Introduce SharingStatus to report more fine-grained status

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

@@ -12,7 +12,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 
 @NotNullByDefault
-public abstract class BaseContactSelectorAdapter<I extends SelectableContactItem, H extends ContactItemViewHolder<I>>
+public abstract class BaseContactSelectorAdapter<I extends BaseSelectableContactItem, H extends ContactItemViewHolder<I>>
 		extends BaseContactListAdapter<I, H> {
 
 	public BaseContactSelectorAdapter(Context context, Class<I> c,
@@ -24,7 +24,7 @@ public abstract class BaseContactSelectorAdapter<I extends SelectableContactItem
 		Collection<ContactId> selected = new ArrayList<>();
 
 		for (int i = 0; i < items.size(); i++) {
-			SelectableContactItem item = items.get(i);
+			BaseSelectableContactItem item = items.get(i);
 			if (item.isSelected()) selected.add(item.getContact().getId());
 		}
 		return selected;

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

@@ -33,7 +33,7 @@ import static org.briarproject.briar.android.contactselection.ContactSelectorAct
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public abstract class BaseContactSelectorFragment<I extends SelectableContactItem, A extends BaseContactSelectorAdapter<I, ? extends ContactItemViewHolder<I>>>
+public abstract class BaseContactSelectorFragment<I extends BaseSelectableContactItem, A extends BaseContactSelectorAdapter<I, ? extends ContactItemViewHolder<I>>>
 		extends BaseFragment
 		implements OnContactClickListener<I> {
 

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

@@ -17,7 +17,7 @@ import static org.briarproject.briar.android.util.UiUtils.GREY_OUT;
 
 @UiThread
 @NotNullByDefault
-public class BaseSelectableContactHolder<I extends SelectableContactItem>
+public abstract class BaseSelectableContactHolder<I extends BaseSelectableContactItem>
 		extends ContactItemViewHolder<I> {
 
 	private final CheckBox checkBox;

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

@@ -0,0 +1,32 @@
+package org.briarproject.briar.android.contactselection;
+
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.briar.android.contact.ContactItem;
+import org.briarproject.briar.api.identity.AuthorInfo;
+import org.briarproject.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.NotThreadSafe;
+
+@NotThreadSafe
+@NotNullByDefault
+public abstract class BaseSelectableContactItem extends ContactItem {
+
+	private boolean selected;
+
+	public BaseSelectableContactItem(Contact contact, AuthorInfo authorInfo,
+			boolean selected) {
+		super(contact, authorInfo);
+		this.selected = selected;
+	}
+
+	boolean isSelected() {
+		return selected;
+	}
+
+	void toggleSelected() {
+		selected = !selected;
+	}
+
+	public abstract boolean isDisabled();
+
+}

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

@@ -10,7 +10,7 @@ import org.briarproject.nullsafety.NotNullByDefault;
 import java.util.Collection;
 
 @NotNullByDefault
-public interface ContactSelectorController<I extends SelectableContactItem>
+public interface ContactSelectorController<I extends BaseSelectableContactItem>
 		extends DbController {
 
 	void loadContacts(GroupId g, Collection<ContactId> selection,

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

@@ -11,6 +11,7 @@ import org.briarproject.briar.android.controller.DbControllerImpl;
 import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
 import org.briarproject.briar.api.identity.AuthorInfo;
 import org.briarproject.briar.api.identity.AuthorManager;
+import org.briarproject.briar.api.sharing.SharingManager.SharingStatus;
 import org.briarproject.nullsafety.NotNullByDefault;
 
 import java.util.ArrayList;
@@ -53,10 +54,8 @@ public abstract class ContactSelectorControllerImpl
 					AuthorInfo authorInfo = authorManager.getAuthorInfo(c);
 					// was this contact already selected?
 					boolean selected = selection.contains(c.getId());
-					// can this contact be selected?
-					boolean disabled = isDisabled(g, c);
 					contacts.add(new SelectableContactItem(c, authorInfo,
-							selected, disabled));
+							selected, getSharingStatus(g, c)));
 				}
 				handler.onResult(contacts);
 			} catch (DbException e) {
@@ -67,7 +66,7 @@ public abstract class ContactSelectorControllerImpl
 	}
 
 	@DatabaseExecutor
-	protected abstract boolean isDisabled(GroupId g, Contact c)
+	protected abstract SharingStatus getSharingStatus(GroupId g, Contact c)
 			throws DbException;
 
 }

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

@@ -2,15 +2,20 @@ package org.briarproject.briar.android.contactselection;
 
 import android.view.View;
 
+import org.briarproject.briar.R;
 import org.briarproject.briar.android.contact.OnContactClickListener;
 import org.briarproject.nullsafety.NotNullByDefault;
 
 import javax.annotation.Nullable;
 
+import androidx.annotation.StringRes;
 import androidx.annotation.UiThread;
 
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.INVITED;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.NOT_SUPPORTED;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHARING;
 
