Implement several parts of the call links admin UX.

app/src/main/java/org/thoughtcrime/securesms/WebRtcCallActivity.java

@@ -50,6 +50,7 @@ import org.greenrobot.eventbus.EventBus;
 import org.greenrobot.eventbus.Subscribe;
 import org.greenrobot.eventbus.ThreadMode;
 import org.signal.core.util.ThreadUtil;
+import org.signal.core.util.concurrent.LifecycleDisposable;
 import org.signal.core.util.concurrent.SignalExecutors;
 import org.signal.core.util.logging.Log;
 import org.signal.libsignal.protocol.IdentityKey;
@@ -61,6 +62,8 @@ import org.thoughtcrime.securesms.components.webrtc.CallParticipantsState;
 import org.thoughtcrime.securesms.components.webrtc.CallStateUpdatePopupWindow;
 import org.thoughtcrime.securesms.components.webrtc.CallToastPopupWindow;
 import org.thoughtcrime.securesms.components.webrtc.GroupCallSafetyNumberChangeNotificationUtil;
+import org.thoughtcrime.securesms.components.webrtc.PendingParticipantsBottomSheet;
+import org.thoughtcrime.securesms.components.webrtc.PendingParticipantsView;
 import org.thoughtcrime.securesms.components.webrtc.WebRtcAudioDevice;
 import org.thoughtcrime.securesms.components.webrtc.WebRtcAudioOutput;
 import org.thoughtcrime.securesms.components.webrtc.WebRtcCallView;
@@ -79,6 +82,7 @@ import org.thoughtcrime.securesms.recipients.RecipientId;
 import org.thoughtcrime.securesms.safety.SafetyNumberBottomSheet;
 import org.thoughtcrime.securesms.service.webrtc.SignalCallManager;
 import org.thoughtcrime.securesms.sms.MessageSender;
+import org.thoughtcrime.securesms.util.BottomSheetUtil;
 import org.thoughtcrime.securesms.util.EllapsedTimeFormatter;
 import org.thoughtcrime.securesms.util.FeatureFlags;
 import org.thoughtcrime.securesms.util.FullscreenHelper;
@@ -137,6 +141,7 @@ public class WebRtcCallActivity extends BaseActivity implements SafetyNumberChan
   private WindowInfoTrackerCallbackAdapter windowInfoTrackerCallbackAdapter;
   private ThrottledDebouncer               requestNewSizesThrottle;
   private PictureInPictureParams.Builder   pipBuilderParams;
+  private LifecycleDisposable              lifecycleDisposable;
 
   private Disposable ephemeralStateDisposable = Disposable.empty();
 
@@ -150,6 +155,10 @@ public class WebRtcCallActivity extends BaseActivity implements SafetyNumberChan
   @Override
   public void onCreate(Bundle savedInstanceState) {
     Log.i(TAG, "onCreate(" + getIntent().getBooleanExtra(EXTRA_STARTED_FROM_FULLSCREEN, false) + ")");
+
+    lifecycleDisposable = new LifecycleDisposable();
+    lifecycleDisposable.bindTo(this);
+
     getWindow().addFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED);
     getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
     super.onCreate(savedInstanceState);
@@ -398,6 +407,12 @@ public class WebRtcCallActivity extends BaseActivity implements SafetyNumberChan
       }
       viewModel.setIsLandscapeEnabled(info.isInPictureInPictureMode());
     });
+
+    callScreen.setPendingParticipantsViewListener(new PendingParticipantsViewListener());
+    Disposable disposable = viewModel.getPendingParticipants()
+                                     .subscribe(callScreen::updatePendingParticipantsList);
+
+    lifecycleDisposable.add(disposable);
   }
 
   private void initializePictureInPictureParams() {
@@ -949,6 +964,24 @@ public class WebRtcCallActivity extends BaseActivity implements SafetyNumberChan
     }
   }
 
+  private class PendingParticipantsViewListener implements PendingParticipantsView.Listener {
+
+    @Override
+    public void onAllowPendingRecipient(@NonNull Recipient pendingRecipient) {
+      ApplicationDependencies.getSignalCallManager().setCallLinkJoinRequestAccepted(pendingRecipient);
+    }
+
+    @Override
+    public void onRejectPendingRecipient(@NonNull Recipient pendingRecipient) {
+      ApplicationDependencies.getSignalCallManager().setCallLinkJoinRequestRejected(pendingRecipient);
+    }
+
+    @Override
+    public void onLaunchPendingRequestsSheet() {
+      new PendingParticipantsBottomSheet().show(getSupportFragmentManager(), BottomSheetUtil.STANDARD_BOTTOM_SHEET_FRAGMENT_TAG);
+    }
+  }
+
   private class WindowLayoutInfoConsumer implements Consumer<WindowLayoutInfo> {
 
     @Override

app/src/main/java/org/thoughtcrime/securesms/components/webrtc/PendingParticipantsBottomSheet.kt

