RoomList: introduce incremental loading to improve performances.

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/roomlist/DynamicRoomList.kt

@@ -16,6 +16,12 @@
 
 package io.element.android.libraries.matrix.api.roomlist
 
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.onEach
+
 /**
  * RoomList with dynamic filtering and loading.
  * This is useful for large lists of rooms.
@@ -23,17 +29,17 @@ package io.element.android.libraries.matrix.api.roomlist
  */
 interface DynamicRoomList : RoomList {
 
-    companion object {
-        const val DEFAULT_PAGE_SIZE = 20
-        const val DEFAULT_PAGES_TO_LOAD = 10
-    }
-
     sealed interface Filter {
         /**
          * No filter applied.
          */
         data object All : Filter
 
+        /**
+         * Filter only the left rooms.
+         */
+        data object AllNonLeft : Filter
+
         /**
          * Filter all rooms.
          */
@@ -45,6 +51,10 @@ interface DynamicRoomList : RoomList {
         data class NormalizedMatchRoomName(val pattern: String) : Filter
     }
 
+    val currentFilter: StateFlow<Filter>
+    val loadedPages: StateFlow<Int>
+    val pageSize: Int
+
     /**
      * Load more rooms into the list if possible.
      */
@@ -61,3 +71,29 @@ interface DynamicRoomList : RoomList {
      */
     suspend fun updateFilter(filter: Filter)
 }
+
+/**
+ * Offers a way to load all the rooms incrementally.
+ * It will load more room until all are loaded.
+ * If total number of rooms increase, it will load more pages if needed.
+ * The number of rooms is independent of the filter.
+ */
+fun DynamicRoomList.loadAllIncrementally(coroutineScope: CoroutineScope) {
+    combine(
+        loadedPages,
+        loadingState,
+    ) { loadedPages, loadingState ->
+        loadedPages to loadingState
+    }
+        .onEach { (loadedPages, loadingState) ->
+            when (loadingState) {
+                is RoomList.LoadingState.Loaded -> {
+                    if (pageSize * loadedPages < loadingState.numberOfRooms) {
+                        loadMore()
+                    }
+                }
+                RoomList.LoadingState.NotLoaded -> Unit
+            }
+        }
+        .launchIn(coroutineScope)
+}

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/roomlist/RoomListService.kt

@@ -38,10 +38,10 @@ interface RoomListService {
     }
 
     /**
-     * returns a [RoomList] object of all rooms we want to display.
+     * returns a [DynamicRoomList] object of all rooms we want to display.
      * This will exclude some rooms like the invites, or spaces.
      */
-    val allRooms: RoomList
+    val allRooms: DynamicRoomList
 
     /**
      * returns a [RoomList] object of all invites.