 @UiThread
 @NotNullByDefault
@@ -27,6 +32,15 @@ class SelectableContactHolder
 		super.bind(item, listener);
 
 		if (item.isDisabled()) {
+			@StringRes int strRes;
+			if (item.getSharingStatus() == SHARING) {
+				strRes = R.string.forum_invitation_already_sharing;
+			} else if (item.getSharingStatus() == INVITED) {
+				strRes = R.string.forum_invitation_already_invited;
+			} else if (item.getSharingStatus() == NOT_SUPPORTED) {
+				strRes = R.string.forum_invitation_not_supported;
+			} else throw new AssertionError("Unhandled SharingStatus");
+			info.setText(strRes);
 			info.setVisibility(VISIBLE);
 		} else {
 			info.setVisibility(GONE);

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

@@ -1,36 +1,33 @@
 package org.briarproject.briar.android.contactselection;
 
 import org.briarproject.bramble.api.contact.Contact;
-import org.briarproject.briar.android.contact.ContactItem;
 import org.briarproject.briar.api.identity.AuthorInfo;
+import org.briarproject.briar.api.sharing.SharingManager.SharingStatus;
 import org.briarproject.nullsafety.NotNullByDefault;
 
 import javax.annotation.concurrent.NotThreadSafe;
 
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHAREABLE;
+
 @NotThreadSafe
 @NotNullByDefault
-public class SelectableContactItem extends ContactItem {
+public class SelectableContactItem extends BaseSelectableContactItem {
 
-	private boolean selected;
+	private final SharingStatus sharingStatus;
-	private final boolean disabled;
 
 	public SelectableContactItem(Contact contact, AuthorInfo authorInfo,
-			boolean selected, boolean disabled) {
+			boolean selected, SharingStatus sharingStatus) {
-		super(contact, authorInfo);
+		super(contact, authorInfo, selected);
-		this.selected = selected;
+		this.sharingStatus = sharingStatus;
-		this.disabled = disabled;
 	}
 
-	boolean isSelected() {
+	public SharingStatus getSharingStatus() {
-		return selected;
+		return sharingStatus;
-	}
-
-	void toggleSelected() {
-		selected = !selected;
 	}
 
+	@Override
 	public boolean isDisabled() {
-		return disabled;
+		return sharingStatus != SHAREABLE;
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/privategroup/creation/CreateGroupControllerImpl.java

@@ -26,6 +26,7 @@ import org.briarproject.briar.api.privategroup.PrivateGroupFactory;
 import org.briarproject.briar.api.privategroup.PrivateGroupManager;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationFactory;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationManager;
+import org.briarproject.briar.api.sharing.SharingManager.SharingStatus;
 import org.briarproject.nullsafety.NotNullByDefault;
 
 import java.util.ArrayList;
@@ -140,8 +141,8 @@ class CreateGroupControllerImpl extends ContactSelectorControllerImpl
 	}
 
 	@Override
-	protected boolean isDisabled(GroupId g, Contact c) throws DbException {
+	protected SharingStatus getSharingStatus(GroupId g, Contact c) throws DbException {
-		return !groupInvitationManager.isInvitationAllowed(c, g);
+		return groupInvitationManager.getSharingStatus(c, g);
 	}
 
 	@Override

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

@@ -92,7 +92,7 @@ class RevealContactsControllerImpl extends DbControllerImpl
 					boolean selected =
 							disabled || selection.contains(c.getId());
 					items.add(new RevealableContactItem(c, authorInfo, selected,
-							disabled, m.getVisibility()));
+							m.getVisibility()));
 				}
 
 			}

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

@@ -1,22 +1,24 @@
 package org.briarproject.briar.android.privategroup.reveal;
 
 import org.briarproject.bramble.api.contact.Contact;
-import org.briarproject.briar.android.contactselection.SelectableContactItem;
+import org.briarproject.briar.android.contactselection.BaseSelectableContactItem;
 import org.briarproject.briar.api.identity.AuthorInfo;
 import org.briarproject.briar.api.privategroup.Visibility;
 import org.briarproject.nullsafety.NotNullByDefault;
 
 import javax.annotation.concurrent.NotThreadSafe;
 
+import static org.briarproject.briar.api.privategroup.Visibility.INVISIBLE;
+
 @NotThreadSafe
 @NotNullByDefault
-class RevealableContactItem extends SelectableContactItem {
+class RevealableContactItem extends BaseSelectableContactItem {
 
 	private final Visibility visibility;
 
 	RevealableContactItem(Contact contact, AuthorInfo authorInfo,
-			boolean selected, boolean disabled, Visibility visibility) {
+			boolean selected, Visibility visibility) {
-		super(contact, authorInfo, selected, disabled);
+		super(contact, authorInfo, selected);
 		this.visibility = visibility;
 	}
 
@@ -24,4 +26,8 @@ class RevealableContactItem extends SelectableContactItem {
 		return visibility;
 	}
 
+	@Override
+	public boolean isDisabled() {
+		return visibility != INVISIBLE;
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/sharing/ShareBlogControllerImpl.java