@@ -0,0 +1,291 @@
+/*
+ * Copyright 2023 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.components.webrtc
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Person
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rxjava3.subscribeAsState
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.platform.LocalInspectionMode
+import androidx.compose.ui.res.colorResource
+import androidx.compose.ui.res.pluralStringResource
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.res.vectorResource
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.viewinterop.AndroidView
+import androidx.core.os.bundleOf
+import androidx.fragment.app.setFragmentResult
+import org.signal.core.ui.BottomSheets
+import org.signal.core.ui.Buttons
+import org.signal.core.ui.theme.SignalTheme
+import org.thoughtcrime.securesms.R
+import org.thoughtcrime.securesms.components.AvatarImageView
+import org.thoughtcrime.securesms.compose.ComposeBottomSheetDialogFragment
+import org.thoughtcrime.securesms.dependencies.ApplicationDependencies
+import org.thoughtcrime.securesms.recipients.Recipient
+import org.thoughtcrime.securesms.service.webrtc.PendingParticipantCollection
+import org.thoughtcrime.securesms.util.activityViewModel
+import kotlin.time.Duration.Companion.milliseconds
+
+/**
+ * Displays a list of pending participants attempting to join this call.
+ */
+class PendingParticipantsBottomSheet : ComposeBottomSheetDialogFragment() {
+
+  companion object {
+    const val REQUEST_KEY = "PendingParticipantsBottomSheet_result"
+  }
+
+  private val viewModel: WebRtcCallViewModel by activityViewModel {
+    error("Should already exist")
+  }
+
+  override val peekHeightPercentage: Float = 1f
+
+  @Composable
+  override fun SheetContent() {
+    val launchTime = remember {
+      System.currentTimeMillis().milliseconds
+    }
+
+    val participants = viewModel.pendingParticipants
+      .map { it.getAllPendingParticipants(launchTime).toList() }
+      .subscribeAsState(initial = emptyList())
+
+    PendingParticipantsSheet(
+      pendingParticipants = participants.value,
+      onApproveAll = this::onApproveAll,
+      onDenyAll = this::onDenyAll,
+      onApprove = this::onApprove,
+      onDeny = this::onDeny
+    )
+  }
+
+  private fun onApprove(recipient: Recipient) {
+    ApplicationDependencies.getSignalCallManager().setCallLinkJoinRequestAccepted(recipient)
+  }
+
+  private fun onDeny(recipient: Recipient) {
+    ApplicationDependencies.getSignalCallManager().setCallLinkJoinRequestRejected(recipient)
+  }
+
+  private fun onApproveAll() {
+    dismiss()
+    setFragmentResult(REQUEST_KEY, bundleOf(REQUEST_KEY to true))
+  }
+
+  private fun onDenyAll() {
+    dismiss()
+    setFragmentResult(REQUEST_KEY, bundleOf(REQUEST_KEY to false))
+  }
+}
+
+@Preview(showSystemUi = true)
+@Composable
+private fun PendingParticipantsSheetPreview() {
+  SignalTheme(isDarkMode = true) {
+    Surface(shape = RoundedCornerShape(18.dp, 18.dp)) {
+      PendingParticipantsSheet(
+        pendingParticipants = (1 until 7).map {
+          PendingParticipantCollection.Entry(Recipient.UNKNOWN, PendingParticipantCollection.State.PENDING, System.currentTimeMillis().milliseconds)
+        },
+        onApproveAll = {},
+        onDenyAll = {},
+        onApprove = {},
+        onDeny = {}
+      )
+    }
+  }
+}
+
+@Composable
+private fun PendingParticipantsSheet(
+  pendingParticipants: List<PendingParticipantCollection.Entry>,
+  onApproveAll: () -> Unit,
+  onDenyAll: () -> Unit,
+  onApprove: (Recipient) -> Unit,
+  onDeny: (Recipient) -> Unit
+) {
+  Box {
+    Column(
+      horizontalAlignment = Alignment.CenterHorizontally,
+      modifier = Modifier.padding(bottom = 64.dp)
+    ) {
+      BottomSheets.Handle()
+
+      Spacer(Modifier.size(14.dp))
+
+      LazyColumn(
+        horizontalAlignment = Alignment.CenterHorizontally
+      ) {
+        item {
+          Text(
+            text = stringResource(id = R.string.PendingParticipantsBottomSheet__requests_to_join_this_call),
+            style = MaterialTheme.typography.titleLarge
+          )
+        }
+
+        item {
+          Text(
+            text = pluralStringResource(
+              id = R.plurals.PendingParticipantsBottomSheet__d_people_waiting,
+              count = pendingParticipants.size,
+              pendingParticipants.size
+            ),
+            style = MaterialTheme.typography.titleMedium,
+            color = MaterialTheme.colorScheme.onSurfaceVariant
+          )
+        }
+
+        item {
+          Spacer(Modifier.size(24.dp))
+        }
+
+        items(pendingParticipants.size) { index ->
+          PendingParticipantRow(
+            participant = pendingParticipants[index],
+            onApprove = onApprove,
+            onDeny = onDeny
+          )
+        }
+      }
+    }
+
+    Row(
+      modifier = Modifier
+        .align(Alignment.BottomStart)
+        .background(color = MaterialTheme.colorScheme.background)
+        .padding(horizontal = 24.dp, vertical = 16.dp)
+    ) {
+      Spacer(modifier = Modifier.weight(1f))
+
+      TextButton(
+        onClick = onDenyAll
+      ) {
+        Text(
+          text = "Deny all",
+          color = MaterialTheme.colorScheme.onSurface
+        )
+      }
+
+      Spacer(modifier = Modifier.size(8.dp))
+
+      Buttons.LargeTonal(onClick = onApproveAll) {
+        Text(
+          text = "Approve all"
+        )
+      }
+    }
+  }
+}
+
+@Composable
+private fun PendingParticipantRow(
+  participant: PendingParticipantCollection.Entry,
+  onApprove: (Recipient) -> Unit,
+  onDeny: (Recipient) -> Unit
+) {
+  val onApproveCallback = remember(participant.recipient) { { onApprove(participant.recipient) } }
+  val onDenyCallback = remember(participant.recipient) { { onDeny(participant.recipient) } }
+
+  Row(
+    verticalAlignment = Alignment.CenterVertically,
+    modifier = Modifier.padding(horizontal = 24.dp, vertical = 12.dp)
+  ) {
+    PendingParticipantAvatar(recipient = participant.recipient)
+
+    Text(
+      text = participant.recipient.getDisplayName(LocalContext.current),
+      style = MaterialTheme.typography.bodyLarge,
+      modifier = Modifier
+        .weight(1f)
+        .padding(horizontal = 16.dp)
+    )
+
+    CircularIconButton(
+      symbol = ImageVector.vectorResource(id = R.drawable.symbol_x_compact_bold_16),
+      contentDescription = stringResource(id = R.string.PendingParticipantsBottomSheet__reject),
+      backgroundColor = colorResource(id = R.color.webrtc_hangup_background),
+      onClick = onDenyCallback
+    )
+
+    Spacer(modifier = Modifier.size(24.dp))
+
+    CircularIconButton(
+      symbol = ImageVector.vectorResource(id = R.drawable.symbol_check_compact_bold_16),
+      contentDescription = stringResource(id = R.string.PendingParticipantsBottomSheet__approve),
+      backgroundColor = colorResource(id = R.color.signal_accent_green),
+      onClick = onApproveCallback
+    )
+  }
+}
+
+@Composable
+private fun CircularIconButton(
+  symbol: ImageVector,
+  contentDescription: String?,
+  backgroundColor: Color,
+  onClick: () -> Unit
+) {
+  Icon(
+    imageVector = symbol,
+    contentDescription = contentDescription,
+    modifier = Modifier
+      .size(28.dp)
+      .background(
+        color = backgroundColor,
+        shape = CircleShape
+      )
+      .clickable(onClick = onClick)
+      .padding(6.dp)
+  )
+}
+
+@Composable
+private fun PendingParticipantAvatar(recipient: Recipient) {
+  if (LocalInspectionMode.current) {
+    Icon(
+      imageVector = Icons.Default.Person,
+      contentDescription = null,
+      modifier = Modifier
+        .size(40.dp)
+        .background(
+          color = Color.Red,
+          shape = CircleShape
+        )
+    )
+  } else {
+    AndroidView(
+      factory = ::AvatarImageView,
+      modifier = Modifier.size(40.dp)
+    ) {
+      it.setAvatar(recipient)
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/components/webrtc/PendingParticipantsView.kt

