Merge branch 'develop' into dependabot/gradle/androidx.constraintlayout-constraintlayout-2.1.2

changelog.d/4246.feature

@@ -0,0 +1 @@
+Make Element Android Thread aware

dependencies.gradle

@@ -49,9 +49,9 @@ ext.libs = [
                 'core'                    : "androidx.core:core-ktx:1.7.0",
                 'recyclerview'            : "androidx.recyclerview:recyclerview:1.2.1",
                 'exifinterface'           : "androidx.exifinterface:exifinterface:1.3.3",
-                'fragmentKtx'             : "androidx.fragment:fragment-ktx:1.3.6",
+                'fragmentKtx'             : "androidx.fragment:fragment-ktx:1.4.0",
                 'constraintLayout'        : "androidx.constraintlayout:constraintlayout:2.1.2",
-                'work'                    : "androidx.work:work-runtime-ktx:2.7.0",
+                'work'                    : "androidx.work:work-runtime-ktx:2.7.1",
                 'autoFill'                : "androidx.autofill:autofill:1.1.0",
                 'preferenceKtx'           : "androidx.preference:preference-ktx:1.1.1",
                 'junit'                   : "androidx.test.ext:junit:1.1.3",

matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/events/model/RelationType.kt

@@ -28,6 +28,10 @@ object RelationType {
     /** Lets you define an event which references an existing event.*/
     const val REFERENCE = "m.reference"
 
+    /** Lets you define an thread event that belongs to another existing event.*/
+//    const val THREAD = "m.thread"         // m.thread is not yet released in the backend
+    const val THREAD = "io.element.thread"  // io.element.thread will be replaced by m.thread when it is released
+
     /** Lets you define an event which adds a response to an existing event.*/
     const val RESPONSE = "org.matrix.response"
 }

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/database/model/EventEntity.kt

@@ -19,6 +19,7 @@ package org.matrix.android.sdk.internal.database.model
 import io.realm.RealmObject
 import io.realm.annotations.Index
 import org.matrix.android.sdk.api.session.room.send.SendState
+import org.matrix.android.sdk.api.util.JsonDict
 import org.matrix.android.sdk.internal.crypto.MXEventDecryptionResult
 import org.matrix.android.sdk.internal.crypto.algorithms.olm.OlmDecryptionResult
 import org.matrix.android.sdk.internal.di.MoshiProvider
@@ -56,10 +57,10 @@ internal open class EventEntity(@Index var eventId: String = "",
 
     companion object
 
-    fun setDecryptionResult(result: MXEventDecryptionResult) {
+    fun setDecryptionResult(result: MXEventDecryptionResult, clearEvent: JsonDict? = null) {
         assertIsManaged()
         val decryptionResult = OlmDecryptionResult(
-                payload = result.clearEvent,
+                payload = clearEvent ?: result.clearEvent,
                 senderKey = result.senderCurve25519Key,
                 keysClaimed = result.claimedEd25519Key?.let { mapOf("ed25519" to it) },
                 forwardingCurve25519KeyChain = result.forwardingCurve25519KeyChain

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/events/DefaultEventService.kt

@@ -29,7 +29,6 @@ internal class DefaultEventService @Inject constructor(
 
     override suspend fun getEvent(roomId: String, eventId: String): Event {
         val event = getEventTask.execute(GetEventTask.Params(roomId, eventId))
-        event.ageLocalTs = event.unsignedData?.age?.let { System.currentTimeMillis() - it }
         // Fast lane to the call event processors: try to make the incoming call ring faster
         if (callEventProcessor.shouldProcessFastLane(event.getClearType())) {
             callEventProcessor.processFastLane(event)

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/timeline/DefaultTimeline.kt

