroupId blogId, MessageId postId) {
-		FeedPostFragment f = new FeedPostFragment();
-
-		Bundle bundle = new Bundle();
-		bundle.putByteArray(GROUP_ID, blogId.getBytes());
-		bundle.putByteArray(POST_ID, postId.getBytes());
-
-		f.setArguments(bundle);
-		return f;
-	}
-
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
-	@Nullable
-	@Override
-	public View onCreateView(LayoutInflater inflater,
-			@Nullable ViewGroup container,
-			@Nullable Bundle savedInstanceState) {
-		Bundle args = requireArguments();
-		byte[] b = args.getByteArray(GROUP_ID);
-		if (b == null) throw new IllegalStateException("No group ID in args");
-		blogId = new GroupId(b);
-
-		return super.onCreateView(inflater, container, savedInstanceState);
-	}
-
-	@Override
-	public String getUniqueTag() {
-		return TAG;
-	}
-
-	@Override
-	public void onStart() {
-		super.onStart();
-		feedController.loadBlogPost(blogId, postId,
-				new UiResultExceptionHandler<BlogPostItem, DbException>(
-						this) {
-					@Override
-					public void onResultUi(BlogPostItem post) {
-						onBlogPostLoaded(post);
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedViewModel.java

@@ -0,0 +1,133 @@
+package org.briarproject.briar.android.blog;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.identity.IdentityManager;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.viewmodel.LiveResult;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.blog.Blog;
+import org.briarproject.briar.api.blog.BlogManager;
+import org.briarproject.briar.api.blog.event.BlogPostAddedEvent;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import androidx.annotation.UiThread;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.now;
+import static org.briarproject.briar.api.blog.BlogManager.CLIENT_ID;
+
+@NotNullByDefault
+class FeedViewModel extends BaseViewModel {
+
+	private static final Logger LOG = getLogger(FeedViewModel.class.getName());
+
+	private final MutableLiveData<Blog> personalBlog = new MutableLiveData<>();
+
+	@Inject
+	FeedViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			EventBus eventBus,
+			IdentityManager identityManager,
+			AndroidNotificationManager notificationManager,
+			BlogManager blogManager) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
+				eventBus, identityManager, notificationManager, blogManager);
+		loadPersonalBlog();
+		loadAllBlogPosts();
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof BlogPostAddedEvent) {
+			BlogPostAddedEvent b = (BlogPostAddedEvent) e;
+			LOG.info("Blog post added");
+			onBlogPostAdded(b.getHeader(), b.isLocal());
+		} else if (e instanceof GroupRemovedEvent) {
+			GroupRemovedEvent g = (GroupRemovedEvent) e;
+			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
+				LOG.info("Blog removed");
+				onBlogRemoved(g.getGroup().getId());
+			}
+		}
+	}
+
+	void blockAndClearAllBlogPostNotifications() {
+		notificationManager.blockAllBlogPostNotifications();
+		notificationManager.clearAllBlogPostNotifications();
+	}
+
+	void unblockAllBlogPostNotifications() {
+		notificationManager.unblockAllBlogPostNotifications();
+	}
+
+	private void loadPersonalBlog() {
+		runOnDbThread(() -> {
+			try {
+				long start = now();
+				Author a = identityManager.getLocalAuthor();
+				Blog b = blogManager.getPersonalBlog(a);
+				logDuration(LOG, "Loading personal blog", start);
+				personalBlog.postValue(b);
+			} catch (DbException e) {
+				handleException(e);
+			}
+		});
+	}
+
+	LiveData<Blog> getPersonalBlog() {
+		return personalBlog;
+	}
+
+	private void loadAllBlogPosts() {
+		loadFromDb(this::loadAllBlogPosts, blogPosts::setValue);
+	}
+
+	@DatabaseExecutor
+	private ListUpdate loadAllBlogPosts(Transaction txn)
+			throws DbException {
+		long start = now();
+		List<BlogPostItem> posts = new ArrayList<>();
+		for (GroupId g : blogManager.getBlogIds(txn)) {
+			posts.addAll(loadBlogPosts(txn, g));
+		}
+		Collections.sort(posts);
+		logDuration(LOG, "Loading all posts", start);
+		return new ListUpdate(null, posts);
+	}
+
+	@UiThread
+	private void onBlogRemoved(GroupId g) {
+		List<BlogPostItem> items = removeListItems(getBlogPostItems(), item ->
+				item.getGroupId().equals(g)
+		);
+		if (items != null) {
+			blogPosts.setValue(new LiveResult<>(new ListUpdate(null, items)));
+		}
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/OnBlogPostClickListener.java

@@ -5,4 +5,6 @@ interface OnBlogPostClickListener {
 	void onBlogPostClick(BlogPostItem post);
 
 	void onAuthorClick(BlogPostItem post);
+
+	void onLinkClick(String url);
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/ReblogActivity.java

@@ -11,7 +11,7 @@ import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
 import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
 
-import static org.briarproject.briar.android.blog.BasePostFragment.POST_ID;
+import static org.briarproject.briar.android.blog.BlogPostFragment.POST_ID;
 
 public class ReblogActivity extends BriarActivity implements
 		BaseFragmentListener {
@@ -39,13 +39,11 @@ public class ReblogActivity extends BriarActivity implements
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		switch (item.getItemId()) {
-			case android.R.id.home:
-				onBackPressed();
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
+		if (item.getItemId() == android.R.id.home) {
+			onBackPressed();
+			return true;
 		}
+		return super.onOptionsItemSelected(item);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/blog/ReblogFragment.java

@@ -7,19 +7,17 @@ import android.view.ViewGroup;
 import android.widget.ProgressBar;
 import android.widget.ScrollView;
 
-import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.controller.handler.UiExceptionHandler;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.view.TextInputView;
 import org.briarproject.briar.android.view.TextSendController;
 import org.briarproject.briar.android.view.TextSendController.SendListener;
+import org.briarproject.briar.android.widget.LinkDialogFragment;
 import org.briarproject.briar.api.attachment.AttachmentHeader;
 
 import java.util.List;
@@ -27,13 +25,15 @@ import java.util.List;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import androidx.lifecycle.ViewModelProvider;
+
 import static android.view.View.FOCUS_DOWN;
 import static android.view.View.GONE;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.blog.BasePostFragment.POST_ID;
+import static org.briarproject.briar.android.blog.BlogPostFragment.POST_ID;
 import static org.briarproject.briar.api.blog.BlogConstants.MAX_BLOG_POST_TEXT_LENGTH;
 
 @MethodsNotNullByDefault
@@ -42,12 +42,13 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 
 	public static final String TAG = ReblogFragment.class.getName();
 
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private BlogViewModel viewModel;
 	private ViewHolder ui;
 	private BlogPostItem item;
 
-	@Inject
-	FeedController feedController;
-
 	static ReblogFragment newInstance(GroupId groupId, MessageId messageId) {
 		ReblogFragment f = new ReblogFragment();
 
@@ -67,6 +68,8 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(BlogViewModel.class);
 	}
 
 	@Override
@@ -90,30 +93,20 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 		ui.input.setMaxTextLength(MAX_BLOG_POST_TEXT_LENGTH);
 		showProgressBar();
 
-		feedController.loadBlogPost(blogId, postId,
-				new UiResultExceptionHandler<BlogPostItem, DbException>(
-						this) {
-					@Override
-					public void onResultUi(BlogPostItem result) {
-						item = result;
-						bindViewHolder();
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
+		viewModel.loadBlogPost(blogId, postId).observe(getViewLifecycleOwner(),
+				result -> result.onError(this::handleException)
+						.onSuccess(this::bindViewHolder)
+		);
 
 		return v;
 	}
 
-	private void bindViewHolder() {
-		if (item == null) return;
+	private void bindViewHolder(BlogPostItem item) {
+		this.item = item;
 
 		hideProgressBar();
 
-		ui.post.bindItem(item);
+		ui.post.bindItem(this.item);
 		ui.post.hideReblogButton();
 
 		ui.input.setReady(true);
@@ -124,13 +117,7 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 	public void onSendClick(@Nullable String text,
 			List<AttachmentHeader> headers) {
 		ui.input.hideSoftKeyboard();
-		feedController.repeatPost(item, text,
-				new UiExceptionHandler<DbException>(this) {
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
+		viewModel.repeatPost(item, text);
 		finish();
 	}
 
@@ -144,7 +131,7 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 		ui.input.setVisibility(VISIBLE);
 	}
 
-	private class ViewHolder {
+	private class ViewHolder implements OnBlogPostClickListener {
 
 		private final ScrollView scrollView;
 		private final ProgressBar progressBar;
@@ -155,18 +142,25 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 			scrollView = v.findViewById(R.id.scrollView);
 			progressBar = v.findViewById(R.id.progressBar);
 			post = new BlogPostViewHolder(v.findViewById(R.id.postLayout),
-					true, new OnBlogPostClickListener() {
-				@Override
-				public void onBlogPostClick(BlogPostItem post) {
-					// do nothing
-				}
-
-				@Override
-				public void onAuthorClick(BlogPostItem post) {
-					// probably don't want to allow author clicks here
-				}
-			}, getFragmentManager());
+					true, this, false);
 			input = v.findViewById(R.id.inputText);
 		}
+
+		@Override
+		public void onBlogPostClick(BlogPostItem post) {
+			// do nothing
+		}
+
+		@Override
+		public void onAuthorClick(BlogPostItem post) {
+			// probably don't want to allow author clicks here
+		}
+
+		@Override
+		public void onLinkClick(String url) {
+			LinkDialogFragment f = LinkDialogFragment.newInstance(url);
+			f.show(getParentFragmentManager(), f.getUniqueTag());
+		}
 	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/contact/BaseContactListAdapter.java

@@ -1,7 +1,6 @@
 package org.briarproject.briar.android.contact;
 
 import android.content.Context;
-import android.view.View;
 
 import org.briarproject.briar.android.util.BriarAdapter;
 
@@ -45,8 +44,4 @@ public abstract class BaseContactListAdapter<I extends ContactItem, VH extends C
 		return true;
 	}
 
-	public interface OnContactClickListener<I> {
-		void onItemClick(View view, I item);
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactItemViewHolder.java

@@ -7,7 +7,6 @@ import android.widget.TextView;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 
 import javax.annotation.Nullable;
 

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListAdapter.java

@@ -7,7 +7,6 @@ import android.view.ViewGroup;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.NullSafety;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 
 import androidx.recyclerview.widget.DiffUtil.ItemCallback;
 import androidx.recyclerview.widget.ListAdapter;
@@ -16,9 +15,6 @@ import androidx.recyclerview.widget.ListAdapter;
 public class ContactListAdapter extends
 		ListAdapter<ContactListItem, ContactListItemViewHolder> {
 
-	// TODO: using the click listener interface from BaseContactListAdapter on
-	// purpose here because it is entangled with ContactListItemViewHolder. At
-	// some point we probably want to change that.
 	protected final OnContactClickListener<ContactListItem> listener;
 
 	public ContactListAdapter(

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListFragment.java

@@ -15,7 +15,6 @@ import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 import org.briarproject.briar.android.contact.add.remote.AddContactActivity;
 import org.briarproject.briar.android.contact.add.remote.PendingContactListActivity;
 import org.briarproject.briar.android.conversation.ConversationActivity;
@@ -34,7 +33,6 @@ import io.github.kobakei.materialfabspeeddial.FabSpeedDial;
 import io.github.kobakei.materialfabspeeddial.FabSpeedDial.OnMenuItemClickListener;
 
 import static com.google.android.material.snackbar.BaseTransientBottomBar.LENGTH_INDEFINITE;
-import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
 