@@ -13,6 +13,7 @@ import org.briarproject.briar.android.contactselection.ContactSelectorController
 import org.briarproject.briar.android.controller.handler.ExceptionHandler;
 import org.briarproject.briar.api.blog.BlogSharingManager;
 import org.briarproject.briar.api.identity.AuthorManager;
+import org.briarproject.briar.api.sharing.SharingManager.SharingStatus;
 import org.briarproject.nullsafety.NotNullByDefault;
 
 import java.util.Collection;
@@ -47,8 +48,9 @@ class ShareBlogControllerImpl extends ContactSelectorControllerImpl
 	}
 
 	@Override
-	protected boolean isDisabled(GroupId g, Contact c) throws DbException {
+	protected SharingStatus getSharingStatus(GroupId g, Contact c)
-		return !blogSharingManager.canBeShared(g, c);
+			throws DbException {
+		return blogSharingManager.getSharingStatus(g, c);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/sharing/ShareForumControllerImpl.java

@@ -13,6 +13,7 @@ import org.briarproject.briar.android.contactselection.ContactSelectorController
 import org.briarproject.briar.android.controller.handler.ExceptionHandler;
 import org.briarproject.briar.api.forum.ForumSharingManager;
 import org.briarproject.briar.api.identity.AuthorManager;
+import org.briarproject.briar.api.sharing.SharingManager.SharingStatus;
 import org.briarproject.nullsafety.NotNullByDefault;
 
 import java.util.Collection;
@@ -47,8 +48,9 @@ class ShareForumControllerImpl extends ContactSelectorControllerImpl
 	}
 
 	@Override
-	protected boolean isDisabled(GroupId g, Contact c) throws DbException {
+	protected SharingStatus getSharingStatus(GroupId g, Contact c)
-		return !forumSharingManager.canBeShared(g, c);
+			throws DbException {
+		return forumSharingManager.getSharingStatus(g, c);
 	}
 
 	@Override

briar-android/src/main/res/values/strings.xml

@@ -461,6 +461,8 @@
 	<string name="forum_declined_toast">Invitation declined</string>
 	<string name="shared_by_format">Shared by %s</string>
 	<string name="forum_invitation_already_sharing">Already sharing</string>
+	<string name="forum_invitation_already_invited">Already invited</string>
+	<string name="forum_invitation_not_supported">Not supported by this contact</string>
 	<string name="forum_invitation_response_accepted_sent">You accepted the forum invitation from %s.</string>
 	<string name="forum_invitation_response_declined_sent">You declined the forum invitation from %s.</string>
 	<string name="forum_invitation_response_declined_auto">The forum invitation from %s was automatically declined.</string>

briar-api/src/main/java/org/briarproject/briar/api/privategroup/invitation/GroupInvitationManager.java

@@ -9,6 +9,7 @@ import org.briarproject.briar.api.client.ProtocolStateException;
 import org.briarproject.briar.api.client.SessionId;
 import org.briarproject.briar.api.conversation.ConversationManager.ConversationClient;
 import org.briarproject.briar.api.privategroup.PrivateGroup;
+import org.briarproject.briar.api.sharing.SharingManager.SharingStatus;
 import org.briarproject.nullsafety.NotNullByDefault;
 
 import java.util.Collection;
@@ -82,5 +83,5 @@ public interface GroupInvitationManager extends ConversationClient {
 	 * Returns true if the given contact can be invited to the given private
 	 * group.
 	 */
-	boolean isInvitationAllowed(Contact c, GroupId g) throws DbException;
+	SharingStatus getSharingStatus(Contact c, GroupId g) throws DbException;
 }

briar-api/src/main/java/org/briarproject/briar/api/sharing/SharingManager.java

@@ -17,6 +17,10 @@ import javax.annotation.Nullable;
 public interface SharingManager<S extends Shareable>
 		extends ConversationClient {
 
+	enum SharingStatus {
+		SHAREABLE, INVITED, SHARING, NOT_SUPPORTED
+	}
+
 	/**
 	 * Sends an invitation to share the given group with the given contact,
 	 * including optional text.
@@ -80,12 +84,12 @@ public interface SharingManager<S extends Shareable>
 	/**
 	 * Returns true if the group not already shared and no invitation is open
 	 */
-	boolean canBeShared(GroupId g, Contact c) throws DbException;
+	SharingStatus getSharingStatus(GroupId g, Contact c) throws DbException;
 
 	/**
 	 * Returns true if the group not already shared and no invitation is open
 	 */
-	boolean canBeShared(Transaction txn, GroupId g, Contact c)
+	SharingStatus getSharingStatus(Transaction txn, GroupId g, Contact c)
 			throws DbException;
 
 }

briar-core/src/main/java/org/briarproject/briar/privategroup/invitation/GroupInvitationManagerImpl.java

@@ -37,6 +37,7 @@ import org.briarproject.briar.api.privategroup.invitation.GroupInvitationItem;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationManager;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationRequest;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationResponse;
+import org.briarproject.briar.api.sharing.SharingManager.SharingStatus;
 import org.briarproject.briar.client.ConversationClientImpl;
 import org.briarproject.nullsafety.NotNullByDefault;
 
