Merge pull request #7571 from hayaksi1/fix/7397-keep-thread-after-redaction

Don't hide the thread of a deleted message inside the removed messages group

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

@@ -12,6 +12,7 @@ import androidx.annotation.VisibleForTesting
 import dev.zacsweers.metro.Inject
 import dev.zacsweers.metro.SingleIn
 import io.element.android.features.messages.impl.timeline.model.TimelineItem
+import io.element.android.features.messages.impl.timeline.model.TimelineItemThreadInfo
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemRedactedContent
 import io.element.android.libraries.di.RoomScope
 import io.element.android.libraries.matrix.api.core.UniqueId
@@ -99,7 +100,8 @@ internal const val MIN_REDACTED_RUN_SIZE = 3
  * Fold runs of [MIN_REDACTED_RUN_SIZE] or more consecutive deleted (redacted) messages into a single
  * [TimelineItem.GroupedEvents], so a long stretch of "Message removed" tiles shows as one expandable
  * "N removed messages" line, like element-web. Shorter runs, and anything that is not a redacted event
- * (day dividers included), are left untouched.
+ * (day dividers included), are left untouched. A deleted message that still heads a thread is left
+ * untouched too, so that its thread summary stays reachable.
  *
  * This runs as the final step of [TimelineItemGrouper.group], after the state and membership events
  * have been grouped. It is deliberately kept out of the normal grouping: a run needs a higher minimum
@@ -134,7 +136,7 @@ internal fun List<TimelineItem>.collapseRedactedRuns(groupIds: MutableMap<String
     }
 
     for (item in this) {
-        if (item is TimelineItem.Event && item.content is TimelineItemRedactedContent) {
+        if (item is TimelineItem.Event && item.content is TimelineItemRedactedContent && item.threadInfo !is TimelineItemThreadInfo.ThreadRoot) {
             run.add(item)
         } else {
             flushRun()

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/timeline/factories/TimelineItemsFactoryTest.kt

@@ -14,9 +14,11 @@ import io.element.android.features.messages.impl.timeline.model.TimelineItem
 import io.element.android.features.messages.impl.timeline.model.TimelineItemGroupPosition
 import io.element.android.features.messages.impl.timeline.model.TimelineItemThreadInfo
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemTextContent
+import io.element.android.libraries.architecture.AsyncData
 import io.element.android.libraries.matrix.api.core.UniqueId
 import io.element.android.libraries.matrix.api.timeline.MatrixTimelineItem
 import io.element.android.libraries.matrix.api.timeline.item.EventThreadInfo
+import io.element.android.libraries.matrix.api.timeline.item.ThreadSummary
 import io.element.android.libraries.matrix.api.timeline.item.event.OtherMessageType
 import io.element.android.libraries.matrix.test.A_THREAD_ID
 import io.element.android.libraries.matrix.test.A_USER_ID
@@ -168,6 +170,43 @@ class TimelineItemsFactoryTest {
         }
     }
 
+    @Test
+    fun `a deleted message keeps the summary of the thread it heads`() = runTest {
+        val factory = aTimelineItemsFactory(
+            config = TimelineItemsFactoryConfig(
+                computeReadReceipts = false,
+                computeReactions = false,
+            )
+        )
+        val items = listOf(
+            MatrixTimelineItem.Event(
+                uniqueId = UniqueId("event-0"),
+                event = anEventTimelineItem(
+                    sender = A_USER_ID,
+                    content = aRedactedContent(
+                        threadInfo = EventThreadInfo.ThreadRoot(
+                            summary = ThreadSummary(latestEvent = AsyncData.Uninitialized, numberOfReplies = 3),
+                        ),
+                    ),
+                ),
+            ),
+        )
+        factory.timelineItems.test {
+            factory.replaceWith(
+                timelineItems = items,
+                roomMembers = emptyList(),
+                renderReadReceipts = false,
+            )
+            val threadInfo = awaitItem()
+                .filterIsInstance<TimelineItem.Event>()
+                .single()
+                .threadInfo
+            assertThat(threadInfo).isInstanceOf(TimelineItemThreadInfo.ThreadRoot::class.java)
+            assertThat((threadInfo as TimelineItemThreadInfo.ThreadRoot).summary.numberOfReplies).isEqualTo(3)
+            cancelAndIgnoreRemainingEvents()
+        }
+    }
+
     private suspend fun TestScope.groupPositionsOf(timestamps: List<Long>): List<TimelineItemGroupPosition> {
         val factory = aTimelineItemsFactory(
             config = TimelineItemsFactoryConfig(

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/timeline/groups/TimelineItemGrouperTest.kt

@@ -15,11 +15,14 @@ import io.element.android.features.messages.impl.timeline.aTimelineItemReactions
 import io.element.android.features.messages.impl.timeline.model.ReadReceiptData
 import io.element.android.features.messages.impl.timeline.model.TimelineItem
 import io.element.android.features.messages.impl.timeline.model.TimelineItemReadReceipts
+import io.element.android.features.messages.impl.timeline.model.TimelineItemThreadInfo
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemRedactedContent
 import io.element.android.features.messages.impl.timeline.model.event.TimelineItemStateEventContent
 import io.element.android.features.messages.impl.timeline.model.virtual.aTimelineItemDaySeparatorModel
+import io.element.android.libraries.architecture.AsyncData
 import io.element.android.libraries.designsystem.components.avatar.anAvatarData
 import io.element.android.libraries.matrix.api.core.UniqueId
+import io.element.android.libraries.matrix.api.timeline.item.ThreadSummary
 import io.element.android.libraries.matrix.api.timeline.item.event.LocalEventSendState
 import io.element.android.libraries.matrix.test.AN_EVENT_ID
 import io.element.android.libraries.matrix.test.A_USER_ID
@@ -190,6 +193,22 @@ class TimelineItemGrouperTest {
         )
     }
 
+    @Test
+    fun `a deleted message that still heads a thread is left out of the removed messages group`() {
+        val threadRoot = aGroupableItem.copy(
+            id = UniqueId("r1"),
+            content = TimelineItemRedactedContent,
+            threadInfo = TimelineItemThreadInfo.ThreadRoot(
+                summary = ThreadSummary(latestEvent = AsyncData.Uninitialized, numberOfReplies = 2),
+                latestEventText = null,
+            ),
+        )
+        val r0 = aGroupableItem.copy(id = UniqueId("r0"), content = TimelineItemRedactedContent)
+        val r2 = aGroupableItem.copy(id = UniqueId("r2"), content = TimelineItemRedactedContent)
+        val result = sut.group(listOf(r0, threadRoot, r2))
+        assertThat(result).isEqualTo(listOf(r0, threadRoot, r2))
+    }
+
     @Test
     fun `a run of fewer than three redacted events is left untouched`() {
         val r0 = aGroupableItem.copy(id = UniqueId("r0"), content = TimelineItemRedactedContent)