Add groups in common screen.

Adds a new screen to show which groups the user has in common with another user.

app/src/main/AndroidManifest.xml

@@ -1148,6 +1148,10 @@
             android:configChanges="touchscreen|keyboard|keyboardHidden|orientation|screenLayout|screenSize"
             android:exported="false"/>
 
+    <activity android:name=".groups.ui.incommon.GroupsInCommonActivity"
+              android:exported="false"
+              android:theme="@style/Signal.DayNight.NoActionBar" />
+
     <service
         android:enabled="true"
         android:exported="false"

app/src/main/java/org/thoughtcrime/securesms/groups/GroupsInCommonRepository.kt

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2025 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.groups
+
+import android.content.Context
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.rx3.asFlow
+import kotlinx.coroutines.withContext
+import org.thoughtcrime.securesms.database.SignalDatabase
+import org.thoughtcrime.securesms.recipients.Recipient
+import org.thoughtcrime.securesms.recipients.RecipientId
+
+/**
+ * Centralizes operations for retrieving groups that a given recipient has in common with another user.
+ */
+class GroupsInCommonRepository(private val context: Context) {
+
+  fun getGroupsInCommon(recipientId: RecipientId): Flow<List<Recipient>> {
+    return Recipient.observable(recipientId)
+      .asFlow()
+      .map { recipient ->
+        if (recipient.hasGroupsInCommon) {
+          getGroupsContainingRecipient(recipientId)
+        } else {
+          emptyList()
+        }
+      }
+  }
+
+  private suspend fun getGroupsContainingRecipient(recipientId: RecipientId): List<Recipient> = withContext(Dispatchers.IO) {
+    SignalDatabase.groups.getPushGroupsContainingMember(recipientId)
+      .asSequence()
+      .filter { it.members.contains(Recipient.self().id) }
+      .map { groupRecord -> Recipient.resolved(groupRecord.recipientId) }
+      .sortedBy { group -> group.getDisplayName(context) }
+      .toList()
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/groups/ui/incommon/GroupsInCommonActivity.kt

