Remove some state events at the start of DMs (#2252)

* Remove some initial events for DMs

changelog.d/2217.misc

@@ -0,0 +1 @@
+Remove room creation, self-join of room creator and 'this is the beginning of X' timeline items for DMs.

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineView.kt

@@ -145,7 +145,7 @@ fun TimelineView(
                     }
                 }
             }
-            if (state.paginationState.beginningOfRoomReached) {
+            if (state.paginationState.beginningOfRoomReached && !state.timelineRoomInfo.isDirect) {
                 item(contentType = "BeginningOfRoomReached") {
                     TimelineItemRoomBeginningView(roomName = roomName)
                 }

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

@@ -27,6 +27,7 @@ import io.element.android.libraries.matrix.impl.timeline.item.event.EventMessage
 import io.element.android.libraries.matrix.impl.timeline.item.event.EventTimelineItemMapper
 import io.element.android.libraries.matrix.impl.timeline.item.event.TimelineEventContentMapper
 import io.element.android.libraries.matrix.impl.timeline.item.virtual.VirtualTimelineItemMapper
+import io.element.android.libraries.matrix.impl.timeline.postprocessor.DmBeginningTimelineProcessor
 import io.element.android.libraries.matrix.impl.timeline.postprocessor.FilterHiddenStateEventsProcessor
 import io.element.android.libraries.matrix.impl.timeline.postprocessor.TimelineEncryptedHistoryPostProcessor
 import kotlinx.coroutines.CompletableDeferred
@@ -85,6 +86,8 @@ class RustMatrixTimeline(
 
     private val filterHiddenStateEventsProcessor = FilterHiddenStateEventsProcessor()
 
+    private val dmBeginningTimelineProcessor = DmBeginningTimelineProcessor()
+
     private val timelineItemFactory = MatrixTimelineItemMapper(
         fetchDetailsForEvent = this::fetchDetailsForEvent,
         roomCoroutineScope = roomCoroutineScope,
@@ -107,6 +110,13 @@ class RustMatrixTimeline(
     override val timelineItems: Flow<List<MatrixTimelineItem>> = _timelineItems
         .mapLatest { items -> encryptedHistoryPostProcessor.process(items) }
         .mapLatest { items -> filterHiddenStateEventsProcessor.process(items) }
+        .mapLatest { items ->
+            dmBeginningTimelineProcessor.process(
+                items = items,
+                isDm = matrixRoom.isDirect && matrixRoom.isOneToOne,
+                isAtStartOfTimeline = paginationState.value.beginningOfRoomReached
+            )
+        }
 
     init {
         Timber.d("Initialize timeline for room ${matrixRoom.roomId}")

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

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.impl.timeline.postprocessor
+
+import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
+import io.element.android.libraries.matrix.api.timeline.item.event.MembershipChange
+import io.element.android.libraries.matrix.api.timeline.item.event.OtherState
+import io.element.android.libraries.matrix.api.timeline.item.event.RoomMembershipContent
+import io.element.android.libraries.matrix.api.timeline.item.event.StateContent
+
+/**
+ * This timeline post-processor removes the room creation event and the self-join event from the timeline for DMs.
+ */
+class DmBeginningTimelineProcessor {
+    fun process(
+        items: List<MatrixTimelineItem>,
+        isDm: Boolean,
+        isAtStartOfTimeline: Boolean
+    ): List<MatrixTimelineItem> {
+        if (!isDm || !isAtStartOfTimeline) return items
+
+        // Find room creation event. This is usually index 0
+        val roomCreationEventIndex = items.indexOfFirst {
+            val stateEventContent = (it as? MatrixTimelineItem.Event)?.event?.content as? StateContent
+            stateEventContent?.content is OtherState.RoomCreate
+        }
+
+        // Find self-join event for room creator. This is usually index 1
+        val roomCreatorUserId = (items.getOrNull(roomCreationEventIndex) as? MatrixTimelineItem.Event)?.event?.sender
+        val selfUserJoinedEventIndex = roomCreatorUserId?.let { creatorUserId ->
+            items.indexOfFirst {
+                val stateEventContent = (it as? MatrixTimelineItem.Event)?.event?.content as? RoomMembershipContent
+                stateEventContent?.change == MembershipChange.JOINED && stateEventContent.userId == creatorUserId
+            }
+        } ?: -1
+
+        // Remove items at the indices we found
+        val newItems = items.toMutableList()
+        if (selfUserJoinedEventIndex in newItems.indices) {
+            newItems.removeAt(selfUserJoinedEventIndex)
+        }
+        if (roomCreationEventIndex in newItems.indices) {
+            newItems.removeAt(roomCreationEventIndex)
+        }
+        return newItems
+    }
+}

libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/timeline/postprocessor/DmBeginningTimelineProcessorTest.kt

