Improve participant count logic

demo-app/src/main/kotlin/io/getstream/video/android/ui/lobby/CallLobbyScreen.kt

@@ -73,6 +73,7 @@ import io.getstream.video.android.compose.ui.components.call.lobby.CallLobby
 import io.getstream.video.android.core.Call
 import io.getstream.video.android.core.call.state.ToggleCamera
 import io.getstream.video.android.core.call.state.ToggleMicrophone
+import io.getstream.video.android.core.events.ParticipantCount
 import io.getstream.video.android.mock.StreamPreviewDataUtils
 import io.getstream.video.android.mock.previewCall
 import io.getstream.video.android.mock.previewUsers
@@ -270,23 +271,26 @@ private fun CallLobbyBody(
 private fun LobbyDescription(
     callLobbyViewModel: CallLobbyViewModel,
 ) {
-    val session by callLobbyViewModel.call.state.session.collectAsState()
-    val participantsSize = session?.participants?.size ?: 0
+    val participantCounts by callLobbyViewModel.call.state.participantCounts.collectAsState()
 
-    LobbyDescriptionContent(participantsSize = participantsSize) {
+    LobbyDescriptionContent(participantCounts = participantCounts) {
         callLobbyViewModel.handleUiEvent(
             CallLobbyEvent.JoinCall,
         )
     }
 }
 
 @Composable
-private fun LobbyDescriptionContent(participantsSize: Int, onClick: () -> Unit) {
-    val text = if (participantsSize > 0) {
+private fun LobbyDescriptionContent(participantCounts: ParticipantCount?, onClick: () -> Unit) {
+    val totalParticipants = participantCounts?.total ?: 0
+    val anonParticipants = participantCounts?.anonymous ?: 0
+
+    val text = if (totalParticipants != 0) {
         Pair(
             stringResource(
                 id = R.string.join_call_description,
-                participantsSize,
+                totalParticipants,
+                anonParticipants,
             ),
             stringResource(id = R.string.join_call),
         )
@@ -384,8 +388,7 @@ private fun CallLobbyBodyPreview() {
             onToggleMicrophone = {},
             onToggleCamera = {},
         ) {
-            LobbyDescriptionContent(participantsSize = 0) {
-            }
+            LobbyDescriptionContent(participantCounts = ParticipantCount(1, 1)) {}
         }
     }
 }

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

@@ -31,7 +31,7 @@
     <string name="join_description">Start a new call, join a meeting by \nentering the call ID or by scanning \na QR code.</string>
     <string name="join_call">Join Call</string>
     <string name="join_call_by_qr_code">Scan QR meeting code</string>
-    <string name="join_call_description">You are about to join a call. %d more people are in the call.</string>
+    <string name="join_call_description">You are about to join a call. %d more people are in the call (%d anonymous).</string>
     <string name="join_call_no_id_hint">Don\'t have a Call ID?</string>
     <string name="join_call_call_id_hint">Call ID</string>
     <string name="start_a_new_call">Start a New Call</string>

stream-video-android-core/src/main/kotlin/io/getstream/video/android/core/CallState.kt

@@ -773,7 +773,7 @@ public class CallState(
             }
 
             is SFUHealthCheckEvent -> {
-                call.state._participantCounts.value = event.participantCount
+                updateParticipantCounts(sfuHealthCheckEvent = event)
             }
 
             is ICETrickleEvent -> {
@@ -877,23 +877,26 @@ public class CallState(
                     )
                 }
 
-                // When in JOINED state, we should use the participant from SFU health check event, as it's more accurate.
-                if (connection.value !is RealtimeConnection.Joined) {
-                    _participantCounts.value = ParticipantCount(
-                        total = event.anonymousParticipantCount + event.participantsCountByRole.values.sum(),
-                        anonymous = event.anonymousParticipantCount,
-                    )
-                }
+                updateParticipantCounts(session = session.value)
             }
 
             is CallSessionParticipantLeftEvent -> {
                 _session.value?.let { callSessionResponse ->
                     val newList = callSessionResponse.participants.toMutableList()
                     newList.removeIf { it.userSessionId == event.participant.userSessionId }
+
+                    val newMap = callSessionResponse.participantsCountByRole.toMutableMap()
+                    newMap
+                        .computeIfPresent(event.participant.role) { _, v -> maxOf(v - 1, 0) }
+                        .also { if (it == 0) newMap.remove(event.participant.role) }
+
                     _session.value = callSessionResponse.copy(
-                        participants = newList.toList(),
+                        participants = newList,
+                        participantsCountByRole = newMap,
                     )
                 }
+
+                updateParticipantCounts(session = session.value)
             }
 
             is CallSessionParticipantJoinedEvent -> {
@@ -902,26 +905,37 @@ public class CallState(
                     val participant = CallParticipantResponse(
                         user = event.participant.user,
                         joinedAt = event.createdAt,
-                        role = "user",
+                        role = event.participant.user.role,
                         userSessionId = event.participant.userSessionId,
                     )
+                    val newMap = callSessionResponse.participantsCountByRole.toMutableMap()
+                    newMap.merge(event.participant.role, 1, Int::plus)
+
+                    // It could happen that the backend delivers the same participant more than once.
+                    // Once with the call.session_started event and once again with the
+                    // call.session_participant_joined event. In this case,
+                    // we should update the existing participant and prevent duplicating it.
                     val index = newList.indexOfFirst { user.id == event.participant.user.id }
                     if (index == -1) {
                         newList.add(participant)
                     } else {
                         newList[index] = participant
                     }
+
                     _session.value = callSessionResponse.copy(
-                        participants = newList.toList(),
+                        participants = newList,
+                        participantsCountByRole = newMap,
                     )
                 }
+
+                updateParticipantCounts(session = session.value)
                 updateRingingState()
             }
         }
     }
 
     private fun updateServerSidePins(pins: List<PinUpdate>) {
-        // Update particioants that are still in the call
+        // Update participants that are still in the call
         val pinnedInCall = pins.filter {
             _participants.value.containsKey(it.sessionId)
         }
@@ -1045,6 +1059,19 @@ public class CallState(
         upsertParticipants(participantStates)
     }
 
+    private fun updateParticipantCounts(session: CallSessionResponse? = null, sfuHealthCheckEvent: SFUHealthCheckEvent? = null) {
+        // When in JOINED state, we should use the participant from SFU health check event, as it's more accurate.
+
+        if (sfuHealthCheckEvent != null) {
+            _participantCounts.value = sfuHealthCheckEvent.participantCount
+        } else if (session != null && connection.value !is RealtimeConnection.Joined) {
+            _participantCounts.value = ParticipantCount(
+                total = session.anonymousParticipantCount + session.participantsCountByRole.values.sum(),
+                anonymous = session.anonymousParticipantCount,
+            )
+        }
+    }
+
     fun markSpeakingAsMuted() {
         _speakingWhileMuted.value = true
         speakingWhileMutedResetJob?.cancel()