@@ -0,0 +1,193 @@
+/*
+ * Copyright 2025 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.groups.ui.incommon
+
+import android.app.Activity
+import android.content.Context
+import android.content.Intent
+import android.os.Bundle
+import androidx.activity.compose.setContent
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBarDefaults
+import androidx.compose.material3.TopAppBarScrollBehavior
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.input.nestedscroll.nestedScroll
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.res.pluralStringResource
+import androidx.compose.ui.unit.dp
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import org.signal.core.ui.compose.Previews
+import org.signal.core.ui.compose.Scaffolds
+import org.signal.core.ui.compose.SignalPreview
+import org.signal.core.ui.compose.theme.SignalTheme
+import org.signal.core.util.getParcelableExtraCompat
+import org.thoughtcrime.securesms.PassphraseRequiredActivity
+import org.thoughtcrime.securesms.R
+import org.thoughtcrime.securesms.avatar.AvatarImage
+import org.thoughtcrime.securesms.compose.StatusBarColorNestedScrollConnection
+import org.thoughtcrime.securesms.groups.GroupsInCommonRepository
+import org.thoughtcrime.securesms.recipients.Recipient
+import org.thoughtcrime.securesms.recipients.RecipientId
+import org.thoughtcrime.securesms.util.viewModel
+import java.text.NumberFormat
+
+/**
+ * Displays a list of groups that the user has in common with the specified [RecipientId].
+ */
+class GroupsInCommonActivity : PassphraseRequiredActivity() {
+  companion object {
+    private const val EXTRA_RECIPIENT_ID = "recipient_id"
+
+    fun createIntent(
+      context: Context,
+      recipientId: RecipientId
+    ): Intent {
+      return Intent(context, GroupsInCommonActivity::class.java).apply {
+        putExtra(EXTRA_RECIPIENT_ID, recipientId)
+      }
+    }
+  }
+
+  private val viewModel by viewModel {
+    GroupsInCommonViewModel(
+      recipientId = intent.getParcelableExtraCompat(EXTRA_RECIPIENT_ID, RecipientId::class.java)!!,
+      groupsInCommonRepo = GroupsInCommonRepository(context = this)
+    )
+  }
+
+  override fun onCreate(savedInstanceState: Bundle?, ready: Boolean) {
+    setContent {
+      SignalTheme {
+        GroupsInCommonScreen(
+          viewModel = viewModel,
+          onBackPress = { supportFinishAfterTransition() },
+          activity = this
+        )
+      }
+    }
+  }
+}
+
+@Composable
+private fun GroupsInCommonScreen(
+  viewModel: GroupsInCommonViewModel,
+  activity: Activity,
+  onBackPress: () -> Unit = {}
+) {
+  val groups by viewModel.groups.collectAsStateWithLifecycle()
+  val nestedScrollConnection = remember { StatusBarColorNestedScrollConnection(activity) }
+
+  GroupsInCommonContent(
+    groups = groups,
+    onBackPress = onBackPress,
+    modifier = Modifier.nestedScroll(nestedScrollConnection)
+  )
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun GroupsInCommonContent(
+  groups: List<Recipient>,
+  onBackPress: () -> Unit = {},
+  modifier: Modifier = Modifier
+) {
+  val scrollBehavior = TopAppBarDefaults.pinnedScrollBehavior()
+
+  Scaffold(
+    topBar = { TopAppBar(groupCount = groups.size, scrollBehavior = scrollBehavior, onBackPress = onBackPress) },
+    modifier = modifier.nestedScroll(scrollBehavior.nestedScrollConnection)
+  ) { padding ->
+    LazyColumn(
+      horizontalAlignment = Alignment.CenterHorizontally,
+      modifier = Modifier.padding(padding)
+    ) {
+      items(groups) {
+        GroupRow(it)
+      }
+    }
+  }
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun TopAppBar(
+  groupCount: Int,
+  scrollBehavior: TopAppBarScrollBehavior,
+  onBackPress: () -> Unit
+) {
+  Scaffolds.DefaultTopAppBar(
+    title = pluralStringResource(R.plurals.GroupsInCommon__n_groups_in_common_title, groupCount, NumberFormat.getInstance().format(groupCount)),
+    titleContent = { _, title -> Text(text = title, style = MaterialTheme.typography.titleLarge) },
+    navigationIconPainter = painterResource(R.drawable.symbol_arrow_left_24),
+    onNavigationClick = onBackPress,
+    scrollBehavior = scrollBehavior
+  )
+}
+
+@Composable
+private fun GroupRow(
+  group: Recipient
+) {
+  Row(
+    modifier = Modifier
+      .fillMaxWidth()
+      .background(MaterialTheme.colorScheme.surface)
+      .padding(start = 24.dp, top = 12.dp, end = 24.dp, bottom = 12.dp),
+    verticalAlignment = Alignment.CenterVertically
+  ) {
+    AvatarImage(
+      recipient = group,
+      modifier = Modifier
+        .size(40.dp)
+        .clip(CircleShape)
+    )
+
+    Spacer(modifier = Modifier.width(16.dp))
+
+    Text(
+      text = group.getGroupName(LocalContext.current)!!,
+      style = MaterialTheme.typography.bodyLarge,
+      color = MaterialTheme.colorScheme.onSurface
+    )
+  }
+}
+
+@SignalPreview
+@Composable
+fun GroupsInCommonContentPreview() {
+  Previews.Preview {
+    GroupsInCommonContent(
+      groups = listOf(
+        Recipient(groupName = "Family"),
+        Recipient(groupName = "happy birthday"),
+        Recipient(groupName = "The Cheesecake is a Lie"),
+        Recipient(groupName = "JEFFPARDY"),
+        Recipient(groupName = "Roommates"),
+        Recipient(groupName = "NYC Rock Climbers"),
+        Recipient(groupName = "Parkdale Run Club")
+      )
+    )
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/groups/ui/incommon/GroupsInCommonViewModel.kt