@@ -56,6 +57,7 @@ import javax.inject.Inject;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
 import static org.briarproject.bramble.api.sync.validation.IncomingMessageHook.DeliveryAction.ACCEPT_DO_NOT_SHARE;
 import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
+import static org.briarproject.briar.privategroup.invitation.CreatorState.JOINED;
 import static org.briarproject.briar.privategroup.invitation.CreatorState.START;
 import static org.briarproject.briar.privategroup.invitation.MessageType.ABORT;
 import static org.briarproject.briar.privategroup.invitation.MessageType.INVITE;
@@ -511,7 +513,7 @@ class GroupInvitationManagerImpl extends ConversationClientImpl
 	}
 
 	@Override
-	public boolean isInvitationAllowed(Contact c, GroupId privateGroupId)
+	public SharingStatus getSharingStatus(Contact c, GroupId privateGroupId)
 			throws DbException {
 		GroupId contactGroupId = getContactGroup(c).getId();
 		SessionId sessionId = getSessionId(privateGroupId);
@@ -523,13 +525,16 @@ class GroupInvitationManagerImpl extends ConversationClientImpl
 			StoredSession ss = getSession(txn, contactGroupId, sessionId);
 			db.commitTransaction(txn);
 			// The group can't be shared unless the contact supports the client
-			if (client != SHARED) return false;
+			if (client != SHARED) return SharingStatus.NOT_SUPPORTED;
 			// If there's no session, the contact can be invited
-			if (ss == null) return true;
+			if (ss == null) return SharingStatus.SHAREABLE;
 			// If the session's in the start state, the contact can be invited
 			CreatorSession session = sessionParser
 					.parseCreatorSession(contactGroupId, ss.bdfSession);
-			return session.getState() == START;
+			CreatorState state = session.getState();
+			if (state == START) return SharingStatus.SHAREABLE;
+			if (state == JOINED) return SharingStatus.SHARING;
+			return SharingStatus.INVITED;
 		} catch (FormatException e) {
 			throw new DbException(e);
 		} finally {

briar-core/src/main/java/org/briarproject/briar/sharing/SharingManagerImpl.java

@@ -51,6 +51,7 @@ import javax.annotation.Nullable;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
 import static org.briarproject.bramble.api.sync.validation.IncomingMessageHook.DeliveryAction.ACCEPT_DO_NOT_SHARE;
 import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHAREABLE;
 import static org.briarproject.briar.sharing.MessageType.ABORT;
 import static org.briarproject.briar.sharing.MessageType.ACCEPT;
 import static org.briarproject.briar.sharing.MessageType.DECLINE;
@@ -269,7 +270,7 @@ abstract class SharingManagerImpl<S extends Shareable>
 		SessionId sessionId = getSessionId(shareableId);
 		try {
 			Contact contact = db.getContact(txn, contactId);
-			if (!canBeShared(txn, shareableId, contact))
+			if (getSharingStatus(txn, shareableId, contact) != SHAREABLE)
 				// we might have received an invitation in the meantime
 				return;
 			// Look up the session, if there is one
@@ -467,34 +468,36 @@ abstract class SharingManagerImpl<S extends Shareable>
 	}
 
 	@Override
-	public boolean canBeShared(GroupId g, Contact c) throws DbException {
+	public SharingStatus getSharingStatus(GroupId g, Contact c) throws DbException {
 		Transaction txn = db.startTransaction(true);
 		try {
-			boolean canBeShared = canBeShared(txn, g, c);
+			SharingStatus sharingStatus = getSharingStatus(txn, g, c);
 			db.commitTransaction(txn);
-			return canBeShared;
+			return sharingStatus;
 		} finally {
 			db.endTransaction(txn);
 		}
 	}
 
 	@Override
-	public boolean canBeShared(Transaction txn, GroupId g, Contact c)
+	public SharingStatus getSharingStatus(Transaction txn, GroupId g, Contact c)
 			throws DbException {
 		// The group can't be shared unless the contact supports the client
 		Visibility client = clientVersioningManager.getClientVisibility(txn,
 				c.getId(), getShareableClientId(), getShareableMajorVersion());
-		if (client != SHARED) return false;
+		if (client != SHARED) return SharingStatus.NOT_SUPPORTED;
 		GroupId contactGroupId = getContactGroup(c).getId();
 		SessionId sessionId = getSessionId(g);
 		try {
 			StoredSession ss = getSession(txn, contactGroupId, sessionId);
 			// If there's no session, we can share the group with the contact
-			if (ss == null) return true;
+			if (ss == null) return SharingStatus.SHAREABLE;
 			// If the session's in the right state, the contact can be invited
 			Session session =
 					sessionParser.parseSession(contactGroupId, ss.bdfSession);
-			return session.getState().canInvite();
+			if (session.getState().canInvite()) return SharingStatus.SHAREABLE;
+			if (session.getState().isSharing()) return SharingStatus.SHARING;
+			return SharingStatus.INVITED;
 		} catch (FormatException e) {
 			throw new DbException(e);
 		}

briar-core/src/main/java/org/briarproject/briar/sharing/State.java

@@ -50,6 +50,10 @@ enum State {
 		return this == START;
 	}
 
+	public boolean isSharing() {
+		return this == SHARING;
+	}
+
 	public boolean isAwaitingResponse() {
 		return this == LOCAL_INVITED || this == REMOTE_INVITED;
 	}

briar-core/src/test/java/org/briarproject/briar/privategroup/invitation/AutoDeleteIntegrationTest.java