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2023 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.components.webrtc
+
+import android.content.Context
+import android.util.AttributeSet
+import android.view.View
+import android.widget.TextView
+import androidx.constraintlayout.widget.Group
+import com.google.android.material.button.MaterialButton
+import com.google.android.material.card.MaterialCardView
+import org.thoughtcrime.securesms.R
+import org.thoughtcrime.securesms.components.AvatarImageView
+import org.thoughtcrime.securesms.recipients.Recipient
+import org.thoughtcrime.securesms.service.webrtc.PendingParticipantCollection
+import org.thoughtcrime.securesms.util.visible
+
+/**
+ * Card which displays pending participants state.
+ */
+class PendingParticipantsView @JvmOverloads constructor(
+  context: Context,
+  attrs: AttributeSet? = null
+) : MaterialCardView(context, attrs) {
+  init {
+    inflate(context, R.layout.pending_participant_view, this)
+  }
+
+  var listener: Listener? = null
+
+  private val avatar: AvatarImageView = findViewById(R.id.pending_participants_avatar)
+  private val name: TextView = findViewById(R.id.pending_participants_name)
+  private val allow: View = findViewById(R.id.pending_participants_allow)
+  private val reject: View = findViewById(R.id.pending_participants_reject)
+  private val requestsGroup: Group = findViewById(R.id.pending_participants_requests_group)
+  private val requestsButton: MaterialButton = findViewById(R.id.pending_participants_requests)
+
+  init {
+    requestsButton.setOnClickListener {
+      listener?.onLaunchPendingRequestsSheet()
+    }
+  }
+
+  fun applyState(pendingParticipantCollection: PendingParticipantCollection) {
+    val unresolvedPendingParticipants: List<Recipient> = pendingParticipantCollection.getUnresolvedPendingParticipants().map { it.recipient }
+    if (unresolvedPendingParticipants.isEmpty()) {
+      visible = false
+      return
+    }
+
+    val firstRecipient: Recipient = unresolvedPendingParticipants.first()
+    avatar.setAvatar(firstRecipient)
+    name.text = firstRecipient.getShortDisplayName(context)
+
+    allow.setOnClickListener { listener?.onAllowPendingRecipient(firstRecipient) }
+    reject.setOnClickListener { listener?.onRejectPendingRecipient(firstRecipient) }
+
+    if (unresolvedPendingParticipants.size > 1) {
+      val requestCount = unresolvedPendingParticipants.size - 1
+      requestsButton.text = resources.getQuantityString(R.plurals.PendingParticipantsView__plus_d_requests, requestCount, requestCount)
+      requestsGroup.visible = true
+    } else {
+      requestsGroup.visible = false
+    }
+
+    visible = true
+  }
+
+  interface Listener {
+    /**
+     * Given recipient should be admitted to the call
+     */
+    fun onAllowPendingRecipient(pendingRecipient: Recipient)
+
+    /**
+     * Given recipient should be rejected from the call
+     */
+    fun onRejectPendingRecipient(pendingRecipient: Recipient)
+
+    /**
+     * Display the sheet containing all of the requests for the given call
+     */
+    fun onLaunchPendingRequestsSheet()
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/components/webrtc/WebRtcCallView.java

@@ -57,6 +57,7 @@ import org.thoughtcrime.securesms.mms.GlideApp;
 import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.recipients.RecipientId;
 import org.thoughtcrime.securesms.ringrtc.CameraState;
+import org.thoughtcrime.securesms.service.webrtc.PendingParticipantCollection;
 import org.thoughtcrime.securesms.util.BlurTransformation;
 import org.thoughtcrime.securesms.util.ThrottledDebouncer;
 import org.thoughtcrime.securesms.util.ViewUtil;
@@ -127,10 +128,12 @@ public class WebRtcCallView extends ConstraintLayout {
   private View                          fullScreenShade;
   private Toolbar                       collapsedToolbar;
   private Toolbar                       headerToolbar;
+  private Stub<PendingParticipantsView> pendingParticipantsViewStub;
 
   private WebRtcCallParticipantsPagerAdapter    pagerAdapter;
   private WebRtcCallParticipantsRecyclerAdapter recyclerAdapter;
   private PictureInPictureExpansionHelper       pictureInPictureExpansionHelper;
+  private PendingParticipantsView.Listener      pendingParticipantsViewListener;
 
   private final Set<View> incomingCallViews    = new HashSet<>();
   private final Set<View> topViews             = new HashSet<>();
@@ -203,6 +206,7 @@ public class WebRtcCallView extends ConstraintLayout {
     fullScreenShade               = findViewById(R.id.call_screen_full_shade);
     collapsedToolbar              = findViewById(R.id.webrtc_call_view_toolbar_text);
     headerToolbar                 = findViewById(R.id.webrtc_call_view_toolbar_no_text);
+    pendingParticipantsViewStub   = new Stub<>(findViewById(R.id.call_screen_pending_recipients));
 
     View      decline                = findViewById(R.id.call_screen_decline_call);
     View      answerLabel            = findViewById(R.id.call_screen_answer_call_label);
@@ -424,6 +428,22 @@ public class WebRtcCallView extends ConstraintLayout {
     micToggle.setChecked(isMicEnabled, false);
   }
 
+  public void setPendingParticipantsViewListener(@Nullable PendingParticipantsView.Listener listener) {
+    pendingParticipantsViewListener = listener;
+  }
+
+  public void updatePendingParticipantsList(@NonNull PendingParticipantCollection pendingParticipantCollection) {
+    if (pendingParticipantCollection.getUnresolvedPendingParticipants().isEmpty()) {
+      if (pendingParticipantsViewStub.resolved()) {
+        pendingParticipantsViewStub.get().setListener(pendingParticipantsViewListener);
+        pendingParticipantsViewStub.get().applyState(pendingParticipantCollection);
+      }
+    } else {
+      pendingParticipantsViewStub.get().setListener(pendingParticipantsViewListener);
+      pendingParticipantsViewStub.get().applyState(pendingParticipantCollection);
+    }
+  }
+
   public void updateCallParticipants(@NonNull CallParticipantsViewState callParticipantsViewState) {
     lastState = callParticipantsViewState;
 

app/src/main/java/org/thoughtcrime/securesms/components/webrtc/WebRtcCallViewModel.java

@@ -30,6 +30,7 @@ import org.thoughtcrime.securesms.keyvalue.SignalStore;
 import org.thoughtcrime.securesms.recipients.LiveRecipient;
 import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.recipients.RecipientId;
+import org.thoughtcrime.securesms.service.webrtc.PendingParticipantCollection;
 import org.thoughtcrime.securesms.service.webrtc.state.WebRtcEphemeralState;
 import org.thoughtcrime.securesms.util.DefaultValueLiveData;
 import org.thoughtcrime.securesms.util.NetworkUtil;
@@ -44,6 +45,10 @@ import java.util.List;
 import java.util.Objects;
 import java.util.Set;
 
+import io.reactivex.rxjava3.android.schedulers.AndroidSchedulers;
+import io.reactivex.rxjava3.core.Observable;
+import io.reactivex.rxjava3.subjects.BehaviorSubject;
+
 public class WebRtcCallViewModel extends ViewModel {
 
   private final MutableLiveData<Boolean>                      microphoneEnabled         = new MutableLiveData<>(true);
@@ -70,6 +75,8 @@ public class WebRtcCallViewModel extends ViewModel {
   private final Observer<List<GroupMemberEntry.FullMember>>   groupMemberStateUpdater   = m -> participantsState.setValue(CallParticipantsState.update(participantsState.getValue(), m));
   private final MutableLiveData<WebRtcEphemeralState>         ephemeralState            = new MutableLiveData<>();
 