 @MethodsNotNullByDefault
@@ -102,7 +100,6 @@ public class ContactListFragment extends BaseFragment
 				.observe(getViewLifecycleOwner(), result -> {
 					result.onError(this::handleException).onSuccess(items -> {
 						adapter.submitList(items);
-						if (requireNonNull(items).size() == 0) list.showData();
 					});
 				});
 		viewModel.getHasPendingContacts()

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListItemViewHolder.java

@@ -5,7 +5,6 @@ import android.widget.TextView;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 
 import java.util.Locale;
 

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListViewModel.java

@@ -3,70 +3,41 @@ package org.briarproject.briar.android.contact;
 import android.app.Application;
 
 import org.briarproject.bramble.api.connection.ConnectionRegistry;
-import org.briarproject.bramble.api.contact.Contact;
-import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
-import org.briarproject.bramble.api.contact.event.ContactAddedEvent;
-import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
 import org.briarproject.bramble.api.contact.event.PendingContactAddedEvent;
 import org.briarproject.bramble.api.contact.event.PendingContactRemovedEvent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.event.ContactConnectedEvent;
-import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent;
 import org.briarproject.bramble.api.system.AndroidExecutor;
-import org.briarproject.briar.android.viewmodel.DbViewModel;
-import org.briarproject.briar.android.viewmodel.LiveResult;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.avatar.event.AvatarUpdatedEvent;
-import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.conversation.ConversationManager;
-import org.briarproject.briar.api.conversation.ConversationMessageHeader;
-import org.briarproject.briar.api.conversation.event.ConversationMessageReceivedEvent;
-import org.briarproject.briar.api.identity.AuthorInfo;
 import org.briarproject.briar.api.identity.AuthorManager;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import androidx.arch.core.util.Function;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.bramble.util.LogUtils.now;
 
 @NotNullByDefault
-class ContactListViewModel extends DbViewModel implements EventListener {
+class ContactListViewModel extends ContactsViewModel {
 
 	private static final Logger LOG =
 			getLogger(ContactListViewModel.class.getName());
 
-	private final ContactManager contactManager;
-	private final AuthorManager authorManager;
-	private final ConversationManager conversationManager;
-	private final ConnectionRegistry connectionRegistry;
-	private final EventBus eventBus;
 	private final AndroidNotificationManager notificationManager;
 
-	private final MutableLiveData<LiveResult<List<ContactListItem>>>
-			contactListItems = new MutableLiveData<>();
-
 	private final MutableLiveData<Boolean> hasPendingContacts =
 			new MutableLiveData<>();
 
@@ -79,99 +50,25 @@ class ContactListViewModel extends DbViewModel implements EventListener {
 			ConversationManager conversationManager,
 			ConnectionRegistry connectionRegistry, EventBus eventBus,
 			AndroidNotificationManager notificationManager) {
-		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
-		this.contactManager = contactManager;
-		this.authorManager = authorManager;
-		this.conversationManager = conversationManager;
-		this.connectionRegistry = connectionRegistry;
-		this.eventBus = eventBus;
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
+				contactManager, authorManager, conversationManager,
+				connectionRegistry, eventBus);
 		this.notificationManager = notificationManager;
-		this.eventBus.addListener(this);
-	}
-
-	@Override
-	protected void onCleared() {
-		super.onCleared();
-		eventBus.removeListener(this);
-	}
-
-	void loadContacts() {
-		loadList(this::loadContacts, contactListItems::setValue);
-	}
-
-	private List<ContactListItem> loadContacts(Transaction txn)
-			throws DbException {
-		long start = now();
-		List<ContactListItem> contacts = new ArrayList<>();
-		for (Contact c : contactManager.getContacts(txn)) {
-			ContactId id = c.getId();
-			AuthorInfo authorInfo = authorManager.getAuthorInfo(txn, c);
-			MessageTracker.GroupCount count =
-					conversationManager.getGroupCount(txn, id);
-			boolean connected = connectionRegistry.isConnected(c.getId());
-			contacts.add(new ContactListItem(c, authorInfo, connected, count));
-		}
-		Collections.sort(contacts);
-		logDuration(LOG, "Full load", start);
-		return contacts;
 	}
 
 	@Override
 	public void eventOccurred(Event e) {
-		if (e instanceof ContactAddedEvent) {
-			LOG.info("Contact added, reloading");
-			loadContacts();
-		} else if (e instanceof ContactConnectedEvent) {
-			updateItem(((ContactConnectedEvent) e).getContactId(),
-					item -> new ContactListItem(item, true), false);
-		} else if (e instanceof ContactDisconnectedEvent) {
-			updateItem(((ContactDisconnectedEvent) e).getContactId(),
-					item -> new ContactListItem(item, false), false);
-		} else if (e instanceof ContactRemovedEvent) {
-			LOG.info("Contact removed, removing item");
-			removeItem(((ContactRemovedEvent) e).getContactId());
-		} else if (e instanceof ConversationMessageReceivedEvent) {
-			LOG.info("Conversation message received, updating item");
-			ConversationMessageReceivedEvent<?> p =
-					(ConversationMessageReceivedEvent<?>) e;
-			ConversationMessageHeader h = p.getMessageHeader();
-			updateItem(p.getContactId(), item -> new ContactListItem(item, h),
-					true);
-		} else if (e instanceof PendingContactAddedEvent ||
+		super.eventOccurred(e);
+		if (e instanceof PendingContactAddedEvent ||
 				e instanceof PendingContactRemovedEvent) {
 			checkForPendingContacts();
-		} else if (e instanceof AvatarUpdatedEvent) {
-			AvatarUpdatedEvent a = (AvatarUpdatedEvent) e;
-			updateItem(a.getContactId(), item -> new ContactListItem(item,
-					a.getAttachmentHeader()), false);
 		}
 	}
 
-	LiveData<LiveResult<List<ContactListItem>>> getContactListItems() {
-		return contactListItems;
-	}
-
 	LiveData<Boolean> getHasPendingContacts() {
 		return hasPendingContacts;
 	}
 
-	private void updateItem(ContactId c,
-			Function<ContactListItem, ContactListItem> replacer, boolean sort) {
-		List<ContactListItem> list = updateListItems(contactListItems,
-				itemToTest -> itemToTest.getContact().getId().equals(c),
-				replacer);
-		if (list == null) return;
-		if (sort) Collections.sort(list);
-		contactListItems.setValue(new LiveResult<>(list));
-	}
-
-	private void removeItem(ContactId c) {
-		List<ContactListItem> list = removeListItems(contactListItems,
-				itemToTest -> itemToTest.getContact().getId().equals(c));
-		if (list == null) return;
-		contactListItems.setValue(new LiveResult<>(list));
-	}
-
 	void checkForPendingContacts() {
 		runOnDbThread(() -> {
 			try {

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactsViewModel.java

@@ -0,0 +1,168 @@
+package org.briarproject.briar.android.contact;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.connection.ConnectionRegistry;
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.ContactManager;
+import org.briarproject.bramble.api.contact.event.ContactAddedEvent;
+import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.event.ContactConnectedEvent;
+import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
+import org.briarproject.briar.android.viewmodel.LiveResult;
+import org.briarproject.briar.api.avatar.event.AvatarUpdatedEvent;
+import org.briarproject.briar.api.client.MessageTracker;
+import org.briarproject.briar.api.conversation.ConversationManager;
+import org.briarproject.briar.api.conversation.ConversationMessageHeader;
+import org.briarproject.briar.api.conversation.event.ConversationMessageReceivedEvent;
+import org.briarproject.briar.api.identity.AuthorInfo;
+import org.briarproject.briar.api.identity.AuthorManager;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import androidx.annotation.UiThread;
+import androidx.arch.core.util.Function;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.now;
+
+@NotNullByDefault
+public class ContactsViewModel extends DbViewModel implements EventListener {
+
+	private static final Logger LOG =
+			getLogger(ContactsViewModel.class.getName());
+
+	protected final ContactManager contactManager;
+	private final AuthorManager authorManager;
+	private final ConversationManager conversationManager;
+	private final ConnectionRegistry connectionRegistry;
+	private final EventBus eventBus;
+
+	private final MutableLiveData<LiveResult<List<ContactListItem>>>
+			contactListItems = new MutableLiveData<>();
+
+	@Inject
+	public ContactsViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager, TransactionManager db,
+			AndroidExecutor androidExecutor, ContactManager contactManager,
+			AuthorManager authorManager,
+			ConversationManager conversationManager,
+			ConnectionRegistry connectionRegistry, EventBus eventBus) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
+		this.contactManager = contactManager;
+		this.authorManager = authorManager;
+		this.conversationManager = conversationManager;
+		this.connectionRegistry = connectionRegistry;
+		this.eventBus = eventBus;
+		this.eventBus.addListener(this);
+	}
+
+	@Override
+	protected void onCleared() {
+		super.onCleared();
+		eventBus.removeListener(this);
+	}
+
+	protected void loadContacts() {
+		loadFromDb(this::loadContacts, contactListItems::setValue);
+	}
+
+	private List<ContactListItem> loadContacts(Transaction txn)
+			throws DbException {
+		long start = now();
+		List<ContactListItem> contacts = new ArrayList<>();
+		for (Contact c : contactManager.getContacts(txn)) {
+			ContactId id = c.getId();
+			if (!displayContact(id)) {
+				continue;
+			}
+			AuthorInfo authorInfo = authorManager.getAuthorInfo(txn, c);
+			MessageTracker.GroupCount count =
+					conversationManager.getGroupCount(txn, id);
+			boolean connected = connectionRegistry.isConnected(c.getId());
+			contacts.add(new ContactListItem(c, authorInfo, connected, count));
+		}
+		Collections.sort(contacts);
+		logDuration(LOG, "Full load", start);
+		return contacts;
+	}
+
+	/**
+	 * Override this method to display only a subset of contacts.
+	 */
+	protected boolean displayContact(ContactId contactId) {
+		return true;
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof ContactAddedEvent) {
+			LOG.info("Contact added, reloading");
+			loadContacts();
+		} else if (e instanceof ContactConnectedEvent) {
+			updateItem(((ContactConnectedEvent) e).getContactId(),
+					item -> new ContactListItem(item, true), false);
+		} else if (e instanceof ContactDisconnectedEvent) {
+			updateItem(((ContactDisconnectedEvent) e).getContactId(),
+					item -> new ContactListItem(item, false), false);
+		} else if (e instanceof ContactRemovedEvent) {
+			LOG.info("Contact removed, removing item");
+			removeItem(((ContactRemovedEvent) e).getContactId());
+		} else if (e instanceof ConversationMessageReceivedEvent) {
+			LOG.info("Conversation message received, updating item");
+			ConversationMessageReceivedEvent<?> p =
+					(ConversationMessageReceivedEvent<?>) e;
+			ConversationMessageHeader h = p.getMessageHeader();
+			updateItem(p.getContactId(), item -> new ContactListItem(item, h),
+					true);
+		} else if (e instanceof AvatarUpdatedEvent) {
+			AvatarUpdatedEvent a = (AvatarUpdatedEvent) e;
+			updateItem(a.getContactId(), item -> new ContactListItem(item,
+					a.getAttachmentHeader()), false);
+		}
+	}
+
+	public LiveData<LiveResult<List<ContactListItem>>> getContactListItems() {
+		return contactListItems;
+	}
+
+	@UiThread
+	private void updateItem(ContactId c,
+			Function<ContactListItem, ContactListItem> replacer, boolean sort) {
+		List<ContactListItem> list = updateListItems(getList(contactListItems),
+				itemToTest -> itemToTest.getContact().getId().equals(c),
+				replacer);
+		if (list == null) return;
+		if (sort) Collections.sort(list);
+		contactListItems.setValue(new LiveResult<>(list));
+	}
+
+	@UiThread
+	private void removeItem(ContactId c) {
+		removeAndUpdateListItems(contactListItems,
+				itemToTest -> itemToTest.getContact().getId().equals(c));
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/LegacyContactListAdapter.java

