only display custodian help recover explainer screen if you are a custodian

briar-android/src/main/java/org/briarproject/briar/android/socialbackup/CustodianHelpRecoverActivity.java

@@ -1,11 +1,22 @@
 package org.briarproject.briar.android.socialbackup;
 
+import android.content.Intent;
 import android.os.Bundle;
+import android.widget.Toast;
 
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
 import org.briarproject.briar.android.fragment.BaseFragment;
+import org.briarproject.briar.api.socialbackup.BackupMetadata;
+import org.briarproject.briar.api.socialbackup.SocialBackupManager;
+
+import javax.inject.Inject;
+
+import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
 
 public class CustodianHelpRecoverActivity extends BriarActivity implements
 		BaseFragment.BaseFragmentListener, CustodianScanQrButtonListener {
@@ -14,15 +25,39 @@ public class CustodianHelpRecoverActivity extends BriarActivity implements
 		component.inject(this);
 	}
 
+	@Inject
+	public SocialBackupManager socialBackupManager;
+
+	@Inject
+	public DatabaseComponent db;
+
 	@Override
 	public void onCreate(Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 		setContentView(R.layout.activity_recover); // TODO change this
-        // TODO check if we have a shard for this secret owner
+
-		// if not we should not even display the menu item
+		Intent intent = getIntent();
+		int id = intent.getIntExtra(CONTACT_ID, -1);
+		if (id == -1) throw new IllegalStateException("No ContactId");
+		ContactId contactId = new ContactId(id);
+
+        // check if we have a shard for this secret owner
+		try {
+			db.transaction(false, txn -> {
+				if (!socialBackupManager.amCustodian(txn, contactId)) {
+					throw new DbException();
+				}
 				CustodianRecoveryModeExplainerFragment fragment =
 						new CustodianRecoveryModeExplainerFragment();
 				showInitialFragment(fragment);
+			});
+		} catch (DbException e) {
+			// TODO improve this
+			Toast.makeText(this,
+					"You do not hold a backup shard from this contact",
+					Toast.LENGTH_SHORT).show();
+			finish();
+		}
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/socialbackup/ThresholdSelectorFragment.java

@@ -8,22 +8,17 @@ import android.view.MenuInflater;
 import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
-import android.widget.ImageView;
 import android.widget.SeekBar;
 import android.widget.TextView;
-import android.widget.Toast;
-
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
 
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.contactselection.ContactSelectorListener;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.magmacollective.darkcrystal.secretsharingwrapper.SecretSharingWrapper;
 
-import static java.util.Objects.requireNonNull;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
 public class ThresholdSelectorFragment extends BaseFragment {
 
@@ -57,20 +52,24 @@ public class ThresholdSelectorFragment extends BaseFragment {
 
 	@Nullable
 	@Override
-    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
+	public View onCreateView(@NonNull LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
 		View view = inflater.inflate(R.layout.fragment_select_threshold,
 				container, false);
 		Bundle args = requireArguments();
 		numberOfCustodians = args.getInt(NUMBER_CUSTODIANS);
 
 		seekBar = view.findViewById(R.id.seekBar);
-        thresholdRepresentation = view.findViewById(R.id.textViewThresholdRepresentation);
+		thresholdRepresentation =
+				view.findViewById(R.id.textViewThresholdRepresentation);
 		message = view.findViewById(R.id.textViewMessage);
 		mOfn = view.findViewById(R.id.textViewmOfn);
 		int max = numberOfCustodians - 3;
 		seekBar.setMax(max);
 		seekBar.setOnSeekBarChangeListener(new SeekBarListener());
-        recommendedThreshold = SecretSharingWrapper.defaultThreshold(numberOfCustodians);
+		recommendedThreshold =
+				SecretSharingWrapper.defaultThreshold(numberOfCustodians);
 		threshold = recommendedThreshold;
 		seekBar.setProgress(threshold - 2);
 
@@ -81,7 +80,9 @@ public class ThresholdSelectorFragment extends BaseFragment {
 	}
 
 	private void setmOfnText() {
-        mOfn.setText(String.format("%d of %d contacts needed to recover your account", threshold, numberOfCustodians));
+		mOfn.setText(String.format(
+				"%d of %d contacts needed to recover your account", threshold,
+				numberOfCustodians));
 	}
 
 	@Override
@@ -122,7 +123,7 @@ public class ThresholdSelectorFragment extends BaseFragment {
 		}
 	}
 
-    private String buildThresholdRepresentationString () {
+	private String buildThresholdRepresentationString() {
 		String thresholdRepresentationText = "";
 		for (int i = 0; i < threshold; i++) {
 			thresholdRepresentationText += getString(R.string.filled_bullet);
@@ -145,9 +146,11 @@ public class ThresholdSelectorFragment extends BaseFragment {
 			);
 			setmOfnText();
 
-            int sanityLevel = SecretSharingWrapper.thresholdSanity(threshold, numberOfCustodians);
+			int sanityLevel = SecretSharingWrapper
+					.thresholdSanity(threshold, numberOfCustodians);
 			int text = R.string.threshold_secure;
-            if (threshold == recommendedThreshold) text = R.string.threshold_recommended;
+			if (threshold == recommendedThreshold)
+				text = R.string.threshold_recommended;
 			if (sanityLevel < -1) text = R.string.threshold_low_insecure;
 			if (sanityLevel > 0) text = R.string.threshold_high_insecure;
 			message.setText(text);