@@ -23,6 +23,7 @@ import io.realm.RealmConfiguration
 import io.realm.RealmQuery
 import io.realm.RealmResults
 import io.realm.Sort
+import kotlinx.coroutines.runBlocking
 import org.matrix.android.sdk.api.MatrixCallback
 import org.matrix.android.sdk.api.extensions.orFalse
 import org.matrix.android.sdk.api.extensions.tryOrNull
@@ -33,6 +34,7 @@ import org.matrix.android.sdk.api.session.room.timeline.TimelineEvent
 import org.matrix.android.sdk.api.session.room.timeline.TimelineSettings
 import org.matrix.android.sdk.api.util.CancelableBag
 import org.matrix.android.sdk.internal.database.RealmSessionProvider
+import org.matrix.android.sdk.internal.database.mapper.EventMapper
 import org.matrix.android.sdk.internal.database.mapper.TimelineEventMapper
 import org.matrix.android.sdk.internal.database.model.ChunkEntity
 import org.matrix.android.sdk.internal.database.model.RoomEntity
@@ -43,6 +45,7 @@ import org.matrix.android.sdk.internal.database.query.where
 import org.matrix.android.sdk.internal.database.query.whereRoomId
 import org.matrix.android.sdk.internal.session.room.membership.LoadRoomMembersTask
 import org.matrix.android.sdk.internal.session.sync.handler.room.ReadReceiptHandler
+import org.matrix.android.sdk.internal.session.sync.handler.room.ThreadsAwarenessHandler
 import org.matrix.android.sdk.internal.task.TaskExecutor
 import org.matrix.android.sdk.internal.task.configureWith
 import org.matrix.android.sdk.internal.util.Debouncer
@@ -72,6 +75,7 @@ internal class DefaultTimeline(
         private val eventDecryptor: TimelineEventDecryptor,
         private val realmSessionProvider: RealmSessionProvider,
         private val loadRoomMembersTask: LoadRoomMembersTask,
+        private val threadsAwarenessHandler: ThreadsAwarenessHandler,
         private val readReceiptHandler: ReadReceiptHandler
 ) : Timeline,
         TimelineInput.Listener,
@@ -577,6 +581,10 @@ internal class DefaultTimeline(
         } else {
             nextDisplayIndex = offsetIndex + 1
         }
+
+        // Prerequisite to in order for the ThreadsAwarenessHandler to work properly
+        fetchRootThreadEventsIfNeeded(offsetResults)
+
         offsetResults.forEach { eventEntity ->
 
             val timelineEvent = buildTimelineEvent(eventEntity)
@@ -601,6 +609,20 @@ internal class DefaultTimeline(
         return offsetResults.size
     }
 
+    /**
+     * This function is responsible to fetch and store the root event of a thread event
+     * in order to be able to display the event to the user appropriately
+     */
+    private fun fetchRootThreadEventsIfNeeded(offsetResults: RealmResults<TimelineEventEntity>) = runBlocking {
+        val eventEntityList = offsetResults
+                .mapNotNull {
+                    it?.root
+                }.map {
+                    EventMapper.map(it)
+                }
+        threadsAwarenessHandler.fetchRootThreadEventsIfNeeded(eventEntityList)
+    }
+
     private fun buildTimelineEvent(eventEntity: TimelineEventEntity): TimelineEvent {
         return timelineEventMapper.map(
                 timelineEventEntity = eventEntity,

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/timeline/DefaultTimelineService.kt

@@ -38,6 +38,7 @@ import org.matrix.android.sdk.internal.database.query.where
 import org.matrix.android.sdk.internal.di.SessionDatabase
 import org.matrix.android.sdk.internal.session.room.membership.LoadRoomMembersTask
 import org.matrix.android.sdk.internal.session.sync.handler.room.ReadReceiptHandler
+import org.matrix.android.sdk.internal.session.sync.handler.room.ThreadsAwarenessHandler
 import org.matrix.android.sdk.internal.task.TaskExecutor
 
 internal class DefaultTimelineService @AssistedInject constructor(
@@ -52,6 +53,7 @@ internal class DefaultTimelineService @AssistedInject constructor(
         private val fetchTokenAndPaginateTask: FetchTokenAndPaginateTask,
         private val timelineEventMapper: TimelineEventMapper,
         private val loadRoomMembersTask: LoadRoomMembersTask,
+        private val threadsAwarenessHandler: ThreadsAwarenessHandler,
         private val readReceiptHandler: ReadReceiptHandler
 ) : TimelineService {
 
@@ -75,6 +77,7 @@ internal class DefaultTimelineService @AssistedInject constructor(
                 fetchTokenAndPaginateTask = fetchTokenAndPaginateTask,
                 realmSessionProvider = realmSessionProvider,
                 loadRoomMembersTask = loadRoomMembersTask,
+                threadsAwarenessHandler = threadsAwarenessHandler,
                 readReceiptHandler = readReceiptHandler
         )
     }