@@ -1,50 +0,0 @@
-package org.briarproject.briar.android.contact;
-
-import android.content.Context;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.briar.R;
-
-@NotNullByDefault
-public class LegacyContactListAdapter extends
-		BaseContactListAdapter<ContactListItem, ContactListItemViewHolder> {
-
-	public LegacyContactListAdapter(Context context,
-			OnContactClickListener<ContactListItem> listener) {
-		super(context, ContactListItem.class, listener);
-	}
-
-	@Override
-	public ContactListItemViewHolder onCreateViewHolder(ViewGroup viewGroup,
-			int i) {
-		View v = LayoutInflater.from(viewGroup.getContext()).inflate(
-				R.layout.list_item_contact, viewGroup, false);
-
-		return new ContactListItemViewHolder(v);
-	}
-
-	@Override
-	public boolean areContentsTheSame(ContactListItem c1, ContactListItem c2) {
-		// check for all properties that influence visual
-		// representation of contact
-		if (c1.isEmpty() != c2.isEmpty()) {
-			return false;
-		}
-		if (c1.getUnreadCount() != c2.getUnreadCount()) {
-			return false;
-		}
-		if (c1.getTimestamp() != c2.getTimestamp()) {
-			return false;
-		}
-		return c1.isConnected() == c2.isConnected();
-	}
-
-	@Override
-	public int compare(ContactListItem c1, ContactListItem c2) {
-		return Long.compare(c2.getTimestamp(), c1.getTimestamp());
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/contact/OnContactClickListener.java

@@ -0,0 +1,9 @@
+package org.briarproject.briar.android.contact;
+
+import android.view.View;
+
+public interface OnContactClickListener<I> {
+
+	void onItemClick(View view, I item);
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contactselection/BaseContactSelectorAdapter.java

@@ -6,6 +6,7 @@ import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.android.contact.BaseContactListAdapter;
 import org.briarproject.briar.android.contact.ContactItemViewHolder;
+import org.briarproject.briar.android.contact.OnContactClickListener;
 
 import java.util.ArrayList;
 import java.util.Collection;

briar-android/src/main/java/org/briarproject/briar/android/contactselection/BaseContactSelectorFragment.java

@@ -12,8 +12,8 @@ import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 import org.briarproject.briar.android.contact.ContactItemViewHolder;
+import org.briarproject.briar.android.contact.OnContactClickListener;
 import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.view.BriarRecyclerView;

briar-android/src/main/java/org/briarproject/briar/android/contactselection/BaseSelectableContactHolder.java

@@ -6,8 +6,8 @@ import android.widget.TextView;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 import org.briarproject.briar.android.contact.ContactItemViewHolder;
+import org.briarproject.briar.android.contact.OnContactClickListener;
 
 import javax.annotation.Nullable;
 

briar-android/src/main/java/org/briarproject/briar/android/contactselection/ContactSelectorAdapter.java

@@ -7,6 +7,7 @@ import android.view.ViewGroup;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.contact.OnContactClickListener;
 
 @NotNullByDefault
 class ContactSelectorAdapter extends

briar-android/src/main/java/org/briarproject/briar/android/contactselection/ContactSelectorFragment.java

@@ -8,7 +8,7 @@ import android.view.MenuItem;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
+import org.briarproject.briar.android.contact.OnContactClickListener;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault

briar-android/src/main/java/org/briarproject/briar/android/contactselection/SelectableContactHolder.java

@@ -3,7 +3,7 @@ package org.briarproject.briar.android.contactselection;
 import android.view.View;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
+import org.briarproject.briar.android.contact.OnContactClickListener;
 
 import javax.annotation.Nullable;
 

briar-android/src/main/java/org/briarproject/briar/android/controller/SharingController.java

@@ -1,77 +0,0 @@
-package org.briarproject.briar.android.controller;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import java.util.Collection;
-
-import androidx.annotation.UiThread;
-
-@Deprecated
-@NotNullByDefault
-public interface SharingController {
-
-	/**
-	 * Sets the listener that is called when contacts go on or offline.
-	 */
-	@UiThread
-	void setSharingListener(SharingListener listener);
-
-	/**
-	 * Unsets the listener.
-	 */
-	@UiThread
-	void unsetSharingListener(SharingListener listener);
-
-	/**
-	 * Call this when your lifecycle starts,
-	 * so the listener will be called when information changes.
-	 */
-	@UiThread
-	void onStart();
-
-	/**
-	 * Call this when your lifecycle stops,
-	 * so that the controller knows it can stops listening to events.
-	 */
-	@UiThread
-	void onStop();
-
-	/**
-	 * Adds one contact to be tracked.
-	 */
-	@UiThread
-	void add(ContactId c);
-
-	/**
-	 * Adds a collection of contacts to be tracked.
-	 */
-	@UiThread
-	void addAll(Collection<ContactId> contacts);
-
-	/**
-	 * Call this when the contact identified by c is no longer sharing
-	 * the given group identified by GroupId g.
-	 */
-	@UiThread
-	void remove(ContactId c);
-
-	/**
-	 * Returns the number of online contacts.
-	 */
-	@UiThread
-	int getOnlineCount();
-
-	/**
-	 * Returns the total number of contacts that have been added.
-	 */
-	@UiThread
-	int getTotalCount();
-
-	interface SharingListener {
-
-		@UiThread
-		void onSharingInfoUpdated(int total, int online);
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/controller/SharingControllerImpl.java

@@ -1,109 +0,0 @@
-package org.briarproject.briar.android.controller;
-
-import org.briarproject.bramble.api.connection.ConnectionRegistry;
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.event.EventListener;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.event.ContactConnectedEvent;
-import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent;
-
-import java.util.Collection;
-import java.util.HashSet;
-import java.util.Set;
-
-import javax.annotation.Nullable;
-import javax.inject.Inject;
-
-import androidx.annotation.UiThread;
-
-@Deprecated
-@NotNullByDefault
-public class SharingControllerImpl implements SharingController, EventListener {
-
-	private final EventBus eventBus;
-	private final ConnectionRegistry connectionRegistry;
-
-	// UI thread
-	private final Set<ContactId> contacts = new HashSet<>();
-
-	// UI thread
-	@Nullable
-	private SharingListener listener;
-
-	@Inject
-	SharingControllerImpl(EventBus eventBus,
-			ConnectionRegistry connectionRegistry) {
-		this.eventBus = eventBus;
-		this.connectionRegistry = connectionRegistry;
-	}
-
-	@Override
-	public void setSharingListener(SharingListener listener) {
-		this.listener = listener;
-	}
-
-	@Override
-	public void unsetSharingListener(SharingListener listener) {
-		if (this.listener == listener) this.listener = null;
-	}
-
-	@Override
-	public void onStart() {
-		eventBus.addListener(this);
-	}
-
-	@Override
-	public void onStop() {
-		eventBus.removeListener(this);
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof ContactConnectedEvent) {
-			setConnected(((ContactConnectedEvent) e).getContactId());
-		} else if (e instanceof ContactDisconnectedEvent) {
-			setConnected(((ContactDisconnectedEvent) e).getContactId());
-		}
-	}
-
-	@UiThread
-	private void setConnected(ContactId c) {
-		if (listener == null) throw new IllegalStateException();
-		if (contacts.contains(c)) {
-			int online = getOnlineCount();
-			listener.onSharingInfoUpdated(contacts.size(), online);
-		}
-	}
-
-	@Override
-	public void addAll(Collection<ContactId> c) {
-		contacts.addAll(c);
-	}
-
-	@Override
-	public void add(ContactId c) {
-		contacts.add(c);
-	}
-
-	@Override
-	public void remove(ContactId c) {
-		contacts.remove(c);
-	}
-
-	@Override
-	public int getOnlineCount() {
-		int online = 0;
-		for (ContactId c : contacts) {
-			if (connectionRegistry.isConnected(c)) online++;
-		}
-		return online;
-	}
-
-	@Override
-	public int getTotalCount() {
-		return contacts.size();
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageActivity.java

@@ -24,10 +24,7 @@ import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.PullDownLayout;
 
-import java.text.SimpleDateFormat;
-import java.util.Date;
 import java.util.List;
-import java.util.Locale;
 
 import javax.inject.Inject;
 
@@ -293,13 +290,10 @@ public class ImageActivity extends BriarActivity
 
 	@RequiresApi(api = 19)
 	private Intent getCreationIntent() {
-		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss",
-				Locale.getDefault());
-		String fileName = sdf.format(new Date());
 		Intent intent = new Intent(ACTION_CREATE_DOCUMENT);
 		intent.addCategory(CATEGORY_OPENABLE);
 		intent.setType(getVisibleAttachment().getMimeType());
-		intent.putExtra(EXTRA_TITLE, fileName);
+		intent.putExtra(EXTRA_TITLE, viewModel.getFileName());
 		return intent;
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageViewModel.java

@@ -225,8 +225,8 @@ public class ImageViewModel extends DbViewModel implements EventListener {
 		});
 	}
 
-	private String getFileName() {
-		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss",
+	String getFileName() {
+		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd",
 				Locale.getDefault());
 		return sdf.format(new Date());
 	}

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumListViewModel.java

@@ -127,7 +127,7 @@ class ForumListViewModel extends DbViewModel implements EventListener {
 	}
 
 	public void loadForums() {
-		loadList(this::loadForums, forumItems::setValue);
+		loadFromDb(this::loadForums, forumItems::setValue);
 	}
 
 	@DatabaseExecutor
@@ -145,7 +145,7 @@ class ForumListViewModel extends DbViewModel implements EventListener {
 
 	@UiThread
 	private void onForumPostReceived(GroupId g, ForumPostHeader header) {
-		List<ForumListItem> list = updateListItems(forumItems,
+		List<ForumListItem> list = updateListItems(getList(forumItems),
 				itemToTest -> itemToTest.getForum().getId().equals(g),
 				itemToUpdate -> new ForumListItem(itemToUpdate, header));
 		if (list == null) return;
@@ -156,11 +156,9 @@ class ForumListViewModel extends DbViewModel implements EventListener {
 
 	@UiThread
 	private void onGroupRemoved(GroupId groupId) {
-		List<ForumListItem> list = removeListItems(forumItems, i ->
+		removeAndUpdateListItems(forumItems, i ->
 				i.getForum().getId().equals(groupId)
 		);
-		if (list == null) return;
-		forumItems.setValue(new LiveResult<>(list));
 	}
 
 	void loadForumInvitations() {

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumViewModel.java

@@ -135,7 +135,7 @@ class ForumViewModel extends ThreadListViewModel<ForumPostItem> {
 