+  private final BehaviorSubject<PendingParticipantCollection> pendingParticipants = BehaviorSubject.create();
+
   private final Handler  elapsedTimeHandler      = new Handler(Looper.getMainLooper());
   private final Runnable elapsedTimeRunnable     = this::handleTick;
   private final Runnable stopOutgoingRingingMode = this::stopOutgoingRingingMode;
@@ -183,6 +190,10 @@ public class WebRtcCallViewModel extends ViewModel {
     return callStarting;
   }
 
+  public @NonNull Observable<PendingParticipantCollection> getPendingParticipants() {
+    return pendingParticipants.observeOn(AndroidSchedulers.mainThread());
+  }
+
   @MainThread
   public void setIsInPipMode(boolean isInPipMode) {
     this.isInPipMode.setValue(isInPipMode);
@@ -272,6 +283,8 @@ public class WebRtcCallViewModel extends ViewModel {
                          webRtcViewModel.getParticipantLimit(),
                          webRtcViewModel.getRecipient().isCallLink());
 
+    pendingParticipants.onNext(webRtcViewModel.getPendingParticipants());
+
     if (newState.isInOutgoingRingingMode()) {
       cancelTimer();
       if (!wasInOutgoingRingingMode) {

app/src/main/java/org/thoughtcrime/securesms/events/WebRtcViewModel.kt

@@ -5,6 +5,7 @@ import org.thoughtcrime.securesms.components.webrtc.BroadcastVideoSink
 import org.thoughtcrime.securesms.events.CallParticipant.Companion.createLocal
 import org.thoughtcrime.securesms.recipients.Recipient
 import org.thoughtcrime.securesms.recipients.RecipientId
+import org.thoughtcrime.securesms.service.webrtc.PendingParticipantCollection
 import org.thoughtcrime.securesms.service.webrtc.state.WebRtcServiceState
 import org.thoughtcrime.securesms.webrtc.audio.SignalAudioManager
 import org.webrtc.PeerConnection
@@ -92,6 +93,7 @@ class WebRtcViewModel(state: WebRtcServiceState) {
   val identityChangedParticipants: Set<RecipientId> = state.callInfoState.identityChangedRecipients
   val remoteDevicesCount: OptionalLong = state.callInfoState.remoteDevicesCount
   val participantLimit: Long? = state.callInfoState.participantLimit
+  val pendingParticipants: PendingParticipantCollection = state.callInfoState.pendingParticipants
 
   @get:JvmName("shouldRingGroup")
   val ringGroup: Boolean = state.getCallSetupState(state.callInfoState.activePeer?.callId).ringGroup

app/src/main/java/org/thoughtcrime/securesms/service/webrtc/CallLinkConnectedActionProcessor.kt

@@ -6,7 +6,15 @@
 package org.thoughtcrime.securesms.service.webrtc
 
 import org.signal.core.util.logging.Log
+import org.signal.ringrtc.CallException
+import org.signal.ringrtc.GroupCall
+import org.signal.ringrtc.PeekInfo
+import org.thoughtcrime.securesms.database.CallLinkTable
+import org.thoughtcrime.securesms.database.SignalDatabase
+import org.thoughtcrime.securesms.recipients.Recipient
+import org.thoughtcrime.securesms.service.webrtc.links.CallLinkRoomId
 import org.thoughtcrime.securesms.service.webrtc.state.WebRtcServiceState
+import org.whispersystems.signalservice.api.push.ServiceId
 
 /**
  * Process actions for when the call link has at least once been connected and joined.
@@ -25,4 +33,67 @@ class CallLinkConnectedActionProcessor(
 
     return currentState
   }
+
+  override fun handleGroupJoinedMembershipChanged(currentState: WebRtcServiceState): WebRtcServiceState {
+    Log.i(tag, "handleGroupJoinedMembershipChanged():")
+
+    val superState: WebRtcServiceState = super.handleGroupJoinedMembershipChanged(currentState)
+    val groupCall: GroupCall = superState.callInfoState.requireGroupCall()
+    val peekInfo: PeekInfo = groupCall.peekInfo ?: return superState
+
+    val callLinkRoomId: CallLinkRoomId = superState.callInfoState.callRecipient.requireCallLinkRoomId()
+    val callLink: CallLinkTable.CallLink = SignalDatabase.callLinks.getCallLinkByRoomId(callLinkRoomId) ?: return superState
+
+    if (callLink.credentials?.adminPassBytes == null) {
+      Log.i(tag, "User is not an admin.")
+      return superState
+    }
+
+    Log.i(tag, "Updating pending list with ${peekInfo.pendingUsers.size} entries.")
+    val pendingParticipants: List<Recipient> = peekInfo.pendingUsers.map { Recipient.externalPush(ServiceId.ACI.from(it)) }
+
+    return superState.builder()
+      .changeCallInfoState()
+      .setPendingParticipants(pendingParticipants)
+      .build()
+  }
+
+  override fun handleSetCallLinkJoinRequestAccepted(currentState: WebRtcServiceState, participant: Recipient): WebRtcServiceState {
+    Log.i(tag, "handleSetCallLinkJoinRequestAccepted():")
+
+    val groupCall: GroupCall = currentState.callInfoState.requireGroupCall()
+
+    return try {
+      groupCall.approveUser(participant.requireAci().rawUuid)
+
+      currentState
+        .builder()
+        .changeCallInfoState()
+        .setPendingParticipantApproved(participant)
+        .build()
+    } catch (e: CallException) {
+      Log.w(tag, "Failed to approve user.", e)
+
+      currentState
+    }
+  }
+
+  override fun handleSetCallLinkJoinRequestRejected(currentState: WebRtcServiceState, participant: Recipient): WebRtcServiceState {
+    Log.i(tag, "handleSetCallLinkJoinRequestRejected():")
+
+    val groupCall: GroupCall = currentState.callInfoState.requireGroupCall()
+
+    return try {
+      groupCall.denyUser(participant.requireAci().rawUuid)
+
+      currentState
+        .builder()
+        .changeCallInfoState()
+        .setPendingParticipantRejected(participant)
+        .build()
+    } catch (e: CallException) {
+      Log.w(tag, "Failed to deny user.", e)
+      currentState
+    }
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/service/webrtc/PendingParticipantCollection.kt