@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.impl.timeline.postprocessor
+
+import com.google.common.truth.Truth.assertThat
+import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
+import io.element.android.libraries.matrix.api.timeline.item.event.MembershipChange
+import io.element.android.libraries.matrix.api.timeline.item.event.OtherState
+import io.element.android.libraries.matrix.api.timeline.item.event.RoomMembershipContent
+import io.element.android.libraries.matrix.api.timeline.item.event.StateContent
+import io.element.android.libraries.matrix.test.A_USER_ID
+import io.element.android.libraries.matrix.test.A_USER_ID_2
+import io.element.android.libraries.matrix.test.timeline.aMessageContent
+import io.element.android.libraries.matrix.test.timeline.anEventTimelineItem
+import org.junit.Test
+
+class DmBeginningTimelineProcessorTest {
+    @Test
+    fun `processor removes room creation event and self-join event from DM timeline`() {
+        val timelineItems = listOf(
+            MatrixTimelineItem.Event("m.room.create", anEventTimelineItem(sender = A_USER_ID, content = StateContent("", OtherState.RoomCreate))),
+            MatrixTimelineItem.Event("m.room.member", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID, MembershipChange.JOINED))),
+        )
+        val processor = DmBeginningTimelineProcessor()
+        val processedItems = processor.process(timelineItems, isDm = true, isAtStartOfTimeline = true)
+        assertThat(processedItems).isEmpty()
+    }
+
+    @Test
+    fun `processor removes room creation event and self-join event from DM timeline even if they're not the first items`() {
+        val timelineItems = listOf(
+            MatrixTimelineItem.Event("m.room.member_other", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID_2, MembershipChange.JOINED))),
+            MatrixTimelineItem.Event("m.room.create", anEventTimelineItem(sender = A_USER_ID, content = StateContent("", OtherState.RoomCreate))),
+            MatrixTimelineItem.Event("m.room.message", anEventTimelineItem(content = aMessageContent("hi"))),
+            MatrixTimelineItem.Event("m.room.member", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID, MembershipChange.JOINED))),
+        )
+        val expected = listOf(
+            MatrixTimelineItem.Event("m.room.member_other", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID_2, MembershipChange.JOINED))),
+            MatrixTimelineItem.Event("m.room.message", anEventTimelineItem(content = aMessageContent("hi"))),
+        )
+        val processor = DmBeginningTimelineProcessor()
+        val processedItems = processor.process(timelineItems, isDm = true, isAtStartOfTimeline = true)
+        assertThat(processedItems).isEqualTo(expected)
+    }
+
+    @Test
+    fun `processor won't remove items if it's not a DM`() {
+        val timelineItems = listOf(
+            MatrixTimelineItem.Event("m.room.create", anEventTimelineItem(sender = A_USER_ID, content = StateContent("", OtherState.RoomCreate))),
+            MatrixTimelineItem.Event("m.room.member", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID, MembershipChange.JOINED))),
+        )
+        val processor = DmBeginningTimelineProcessor()
+        val processedItems = processor.process(timelineItems, isDm = false, isAtStartOfTimeline = true)
+        assertThat(processedItems).isEqualTo(timelineItems)
+    }
+
+    @Test
+    fun `processor won't remove items if it's not at the start of the timeline`() {
+        val timelineItems = listOf(
+            MatrixTimelineItem.Event("m.room.create", anEventTimelineItem(sender = A_USER_ID, content = StateContent("", OtherState.RoomCreate))),
+            MatrixTimelineItem.Event("m.room.member", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID, MembershipChange.JOINED))),
+        )
+        val processor = DmBeginningTimelineProcessor()
+        val processedItems = processor.process(timelineItems, isDm = true, isAtStartOfTimeline = false)
+        assertThat(processedItems).isEqualTo(timelineItems)
+    }
+
+    @Test
+    fun `processor won't remove the first member join event if it can't find the room creation event`() {
+        val timelineItems = listOf(
+            MatrixTimelineItem.Event("m.room.member", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID, MembershipChange.JOINED))),
+        )
+        val processor = DmBeginningTimelineProcessor()
+        val processedItems = processor.process(timelineItems, isDm = true, isAtStartOfTimeline = false)
+        assertThat(processedItems).isEqualTo(timelineItems)
+    }
+
+    @Test
+    fun `processor won't remove the first member join event if it's not from the room creator`() {
+        val timelineItems = listOf(
+            MatrixTimelineItem.Event("m.room.create", anEventTimelineItem(sender = A_USER_ID, content = StateContent("", OtherState.RoomCreate))),
+            MatrixTimelineItem.Event("m.room.member", anEventTimelineItem(content = RoomMembershipContent(A_USER_ID_2, MembershipChange.JOINED))),
+        )
+        val processor = DmBeginningTimelineProcessor()
+        val processedItems = processor.process(timelineItems, isDm = true, isAtStartOfTimeline = false)
+        assertThat(processedItems).isEqualTo(timelineItems)
+    }
+}