 	@Override
 	public void loadItems() {
-		loadList(txn -> {
+		loadFromDb(txn -> {
 			long start = now();
 			List<ForumPostHeader> headers =
 					forumManager.getPostHeaders(txn, groupId);

briar-android/src/main/java/org/briarproject/briar/android/fragment/BaseFragment.java

@@ -10,9 +10,8 @@ import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.android.DestroyableContext;
 import org.briarproject.briar.android.activity.ActivityComponent;
 
-import javax.annotation.Nullable;
-
 import androidx.annotation.CallSuper;
+import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentActivity;
@@ -47,13 +46,11 @@ public abstract class BaseFragment extends Fragment
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		switch (item.getItemId()) {
-			case android.R.id.home:
-				listener.onBackPressed();
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
+		if (item.getItemId() == android.R.id.home) {
+			requireActivity().onBackPressed();
+			return true;
 		}
+		return super.onOptionsItemSelected(item);
 	}
 
 	@UiThread
@@ -79,6 +76,7 @@ public abstract class BaseFragment extends Fragment
 		void handleException(Exception e);
 	}
 
+	@Deprecated
 	@CallSuper
 	@Override
 	public void runOnUiThreadUnlessDestroyed(Runnable r) {

briar-android/src/main/java/org/briarproject/briar/android/introduction/ContactChooserFragment.java

@@ -5,74 +5,41 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
-import org.briarproject.bramble.api.connection.ConnectionRegistry;
-import org.briarproject.bramble.api.contact.Contact;
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.contact.ContactManager;
-import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
+import org.briarproject.briar.android.contact.ContactListAdapter;
 import org.briarproject.briar.android.contact.ContactListItem;
-import org.briarproject.briar.android.contact.LegacyContactListAdapter;
+import org.briarproject.briar.android.contact.OnContactClickListener;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.view.BriarRecyclerView;
-import org.briarproject.briar.api.client.MessageTracker.GroupCount;
-import org.briarproject.briar.api.conversation.ConversationManager;
-import org.briarproject.briar.api.identity.AuthorInfo;
-import org.briarproject.briar.api.identity.AuthorManager;
-
-import java.util.ArrayList;
-import java.util.List;
-import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
-import androidx.annotation.UiThread;
+import androidx.lifecycle.ViewModelProvider;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
-import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
-
-@UiThread
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class ContactChooserFragment extends BaseFragment {
+public class ContactChooserFragment extends BaseFragment
+		implements OnContactClickListener<ContactListItem> {
 
-	public static final String TAG = ContactChooserFragment.class.getName();
-	private static final Logger LOG = Logger.getLogger(TAG);
+	private static final String TAG = ContactChooserFragment.class.getName();
 
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private IntroductionViewModel viewModel;
+	private final ContactListAdapter adapter = new ContactListAdapter(this);
 	private BriarRecyclerView list;
-	private LegacyContactListAdapter adapter;
-	private ContactId contactId;
-
-	// Fields that are accessed from background threads must be volatile
-	private volatile Contact c1;
-	@Inject
-	volatile ContactManager contactManager;
-	@Inject
-	volatile AuthorManager authorManager;
-	@Inject
-	volatile ConversationManager conversationManager;
-	@Inject
-	volatile ConnectionRegistry connectionRegistry;
-
-	public static ContactChooserFragment newInstance(ContactId id) {
-		Bundle args = new Bundle();
-
-		ContactChooserFragment fragment = new ContactChooserFragment();
-		args.putInt(CONTACT_ID, id.getInt());
-		fragment.setArguments(args);
-		return fragment;
-	}
 
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(IntroductionViewModel.class);
 	}
 
 	@Override
@@ -80,23 +47,20 @@ public class ContactChooserFragment extends BaseFragment {
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 
-		View contentView = inflater.inflate(R.layout.list, container, false);
+		// change toolbar text (relevant when navigating back to this fragment)
+		requireActivity().setTitle(R.string.introduction_activity_title);
 
-		OnContactClickListener<ContactListItem> onContactClickListener =
-				(view, item) -> {
-					if (c1 == null) throw new IllegalStateException();
-					Contact c2 = item.getContact();
-					showMessageScreen(c1, c2);
-				};
-		adapter = new LegacyContactListAdapter(requireActivity(),
-				onContactClickListener);
+		View contentView = inflater.inflate(R.layout.list, container, false);
 
 		list = contentView.findViewById(R.id.list);
 		list.setLayoutManager(new LinearLayoutManager(getActivity()));
 		list.setAdapter(adapter);
 		list.setEmptyText(R.string.no_contacts);
 
-		contactId = new ContactId(requireArguments().getInt(CONTACT_ID));
+		viewModel.getContactListItems().observe(getViewLifecycleOwner(),
+				result -> result.onError(this::handleException)
+						.onSuccess(adapter::submitList)
+		);
 
 		return contentView;
 	}
@@ -104,14 +68,13 @@ public class ContactChooserFragment extends BaseFragment {
 	@Override
 	public void onStart() {
 		super.onStart();
-		loadContacts();
+		list.startPeriodicUpdate();
 	}
 
 	@Override
 	public void onStop() {
 		super.onStop();
-		adapter.clear();
-		list.showProgressBar();
+		list.stopPeriodicUpdate();
 	}
 
 	@Override
@@ -119,43 +82,9 @@ public class ContactChooserFragment extends BaseFragment {
 		return TAG;
 	}
 
-	private void loadContacts() {
-		listener.runOnDbThread(() -> {
-			try {
-				List<ContactListItem> contacts = new ArrayList<>();
-				for (Contact c : contactManager.getContacts()) {
-					if (c.getId().equals(contactId)) {
-						c1 = c;
-					} else {
-						AuthorInfo authorInfo = authorManager.getAuthorInfo(c);
-						ContactId id = c.getId();
-						GroupCount count =
-								conversationManager.getGroupCount(id);
-						boolean connected =
-								connectionRegistry.isConnected(c.getId());
-						contacts.add(new ContactListItem(c, authorInfo,
-								connected, count));
-					}
-				}
-				displayContacts(contacts);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
-		});
+	@Override
+	public void onItemClick(View view, ContactListItem item) {
+		viewModel.setSecondContactId(item.getContact().getId());
+		viewModel.triggerContactSelected();
 	}
-
-	private void displayContacts(List<ContactListItem> contacts) {
-		runOnUiThreadUnlessDestroyed(() -> {
-			if (contacts.isEmpty()) list.showData();
-			else adapter.addAll(contacts);
-		});
-	}
-
-	private void showMessageScreen(Contact c1, Contact c2) {
-		IntroductionMessageFragment messageFragment =
-				IntroductionMessageFragment
-						.newInstance(c1.getId().getInt(), c2.getId().getInt());
-		showNextFragment(messageFragment);
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/introduction/IntroductionActivity.java

@@ -9,30 +9,67 @@ import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
 import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
 
+import javax.inject.Inject;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.ViewModelProvider;
+
 import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
 
 public class IntroductionActivity extends BriarActivity
 		implements BaseFragmentListener {
 
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private IntroductionViewModel viewModel;
+
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(IntroductionViewModel.class);
+	}
+
+	private static final String BUNDLE_CONTACT2 = "contact2";
+
 	@Override
 	public void onCreate(Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 
 		Intent intent = getIntent();
-		int id = intent.getIntExtra(CONTACT_ID, -1);
-		if (id == -1) throw new IllegalStateException("No ContactId");
-		ContactId contactId = new ContactId(id);
+		int contactId1 = intent.getIntExtra(CONTACT_ID, -1);
+		if (contactId1 == -1)
+			throw new IllegalStateException("No ContactId");
+		ContactId firstContactId = new ContactId(contactId1);
+
+		viewModel.setFirstContactId(firstContactId);
 
 		setContentView(R.layout.activity_fragment_container);
 
 		if (savedInstanceState == null) {
-			showInitialFragment(ContactChooserFragment.newInstance(contactId));
+			showInitialFragment(new ContactChooserFragment());
+		} else {
+			int contactId2 = savedInstanceState.getInt(BUNDLE_CONTACT2);
+			ContactId secondContactId = new ContactId(contactId2);
+			viewModel.setSecondContactId(secondContactId);
 		}
+
+		viewModel.getSecondContactSelected().observeEvent(this, e -> {
+			IntroductionMessageFragment fragment =
+					new IntroductionMessageFragment();
+			showNextFragment(fragment);
+		});
 	}
 
 	@Override
-	public void injectActivity(ActivityComponent component) {
-		component.inject(this);
+	public void onSaveInstanceState(@NonNull Bundle outState) {
+		super.onSaveInstanceState(outState);
+
+		ContactId secondContactId = viewModel.getSecondContactId();
+		if (secondContactId != null) {
+			outState.putInt(BUNDLE_CONTACT2, secondContactId.getInt());
+		}
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/introduction/IntroductionInfo.java

@@ -0,0 +1,28 @@
+package org.briarproject.briar.android.introduction;
+
+import org.briarproject.briar.android.contact.ContactItem;
+
+class IntroductionInfo {
+	private final ContactItem c1;
+	private final ContactItem c2;
+	private final boolean possible;
+
+	IntroductionInfo(ContactItem c1, ContactItem c2,
+			boolean possible) {
+		this.c1 = c1;
+		this.c2 = c2;
+		this.possible = possible;
+	}
+
+	ContactItem getContact1() {
+		return c1;
+	}
+
+	ContactItem getContact2() {
+		return c2;
+	}
+
+	boolean isPossible() {
+		return possible;
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/introduction/IntroductionMessageFragment.java

@@ -1,6 +1,5 @@
 package org.briarproject.briar.android.introduction;
 
-import android.content.Context;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.MenuItem;
@@ -8,12 +7,7 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ProgressBar;
 import android.widget.TextView;
-import android.widget.Toast;
 
-import org.briarproject.bramble.api.contact.Contact;
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.contact.ContactManager;
-import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
@@ -24,25 +18,19 @@ import org.briarproject.briar.android.view.TextInputView;
 import org.briarproject.briar.android.view.TextSendController;
 import org.briarproject.briar.android.view.TextSendController.SendListener;
 import org.briarproject.briar.api.attachment.AttachmentHeader;
-import org.briarproject.briar.api.identity.AuthorInfo;
-import org.briarproject.briar.api.identity.AuthorManager;
-import org.briarproject.briar.api.introduction.IntroductionManager;
 
 import java.util.List;
-import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
-import androidx.appcompat.app.ActionBar;
+import androidx.fragment.app.FragmentActivity;
+import androidx.lifecycle.ViewModelProvider;
 import de.hdodenhof.circleimageview.CircleImageView;
 
 import static android.app.Activity.RESULT_OK;
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
-import static android.widget.Toast.LENGTH_SHORT;
-import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.android.util.UiUtils.getContactDisplayName;
 import static org.briarproject.briar.android.util.UiUtils.hideSoftKeyboard;
 import static org.briarproject.briar.android.view.AuthorView.setAvatar;
@@ -53,45 +41,21 @@ import static org.briarproject.briar.api.introduction.IntroductionConstants.MAX_
 public class IntroductionMessageFragment extends BaseFragment
 		implements SendListener {
 
-	public static final String TAG =
+	private static final String TAG =
 			IntroductionMessageFragment.class.getName();
-	private static final Logger LOG = Logger.getLogger(TAG);
 