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/timeline/GetEventTask.kt

@@ -59,6 +59,8 @@ internal class DefaultGetEventTask @Inject constructor(
                     }
         }
 
+        event.ageLocalTs = event.unsignedData?.age?.let { System.currentTimeMillis() - it }
+
         return event
     }
 }

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/timeline/TimelineEventDecryptor.kt

@@ -26,6 +26,7 @@ import org.matrix.android.sdk.internal.crypto.model.event.EncryptedEventContent
 import org.matrix.android.sdk.internal.database.model.EventEntity
 import org.matrix.android.sdk.internal.database.query.where
 import org.matrix.android.sdk.internal.di.SessionDatabase
+import org.matrix.android.sdk.internal.session.sync.handler.room.ThreadsAwarenessHandler
 import timber.log.Timber
 import java.util.concurrent.ExecutorService
 import java.util.concurrent.Executors
@@ -34,7 +35,8 @@ import javax.inject.Inject
 internal class TimelineEventDecryptor @Inject constructor(
         @SessionDatabase
         private val realmConfiguration: RealmConfiguration,
-        private val cryptoService: CryptoService
+        private val cryptoService: CryptoService,
+        private val threadsAwarenessHandler: ThreadsAwarenessHandler
 ) {
 
     private val newSessionListener = object : NewSessionListener {
@@ -106,10 +108,19 @@ internal class TimelineEventDecryptor @Inject constructor(
             val result = cryptoService.decryptEvent(request.event, timelineId)
             Timber.v("Successfully decrypted event ${event.eventId}")
             realm.executeTransaction {
-                val eventId = event.eventId ?: ""
-                EventEntity.where(it, eventId = eventId)
+                val eventId = event.eventId ?: return@executeTransaction
+                val eventEntity = EventEntity
+                        .where(it, eventId = eventId)
                         .findFirst()
-                        ?.setDecryptionResult(result)
+
+                eventEntity?.apply {
+                    val decryptedPayload = threadsAwarenessHandler.handleIfNeededDuringDecryption(
+                            it,
+                            roomId = event.roomId,
+                            event,
+                            result)
+                    setDecryptionResult(result, decryptedPayload)
+                }
             }
         } catch (e: MXCryptoError) {
             Timber.v("Failed to decrypt event ${event.eventId} : ${e.localizedMessage}")

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/sync/SyncResponseHandler.kt

@@ -41,6 +41,7 @@ import org.matrix.android.sdk.internal.session.sync.handler.PresenceSyncHandler
 import org.matrix.android.sdk.internal.session.sync.handler.SyncResponsePostTreatmentAggregatorHandler
 import org.matrix.android.sdk.internal.session.sync.handler.UserAccountDataSyncHandler
 import org.matrix.android.sdk.internal.session.sync.handler.room.RoomSyncHandler
+import org.matrix.android.sdk.internal.session.sync.handler.room.ThreadsAwarenessHandler
 import org.matrix.android.sdk.internal.util.awaitTransaction
 import org.matrix.android.sdk.internal.worker.WorkerParamsFactory
 import timber.log.Timber
@@ -65,6 +66,7 @@ internal class SyncResponseHandler @Inject constructor(
         private val tokenStore: SyncTokenStore,
         private val processEventForPushTask: ProcessEventForPushTask,
         private val pushRuleService: PushRuleService,
+        private val threadsAwarenessHandler: ThreadsAwarenessHandler,
         private val presenceSyncHandler: PresenceSyncHandler
 ) {
 
@@ -97,6 +99,10 @@ internal class SyncResponseHandler @Inject constructor(
             Timber.v("Finish handling toDevice in $it ms")
         }
         val aggregator = SyncResponsePostTreatmentAggregator()
+
+        // Prerequisite for thread events handling in RoomSyncHandler
+        threadsAwarenessHandler.fetchRootThreadEventsIfNeeded(syncResponse)
+
         // Start one big transaction
         monarchy.awaitTransaction { realm ->
             measureTimeMillis {

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/sync/handler/room/RoomSyncHandler.kt