@@ -23,6 +23,8 @@ import javax.annotation.Nullable;
 import static org.briarproject.bramble.api.cleanup.CleanupManager.BATCH_DELAY_MS;
 import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.MIN_AUTO_DELETE_TIMER_MS;
 import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHAREABLE;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHARING;
 import static org.briarproject.briar.test.TestEventListener.assertEvent;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -157,8 +159,8 @@ public class AutoDeleteIntegrationTest extends AbstractAutoDeleteTest {
 		waitForEvents(c1);
 
 		// 0 can invite 1 again
-		assertTrue(groupInvitationManager0
+		assertEquals(SHAREABLE, groupInvitationManager0
-				.isInvitationAllowed(contact1From0, privateGroup.getId()));
+				.getSharingStatus(contact1From0, privateGroup.getId()));
 
 		// Before 1's timer elapses, 1 should still see the auto-decline message
 		c0.getTimeTravel().addCurrentTimeMillis(timerLatency - 1);
@@ -194,8 +196,8 @@ public class AutoDeleteIntegrationTest extends AbstractAutoDeleteTest {
 		assertEquals(0, getMessageHeaders(c0, contactId1From0).size());
 
 		// 0 can invite 1 again and really does invite
-		assertTrue(groupInvitationManager0
+		assertEquals(SHAREABLE, groupInvitationManager0
-				.isInvitationAllowed(contact1From0, privateGroup.getId()));
+				.getSharingStatus(contact1From0, privateGroup.getId()));
 		sendInvitation(privateGroup, contact1From0.getId(),
 				"Join this faster please!");
 		sync0To1(1, true);
@@ -395,8 +397,8 @@ public class AutoDeleteIntegrationTest extends AbstractAutoDeleteTest {
 		// 1 joined the PrivateGroup
 		assertEquals(pg,
 				c1.getPrivateGroupManager().getPrivateGroup(pg.getId()));
-		assertFalse(groupInvitationManager0
+		assertEquals(SHARING, groupInvitationManager0
-				.isInvitationAllowed(contact1From0, pg.getId()));
+				.getSharingStatus(contact1From0, pg.getId()));
 	}
 
 	@Test

briar-core/src/test/java/org/briarproject/briar/privategroup/invitation/GroupInvitationIntegrationTest.java

@@ -29,6 +29,9 @@ import javax.annotation.Nullable;
 
 import static java.util.Collections.emptySet;
 import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.MIN_AUTO_DELETE_TIMER_MS;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.INVITED;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHAREABLE;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHARING;
 import static org.briarproject.briar.test.BriarTestUtils.assertGroupCount;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -319,8 +322,8 @@ public class GroupInvitationIntegrationTest
 		sendInvitation(c0.getClock().currentTimeMillis(), null);
 
 		// invitation is not allowed before the first hasn't been answered
-		assertFalse(groupInvitationManager0
+		assertEquals(INVITED, groupInvitationManager0
-				.isInvitationAllowed(contact1From0, privateGroup.getId()));
+				.getSharingStatus(contact1From0, privateGroup.getId()));
 
 		// deliver invitation and response
 		sync0To1(1, true);
@@ -329,8 +332,8 @@ public class GroupInvitationIntegrationTest
 		sync1To0(1, true);
 
 		// after invitation was declined, inviting again is possible
-		assertTrue(groupInvitationManager0
+		assertEquals(SHAREABLE, groupInvitationManager0
-				.isInvitationAllowed(contact1From0, privateGroup.getId()));
+				.getSharingStatus(contact1From0, privateGroup.getId()));
 
 		// send and accept the second invitation
 		sendInvitation(c0.getClock().currentTimeMillis(), "Second Invitation");
@@ -340,8 +343,8 @@ public class GroupInvitationIntegrationTest
 		sync1To0(1, true);
 
 		// invitation is not allowed since the member joined the group now
-		assertFalse(groupInvitationManager0
+		assertEquals(SHARING, groupInvitationManager0
-				.isInvitationAllowed(contact1From0, privateGroup.getId()));
+				.getSharingStatus(contact1From0, privateGroup.getId()));
 
 		// don't allow another invitation request
 		try {
@@ -723,8 +726,8 @@ public class GroupInvitationIntegrationTest
 		sync1To0(1, true);
 
 		// inviting again is not possible
-		assertFalse(groupInvitationManager0
+		assertEquals(SHARING, groupInvitationManager0
-				.isInvitationAllowed(contact1From0, privateGroup.getId()));
+				.getSharingStatus(contact1From0, privateGroup.getId()));
 
 		// contacts remove each other
 		removeAllContacts();
@@ -737,8 +740,8 @@ public class GroupInvitationIntegrationTest
 		addDefaultContacts();
 