@@ -0,0 +1,128 @@
+/*
+ * Copyright 2023 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.service.webrtc
+
+import org.thoughtcrime.securesms.recipients.Recipient
+import org.thoughtcrime.securesms.recipients.RecipientId
+import kotlin.time.Duration
+import kotlin.time.Duration.Companion.milliseconds
+
+/**
+ * Holds state information about what users wish to join a given call link.
+ *
+ * Also holds information about approvals and denials, so that this state is
+ * persisted over the lifecycle of the user's time in the call.
+ */
+data class PendingParticipantCollection(
+  private val participantMap: Map<RecipientId, Entry> = emptyMap(),
+  private val nowProvider: () -> Duration = { System.currentTimeMillis().milliseconds }
+) {
+
+  /**
+   * Creates a new collection with the given recipients applied to it with the following rules:
+   *
+   * 1. If the recipient is already in the collection, ignore it
+   * 1. Otherwise, insert the recipient at the end of the colleciton in the pending state
+   * 1. Any recipients in the resulting collection that are [State.PENDING] and NOT in the passed recipient list are removed.
+   */
+  fun withRecipients(recipients: List<Recipient>): PendingParticipantCollection {
+    val now = nowProvider()
+    val newEntries = recipients.filterNot { it.id in participantMap.keys }.map {
+      it.id to Entry(
+        it,
+        State.PENDING,
+        now
+      )
+    }
+
+    val recipientIds = recipients.map { it.id }
+    val newEntryMap = (participantMap + newEntries).filterNot { it.value.state == State.PENDING && it.key !in recipientIds }
+
+    return copy(participantMap = newEntryMap)
+  }
+
+  /**
+   * Creates a new collection with the given recipient marked as [State.APPROVED]
+   */
+  fun withApproval(recipient: Recipient): PendingParticipantCollection {
+    val now = nowProvider()
+    val entry = Entry(
+      recipient = recipient,
+      state = State.APPROVED,
+      stateChangeAt = now
+    )
+
+    return copy(
+      participantMap = participantMap + (recipient.id to entry)
+    )
+  }
+
+  /**
+   * Creates a new collection with the given recipient marked as [State.DENIED]
+   */
+  fun withDenial(recipient: Recipient): PendingParticipantCollection {
+    val now = nowProvider()
+    val entry = Entry(
+      recipient = recipient,
+      state = State.DENIED,
+      stateChangeAt = now
+    )
+
+    return copy(
+      participantMap = participantMap + (recipient.id to entry)
+    )
+  }
+
+  /**
+   * Gets all of the pending participants in the [State.PENDING] state.
+   */
+  fun getUnresolvedPendingParticipants(): Set<Entry> {
+    return participantMap.values.filter { it.state == State.PENDING }.toSet()
+  }
+
+  /**
+   * Gets all of the pending participants regardless of state. Filterable
+   * via a 'since' parameter so that we only display non-[State.PENDING] entries with
+   * state change timestamps AFTER that parameter. [State.PENDING] entries will always
+   * be returned.
+   *
+   * @param since A timestamp, for which we will only return non-[State.PENDING] occurring afterwards.
+   */
+  fun getAllPendingParticipants(since: Duration): Set<Entry> {
+    return participantMap.values.filter {
+      it.state == State.PENDING || it.stateChangeAt > since
+    }.toSet()
+  }
+
+  /**
+   * A [Recipient] and some [State] metadata
+   */
+  data class Entry(
+    val recipient: Recipient,
+    val state: State,
+    val stateChangeAt: Duration
+  )
+
+  /**
+   * The state of a given recipient's approval
+   */
+  enum class State {
+    /**
+     * No action has been taken
+     */
+    PENDING,
+
+    /**
+     * The user has approved this recipient
+     */
+    APPROVED,
+
+    /**
+     * The user has denied this recipient
+     */
+    DENIED
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/service/webrtc/SignalCallManager.java

@@ -354,6 +354,22 @@ private void processStateless(@NonNull Function1<WebRtcEphemeralState, WebRtcEph
     process((s, p) -> p.handleDropCall(s, callId));
   }
 
+  public void setCallLinkJoinRequestAccepted(@NonNull Recipient participant) {
+    process((s, p) -> p.handleSetCallLinkJoinRequestAccepted(s, participant));
+  }
+
+  public void setCallLinkJoinRequestRejected(@NonNull Recipient participant) {
+    process((s, p) -> p.handleSetCallLinkJoinRequestRejected(s, participant));
+  }
+
+  public void removeFromCallLink(@NonNull Recipient participant) {
+    process((s, p) -> p.handleRemoveFromCallLink(s, participant));
+  }
+
+  public void blockFromCallLink(@NonNull Recipient participant) {
+    process((s, p) -> p.handleBlockFromCallLink(s, participant));
+  }
+
   public void peekCallLinkCall(@NonNull RecipientId id) {
     if (callManager == null) {
       Log.i(TAG, "Unable to peekCallLinkCall, call manager is null");

app/src/main/java/org/thoughtcrime/securesms/service/webrtc/WebRtcActionProcessor.java

@@ -874,4 +874,32 @@ public abstract class WebRtcActionProcessor {
   }
 
   //endregion
+
+  //region Call Links
+
+  protected @NonNull WebRtcServiceState handleSetCallLinkJoinRequestAccepted(@NonNull WebRtcServiceState currentState, @NonNull Recipient participant) {
+    Log.i(tag, "handleSetCallLinkJoinRequestAccepted not processed");
+
+    return currentState;
+  }
+
+  protected @NonNull WebRtcServiceState handleSetCallLinkJoinRequestRejected(@NonNull WebRtcServiceState currentState, @NonNull Recipient participant) {
+    Log.i(tag, "handleSetCallLinkJoinRequestRejected not processed");
+
+    return currentState;
+  }
+
+  protected @NonNull WebRtcServiceState handleRemoveFromCallLink(@NonNull WebRtcServiceState currentState, @NonNull Recipient participant) {
+    Log.i(tag, "handleRemoveFromCallLink not processed");
+
+    return currentState;
+  }
+
+  protected @NonNull WebRtcServiceState handleBlockFromCallLink(@NonNull WebRtcServiceState currentState, @NonNull Recipient participant) {
+    Log.i(tag, "handleBlockFromCallLink not processed");
+
+    return currentState;
+  }
+
+  //endregion
 }

app/src/main/java/org/thoughtcrime/securesms/service/webrtc/state/CallInfoState.kt

@@ -9,9 +9,12 @@ import org.thoughtcrime.securesms.events.WebRtcViewModel
 import org.thoughtcrime.securesms.recipients.Recipient
 import org.thoughtcrime.securesms.recipients.RecipientId
 import org.thoughtcrime.securesms.ringrtc.RemotePeer
+import org.thoughtcrime.securesms.service.webrtc.PendingParticipantCollection
 
 /**
  * General state of ongoing calls.
+ *
+ * @param pendingParticipants A list of pending users wishing to join a given call link.
  */
 data class CallInfoState(
   var callState: WebRtcViewModel.State = WebRtcViewModel.State.IDLE,
@@ -24,7 +27,8 @@ data class CallInfoState(
   @get:JvmName("getGroupCallState") var groupState: WebRtcViewModel.GroupCallState = WebRtcViewModel.GroupCallState.IDLE,
   var identityChangedRecipients: MutableSet<RecipientId> = mutableSetOf(),
   var remoteDevicesCount: OptionalLong = OptionalLong.empty(),
-  var participantLimit: Long? = null
+  var participantLimit: Long? = null,
+  var pendingParticipants: PendingParticipantCollection = PendingParticipantCollection()
 ) {
 
   val remoteCallParticipants: List<CallParticipant>

app/src/main/java/org/thoughtcrime/securesms/service/webrtc/state/WebRtcServiceStateBuilder.java