-	private final static String CONTACT_ID_1 = "contact1";
-	private final static String CONTACT_ID_2 = "contact2";
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private IntroductionViewModel viewModel;
 
-	private IntroductionActivity introductionActivity;
 	private ViewHolder ui;
-	private Contact contact1, contact2;
-
-	// Fields that are accessed from background threads must be volatile
-	@Inject
-	protected volatile ContactManager contactManager;
-	@Inject
-	protected volatile AuthorManager authorManager;
-	@Inject
-	protected volatile IntroductionManager introductionManager;
-
-	public static IntroductionMessageFragment newInstance(int contactId1,
-			int contactId2) {
-		Bundle args = new Bundle();
-		args.putInt(CONTACT_ID_1, contactId1);
-		args.putInt(CONTACT_ID_2, contactId2);
-		IntroductionMessageFragment fragment =
-				new IntroductionMessageFragment();
-		fragment.setArguments(args);
-		return fragment;
-	}
-
-	@Override
-	public void onAttach(Context context) {
-		super.onAttach(context);
-		introductionActivity = (IntroductionActivity) context;
-	}
 
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(IntroductionViewModel.class);
 	}
 
 	@Override
@@ -100,18 +64,7 @@ public class IntroductionMessageFragment extends BaseFragment
 			@Nullable Bundle savedInstanceState) {
 
 		// change toolbar text
-		ActionBar actionBar = introductionActivity.getSupportActionBar();
-		if (actionBar != null) {
-			actionBar.setTitle(R.string.introduction_message_title);
-		}
-
-		// get contact IDs from fragment arguments
-		Bundle args = requireArguments();
-		int contactId1 = args.getInt(CONTACT_ID_1, -1);
-		int contactId2 = args.getInt(CONTACT_ID_2, -1);
-		if (contactId1 == -1 || contactId2 == -1) {
-			throw new AssertionError("Use newInstance() to instantiate");
-		}
+		requireActivity().setTitle(R.string.introduction_message_title);
 
 		// inflate view
 		View v = inflater.inflate(R.layout.introduction_message, container,
@@ -123,69 +76,44 @@ public class IntroductionMessageFragment extends BaseFragment
 		ui.message.setMaxTextLength(MAX_INTRODUCTION_TEXT_LENGTH);
 		ui.message.setReady(false);
 
-		// get contacts and then show view
-		prepareToSetUpViews(contactId1, contactId2);
+		viewModel.getIntroductionInfo().observe(getViewLifecycleOwner(), ii -> {
+			if (ii == null) {
+				return;
+			}
+			setUpViews(ii.getContact1(), ii.getContact2(),
+					ii.isPossible());
+		});
 
 		return v;
 	}
 
-	@Override
-	public void onStart() {
-		super.onStart();
-	}
-
 	@Override
 	public String getUniqueTag() {
 		return TAG;
 	}
 
-	private void prepareToSetUpViews(int contactId1, int contactId2) {
-		introductionActivity.runOnDbThread(() -> {
-			try {
-				Contact contact1 =
-						contactManager.getContact(new ContactId(contactId1));
-				Contact contact2 =
-						contactManager.getContact(new ContactId(contactId2));
-				AuthorInfo a1 = authorManager.getAuthorInfo(contact1);
-				AuthorInfo a2 = authorManager.getAuthorInfo(contact2);
-				boolean possible =
-						introductionManager.canIntroduce(contact1, contact2);
-				ContactItem c1 = new ContactItem(contact1, a1);
-				ContactItem c2 = new ContactItem(contact2, a2);
-				setUpViews(c1, c2, possible);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
-		});
-	}
-
 	private void setUpViews(ContactItem c1, ContactItem c2, boolean possible) {
-		introductionActivity.runOnUiThreadUnlessDestroyed(() -> {
-			contact1 = c1.getContact();
-			contact2 = c2.getContact();
+		// set avatars
+		setAvatar(ui.avatar1, c1);
+		setAvatar(ui.avatar2, c2);
 
-			// set avatars
-			setAvatar(ui.avatar1, c1);
-			setAvatar(ui.avatar2, c2);
+		// set contact names
+		ui.contactName1.setText(getContactDisplayName(c1.getContact()));
+		ui.contactName2.setText(getContactDisplayName(c2.getContact()));
 
-			// set contact names
-			ui.contactName1.setText(getContactDisplayName(c1.getContact()));
-			ui.contactName2.setText(getContactDisplayName(c2.getContact()));
+		// hide progress bar
+		ui.progressBar.setVisibility(GONE);
 
-			// hide progress bar
-			ui.progressBar.setVisibility(GONE);
-
-			if (possible) {
-				// show views
-				ui.notPossible.setVisibility(GONE);
-				ui.message.setVisibility(VISIBLE);
-				ui.message.setReady(true);
-				ui.message.showSoftKeyboard();
-			} else {
-				ui.notPossible.setVisibility(VISIBLE);
-				ui.message.setVisibility(GONE);
-			}
-		});
+		if (possible) {
+			// show views
+			ui.notPossible.setVisibility(GONE);
+			ui.message.setVisibility(VISIBLE);
+			ui.message.setReady(true);
+			ui.message.showSoftKeyboard();
+		} else {
+			ui.notPossible.setVisibility(VISIBLE);
+			ui.message.setVisibility(GONE);
+		}
 	}
 
 	@Override
@@ -193,7 +121,7 @@ public class IntroductionMessageFragment extends BaseFragment
 		switch (item.getItemId()) {
 			case android.R.id.home:
 				hideSoftKeyboard(ui.message);
-				introductionActivity.onBackPressed();
+				requireActivity().onBackPressed();
 				return true;
 			default:
 				return super.onOptionsItemSelected(item);
@@ -206,32 +134,13 @@ public class IntroductionMessageFragment extends BaseFragment
 		// disable button to prevent accidental double invitations
 		ui.message.setReady(false);
 
-		makeIntroduction(contact1, contact2, text);
+		viewModel.makeIntroduction(text);
 
 		// don't wait for the introduction to be made before finishing activity
 		hideSoftKeyboard(ui.message);
-		introductionActivity.setResult(RESULT_OK);
-		introductionActivity.supportFinishAfterTransition();
-	}
-
-	private void makeIntroduction(Contact c1, Contact c2,
-			@Nullable String text) {
-		introductionActivity.runOnDbThread(() -> {
-			// actually make the introduction
-			try {
-				long timestamp = System.currentTimeMillis();
-				introductionManager.makeIntroduction(c1, c2, text, timestamp);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				introductionError();
-			}
-		});
-	}
-
-	private void introductionError() {
-		introductionActivity.runOnUiThreadUnlessDestroyed(
-				() -> Toast.makeText(introductionActivity,
-						R.string.introduction_error, LENGTH_SHORT).show());
+		FragmentActivity activity = requireActivity();
+		activity.setResult(RESULT_OK);
+		activity.supportFinishAfterTransition();
 	}
 
 	private static class ViewHolder {

briar-android/src/main/java/org/briarproject/briar/android/introduction/IntroductionModule.java

@@ -0,0 +1,19 @@
+package org.briarproject.briar.android.introduction;
+
+import org.briarproject.briar.android.viewmodel.ViewModelKey;
+
+import androidx.lifecycle.ViewModel;
+import dagger.Binds;
+import dagger.Module;
+import dagger.multibindings.IntoMap;
+
+@Module
+public abstract class IntroductionModule {
+
+	@Binds
+	@IntoMap
+	@ViewModelKey(IntroductionViewModel.class)
+	abstract ViewModel bindIntroductionViewModel(
+			IntroductionViewModel introductionViewModel);
+
+}

briar-android/src/main/java/org/briarproject/briar/android/introduction/IntroductionViewModel.java

@@ -0,0 +1,181 @@
+package org.briarproject.briar.android.introduction;
+
+import android.app.Application;
+import android.widget.Toast;
+
+import org.briarproject.bramble.api.connection.ConnectionRegistry;
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.ContactManager;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.contact.ContactItem;
+import org.briarproject.briar.android.contact.ContactsViewModel;
+import org.briarproject.briar.android.viewmodel.LiveEvent;
+import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
+import org.briarproject.briar.api.conversation.ConversationManager;
+import org.briarproject.briar.api.identity.AuthorInfo;
+import org.briarproject.briar.api.identity.AuthorManager;
+import org.briarproject.briar.api.introduction.IntroductionManager;
+
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import androidx.annotation.Nullable;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import static android.widget.Toast.LENGTH_SHORT;
+import static java.util.Objects.requireNonNull;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@NotNullByDefault
+class IntroductionViewModel extends ContactsViewModel {
+
+	private static final Logger LOG =
+			getLogger(IntroductionViewModel.class.getName());
+
+	private final ContactManager contactManager;
+	private final AuthorManager authorManager;
+	private final IntroductionManager introductionManager;
+
+	@Inject
+	IntroductionViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager, TransactionManager db,
+			AndroidExecutor androidExecutor, ContactManager contactManager,
+			AuthorManager authorManager,
+			ConversationManager conversationManager,
+			ConnectionRegistry connectionRegistry, EventBus eventBus,
+			IntroductionManager introductionManager) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
+				contactManager, authorManager, conversationManager,
+				connectionRegistry, eventBus);
+		this.contactManager = contactManager;
+		this.authorManager = authorManager;
+		this.introductionManager = introductionManager;
+	}
+
+	/*
+	 * This is the contact from whose conversation we started the introduction
+	 * using the menu item.
+	 */
+	@Nullable
+	private ContactId firstContactId;
+	/*
+	 * This is the contact we selected from the list of contacts as a second
+	 * contact for the introduction.
+	 */
+	@Nullable
+	private ContactId secondContactId;
+
+	private final MutableLiveEvent<Boolean> secondContactSelected =
+			new MutableLiveEvent<>();
+
+	private final MutableLiveData<IntroductionInfo> introductionInfo =
+			new MutableLiveData<>();
+
+	void setFirstContactId(ContactId contactId) {
+		this.firstContactId = contactId;
+		loadContacts();
+	}
+
+	@Nullable
+	ContactId getSecondContactId() {
+		return secondContactId;
+	}
+
+	void setSecondContactId(ContactId contactId) {
+		secondContactId = contactId;
+		// Setting this to null here so that IntroductionMessageFragment can
+		// tell whether the correct value has been loaded from the database when
+		// selecting a second contact repeatedly.
+		introductionInfo.setValue(null);
+		loadIntroductionInfo();
+	}
+
+	/**
+	 * Trigger the event that the second contact has been selected from the
+	 * contact list by the user.
+	 */
+	void triggerContactSelected() {
+		secondContactSelected.setEvent(true);
+	}
+
+	/**
+	 * This event will be triggered once the second contact has been selected
+	 * from the list of contacts displayed. It is not fired when the second
+	 * contact gets restored from the saved instance state.
+	 */
+	LiveEvent<Boolean> getSecondContactSelected() {
+		return secondContactSelected;
+	}
+
+	/**
+	 * Holder for the introduction info object with data about both contacts
+	 * and whether the introduction is possible. May wrap null if the data
+	 * is not available yet. This happens when it is reset by selecting a
+	 * contact with the same view model instance more than once.
+	 */
+	LiveData<IntroductionInfo> getIntroductionInfo() {
+		return introductionInfo;
+	}
+
+	@Override
+	protected boolean displayContact(ContactId contactId) {
+		return !requireNonNull(firstContactId).equals(contactId);
+	}
+
+	private void loadIntroductionInfo() {
+		final ContactId firstContactId = requireNonNull(this.firstContactId);
+		final ContactId secondContactId = requireNonNull(this.secondContactId);
+		runOnDbThread(() -> {
+			try {
+				Contact firstContact =
+						contactManager.getContact(firstContactId);
+				Contact secondContact =
+						contactManager.getContact(secondContactId);
+				AuthorInfo a1 = authorManager.getAuthorInfo(firstContact);
+				AuthorInfo a2 = authorManager.getAuthorInfo(secondContact);
+				boolean possible = introductionManager
+						.canIntroduce(firstContact, secondContact);
+				ContactItem c1 = new ContactItem(firstContact, a1);
+				ContactItem c2 = new ContactItem(secondContact, a2);
+				introductionInfo.postValue(
+						new IntroductionInfo(c1, c2, possible));
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	void makeIntroduction(@Nullable String text) {
+		final IntroductionInfo info =
+				requireNonNull(introductionInfo.getValue());
+		runOnDbThread(() -> {
+			// actually make the introduction
+			try {
+				long timestamp = System.currentTimeMillis();
+				introductionManager.makeIntroduction(
+						info.getContact1().getContact(),
+						info.getContact2().getContact(), text, timestamp);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				androidExecutor.runOnUiThread(() -> Toast.makeText(
+						getApplication(), R.string.introduction_error,
+						LENGTH_SHORT).show());
+			}
+		});
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/KeyAgreementActivity.java