 		// creator can still not invite again
-		assertFalse(groupInvitationManager0
+		assertEquals(INVITED, groupInvitationManager0
-				.isInvitationAllowed(contact1From0, privateGroup.getId()));
+				.getSharingStatus(contact1From0, privateGroup.getId()));
 
 		// finally invitee can remove group without issues
 		groupManager1.removePrivateGroup(privateGroup.getId());

briar-core/src/test/java/org/briarproject/briar/privategroup/invitation/GroupInvitationManagerImplTest.java

@@ -62,12 +62,14 @@ import static org.briarproject.briar.api.privategroup.PrivateGroupConstants.GROU
 import static org.briarproject.briar.api.privategroup.PrivateGroupConstants.MAX_GROUP_NAME_LENGTH;
 import static org.briarproject.briar.api.privategroup.invitation.GroupInvitationManager.CLIENT_ID;
 import static org.briarproject.briar.api.privategroup.invitation.GroupInvitationManager.MAJOR_VERSION;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.INVITED;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHAREABLE;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHARING;
 import static org.briarproject.briar.privategroup.invitation.MessageType.ABORT;
 import static org.briarproject.briar.privategroup.invitation.MessageType.INVITE;
 import static org.briarproject.briar.privategroup.invitation.MessageType.JOIN;
 import static org.briarproject.briar.privategroup.invitation.MessageType.LEAVE;
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 public class GroupInvitationManagerImplTest extends BrambleMockTestCase {
@@ -871,31 +873,31 @@ public class GroupInvitationManagerImplTest extends BrambleMockTestCase {
 	@Test
 	public void testIsInvitationAllowed() throws Exception {
 		expectIsInvitationAllowed(CreatorState.START);
-		assertTrue(groupInvitationManager
+		assertEquals(SHAREABLE, groupInvitationManager
-				.isInvitationAllowed(contact, privateGroup.getId()));
+				.getSharingStatus(contact, privateGroup.getId()));
 	}
 
 	@Test
 	public void testIsNotInvitationAllowed() throws Exception {
 		expectIsInvitationAllowed(CreatorState.DISSOLVED);
-		assertFalse(groupInvitationManager
+		assertEquals(INVITED, groupInvitationManager
-				.isInvitationAllowed(contact, privateGroup.getId()));
+				.getSharingStatus(contact, privateGroup.getId()));
 
 		expectIsInvitationAllowed(CreatorState.ERROR);
-		assertFalse(groupInvitationManager
+		assertEquals(INVITED, groupInvitationManager
-				.isInvitationAllowed(contact, privateGroup.getId()));
+				.getSharingStatus(contact, privateGroup.getId()));
 
 		expectIsInvitationAllowed(CreatorState.INVITED);
-		assertFalse(groupInvitationManager
+		assertEquals(INVITED, groupInvitationManager
-				.isInvitationAllowed(contact, privateGroup.getId()));
+				.getSharingStatus(contact, privateGroup.getId()));
 
 		expectIsInvitationAllowed(CreatorState.JOINED);
-		assertFalse(groupInvitationManager
+		assertEquals(SHARING, groupInvitationManager
-				.isInvitationAllowed(contact, privateGroup.getId()));
+				.getSharingStatus(contact, privateGroup.getId()));
 
 		expectIsInvitationAllowed(CreatorState.LEFT);
-		assertFalse(groupInvitationManager
+		assertEquals(INVITED, groupInvitationManager
-				.isInvitationAllowed(contact, privateGroup.getId()));
+				.getSharingStatus(contact, privateGroup.getId()));
 	}
 
 	private void expectIsInvitationAllowed(CreatorState state)

briar-core/src/test/java/org/briarproject/briar/sharing/AbstractAutoDeleteIntegrationTest.java

@@ -19,6 +19,7 @@ import java.util.Collection;
 
 import static org.briarproject.bramble.api.cleanup.CleanupManager.BATCH_DELAY_MS;
 import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.MIN_AUTO_DELETE_TIMER_MS;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHAREABLE;
 import static org.briarproject.briar.test.TestEventListener.assertEvent;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -146,8 +147,8 @@ public abstract class AbstractAutoDeleteIntegrationTest
 		waitForEvents(c1);
 
 		// 0 can invite 1 again
-		assertTrue(getSharingManager0()
+		assertEquals(SHAREABLE, getSharingManager0().getSharingStatus(
-				.canBeShared(getShareable().getId(), contact1From0));
+				getShareable().getId(), contact1From0));
 
 		// Before 1's timer elapses, 1 should still see the auto-decline message
 		c0.getTimeTravel().addCurrentTimeMillis(timerLatency - 1);
@@ -183,8 +184,8 @@ public abstract class AbstractAutoDeleteIntegrationTest
 		assertEquals(0, getMessageHeaders(c0, contactId1From0).size());
 
 		// 0 can invite 1 again and really does invite
-		assertTrue(getSharingManager0()
+		assertEquals(SHAREABLE, getSharingManager0()
-				.canBeShared(getShareable().getId(), contact1From0));
+				.getSharingStatus(getShareable().getId(), contact1From0));
 		// Send invitation
 		getSharingManager0()
 				.sendInvitation(getShareable().getId(), contactId1From0,

briar-core/src/test/java/org/briarproject/briar/sharing/BlogSharingIntegrationTest.java

