Send read receipts (#713)

* Send read receipts

* Add changelog

* Add tests.

* Optimise how sending read receipts work in the timeline.

* Move the check for send read receipts to the presenter

Also improve the way we find the first visible `Event` if we have `Virtual` ones in the timeline.

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/MatrixTimeline.kt

@@ -32,4 +32,6 @@ interface MatrixTimeline {
 
     suspend fun paginateBackwards(requestSize: Int, untilNumberOfItems: Int): Result<Unit>
     suspend fun fetchDetailsForEvent(eventId: EventId): Result<Unit>
+
+    suspend fun sendReadReceipt(eventId: EventId): Result<Unit>
 }

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

@@ -107,4 +107,10 @@ class RustMatrixTimeline(
             Timber.v("Success back paginating for room ${matrixRoom.roomId}")
         }
     }
+
+    override suspend fun sendReadReceipt(eventId: EventId) = withContext(coroutineDispatchers.io) {
+        runCatching {
+            innerRoom.sendReadReceipt(eventId = eventId.value)
+        }
+    }
 }

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/timeline/FakeMatrixTimeline.kt

@@ -32,6 +32,9 @@ class FakeMatrixTimeline(
     private val paginationState: MutableStateFlow<MatrixTimeline.PaginationState> = MutableStateFlow(initialPaginationState)
     private val timelineItems: MutableStateFlow<List<MatrixTimelineItem>> = MutableStateFlow(initialTimelineItems)
 
+    var sendReadReceiptCount = 0
+        private set
+
     fun updatePaginationState(update: (MatrixTimeline.PaginationState.() -> MatrixTimeline.PaginationState)) {
         paginationState.value = update(paginationState.value)
     }
@@ -66,4 +69,9 @@ class FakeMatrixTimeline(
     override suspend fun fetchDetailsForEvent(eventId: EventId): Result<Unit> {
         return Result.success(Unit)
     }
+
+    override suspend fun sendReadReceipt(eventId: EventId): Result<Unit> {
+        sendReadReceiptCount++
+        return Result.success(Unit)
+    }
 }