@@ -23,6 +23,7 @@ import org.thoughtcrime.securesms.webrtc.audio.SignalAudioManager;
 import org.webrtc.PeerConnection;
 
 import java.util.Collection;
+import java.util.List;
 import java.util.Set;
 
 /**
@@ -342,5 +343,20 @@ public class WebRtcServiceStateBuilder {
       toBuild.setParticipantLimit(participantLimit);
       return this;
     }
+
+    public @NonNull CallInfoStateBuilder setPendingParticipants(@NonNull List<Recipient> pendingParticipants) {
+      toBuild.setPendingParticipants(toBuild.getPendingParticipants().withRecipients(pendingParticipants));
+      return this;
+    }
+
+    public @NonNull CallInfoStateBuilder setPendingParticipantApproved(@NonNull Recipient participant) {
+      toBuild.setPendingParticipants(toBuild.getPendingParticipants().withApproval(participant));
+      return this;
+    }
+
+    public @NonNull CallInfoStateBuilder setPendingParticipantRejected(@NonNull Recipient participant) {
+      toBuild.setPendingParticipants(toBuild.getPendingParticipants().withDenial(participant));
+      return this;
+    }
   }
 }

app/src/main/res/drawable/ic_deny_28_tinted.xml

@@ -1,5 +1,4 @@
-<vector xmlns:android="http://schemas.android.com/apk/res/android"
-    android:width="28dp"
+<vector xmlns:android="http://schemas.android.com/apk/res/android" android:width="28dp"
     android:height="28dp"
     android:viewportWidth="28"
     android:viewportHeight="28">

app/src/main/res/drawable/symbol_check_bold_24.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M19.04 5.16c0.46 0.3 0.6 0.91 0.3 1.38l-8.32 13c-0.17 0.27-0.47 0.44-0.8 0.46C9.9 20 9.6 19.87 9.4 19.62l-4.68-5.98c-0.34-0.44-0.26-1.07 0.17-1.4 0.44-0.35 1.07-0.27 1.4 0.16l3.82 4.87 7.56-11.8c0.3-0.47 0.91-0.61 1.38-0.31Z"/>
+</vector>

app/src/main/res/drawable/symbol_check_compact_bold_16.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="16dp"
+    android:height="16dp"
+    android:viewportWidth="16"
+    android:viewportHeight="16">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M13.15 2.87c0.35 0.22 0.46 0.68 0.23 1.03l-6 9.5c-0.13 0.2-0.35 0.34-0.6 0.35-0.24 0.01-0.47-0.1-0.62-0.29l-3.5-4.5c-0.26-0.33-0.2-0.8 0.13-1.05 0.33-0.26 0.8-0.2 1.05 0.13L6.7 11.7l5.43-8.6c0.22-0.35 0.68-0.46 1.03-0.23Z"/>
+</vector>

app/src/main/res/drawable/symbol_x_bold_24.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M18.7 6.7c0.4-0.38 0.4-1.02 0-1.4-0.38-0.4-1.02-0.4-1.4 0L12 10.58l-5.3-5.3C6.33 4.9 5.69 4.9 5.3 5.3c-0.4 0.4-0.4 1.03 0 1.42L10.58 12l-5.3 5.3c-0.39 0.38-0.39 1.02 0 1.4 0.4 0.4 1.03 0.4 1.42 0L12 13.42l5.3 5.3c0.38 0.39 1.02 0.39 1.4 0 0.4-0.4 0.4-1.03 0-1.42L13.42 12l5.3-5.3Z"/>
+</vector>

app/src/main/res/drawable/symbol_x_compact_bold_16.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="16dp"
+    android:height="16dp"
+    android:viewportWidth="16"
+    android:viewportHeight="16">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M4.53 3.47c-0.3-0.3-0.77-0.3-1.06 0-0.3 0.3-0.3 0.77 0 1.06L6.94 8l-3.47 3.47c-0.3 0.3-0.3 0.77 0 1.06 0.3 0.3 0.77 0.3 1.06 0L8 9.06l3.47 3.47c0.3 0.3 0.77 0.3 1.06 0 0.3-0.3 0.3-0.77 0-1.06L9.06 8l3.47-3.47c0.3-0.3 0.3-0.77 0-1.06-0.3-0.3-0.77-0.3-1.06 0L8 6.94 4.53 3.47Z"/>
+</vector>

app/src/main/res/layout/call_screen_pending_participants_view.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2023 Signal Messenger, LLC
+  ~ SPDX-License-Identifier: AGPL-3.0-only
+  -->
+<org.thoughtcrime.securesms.components.webrtc.PendingParticipantsView xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:layout_marginHorizontal="24dp"
+    android:layout_marginBottom="32dp"
+    android:minHeight="72dp"
+    app:cardBackgroundColor="@color/signal_colorSurface3"
+    app:cardCornerRadius="18dp"
+    app:cardElevation="0dp" />