@@ -33,6 +33,8 @@ import java.util.Collection;
 import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.MIN_AUTO_DELETE_TIMER_MS;
 import static org.briarproject.briar.api.blog.BlogSharingManager.CLIENT_ID;
 import static org.briarproject.briar.api.blog.BlogSharingManager.MAJOR_VERSION;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHAREABLE;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHARING;
 import static org.briarproject.briar.test.BriarTestUtils.assertGroupCount;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -106,14 +108,18 @@ public class BlogSharingIntegrationTest
 	public void testPersonalBlogCannotBeSharedWithOwner() throws Exception {
 		listenToEvents(true);
 
-		assertFalse(blogSharingManager0.canBeShared(blog1.getId(),
+		assertEquals(SHARING,
-				contact1From0));
+				blogSharingManager0.getSharingStatus(blog1.getId(),
-		assertFalse(blogSharingManager0.canBeShared(blog2.getId(),
+						contact1From0));
-				contact2From0));
+		assertEquals(SHARING,
-		assertFalse(blogSharingManager1.canBeShared(blog0.getId(),
+				blogSharingManager0.getSharingStatus(blog2.getId(),
-				contact0From1));
+						contact2From0));
-		assertFalse(blogSharingManager2.canBeShared(blog0.getId(),
+		assertEquals(SHARING,
-				contact0From2));
+				blogSharingManager1.getSharingStatus(blog0.getId(),
+						contact0From1));
+		assertEquals(SHARING,
+				blogSharingManager2.getSharingStatus(blog0.getId(),
+						contact0From2));
 	}
 
 	@Test
@@ -191,13 +197,13 @@ public class BlogSharingIntegrationTest
 		}
 		// sharer has own invitation message and response
 		assertEquals(2, db0.transactionWithResult(true, txn ->
-				blogSharingManager0.getMessageHeaders(txn, contactId1From0))
+						blogSharingManager0.getMessageHeaders(txn, contactId1From0))
 				.size());
 		// blog can not be shared again
-		assertFalse(blogSharingManager0.canBeShared(blog2.getId(),
+		assertEquals(SHARING, blogSharingManager0.getSharingStatus(
-				contact1From0));
+				blog2.getId(), contact1From0));
-		assertFalse(blogSharingManager1.canBeShared(blog2.getId(),
+		assertEquals(SHARING, blogSharingManager1.getSharingStatus(
-				contact0From1));
+				blog2.getId(), contact0From1));
 
 		// group message count is still correct
 		assertGroupCount(messageTracker0, g, 2, 1);
@@ -300,13 +306,13 @@ public class BlogSharingIntegrationTest
 		}
 		// sharer has own invitation message and response
 		assertEquals(2, db0.transactionWithResult(true, txn ->
-				blogSharingManager0.getMessageHeaders(txn, contactId1From0))
+						blogSharingManager0.getMessageHeaders(txn, contactId1From0))
 				.size());
 		// blog can not be shared again
-		assertFalse(blogSharingManager0.canBeShared(rssBlog.getId(),
+		assertEquals(SHARING, blogSharingManager0.getSharingStatus(
-				contact1From0));
+				rssBlog.getId(), contact1From0));
-		assertFalse(blogSharingManager1.canBeShared(rssBlog.getId(),
+		assertEquals(SHARING, blogSharingManager1.getSharingStatus(
-				contact0From1));
+				rssBlog.getId(), contact0From1));
 
 		// group message count is still correct
 		assertGroupCount(messageTracker0, g, 2, 1);
@@ -361,11 +367,11 @@ public class BlogSharingIntegrationTest
 		}
 		// sharer has own invitation message and response
 		assertEquals(2, db0.transactionWithResult(true, txn ->
-				blogSharingManager0.getMessageHeaders(txn, contactId1From0))
+						blogSharingManager0.getMessageHeaders(txn, contactId1From0))
 				.size());
 		// blog can be shared again
-		assertTrue(
+		assertEquals(SHAREABLE, blogSharingManager0.getSharingStatus(
-				blogSharingManager0.canBeShared(blog2.getId(), contact1From0));
+				blog2.getId(), contact1From0));
 	}
 
 	@Test
@@ -416,8 +422,8 @@ public class BlogSharingIntegrationTest
 		assertEquals(0,
 				blogSharingManager1.getSharedWith(blog2.getId()).size());
 		// blog can be shared again by sharer
-		assertTrue(
+		assertEquals(SHAREABLE, blogSharingManager0.getSharingStatus(
-				blogSharingManager0.canBeShared(blog2.getId(), contact1From0));
+				blog2.getId(), contact1From0));
 	}
 
 	@Test
@@ -534,8 +540,8 @@ public class BlogSharingIntegrationTest
 				.contains(contact0From1));
 