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2025 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.groups.ui.incommon
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.stateIn
+import org.thoughtcrime.securesms.groups.GroupsInCommonRepository
+import org.thoughtcrime.securesms.recipients.Recipient
+import org.thoughtcrime.securesms.recipients.RecipientId
+
+class GroupsInCommonViewModel(
+  recipientId: RecipientId,
+  groupsInCommonRepo: GroupsInCommonRepository
+) : ViewModel() {
+
+  val groups: StateFlow<List<Recipient>> = groupsInCommonRepo.getGroupsInCommon(recipientId)
+    .stateIn(
+      scope = viewModelScope,
+      started = SharingStarted.WhileSubscribed(),
+      initialValue = emptyList()
+    )
+}

app/src/main/java/org/thoughtcrime/securesms/recipients/ui/about/AboutSheet.kt

@@ -50,6 +50,7 @@ import org.thoughtcrime.securesms.avatar.AvatarImage
 import org.thoughtcrime.securesms.components.emoji.EmojiTextView
 import org.thoughtcrime.securesms.compose.ComposeBottomSheetDialogFragment
 import org.thoughtcrime.securesms.conversation.v2.UnverifiedProfileNameBottomSheet
+import org.thoughtcrime.securesms.groups.ui.incommon.GroupsInCommonActivity
 import org.thoughtcrime.securesms.nicknames.ViewNoteSheet
 import org.thoughtcrime.securesms.recipients.Recipient
 import org.thoughtcrime.securesms.recipients.RecipientId
@@ -115,7 +116,8 @@ class AboutSheet : ComposeBottomSheetDialogFragment() {
         onClickSignalConnections = this::openSignalConnectionsSheet,
         onAvatarClicked = this::openProfilePhotoViewer,
         onNoteClicked = this::openNoteSheet,
-        onUnverifiedProfileClicked = this::openUnverifiedProfileSheet
+        onUnverifiedProfileClicked = this::openUnverifiedProfileSheet,
+        onGroupsInCommonClicked = this::openGroupsInCommon
       )
     }
   }
@@ -138,6 +140,10 @@ class AboutSheet : ComposeBottomSheetDialogFragment() {
     dismiss()
     UnverifiedProfileNameBottomSheet.show(fragmentManager = parentFragmentManager, forGroup = false)
   }
+
+  private fun openGroupsInCommon() {
+    startActivity(GroupsInCommonActivity.createIntent(requireContext(), recipientId))
+  }
 }
 
 private data class AboutModel(
@@ -162,7 +168,8 @@ private fun Content(
   onClickSignalConnections: () -> Unit,
   onAvatarClicked: () -> Unit,
   onNoteClicked: () -> Unit,
-  onUnverifiedProfileClicked: () -> Unit = {}
+  onUnverifiedProfileClicked: () -> Unit = {},
+  onGroupsInCommonClicked: () -> Unit = {}
 ) {
   Box(
     contentAlignment = Alignment.Center,
@@ -303,6 +310,8 @@ private fun Content(
       AboutRow(
         startIcon = groupsInCommonIcon,
         text = groupsInCommonText,
+        endIcon = if (model.groupsInCommon > 0) ImageVector.vectorResource(id = R.drawable.symbol_chevron_right_compact_bold_16) else null,
+        onClick = if (model.groupsInCommon > 0) onGroupsInCommonClicked else null,
         modifier = Modifier.fillMaxWidth()
       )
     }

app/src/main/res/values/strings.xml

@@ -2575,6 +2575,12 @@
     <!-- Displays the name of a contact. The first placeholder is the name the user has assigned to that contact, the second name is the name the contact assigned to themselves -->
     <string name="AboutSheet__user_set_display_name_and_profile_name">%1$s (%2$s)</string>
 
+    <!-- Title of the screen showing which groups they have in common with another user. -->
+    <plurals name="GroupsInCommon__n_groups_in_common_title">
+        <item quantity="one">%1$s group in common</item>
+        <item quantity="other">%1$s groups in common</item>
+    </plurals>
+
     <!-- CallParticipantsListDialog -->
     <plurals name="CallParticipantsListDialog_in_this_call">
         <item quantity="one">In this call (%1$d)</item>

core-ui/src/main/java/org/signal/core/ui/compose/SignalPreview.kt

@@ -12,6 +12,6 @@ import androidx.compose.ui.tooling.preview.Preview
  * Our very own preview that will generate light and dark previews for
  * composables
  */
-@Preview(uiMode = Configuration.UI_MODE_NIGHT_NO)
+@Preview(name = "Light Theme", uiMode = Configuration.UI_MODE_NIGHT_NO)
-@Preview(uiMode = Configuration.UI_MODE_NIGHT_YES)
+@Preview(name = "Dark Theme", uiMode = Configuration.UI_MODE_NIGHT_YES)
 annotation class SignalPreview()