app/src/main/res/layout/pending_participant_view.xml

@@ -0,0 +1,130 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2023 Signal Messenger, LLC
+  ~ SPDX-License-Identifier: AGPL-3.0-only
+  -->
+<merge xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:minHeight="72dp"
+    app:cardBackgroundColor="@color/signal_colorSurface3"
+    app:cardCornerRadius="18dp"
+    app:cardElevation="0dp"
+    tools:layout_marginHorizontal="24dp"
+    tools:parentTag="com.google.android.material.card.MaterialCardView">
+
+    <androidx.constraintlayout.widget.ConstraintLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:minHeight="72dp">
+
+        <org.thoughtcrime.securesms.components.AvatarImageView
+            android:id="@+id/pending_participants_avatar"
+            android:layout_width="48dp"
+            android:layout_height="48dp"
+            android:layout_marginStart="12dp"
+            android:layout_marginTop="12dp"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            tools:background="@color/red_100" />
+
+        <org.thoughtcrime.securesms.components.emoji.EmojiTextView
+            android:id="@+id/pending_participants_name"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="8dp"
+            android:textAppearance="@style/Signal.Text.TitleSmall"
+            android:textColor="@color/signal_colorOnSurface"
+            app:layout_constraintBottom_toTopOf="@id/pending_participants_status"
+            app:layout_constraintStart_toEndOf="@id/pending_participants_avatar"
+            app:layout_constraintTop_toTopOf="@id/pending_participants_avatar"
+            app:layout_constraintVertical_chainStyle="packed"
+            tools:text="Candice" />
+
+        <TextView
+            android:id="@+id/pending_participants_status"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="8dp"
+            android:text="@string/PendingParticipantsView__would_like_to_join"
+            android:textAppearance="@style/Signal.Text.BodyMedium"
+            android:textColor="@color/signal_colorOnSurfaceVariant"
+            app:layout_constraintBottom_toBottomOf="@id/pending_participants_avatar"
+            app:layout_constraintStart_toEndOf="@id/pending_participants_avatar"
+            app:layout_constraintTop_toBottomOf="@id/pending_participants_name" />
+
+        <com.google.android.material.imageview.ShapeableImageView
+            android:id="@+id/pending_participants_reject"
+            android:layout_width="48dp"
+            android:layout_height="48dp"
+            android:layout_marginTop="12dp"
+            android:layout_marginEnd="8dp"
+            android:background="@color/webrtc_hangup_background"
+            android:padding="6dp"
+            android:tint="@color/core_white"
+            app:contentPadding="8dp"
+            app:layout_constraintEnd_toStartOf="@id/pending_participants_allow"
+            app:layout_constraintTop_toTopOf="parent"
+            app:shapeAppearanceOverlay="@style/ShapeAppearanceOverlay.Signal.Circle"
+            app:srcCompat="@drawable/symbol_x_24" />
+
+        <com.google.android.material.imageview.ShapeableImageView
+            android:id="@+id/pending_participants_allow"
+            android:layout_width="48dp"
+            android:layout_height="48dp"
+            android:layout_marginTop="12dp"
+            android:layout_marginEnd="6dp"
+            android:background="@color/signal_accent_green"
+            android:padding="6dp"
+            android:tint="@color/core_white"
+            app:contentPadding="8dp"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            app:shapeAppearanceOverlay="@style/ShapeAppearanceOverlay.Signal.Circle"
+            app:srcCompat="@drawable/symbol_check_24" />
+
+        <androidx.constraintlayout.widget.Barrier
+            android:id="@+id/pending_participants_barrier"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            app:barrierDirection="bottom"
+            app:barrierMargin="12dp"
+            app:constraint_referenced_ids="pending_participants_avatar,pending_participants_status,pending_participants_allow,pending_participants_reject" />
+
+        <View
+            android:id="@+id/pending_participants_requests_backdrop"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            android:background="@color/signal_colorSurface5"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/pending_participants_barrier" />
+
+        <com.google.android.material.button.MaterialButton
+            android:id="@+id/pending_participants_requests"
+            style="@style/Signal.Widget.Button.Small.Secondary"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="8dp"
+            android:layout_marginBottom="8dp"
+            android:textColor="@color/signal_colorOnSecondaryContainer"
+            app:backgroundTint="@color/signal_colorSecondaryContainer"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/pending_participants_barrier"
+            tools:text="+5 requests" />
+
+        <androidx.constraintlayout.widget.Group
+            android:id="@+id/pending_participants_requests_group"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:visibility="gone"
+            app:constraint_referenced_ids="pending_participants_requests,pending_participants_requests_backdrop"
+            tools:visibility="visible" />
+
+    </androidx.constraintlayout.widget.ConstraintLayout>
+
+</merge>

app/src/main/res/layout/webrtc_call_view.xml

@@ -474,6 +474,18 @@
             app:layout_constraintEnd_toEndOf="parent"
             app:layout_constraintStart_toStartOf="parent" />
 
+        <ViewStub
+            android:id="@+id/call_screen_pending_recipients"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginHorizontal="24dp"
+            android:layout_marginBottom="32dp"
+            android:inflatedId="@+id/call_screen_pending_recipients_view"
+            android:layout="@layout/call_screen_pending_participants_view"
+            app:layout_constraintBottom_toTopOf="@id/call_screen_footer_gradient_barrier"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent" />
+
         <androidx.constraintlayout.widget.Barrier
             android:id="@+id/call_screen_footer_gradient_barrier"
             android:layout_width="wrap_content"

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

@@ -6193,6 +6193,27 @@
     <!-- Body of a dialog that is displayed when we experienced a network error when looking up a username. -->
     <string name="UsernameLinkSettings_qr_result_network_error">Experienced a network error. Please try again.</string>
 
+    <!-- PendingParticipantsView -->
+    <!-- Displayed in the popup card when a remote user attempts to join a call link -->
+    <string name="PendingParticipantsView__would_like_to_join">Would like to join…</string>
+    <!-- Displayed in a button on the popup card denoting that there are other pending requests to join a call link -->
+    <plurals name="PendingParticipantsView__plus_d_requests">
+        <item quantity="one">+%1$d request</item>
+        <item quantity="other">+%1$d requests</item>
+    </plurals>
+
+    <!-- PendingParticipantsBottomSheet -->
+    <!-- Title of the bottom sheet displaying requests to join the call link -->
+    <string name="PendingParticipantsBottomSheet__requests_to_join_this_call">Requests to join this call</string>
+    <!-- Subtitle of the bottom sheet denoting the total number of people waiting -->
+    <plurals name="PendingParticipantsBottomSheet__d_people_waiting">
+        <item quantity="one">%1$d person waiting</item>
+        <item quantity="other">%1$d people waiting</item>
+    </plurals>
+    <!-- Content description for rejecting a user -->
+    <string name="PendingParticipantsBottomSheet__reject">Reject</string>
+    <!-- Content desccription for confirming a user -->
+    <string name="PendingParticipantsBottomSheet__approve">Approve</string>
 
     <!-- EOF -->
 </resources>

app/src/test/java/org/thoughtcrime/securesms/service/webrtc/PendingParticipantCollectionTest.kt

