Threads - first iteration (#5165)

* Initial threads support: parse `ThreadSummary`.

Replace several `isThreaded` values with `EventThreadInfo`, which contains the info about the event either being the root of a thread or part of it.

* Add `Threaded` timeline mode

* Add a `liveTimeline` parameter to `TimelineController`'s  constructor. This way we can customise which timeline will be used as the 'live' one. Also add `@LiveTimeline` DI qualifier for the actual live timeline of the room.

* Create `ThreadedMessagesNode`. Allow opening a thread in a separate screen.

* Add the callbacks for the list menu actions - even if they're the wrong ones and will send the data to the room instead

* Send attachments and location in threads

* Fix polls in threads, add support for sending voice messages in threads

* Display thread summaries only when the feature flag is enabled

* Use 'Reply' instead of 'Reply in thread' when in threaded timeline mode

* Remove incorrect usage of `Timeline` in `MessageComposerPresenter`. This led to replies to threaded events not appearing as actual replies.

---------

Co-authored-by: ElementBot <android@element.io>

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/core/EventId.kt

@@ -20,3 +20,5 @@ value class EventId(val value: String) : Serializable {
 
     override fun toString(): String = value
 }
+
+fun EventId.toThreadId(): ThreadId = ThreadId(value)

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/room/CreateTimelineParams.kt

@@ -8,10 +8,12 @@
 package io.element.android.libraries.matrix.api.room
 
 import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.core.ThreadId
 
 sealed interface CreateTimelineParams {
     data class Focused(val focusedEventId: EventId) : CreateTimelineParams
     data object MediaOnly : CreateTimelineParams
     data class MediaOnlyFocused(val focusedEventId: EventId) : CreateTimelineParams
     data object PinnedOnly : CreateTimelineParams
+    data class Threaded(val threadRootEventId: ThreadId) : CreateTimelineParams
 }

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

@@ -7,8 +7,10 @@
 
 package io.element.android.libraries.matrix.api.timeline
 
+import android.os.Parcelable
 import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.RoomId
+import io.element.android.libraries.matrix.api.core.ThreadId
 import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.media.AudioInfo
 import io.element.android.libraries.matrix.api.media.FileInfo
@@ -23,6 +25,7 @@ import io.element.android.libraries.matrix.api.timeline.item.event.InReplyTo
 import io.element.android.libraries.matrix.api.timeline.item.event.toEventOrTransactionId
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.StateFlow
+import kotlinx.parcelize.Parcelize
 import java.io.File
 
 interface Timeline : AutoCloseable {
@@ -38,13 +41,16 @@ interface Timeline : AutoCloseable {
         FORWARDS
     }
 
-    enum class Mode {
-        LIVE,
-        FOCUSED_ON_EVENT,
-        PINNED_EVENTS,
-        MEDIA,
+    @Parcelize
+    sealed interface Mode : Parcelable {
+        data object Live : Mode
+        data class FocusedOnEvent(val eventId: EventId) : Mode
+        data object PinnedEvents : Mode
+        data object Media : Mode
+        data class Thread(val threadRootId: ThreadId) : Mode
     }
 
+    val mode: Mode
     val membershipChangeEventReceived: Flow<Unit>
     suspend fun sendReadReceipt(eventId: EventId, receiptType: ReceiptType): Result<Unit>
     suspend fun paginate(direction: PaginationDirection): Result<Boolean>

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

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.api.timeline.item
+
+import io.element.android.libraries.architecture.AsyncData
+import io.element.android.libraries.matrix.api.core.ThreadId
+import io.element.android.libraries.matrix.api.core.UserId
+import io.element.android.libraries.matrix.api.timeline.item.event.EventContent
+import io.element.android.libraries.matrix.api.timeline.item.event.EventOrTransactionId
+import io.element.android.libraries.matrix.api.timeline.item.event.ProfileTimelineDetails
+
+data class EventThreadInfo(
+    val threadRootId: ThreadId?,
+    val threadSummary: ThreadSummary?,
+)
+
+data class ThreadSummary(
+    val latestEvent: AsyncData<EmbeddedEventInfo>,
+    val numberOfReplies: Long,
+)
+
+data class EmbeddedEventInfo(
+    val eventOrTransactionId: EventOrTransactionId,
+    val content: EventContent,
+    val senderId: UserId,
+    val senderProfile: ProfileTimelineDetails,
+    val timestamp: Long,
+)

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/event/EventContent.kt

@@ -13,6 +13,7 @@ import io.element.android.libraries.matrix.api.media.ImageInfo
 import io.element.android.libraries.matrix.api.media.MediaSource
 import io.element.android.libraries.matrix.api.poll.PollAnswer
 import io.element.android.libraries.matrix.api.poll.PollKind
+import io.element.android.libraries.matrix.api.timeline.item.EventThreadInfo
 import kotlinx.collections.immutable.ImmutableList
 import kotlinx.collections.immutable.ImmutableMap
 
@@ -23,7 +24,7 @@ data class MessageContent(
     val body: String,
     val inReplyTo: InReplyTo?,
     val isEdited: Boolean,
-    val isThreaded: Boolean,
+    val threadInfo: EventThreadInfo,
     val type: MessageType
 ) : EventContent
 

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/event/EventTimelineItem.kt

@@ -11,6 +11,7 @@ import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.SendHandle
 import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.core.UserId
+import io.element.android.libraries.matrix.api.timeline.item.EventThreadInfo
 import io.element.android.libraries.matrix.api.timeline.item.TimelineItemDebugInfo
 import kotlinx.collections.immutable.ImmutableList
 
@@ -37,9 +38,7 @@ data class EventTimelineItem(
         return (content as? MessageContent)?.inReplyTo
     }
 
-    fun isThreaded(): Boolean {
-        return (content as? MessageContent)?.isThreaded ?: false
-    }
+    fun threadInfo(): EventThreadInfo? = (content as? MessageContent)?.threadInfo
 
     fun hasNotLoadedInReplyTo(): Boolean {
         val details = inReplyTo()