@@ -411,6 +411,8 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 	@UiThread
 	public void onRequestPermissionsResult(int requestCode,
 			String[] permissions, int[] grantResults) {
+		super.onRequestPermissionsResult(requestCode, permissions,
+				grantResults);
 		if (requestCode != REQUEST_PERMISSION_CAMERA_LOCATION)
 			throw new AssertionError();
 		if (gotPermission(CAMERA, permissions, grantResults)) {

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerActivity.java

@@ -49,14 +49,12 @@ import androidx.annotation.DrawableRes;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.StringRes;
-import androidx.appcompat.app.ActionBar;
 import androidx.appcompat.app.ActionBarDrawerToggle;
 import androidx.appcompat.widget.Toolbar;
 import androidx.core.app.ActivityCompat;
 import androidx.core.content.ContextCompat;
 import androidx.drawerlayout.widget.DrawerLayout;
 import androidx.fragment.app.FragmentManager;
-import androidx.fragment.app.FragmentTransaction;
 import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.lifecycle.ViewModelProviders;
@@ -67,9 +65,7 @@ import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
 import static androidx.core.view.GravityCompat.START;
 import static androidx.drawerlayout.widget.DrawerLayout.LOCK_MODE_LOCKED_CLOSED;
-import static androidx.fragment.app.FragmentManager.POP_BACK_STACK_INCLUSIVE;
 import static androidx.lifecycle.Lifecycle.State.STARTED;
-import static java.util.Objects.requireNonNull;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.RUNNING;
 import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
@@ -146,7 +142,7 @@ public class NavDrawerActivity extends BriarActivity implements
 			if (ask) showDozeDialog(getString(R.string.setup_doze_intro));
 		});
 
-		Toolbar toolbar = findViewById(R.id.toolbar);
+		Toolbar toolbar = setUpCustomToolbar(false);
 		drawerLayout = findViewById(R.id.drawer_layout);
 		navigation = findViewById(R.id.navigation);
 		GridView transportsView = findViewById(R.id.transportsView);
@@ -156,11 +152,6 @@ public class NavDrawerActivity extends BriarActivity implements
 			startActivity(new Intent(this, TransportsActivity.class));
 		});
 
-		setSupportActionBar(toolbar);
-		ActionBar actionBar = requireNonNull(getSupportActionBar());
-		actionBar.setDisplayHomeAsUpEnabled(true);
-		actionBar.setHomeButtonEnabled(true);
-
 		drawerToggle = new ActionBarDrawerToggle(this, drawerLayout, toolbar,
 				R.string.nav_drawer_open_description,
 				R.string.nav_drawer_close_description) {
@@ -184,9 +175,6 @@ public class NavDrawerActivity extends BriarActivity implements
 
 		if (lifecycleManager.getLifecycleState().isAfter(RUNNING)) {
 			showSignOutFragment();
-		} else if (state == null) {
-			startFragment(ContactListFragment.newInstance(),
-					R.id.nav_btn_contacts);
 		}
 		if (state == null) {
 			// do not call this again when there's existing state
@@ -276,7 +264,6 @@ public class NavDrawerActivity extends BriarActivity implements
 	@Override
 	public boolean onNavigationItemSelected(@NonNull MenuItem item) {
 		drawerLayout.closeDrawer(START);
-		clearBackStack();
 		if (item.getItemId() == R.id.nav_btn_lock) {
 			lockManager.setLocked(true);
 			ActivityCompat.finishAfterTransition(this);
@@ -296,8 +283,8 @@ public class NavDrawerActivity extends BriarActivity implements
 			FragmentManager fm = getSupportFragmentManager();
 			if (fm.findFragmentByTag(SignOutFragment.TAG) != null) {
 				finish();
-			} else if (fm.getBackStackEntryCount() == 0
-					&& fm.findFragmentByTag(ContactListFragment.TAG) == null) {
+			} else if (fm.getBackStackEntryCount() == 0 &&
+					fm.findFragmentByTag(ContactListFragment.TAG) == null) {
 				// don't start fragments in the wrong part of lifecycle (#1904)
 				if (!getLifecycle().getCurrentState().isAtLeast(STARTED)) {
 					LOG.warning("Tried to start contacts fragment in state " +
@@ -346,30 +333,12 @@ public class NavDrawerActivity extends BriarActivity implements
 		startFragment(fragment);
 	}
 
-	private void startFragment(BaseFragment fragment) {
-		if (getSupportFragmentManager().getBackStackEntryCount() == 0)
-			startFragment(fragment, false);
-		else startFragment(fragment, true);
-	}
-
-	private void startFragment(BaseFragment fragment,
-			boolean isAddedToBackStack) {
-		FragmentTransaction trans =
-				getSupportFragmentManager().beginTransaction()
-						.setCustomAnimations(R.anim.fade_in,
-								R.anim.fade_out, R.anim.fade_in,
-								R.anim.fade_out)
-						.replace(R.id.fragmentContainer, fragment,
-								fragment.getUniqueTag());
-		if (isAddedToBackStack) {
-			trans.addToBackStack(fragment.getUniqueTag());
-		}
-		trans.commit();
-	}
-
-	private void clearBackStack() {
-		getSupportFragmentManager().popBackStackImmediate(null,
-				POP_BACK_STACK_INCLUSIVE);
+	private void startFragment(BaseFragment f) {
+		getSupportFragmentManager().beginTransaction()
+				.setCustomAnimations(R.anim.fade_in, R.anim.fade_out,
+						R.anim.fade_in, R.anim.fade_out)
+				.replace(R.id.fragmentContainer, f, f.getUniqueTag())
+				.commit();
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupActivity.java

@@ -79,9 +79,10 @@ public class GroupActivity extends
 
 		// start with group disabled and enable when not dissolved
 		setGroupEnabled(false);
-		viewModel.isDissolved().observeEvent(this, dissolved -> {
+		viewModel.isDissolved().observe(this, dissolved -> {
 			setGroupEnabled(!dissolved);
-			if (dissolved) onGroupDissolved();
+			// only show dialog when no prior state
+			if (dissolved && state == null) onGroupDissolved();
 		});
 	}
 
@@ -153,7 +154,7 @@ public class GroupActivity extends
 
 	@Override
 	public void onReplyClick(GroupMessageItem item) {
-		Boolean isDissolved = viewModel.isDissolved().getLastValue();
+		Boolean isDissolved = viewModel.isDissolved().getValue();
 		if (isDissolved != null && !isDissolved) super.onReplyClick(item);
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupViewModel.java

@@ -22,8 +22,6 @@ import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.briar.android.sharing.SharingController;
 import org.briarproject.briar.android.threaded.ThreadListViewModel;
-import org.briarproject.briar.android.viewmodel.LiveEvent;
-import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.MessageTracker.GroupCount;
@@ -71,8 +69,8 @@ class GroupViewModel extends ThreadListViewModel<GroupMessageItem> {
 	private final MutableLiveData<PrivateGroup> privateGroup =
 			new MutableLiveData<>();
 	private final MutableLiveData<Boolean> isCreator = new MutableLiveData<>();
-	private final MutableLiveEvent<Boolean> isDissolved =
-			new MutableLiveEvent<>();
+	private final MutableLiveData<Boolean> isDissolved =
+			new MutableLiveData<>();
 
 	@Inject
 	GroupViewModel(Application application,
@@ -129,7 +127,7 @@ class GroupViewModel extends ThreadListViewModel<GroupMessageItem> {
 		} else if (e instanceof GroupDissolvedEvent) {
 			GroupDissolvedEvent g = (GroupDissolvedEvent) e;
 			if (g.getGroupId().equals(groupId)) {
-				isDissolved.setEvent(true);
+				isDissolved.setValue(true);
 			}
 		} else {
 			super.eventOccurred(e);
@@ -161,10 +159,10 @@ class GroupViewModel extends ThreadListViewModel<GroupMessageItem> {
 
 	@Override
 	public void loadItems() {
-		loadList(txn -> {
+		loadFromDb(txn -> {
 			// check first if group is dissolved
 			isDissolved
-					.postEvent(privateGroupManager.isDissolved(txn, groupId));
+					.postValue(privateGroupManager.isDissolved(txn, groupId));
 			// now continue to load the items
 			long start = now();
 			List<GroupMessageHeader> headers =
@@ -282,7 +280,7 @@ class GroupViewModel extends ThreadListViewModel<GroupMessageItem> {
 		return isCreator;
 	}
 
-	LiveEvent<Boolean> isDissolved() {
+	LiveData<Boolean> isDissolved() {
 		return isDissolved;
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListViewModel.java

@@ -2,7 +2,6 @@ package org.briarproject.briar.android.privategroup.list;
 
 import android.app.Application;
 
-import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
@@ -142,7 +141,7 @@ class GroupListViewModel extends DbViewModel implements EventListener {
 	}
 
 	void loadGroups() {
-		loadList(this::loadGroups, groupItems::setValue);
+		loadFromDb(this::loadGroups, groupItems::setValue);
 	}
 
 	@DatabaseExecutor
@@ -173,7 +172,7 @@ class GroupListViewModel extends DbViewModel implements EventListener {
 	@UiThread
 	private void onGroupMessageAdded(GroupMessageHeader header) {
 		GroupId g = header.getGroupId();
-		List<GroupItem> list = updateListItems(groupItems,
+		List<GroupItem> list = updateListItems(getList(groupItems),
 				itemToTest -> itemToTest.getId().equals(g),
 				itemToUpdate -> new GroupItem(itemToUpdate, header));
 		if (list == null) return;
@@ -184,7 +183,7 @@ class GroupListViewModel extends DbViewModel implements EventListener {
 
 	@UiThread
 	private void onGroupDissolved(GroupId groupId) {
-		List<GroupItem> list = updateListItems(groupItems,
+		List<GroupItem> list = updateListItems(getList(groupItems),
 				itemToTest -> itemToTest.getId().equals(groupId),
 				itemToUpdate -> new GroupItem(itemToUpdate, true));
 		if (list == null) return;
@@ -193,10 +192,7 @@ class GroupListViewModel extends DbViewModel implements EventListener {
 