@@ -0,0 +1,240 @@
+/*
+ * Copyright 2023 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.service.webrtc
+
+import android.app.Application
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.Config
+import org.thoughtcrime.securesms.database.RecipientDatabaseTestUtils
+import org.thoughtcrime.securesms.recipients.Recipient
+import kotlin.time.Duration
+import kotlin.time.Duration.Companion.milliseconds
+
+@RunWith(RobolectricTestRunner::class)
+@Config(application = Application::class)
+class PendingParticipantCollectionTest {
+
+  private val fakeNowProvider = FakeNowProvider()
+  private val testSubject = PendingParticipantCollection(
+    participantMap = emptyMap(),
+    nowProvider = fakeNowProvider
+  )
+
+  @Test
+  fun `Given an empty collection, when I getUnresolvedPendingParticipants, then I expect an empty set`() {
+    val expected = emptySet<PendingParticipantCollection.Entry>()
+    val actual = testSubject.getUnresolvedPendingParticipants()
+
+    assertEquals(expected, actual)
+  }
+
+  @Test
+  fun `Given an empty collection, when I getAllPendingParticipants, then I expect an empty set`() {
+    val expected = emptySet<PendingParticipantCollection.Entry>()
+    val actual = testSubject.getAllPendingParticipants(0.milliseconds)
+
+    assertEquals(expected, actual)
+  }
+
+  @Test
+  fun `Given an empty collection, when I withRecipients, then I expect all recipients to be added`() {
+    val recipients = createRecipients(10)
+    val expected = (0 until 10)
+      .map {
+        PendingParticipantCollection.Entry(
+          recipient = recipients[it],
+          state = PendingParticipantCollection.State.PENDING,
+          stateChangeAt = 0.milliseconds
+        )
+      }
+      .toSet()
+
+    val actual = testSubject.withRecipients(recipients).getUnresolvedPendingParticipants()
+
+    assertEquals(expected, actual)
+  }
+
+  @Test
+  fun `Given a collection with 10 PENDING entries, when I getAllPendingParticipants, then I expect all entries`() {
+    val recipients = createRecipients(10)
+    val expected = (0 until 10)
+      .map {
+        PendingParticipantCollection.Entry(
+          recipient = recipients[it],
+          state = PendingParticipantCollection.State.PENDING,
+          stateChangeAt = 0.milliseconds
+        )
+      }
+      .toSet()
+
+    val actual = testSubject.withRecipients(recipients).getAllPendingParticipants(0.milliseconds)
+
+    assertEquals(expected, actual)
+  }
+
+  @Test
+  fun `Given a collection with 10 PENDING entries and duration in the future, when I getAllPendingParticipants, then I expect all entries`() {
+    val recipients = createRecipients(10)
+    val expected = (0 until 10)
+      .map {
+        PendingParticipantCollection.Entry(
+          recipient = recipients[it],
+          state = PendingParticipantCollection.State.PENDING,
+          stateChangeAt = 0.milliseconds
+        )
+      }
+      .toSet()
+
+    val actual = testSubject.withRecipients(recipients).getAllPendingParticipants(1.milliseconds)
+
+    assertEquals(expected, actual)
+  }
+
+  @Test
+  fun `Given a collection with 10 PENDING entries and duration in the past, when I getAllPendingParticipants, then I expect all entries`() {
+    fakeNowProvider.invoke()
+    val recipients = createRecipients(10)
+    val expected = (0 until 10)
+      .map {
+        PendingParticipantCollection.Entry(
+          recipient = recipients[it],
+          state = PendingParticipantCollection.State.PENDING,
+          stateChangeAt = 1.milliseconds
+        )
+      }
+      .toSet()
+
+    val actual = testSubject.withRecipients(recipients).getAllPendingParticipants(0.milliseconds)
+
+    assertEquals(expected, actual)
+  }
+
+  @Test
+  fun `Given an approved recipient with a state change after since, when I getAllPendingParticipants, then I expect approved recipient`() {
+    val recipients = createRecipients(2)
+    val subject = testSubject.withRecipients(recipients).withApproval(recipients[0])
+    val expected = PendingParticipantCollection.Entry(
+      recipient = recipients[0],
+      state = PendingParticipantCollection.State.APPROVED,
+      stateChangeAt = 1.milliseconds
+    )
+    val actual = subject.getAllPendingParticipants(0.milliseconds).first()
+
+    assertEquals(expected, actual)
+  }
+
+  @Test
+  fun `Given an approved recipient with a state change before since, when I getAllPendingParticipants, then I do not expect the approved recipient`() {
+    val recipients = createRecipients(2)
+    val subject = testSubject.withRecipients(recipients).withApproval(recipients[0])
+    val expected = PendingParticipantCollection.Entry(
+      recipient = recipients[1],
+      state = PendingParticipantCollection.State.PENDING,
+      stateChangeAt = 0.milliseconds
+    )
+    val actual = subject.getAllPendingParticipants(2.milliseconds).first()
+
+    assertEquals(expected, actual)
+  }
+
+  @Test
+  fun `Given an approved recipient, when I getUnresolvedPendingParticipants, then I do not expect the approved recipient`() {
+    val recipients = createRecipients(2)
+    val subject = testSubject.withRecipients(recipients).withApproval(recipients[0])
+    val expected = PendingParticipantCollection.Entry(
+      recipient = recipients[1],
+      state = PendingParticipantCollection.State.PENDING,
+      stateChangeAt = 0.milliseconds
+    )
+    val actual = subject.getUnresolvedPendingParticipants().first()
+
+    assertEquals(expected, actual)
+  }
+
+  @Test
+  fun `Given a denied recipient with a state change after since, when I getAllPendingParticipants, then I expect denied recipient`() {
+    val recipients = createRecipients(2)
+    val subject = testSubject.withRecipients(recipients).withDenial(recipients[0])
+    val expected = PendingParticipantCollection.Entry(
+      recipient = recipients[0],
+      state = PendingParticipantCollection.State.DENIED,
+      stateChangeAt = 1.milliseconds
+    )
+    val actual = subject.getAllPendingParticipants(0.milliseconds).first()
+
+    assertEquals(expected, actual)
+  }
+
+  @Test
+  fun `Given a denied recipient with a state change before since, when I getAllPendingParticipants, then I do not expect the denied recipient`() {
+    val recipients = createRecipients(2)
+    val subject = testSubject.withRecipients(recipients).withDenial(recipients[0])
+    val expected = PendingParticipantCollection.Entry(
+      recipient = recipients[1],
+      state = PendingParticipantCollection.State.PENDING,
+      stateChangeAt = 0.milliseconds
+    )
+    val actual = subject.getAllPendingParticipants(2.milliseconds).first()
+
+    assertEquals(expected, actual)
+  }
+
+  @Test
+  fun `Given a denied recipient, when I getUnresolvedPendingParticipants, then I do not expect the denied recipient`() {
+    val recipients = createRecipients(2)
+    val subject = testSubject.withRecipients(recipients).withDenial(recipients[0])
+    val expected = PendingParticipantCollection.Entry(
+      recipient = recipients[1],
+      state = PendingParticipantCollection.State.PENDING,
+      stateChangeAt = 0.milliseconds
+    )
+    val actual = subject.getUnresolvedPendingParticipants().first()
+
+    assertEquals(expected, actual)
+  }
+
+  @Test
+  fun `Given a list of PENDING, when I withRecipients with empty list, then I clear the collection`() {
+    val recipients = createRecipients(10)
+    val subject = testSubject.withRecipients(recipients).withRecipients(emptyList())
+    val expected = emptySet<PendingParticipantCollection.Entry>()
+    val actual = subject.getUnresolvedPendingParticipants()
+
+    assertEquals(expected, actual)
+  }
+
+  @Test
+  fun `Given a mixed list, when I withRecipients with empty list, then I clear the PENDINGs`() {
+    val recipients = createRecipients(2)
+    val subject = testSubject.withRecipients(recipients).withApproval(recipients[0]).withRecipients(emptyList())
+    val expected = setOf(
+      PendingParticipantCollection.Entry(
+        recipient = recipients[0],
+        state = PendingParticipantCollection.State.APPROVED,
+        stateChangeAt = 1.milliseconds
+      )
+    )
+    val actual = subject.getAllPendingParticipants(0.milliseconds)
+
+    assertEquals(expected, actual)
+  }
+
+  private fun createRecipients(count: Int): List<Recipient> {
+    return (1..count).map { RecipientDatabaseTestUtils.createRecipient() }
+  }
+
+  private class FakeNowProvider : () -> Duration {
+
+    private val nowIterator = (0 until 500).iterator()
+
+    override fun invoke(): Duration {
+      return nowIterator.next().milliseconds
+    }
+  }
+}