 		// 1 can again share blog 1 with 0
-		assertTrue(
+		assertEquals(SHAREABLE, blogSharingManager1.getSharingStatus(
-				blogSharingManager1.canBeShared(blog1.getId(), contact0From1));
+				blog1.getId(), contact0From1));
 	}
 
 	@Test
@@ -592,8 +598,8 @@ public class BlogSharingIntegrationTest
 		}
 
 		// 0 can share blog2 again with 1
-		assertTrue(
+		assertEquals(SHAREABLE, blogSharingManager0.getSharingStatus(
-				blogSharingManager0.canBeShared(blog2.getId(), contact1From0));
+				blog2.getId(), contact1From0));
 	}
 
 	@NotNullByDefault

briar-core/src/test/java/org/briarproject/briar/sharing/ForumSharingIntegrationTest.java

@@ -47,6 +47,9 @@ import static org.briarproject.bramble.util.StringUtils.getRandomString;
 import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.MIN_AUTO_DELETE_TIMER_MS;
 import static org.briarproject.briar.api.forum.ForumSharingManager.CLIENT_ID;
 import static org.briarproject.briar.api.forum.ForumSharingManager.MAJOR_VERSION;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.INVITED;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHAREABLE;
+import static org.briarproject.briar.api.sharing.SharingManager.SharingStatus.SHARING;
 import static org.briarproject.briar.test.BriarTestUtils.assertGroupCount;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -183,9 +186,11 @@ public class ForumSharingIntegrationTest
 		assertEquals(2, getMessages1From0().size());
 		// forum can not be shared again
 		Contact c1 = contactManager0.getContact(contactId1From0);
-		assertFalse(forumSharingManager0.canBeShared(forum.getId(), c1));
+		assertEquals(SHARING,
+				forumSharingManager0.getSharingStatus(forum.getId(), c1));
 		Contact c0 = contactManager1.getContact(contactId0From1);
-		assertFalse(forumSharingManager1.canBeShared(forum.getId(), c0));
+		assertEquals(SHARING,
+				forumSharingManager1.getSharingStatus(forum.getId(), c0));
 	}
 
 	@Test
@@ -271,7 +276,8 @@ public class ForumSharingIntegrationTest
 		assertEquals(2, getMessages1From0().size());
 		// forum can be shared again
 		Contact c1 = contactManager0.getContact(contactId1From0);
-		assertTrue(forumSharingManager0.canBeShared(forum.getId(), c1));
+		assertEquals(SHAREABLE,
+				forumSharingManager0.getSharingStatus(forum.getId(), c1));
 
 		// sharer un-subscribes from forum
 		forumManager0.removeForum(forum);
@@ -340,18 +346,18 @@ public class ForumSharingIntegrationTest
 		assertFalse(forumSharingManager1.getSharedWith(forum.getId())
 				.contains(contact0));
 		// forum can be shared again by sharer
-		assertTrue(forumSharingManager0
+		assertEquals(SHAREABLE, forumSharingManager0
-				.canBeShared(forum.getId(), contact1From0));
+				.getSharingStatus(forum.getId(), contact1From0));
 		// invitee that left can not yet share again
-		assertFalse(forumSharingManager1
+		assertEquals(INVITED, forumSharingManager1
-				.canBeShared(forum.getId(), contact0From1));
+				.getSharingStatus(forum.getId(), contact0From1));
 
 		// sharer responds with leave message
 		sync0To1(1, true);
 
 		// invitee that left can now share again
-		assertTrue(forumSharingManager1
+		assertEquals(SHAREABLE, forumSharingManager1
-				.canBeShared(forum.getId(), contact0From1));
+				.getSharingStatus(forum.getId(), contact0From1));
 	}
 
 	@Test
@@ -405,13 +411,15 @@ public class ForumSharingIntegrationTest
 		assertFalse(forumSharingManager1.getSharedWith(forum.getId())
 				.contains(contact0));
 		// forum can be re-shared by invitee now
-		assertTrue(forumSharingManager1.canBeShared(forum.getId(), c0));
+		assertEquals(SHAREABLE,
+				forumSharingManager1.getSharingStatus(forum.getId(), c0));
 
 		// invitee responds with LEAVE message
 		sync1To0(1, true);
 
 		// sharer can share forum again as well now
-		assertTrue(forumSharingManager0.canBeShared(forum.getId(), c1));
+		assertEquals(SHAREABLE,
+				forumSharingManager0.getSharingStatus(forum.getId(), c1));
 
 		// invitee also un-subscribes forum without effect
 		forumManager1.removeForum(forum);
@@ -621,10 +629,10 @@ public class ForumSharingIntegrationTest
 		addContacts1And2();
 
 		// forum can be shared with contacts again
-		assertTrue(forumSharingManager0
+		assertEquals(SHAREABLE, forumSharingManager0
-				.canBeShared(forum.getId(), contact1From0));
+				.getSharingStatus(forum.getId(), contact1From0));
-		assertTrue(forumSharingManager0
+		assertEquals(SHAREABLE, forumSharingManager0
-				.canBeShared(forum.getId(), contact2From0));
+				.getSharingStatus(forum.getId(), contact2From0));
 
 		// send invitation
 		forumSharingManager0