 	@UiThread
 	private void onGroupRemoved(GroupId groupId) {
-		List<GroupItem> list =
-				removeListItems(groupItems, i -> i.getId().equals(groupId));
-		if (list == null) return;
-		groupItems.setValue(new LiveResult<>(list));
+		removeAndUpdateListItems(groupItems, i -> i.getId().equals(groupId));
 	}
 
 	void removeGroup(GroupId g) {

briar-android/src/main/java/org/briarproject/briar/android/privategroup/reveal/RevealContactsFragment.java

@@ -8,7 +8,7 @@ import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
+import org.briarproject.briar.android.contact.OnContactClickListener;
 import org.briarproject.briar.android.contactselection.BaseContactSelectorFragment;
 import org.briarproject.briar.android.contactselection.ContactSelectorController;
 

briar-android/src/main/java/org/briarproject/briar/android/privategroup/reveal/RevealableContactAdapter.java

@@ -8,6 +8,7 @@ import android.view.ViewGroup;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.contact.OnContactClickListener;
 import org.briarproject.briar.android.contactselection.BaseContactSelectorAdapter;
 
 import java.util.ArrayList;

briar-android/src/main/java/org/briarproject/briar/android/privategroup/reveal/RevealableContactViewHolder.java

@@ -5,7 +5,7 @@ import android.widget.ImageView;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
+import org.briarproject.briar.android.contact.OnContactClickListener;
 import org.briarproject.briar.android.contactselection.BaseSelectableContactHolder;
 
 import javax.annotation.Nullable;

briar-android/src/main/java/org/briarproject/briar/android/reporting/ReportData.java

@@ -51,15 +51,15 @@ class ReportData {
 		final boolean isOptional;
 		boolean isIncluded = true;
 
-		ReportItem(String name, int nameRes, ReportInfo info) {
+		ReportItem(String name, @StringRes int nameRes, ReportInfo info) {
 			this(name, nameRes, info, true);
 		}
 
-		ReportItem(String name, int nameRes, String info) {
+		ReportItem(String name, @StringRes int nameRes, String info) {
 			this(name, nameRes, new SingleReportInfo(info), true);
 		}
 
-		ReportItem(String name, int nameRes, ReportInfo info,
+		ReportItem(String name, @StringRes int nameRes, ReportInfo info,
 				boolean isOptional) {
 			this.name = name;
 			this.nameRes = nameRes;

briar-android/src/main/java/org/briarproject/briar/android/reporting/ReportViewModel.java

@@ -15,6 +15,7 @@ import org.briarproject.briar.android.logging.BriefLogFormatter;
 import org.briarproject.briar.android.logging.CachingLogHandler;
 import org.briarproject.briar.android.logging.LogDecrypter;
 import org.briarproject.briar.android.reporting.ReportData.MultiReportInfo;
+import org.briarproject.briar.android.reporting.ReportData.ReportItem;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 import org.json.JSONException;
@@ -156,7 +157,8 @@ class ReportViewModel extends AndroidViewModel {
 			MultiReportInfo userInfo = new MultiReportInfo();
 			if (!isNullOrEmpty(comment)) userInfo.add("Comment", comment);
 			if (!isNullOrEmpty(email)) userInfo.add("Email", email);
-			data.add(new ReportData.ReportItem("UserInfo", 0, userInfo, false));
+			data.add(new ReportItem("UserInfo", R.string.dev_report_user_info,
+					userInfo, false));
 		}
 
 		// check the state of the TorPlugin, if this is feedback

briar-android/src/main/java/org/briarproject/briar/android/settings/ConfirmAvatarDialogFragment.java

@@ -9,10 +9,13 @@ import android.view.View;
 import android.widget.ImageView;
 import android.widget.TextView;
 
+import com.bumptech.glide.load.engine.DiskCacheStrategy;
+
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.BaseActivity;
+import org.briarproject.briar.android.conversation.glide.GlideApp;
 
 import javax.inject.Inject;
 
@@ -32,7 +35,7 @@ public class ConfirmAvatarDialogFragment extends DialogFragment {
 
 	@Inject
 	ViewModelProvider.Factory viewModelFactory;
-	private SettingsViewModel settingsViewModel;
+	private SettingsViewModel viewModel;
 
 	private static final String ARG_URI = "uri";
 	private Uri uri;
@@ -51,6 +54,9 @@ public class ConfirmAvatarDialogFragment extends DialogFragment {
 	public void onAttach(Context ctx) {
 		super.onAttach(ctx);
 		((BaseActivity) requireActivity()).getActivityComponent().inject(this);
+		ViewModelProvider provider =
+				new ViewModelProvider(requireActivity(), viewModelFactory);
+		viewModel = provider.get(SettingsViewModel.class);
 	}
 
 	@Override
@@ -60,32 +66,34 @@ public class ConfirmAvatarDialogFragment extends DialogFragment {
 		uri = Uri.parse(argUri);
 
 		FragmentActivity activity = requireActivity();
-
-		ViewModelProvider provider =
-				new ViewModelProvider(activity, viewModelFactory);
-		settingsViewModel = provider.get(SettingsViewModel.class);
-
-		AlertDialog.Builder builder =
-				new AlertDialog.Builder(activity, R.style.BriarDialogTheme);
-
-		LayoutInflater inflater = LayoutInflater.from(getContext());
+		LayoutInflater inflater = LayoutInflater.from(activity);
 		final View view =
 				inflater.inflate(R.layout.fragment_confirm_avatar_dialog, null);
-		builder.setView(view);
-
-		builder.setTitle(R.string.dialog_confirm_profile_picture_title);
-		builder.setNegativeButton(R.string.cancel, null);
-		builder.setPositiveButton(R.string.change,
-				(dialog, id) -> settingsViewModel.setAvatar(uri));
-
 		ImageView imageView = view.findViewById(R.id.image);
-		imageView.setImageURI(uri);
-
 		TextView textViewUserName = view.findViewById(R.id.username);
-		settingsViewModel.getOwnIdentityInfo().observe(activity,
-				us -> textViewUserName.setText(us.getLocalAuthor().getName()));
 
-		return builder.create();
+		GlideApp.with(imageView)
+				.load(uri)
+				.diskCacheStrategy(DiskCacheStrategy.NONE)
+				.error(R.drawable.ic_image_broken)
+				.into(imageView)
+				.waitForLayout();
+
+		// we can't use getViewLifecycleOwner() here
+		// as this fragment technically doesn't have a view
+		viewModel.getOwnIdentityInfo().observe(activity, us ->
+				textViewUserName.setText(us.getLocalAuthor().getName())
+		);
+
+		int theme = R.style.BriarDialogTheme;
+		return new AlertDialog.Builder(activity, theme)
+				.setView(view)
+				.setTitle(R.string.dialog_confirm_profile_picture_title)
+				.setNegativeButton(R.string.cancel, null)
+				.setPositiveButton(R.string.change, (d, id) ->
+						viewModel.setAvatar(uri)
+				)
+				.create();
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/settings/SettingsViewModel.java

@@ -79,7 +79,7 @@ class SettingsViewModel extends AndroidViewModel {
 		return ownIdentityInfo;
 	}
 
-	public LiveEvent<Boolean> getSetAvatarFailed() {
+	LiveEvent<Boolean> getSetAvatarFailed() {
 		return setAvatarFailed;
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/splash/ExpiredActivity.java

@@ -1,5 +1,6 @@
 package org.briarproject.briar.android.splash;
 
+import android.content.Context;
 import android.content.Intent;
 import android.net.Uri;
 import android.os.Bundle;
@@ -7,6 +8,7 @@ import android.view.View;
 import android.view.View.OnClickListener;
 
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.Localizer;
 
 import androidx.appcompat.app.AppCompatActivity;
 
@@ -27,6 +29,13 @@ public class ExpiredActivity extends AppCompatActivity
 		findViewById(R.id.download_briar_button).setOnClickListener(this);
 	}
 
+	@Override
+	protected void attachBaseContext(Context base) {
+		super.attachBaseContext(
+				Localizer.getInstance().setLocale(base));
+		Localizer.getInstance().setLocale(this);
+	}
+
 	@Override
 	public void onClick(View v) {
 		Uri uri = Uri.parse("https://briarproject.org/download.html");

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadListViewModel.java

@@ -197,6 +197,10 @@ public abstract class ThreadListViewModel<I extends ThreadItem>
 	 */
 	@UiThread
 	protected void addItem(I item, boolean scrollToItem) {
+		// If items haven't loaded, we need to wait until they have.
+		// Since this was a R/W DB transaction, the load will pick up this item.
+		if (items.getValue() == null) return;
+
 		messageTree.add(item);
 		if (scrollToItem) this.scrollToItem.set(item.getId());
 		items.setValue(new LiveResult<>(messageTree.depthFirstOrder()));

briar-android/src/main/java/org/briarproject/briar/android/util/UiUtils.java

@@ -34,7 +34,6 @@ import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.reporting.FeedbackActivity;
 import org.briarproject.briar.android.view.ArticleMovementMethod;
-import org.briarproject.briar.android.widget.LinkDialogFragment;
 
 import java.util.Locale;
 
@@ -49,8 +48,8 @@ import androidx.appcompat.app.AlertDialog;
 import androidx.core.content.ContextCompat;
 import androidx.core.hardware.fingerprint.FingerprintManagerCompat;
 import androidx.core.text.HtmlCompat;
+import androidx.core.util.Consumer;
 import androidx.fragment.app.FragmentActivity;
-import androidx.fragment.app.FragmentManager;
 import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.Observer;
@@ -198,8 +197,7 @@ public class UiUtils {
 	}
 
 	public static void makeLinksClickable(TextView v,
-			@Nullable FragmentManager fm) {
-		if (fm == null) return;
+			Consumer<String> onLinkClicked) {
 		SpannableStringBuilder ssb = new SpannableStringBuilder(v.getText());
 		URLSpan[] spans = ssb.getSpans(0, ssb.length(), URLSpan.class);
 		for (URLSpan span : spans) {
@@ -210,8 +208,7 @@ public class UiUtils {
 			ClickableSpan cSpan = new ClickableSpan() {
 				@Override
 				public void onClick(View v2) {
-					LinkDialogFragment f = LinkDialogFragment.newInstance(url);
-					f.show(fm, f.getUniqueTag());
+					onLinkClicked.accept(url);
 				}
 			};
 			ssb.setSpan(cSpan, start, end, 0);

briar-android/src/main/java/org/briarproject/briar/android/view/BriarRecyclerView.java

