Avoid missing timestamps due to missing previewable event

Just use a non-previewable event instead.
Improves sorting of the room list: don't drop rooms to the bottom
because of too much un-previewable activity.

Change-Id: Ib1ad8050caae85a3e7c8a686c2fa63a2924db890

matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/room/model/RoomSummary.kt

@@ -53,6 +53,7 @@ data class RoomSummary(
         val hasUnreadMessages: Boolean = false,
         val hasUnreadContentMessages: Boolean = false,
         val hasUnreadOriginalContentMessages: Boolean = false,
+        val lastActivityTime: Long? = null,
         val unreadCount: Int? = null,
         val markedUnread: Boolean = false,
         val aggregatedUnreadCount: Int = 0,

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/database/mapper/RoomSummaryMapper.kt

@@ -73,6 +73,7 @@ internal class RoomSummaryMapper @Inject constructor(private val timelineEventMa
                 hasUnreadMessages = roomSummaryEntity.hasUnreadMessages,
                 hasUnreadContentMessages = roomSummaryEntity.hasUnreadContentMessages,
                 hasUnreadOriginalContentMessages = roomSummaryEntity.hasUnreadOriginalContentMessages,
+                lastActivityTime = roomSummaryEntity.lastActivityTime,
                 markedUnread = roomSummaryEntity.markedUnread,
                 tags = tags,
                 typingUsers = typingUsers,

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/summary/RoomSummaryUpdater.kt

@@ -56,6 +56,7 @@ import org.matrix.android.sdk.internal.database.query.findAllInRoomWithSendState
 import org.matrix.android.sdk.internal.database.query.getOrCreate
 import org.matrix.android.sdk.internal.database.query.getOrNull
 import org.matrix.android.sdk.internal.database.query.isEventRead
+import org.matrix.android.sdk.internal.database.query.latestEvent
 import org.matrix.android.sdk.internal.database.query.where
 import org.matrix.android.sdk.internal.di.UserId
 import org.matrix.android.sdk.internal.extensions.clearWith
@@ -153,12 +154,24 @@ internal class RoomSummaryUpdater @Inject constructor(
         val lastActivityFromEvent = scLatestPreviewableEvent?.root?.originServerTs
         if (lastActivityFromEvent != null) {
             roomSummaryEntity.lastActivityTime = lastActivityFromEvent
-            attemptToDecryptLatestPreviewables(
-                    roomSummaryEntity.latestPreviewableEvent,
-                    roomSummaryEntity.latestPreviewableContentEvent,
-                    roomSummaryEntity.latestPreviewableOriginalContentEvent
-            )
+        } else if (latestPreviewableEvent != scLatestPreviewableEvent) {
+            // Try using a less aggressive previewable filter for last activity, so we avoid null timestamps, which would just drop the room to the bottom
+            roomSummaryEntity.lastActivityTime = latestPreviewableEvent?.root?.originServerTs
         }
+        // If we still did not find a timestamp for the last activity:
+        // Any (non-previewable) event is still better for sorting than just dropping the room to the bottom in the list
+        if (roomSummaryEntity.lastActivityTime == null) {
+            roomSummaryEntity.lastActivityTime = TimelineEventEntity.latestEvent(
+                    realm = realm,
+                    roomId = roomId,
+                    includesSending = true
+            )?.root?.originServerTs
+        }
+        attemptToDecryptLatestPreviewables(
+                roomSummaryEntity.latestPreviewableEvent,
+                roomSummaryEntity.latestPreviewableContentEvent,
+                roomSummaryEntity.latestPreviewableOriginalContentEvent
+        )
 
         val roomSummaryUnreadCount = roomSummaryEntity.unreadCount
         if (roomSummaryUnreadCount != null /* && preferences.prioritizeUnreadCountsOverRoomPreviewsForUnreadCalculation() */) {

vector/src/main/java/im/vector/app/features/home/room/list/RoomSummaryItemFactory.kt

@@ -117,6 +117,8 @@ class RoomSummaryItemFactory @Inject constructor(private val displayableEventFor
         if (latestEvent != null) {
             latestFormattedEvent = displayableEventFormatter.format(latestEvent, roomSummary.isDirect, roomSummary.isDirect.not())
             latestEventTime = dateFormatter.format(latestEvent.root.originServerTs, DateFormatKind.ROOM_LIST)
+        } else if (roomSummary.lastActivityTime != null) {
+            latestEventTime = dateFormatter.format(roomSummary.lastActivityTime, DateFormatKind.ROOM_LIST)
         }
         val typingMessage = typingHelper.getTypingMessage(roomSummary.typingUsers)
         return RoomSummaryItem_()