From 83537b13678bf5eec8790ed525bbe796814e198b Mon Sep 17 00:00:00 2001
From: Adam Brown <adampsbrown@gmail.com>
Date: Sat, 11 Jun 2022 23:11:48 +0100
Subject: [PATCH] handling the first sync without any local cache as a loading
 state rather than showing the empty view

---
 .../app/dapk/st/directory/DirectoryUseCase.kt | 41 +++++++++++--------
 .../st/notifications/PushAndroidService.kt    | 10 ++---
 2 files changed, 30 insertions(+), 21 deletions(-)

diff --git a/features/directory/src/main/kotlin/app/dapk/st/directory/DirectoryUseCase.kt b/features/directory/src/main/kotlin/app/dapk/st/directory/DirectoryUseCase.kt
index 7e327fc..e4f1aa8 100644
--- a/features/directory/src/main/kotlin/app/dapk/st/directory/DirectoryUseCase.kt
+++ b/features/directory/src/main/kotlin/app/dapk/st/directory/DirectoryUseCase.kt
@@ -8,9 +8,7 @@ import app.dapk.st.matrix.message.MessageService
 import app.dapk.st.matrix.room.RoomService
 import app.dapk.st.matrix.sync.*
 import app.dapk.st.matrix.sync.SyncService.SyncEvent.Typing
-import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.combine
-import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.*
 
 @JvmInline
 value class UnreadCount(val value: Int)
@@ -32,23 +30,34 @@ class DirectoryUseCase(
 ) {
 
     fun state(): Flow<DirectoryState> {
-        return combine(
-            syncService.startSyncing().map { credentialsStore.credentials()!!.userId },
-            syncService.overview(),
-            messageService.localEchos(),
-            roomStore.observeUnreadCountById(),
-            syncService.events()
-        ) { userId, overviewState, localEchos, unread, events ->
-            overviewState.mergeWithLocalEchos(localEchos, userId).map { roomOverview ->
-                RoomFoo(
-                    overview = roomOverview,
-                    unreadCount = UnreadCount(unread[roomOverview.roomId] ?: 0),
-                    typing = events.filterIsInstance<Typing>().firstOrNull { it.roomId == roomOverview.roomId }
-                )
+        return flow { emit(credentialsStore.credentials()!!.userId) }.flatMapMerge { userId ->
+            combine(
+                overviewDatasource(),
+                messageService.localEchos(),
+                roomStore.observeUnreadCountById(),
+                syncService.events()
+            ) { overviewState, localEchos, unread, events ->
+                overviewState.mergeWithLocalEchos(localEchos, userId).map { roomOverview ->
+                    RoomFoo(
+                        overview = roomOverview,
+                        unreadCount = UnreadCount(unread[roomOverview.roomId] ?: 0),
+                        typing = events.filterIsInstance<Typing>().firstOrNull { it.roomId == roomOverview.roomId }
+                    )
+                }
             }
         }
     }
 
+    private fun overviewDatasource() = combine(
+        syncService.startSyncing().map { false }.onStart { emit(true) },
+        syncService.overview()
+    ) { isFirstLoad, overview ->
+        when {
+            isFirstLoad && overview.isEmpty() -> null
+            else -> overview
+        }
+    }.filterNotNull()
+
     private suspend fun OverviewState.mergeWithLocalEchos(localEchos: Map<RoomId, List<MessageService.LocalEcho>>, userId: UserId): OverviewState {
         return when {
             localEchos.isEmpty() -> this
diff --git a/features/notifications/src/main/kotlin/app/dapk/st/notifications/PushAndroidService.kt b/features/notifications/src/main/kotlin/app/dapk/st/notifications/PushAndroidService.kt
index 9f6bf55..cd56aa8 100644
--- a/features/notifications/src/main/kotlin/app/dapk/st/notifications/PushAndroidService.kt
+++ b/features/notifications/src/main/kotlin/app/dapk/st/notifications/PushAndroidService.kt
@@ -11,9 +11,7 @@ import app.dapk.st.work.WorkScheduler
 import com.google.firebase.messaging.FirebaseMessagingService
 import com.google.firebase.messaging.RemoteMessage
 import kotlinx.coroutines.*
-import kotlinx.coroutines.flow.combine
-import kotlinx.coroutines.flow.first
-import kotlinx.coroutines.flow.firstOrNull
+import kotlinx.coroutines.flow.*
 
 private var previousJob: Job? = null
 
@@ -72,7 +70,7 @@ class PushAndroidService : FirebaseMessagingService() {
 
     private suspend fun waitForEvent(timeout: Long, eventId: EventId): EventId? {
         return withTimeoutOrNull(timeout) {
-            combine(module.syncService().startSyncing(), module.syncService().observeEvent(eventId)) { _, event -> event }
+            combine(module.syncService().startSyncing().startInstantly(), module.syncService().observeEvent(eventId)) { _, event -> event }
                 .firstOrNull {
                     it == eventId
                 }
@@ -81,10 +79,12 @@ class PushAndroidService : FirebaseMessagingService() {
 
     private suspend fun waitForUnreadChange(timeout: Long): String? {
         return withTimeoutOrNull(timeout) {
-            combine(module.syncService().startSyncing(), module.roomStore().observeUnread()) { _, unread -> unread }
+            combine(module.syncService().startSyncing().startInstantly(), module.roomStore().observeUnread()) { _, unread -> unread }
                 .first()
             "ignored"
         }
     }
 
 }
+
+private fun Flow<Unit>.startInstantly() = this.onStart { emit(Unit) }
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