@@ -52,7 +52,8 @@ public class BriarRecyclerView extends FrameLayout {
 				R.styleable.BriarRecyclerView);
 		isScrollingToEnd = attributes
 				.getBoolean(R.styleable.BriarRecyclerView_scrollToEnd, true);
-		int drawableRes = attributes.getResourceId(R.styleable.BriarRecyclerView_emptyImage, -1);
+		int drawableRes = attributes
+				.getResourceId(R.styleable.BriarRecyclerView_emptyImage, -1);
 		if (drawableRes != -1) setEmptyImage(drawableRes);
 		String emtpyText =
 				attributes.getString(R.styleable.BriarRecyclerView_emptyText);
@@ -87,10 +88,30 @@ public class BriarRecyclerView extends FrameLayout {
 		}
 
 		emptyObserver = new RecyclerView.AdapterDataObserver() {
+
+			@Override
+			public void onChanged() {
+				super.onChanged();
+				showData();
+			}
+
+			@Override
+			public void onItemRangeChanged(int positionStart, int itemCount) {
+				super.onItemRangeChanged(positionStart, itemCount);
+				if (itemCount > 0) showData();
+			}
+
+			@Override
+			public void onItemRangeMoved(int fromPosition, int toPosition,
+					int itemCount) {
+				super.onItemRangeMoved(fromPosition, toPosition, itemCount);
+				if (itemCount > 0) showData();
+			}
+
 			@Override
 			public void onItemRangeInserted(int positionStart, int itemCount) {
 				super.onItemRangeInserted(positionStart, itemCount);
-				if (itemCount > 0) showData();
+				showData();
 			}
 
 			@Override

briar-android/src/main/java/org/briarproject/briar/android/viewmodel/DbViewModel.java

@@ -1,6 +1,7 @@
 package org.briarproject.briar.android.viewmodel;
 
 import android.app.Application;
+import android.widget.Toast;
 
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbCallable;
@@ -11,8 +12,10 @@ import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.bramble.util.StringUtils;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 import java.util.ListIterator;
 import java.util.concurrent.Executor;
@@ -20,6 +23,7 @@ import java.util.logging.Logger;
 
 import javax.annotation.concurrent.Immutable;
 
+import androidx.annotation.AnyThread;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
@@ -27,8 +31,10 @@ import androidx.arch.core.util.Function;
 import androidx.core.util.Consumer;
 import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
 import androidx.recyclerview.widget.RecyclerView;
 
+import static android.widget.Toast.LENGTH_LONG;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -43,7 +49,7 @@ public abstract class DbViewModel extends AndroidViewModel {
 	private final Executor dbExecutor;
 	private final LifecycleManager lifecycleManager;
 	private final TransactionManager db;
-	private final AndroidExecutor androidExecutor;
+	protected final AndroidExecutor androidExecutor;
 
 	public DbViewModel(
 			@NonNull Application application,
@@ -64,7 +70,7 @@ public abstract class DbViewModel extends AndroidViewModel {
 	 * <p>
 	 * If you need a list of items to be displayed in a
 	 * {@link RecyclerView.Adapter},
-	 * use {@link #loadList(DbCallable, UiConsumer)} instead.
+	 * use {@link #loadFromDb(DbCallable, UiConsumer)} instead.
 	 */
 	protected void runOnDbThread(Runnable task) {
 		dbExecutor.execute(() -> {
@@ -84,7 +90,7 @@ public abstract class DbViewModel extends AndroidViewModel {
 	 * <p>
 	 * If you need a list of items to be displayed in a
 	 * {@link RecyclerView.Adapter},
-	 * use {@link #loadList(DbCallable, UiConsumer)} instead.
+	 * use {@link #loadFromDb(DbCallable, UiConsumer)} instead.
 	 */
 	protected void runOnDbThread(boolean readOnly,
 			DbRunnable<Exception> task, Consumer<Exception> err) {
@@ -102,21 +108,20 @@ public abstract class DbViewModel extends AndroidViewModel {
 	}
 
 	/**
-	 * Loads a list of items on the {@link DatabaseExecutor} within a single
+	 * Loads a data on the {@link DatabaseExecutor} within a single
 	 * {@link Transaction} and publishes it as a {@link LiveResult}
 	 * to the {@link UiThread}.
 	 * <p>
-	 * Use this to ensure that modifications to your local list do not get
+	 * Use this to ensure that modifications to your local UI data do not get
 	 * overridden by database loads that were in progress while the modification
 	 * was made.
 	 * E.g. An event about the removal of a message causes the message item to
-	 * be removed from the local list while all messages are reloaded.
+	 * be removed from the local data set while all messages are reloaded.
 	 * This method ensures that those operations can be processed on the
 	 * UiThread in the correct order so that the removed message will not be
 	 * re-added when the re-load completes.
 	 */
-	protected <T extends List<?>> void loadList(
-			DbCallable<T, DbException> task,
+	protected <T> void loadFromDb(DbCallable<T, DbException> task,
 			UiConsumer<LiveResult<T>> uiConsumer) {
 		dbExecutor.execute(() -> {
 			try {
@@ -143,25 +148,46 @@ public abstract class DbViewModel extends AndroidViewModel {
 	}
 
 	/**
-	 * Creates a copy of the list available in the given LiveData
-	 * and replaces items where the given test function returns true.
+	 * Creates a copy of the given list and adds the given item to the copy.
 	 *
-	 * @return a copy of the list in the LiveData with item(s) replaced
-	 * or null when the
-	 * <ul>
-	 * <li> LiveData does not have a value
-	 * <li> LiveResult in the LiveData has an error
-	 * <li> test function did return false for all items in the list
-	 * </ul>
+	 * @return an updated copy of the list, or null if the list is null
 	 */
 	@Nullable
-	protected <T> List<T> updateListItems(
-			LiveData<LiveResult<List<T>>> liveData, Function<T, Boolean> test,
-			Function<T, T> replacer) {
-		List<T> items = getListCopy(liveData);
-		if (items == null) return null;
+	protected <T> List<T> addListItem(@Nullable List<T> list, T item) {
+		if (list == null) return null;
+		List<T> copy = new ArrayList<>(list);
+		copy.add(item);
+		return copy;
+	}
 
-		ListIterator<T> iterator = items.listIterator();
+	/**
+	 * Creates a copy of the given list and adds the given items to the copy.
+	 *
+	 * @return an updated copy of the list, or null if the list is null
+	 */
+	@Nullable
+	protected <T> List<T> addListItems(@Nullable List<T> list,
+			Collection<T> items) {
+		if (list == null) return null;
+		List<T> copy = new ArrayList<>(list);
+		copy.addAll(items);
+		return copy;
+	}
+
+	/**
+	 * Creates a copy of the given list, replacing items where the given test
+	 * function returns true.
+	 *
+	 * @return an updated copy of the list, or null if either the list is null
+	 * or the test function returns false for all items
+	 */
+	@Nullable
+	protected <T> List<T> updateListItems(@Nullable List<T> list,
+			Function<T, Boolean> test, Function<T, T> replacer) {
+		if (list == null) return null;
+		List<T> copy = new ArrayList<>(list);
+
+		ListIterator<T> iterator = copy.listIterator();
 		boolean changed = false;
 		while (iterator.hasNext()) {
 			T item = iterator.next();
@@ -170,28 +196,23 @@ public abstract class DbViewModel extends AndroidViewModel {
 				iterator.set(replacer.apply(item));
 			}
 		}
-		return changed ? items : null;
+		return changed ? copy : null;
 	}
 
 	/**
-	 * Creates a copy of the list available in the given LiveData
-	 * and removes the items from it where the given test function returns true.
+	 * Creates a copy of the given list, removing items from it where the given
+	 * test function returns true.
 	 *
-	 * @return a copy of the list in the LiveData with item(s) removed
-	 * or null when the
-	 * <ul>
-	 * <li> LiveData does not have a value
-	 * <li> LiveResult in the LiveData has an error
-	 * <li> test function did return false for all items in the list
-	 * </ul>
+	 * @return an updated copy of the list, or null if either the list is null
+	 * or the test function returns false for all items
 	 */
 	@Nullable
-	protected <T> List<T> removeListItems(
-			LiveData<LiveResult<List<T>>> liveData, Function<T, Boolean> test) {
-		List<T> items = getListCopy(liveData);
-		if (items == null) return null;
+	protected <T> List<T> removeListItems(@Nullable List<T> list,
+			Function<T, Boolean> test) {
+		if (list == null) return null;
+		List<T> copy = new ArrayList<>(list);
 
-		ListIterator<T> iterator = items.listIterator();
+		ListIterator<T> iterator = copy.listIterator();
 		boolean changed = false;
 		while (iterator.hasNext()) {
 			T item = iterator.next();
@@ -200,21 +221,58 @@ public abstract class DbViewModel extends AndroidViewModel {
 				iterator.remove();
 			}
 		}
-		return changed ? items : null;
+		return changed ? copy : null;
 	}
 
 	/**
-	 * Retrieves a copy of the list of items from the given LiveData
-	 * or null if it is not available.
-	 * The list copy can be safely mutated.
+	 * Updates the given LiveData with a copy of its list
+	 * with the items removed where the given test function returns true.
+	 * <p>
+	 * Nothing is updated, if the
+	 * <ul>
+	 * <li> LiveData does not have a value
+	 * <li> LiveResult in the LiveData has an error
+	 * <li> test function returned false for all items in the list
+	 * </ul>
+	 */
+	@UiThread
+	protected <T> void removeAndUpdateListItems(
+			MutableLiveData<LiveResult<List<T>>> liveData,
+			Function<T, Boolean> test) {
+		List<T> copy = removeListItems(getList(liveData), test);
+		if (copy != null) liveData.setValue(new LiveResult<>(copy));
+	}
+
+	/**
+	 * Returns the list of items from the given LiveData, or null if no list is
+	 * available.
 	 */
 	@Nullable
-	private <T> List<T> getListCopy(LiveData<LiveResult<List<T>>> liveData) {
+	protected <T> List<T> getList(LiveData<LiveResult<List<T>>> liveData) {
 		LiveResult<List<T>> value = liveData.getValue();
 		if (value == null) return null;
-		List<T> list = value.getResultOrNull();
-		if (list == null) return null;
-		return new ArrayList<>(list);
+		return value.getResultOrNull();
+	}
+
+	/**
+	 * Logs the exception and shows a Toast to the user.
+	 * <p>
+	 * Errors that are likely or expected to happen should not use this method
+	 * and show proper error states in UI.
+	 */
+	@AnyThread
+	protected void handleException(Exception e) {
+		logException(LOG, WARNING, e);
+		androidExecutor.runOnUiThread(() -> {
+			String msg = "Error: " + e.getClass().getSimpleName();
+			if (!StringUtils.isNullOrEmpty(e.getMessage())) {
+				msg += " " + e.getMessage();
+			}
+			if (e.getCause() != null) {
+				msg += " caused by " + e.getCause().getClass().getSimpleName();
+			}
+			Toast.makeText(getApplication(), msg, LENGTH_LONG).show();
+		});
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/api/android/AndroidNotificationManager.java

@@ -39,7 +39,8 @@ public interface AndroidNotificationManager {
 	String BLOG_CHANNEL_ID = "blogs";
 	// Channels are sorted by channel ID in the Settings app, so use IDs
 	// that will sort below the main channels such as contacts
-	String ONGOING_CHANNEL_ID = "zForegroundService";
+	String ONGOING_CHANNEL_OLD_ID = "zForegroundService";
+	String ONGOING_CHANNEL_ID = "zForegroundService2";
 	String FAILURE_CHANNEL_ID = "zStartupFailure";
 	String REMINDER_CHANNEL_ID = "zSignInReminder";
 

briar-android/src/main/java/org/briarproject/briar/api/android/LockManager.java

@@ -8,6 +8,7 @@ import androidx.lifecycle.LiveData;
 public interface LockManager {
 
 	String ACTION_LOCK = "lock";
+	String EXTRA_PID = "PID";
 
 	/**
 	 * Stops the inactivity timer when the user interacts with the app.