Timeline : use the new LiveBackPaginationStatus api

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/RoomTimelineExtensions.kt

@@ -25,11 +25,27 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.buffer
 import kotlinx.coroutines.flow.callbackFlow
 import kotlinx.coroutines.flow.catch
+import org.matrix.rustcomponents.sdk.PaginationStatusListener
 import org.matrix.rustcomponents.sdk.Timeline
 import org.matrix.rustcomponents.sdk.TimelineDiff
 import org.matrix.rustcomponents.sdk.TimelineItem
 import org.matrix.rustcomponents.sdk.TimelineListener
 import timber.log.Timber
+import uniffi.matrix_sdk_ui.LiveBackPaginationStatus
+
+internal fun Timeline.liveBackPaginationStatus(): Flow<LiveBackPaginationStatus> = callbackFlow {
+    val listener = object : PaginationStatusListener {
+        override fun onUpdate(status: LiveBackPaginationStatus) {
+            trySend(status)
+        }
+    }
+    val result = subscribeToBackPaginationStatus(listener)
+    awaitClose {
+        result.cancelAndDestroy()
+    }
+}.catch {
+    Timber.d(it, "liveBackPaginationStatus() failed")
+}.buffer(Channel.UNLIMITED)
 
 internal fun Timeline.timelineDiffFlow(onInitialList: suspend (List<TimelineItem>) -> Unit): Flow<List<TimelineDiff>> =
     callbackFlow {

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/RustTimeline.kt

@@ -79,6 +79,7 @@ import org.matrix.rustcomponents.sdk.messageEventContentFromMarkdown
 import org.matrix.rustcomponents.sdk.use
 import timber.log.Timber
 import uniffi.matrix_sdk_ui.EventItemOrigin
+import uniffi.matrix_sdk_ui.LiveBackPaginationStatus
 import java.io.File
 import java.util.Date
 import java.util.concurrent.atomic.AtomicBoolean
@@ -154,6 +155,21 @@ class RustTimeline(
             launch {
                 fetchMembers()
             }
+
+            if (isLive) {
+                // When timeline is live, we need to listen to the back pagination status as
+                // sdk can automatically paginate backwards.
+                inner.liveBackPaginationStatus()
+                    .onEach { backPaginationStatus ->
+                        updatePaginationStatus(Timeline.PaginationDirection.BACKWARDS) {
+                            when (backPaginationStatus) {
+                                is LiveBackPaginationStatus.Idle -> it.copy(isPaginating = false, hasMoreToLoad = !backPaginationStatus.hitStartOfTimeline)
+                                is LiveBackPaginationStatus.Paginating -> it.copy(isPaginating = true, hasMoreToLoad = true)
+                            }
+                        }
+                    }
+                    .launchIn(this)
+            }
         }
     }