@@ -76,6 +76,7 @@ internal class RoomSyncHandler @Inject constructor(private val readReceiptHandle
                                                    private val cryptoService: DefaultCryptoService,
                                                    private val roomMemberEventHandler: RoomMemberEventHandler,
                                                    private val roomTypingUsersHandler: RoomTypingUsersHandler,
+                                                   private val threadsAwarenessHandler: ThreadsAwarenessHandler,
                                                    private val roomChangeMembershipStateDataSource: RoomChangeMembershipStateDataSource,
                                                    @UserId private val userId: String,
                                                    private val timelineInput: TimelineInput) {
@@ -362,10 +363,17 @@ internal class RoomSyncHandler @Inject constructor(private val readReceiptHandle
             }
             eventIds.add(event.eventId)
 
-            if (event.isEncrypted() && insertType != EventInsertType.INITIAL_SYNC) {
+            val isInitialSync = insertType == EventInsertType.INITIAL_SYNC
+
+            if (event.isEncrypted() && !isInitialSync) {
                 decryptIfNeeded(event, roomId)
             }
 
+            threadsAwarenessHandler.handleIfNeeded(
+                    realm = realm,
+                    roomId = roomId,
+                    event = event)
+
             val ageLocalTs = event.unsignedData?.age?.let { syncLocalTimestampMillis - it }
             val eventEntity = event.toEntity(roomId, SendState.SYNCED, ageLocalTs).copyToRealmOrIgnore(realm, insertType)
             if (event.stateKey != null) {

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/sync/handler/room/ThreadsAwarenessHandler.kt

@@ -0,0 +1,263 @@
+/*
+ * Copyright 2021 The Matrix.org Foundation C.I.C.
+ *
+ * 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 org.matrix.android.sdk.internal.session.sync.handler.room
+
+import com.zhuinden.monarchy.Monarchy
+import io.realm.Realm
+import org.matrix.android.sdk.api.session.crypto.CryptoService
+import org.matrix.android.sdk.api.session.crypto.MXCryptoError
+import org.matrix.android.sdk.api.session.events.model.Event
+import org.matrix.android.sdk.api.session.events.model.RelationType
+import org.matrix.android.sdk.api.session.events.model.toContent
+import org.matrix.android.sdk.api.session.events.model.toModel
+import org.matrix.android.sdk.api.session.room.model.message.MessageFormat
+import org.matrix.android.sdk.api.session.room.model.message.MessageRelationContent
+import org.matrix.android.sdk.api.session.room.model.message.MessageTextContent
+import org.matrix.android.sdk.api.session.room.send.SendState
+import org.matrix.android.sdk.api.session.sync.model.SyncResponse
+import org.matrix.android.sdk.api.util.JsonDict
+import org.matrix.android.sdk.internal.crypto.MXEventDecryptionResult
+import org.matrix.android.sdk.internal.crypto.algorithms.olm.OlmDecryptionResult
+import org.matrix.android.sdk.internal.database.mapper.EventMapper
+import org.matrix.android.sdk.internal.database.mapper.toEntity
+import org.matrix.android.sdk.internal.database.model.EventEntity
+import org.matrix.android.sdk.internal.database.model.EventInsertType
+import org.matrix.android.sdk.internal.database.query.copyToRealmOrIgnore
+import org.matrix.android.sdk.internal.database.query.where
+import org.matrix.android.sdk.internal.di.SessionDatabase
+import org.matrix.android.sdk.internal.session.permalinks.PermalinkFactory
+import org.matrix.android.sdk.internal.session.room.send.LocalEchoEventFactory
+import org.matrix.android.sdk.internal.session.room.timeline.GetEventTask
+import org.matrix.android.sdk.internal.util.awaitTransaction
+import javax.inject.Inject
+
+/**
+ * This handler is responsible for a smooth threads migration. It will map all incoming
+ * threads as replies. So a device without threads enabled/updated will be able to view
+ * threads response as replies to the original message
+ */
+internal class ThreadsAwarenessHandler @Inject constructor(
+        private val permalinkFactory: PermalinkFactory,
+        private val cryptoService: CryptoService,
+        @SessionDatabase private val monarchy: Monarchy,
+        private val getEventTask: GetEventTask
+) {
+
+    /**
+     * Fetch root thread events if they are missing from the local storage
+     * @param syncResponse the sync response
+     */
+    suspend fun fetchRootThreadEventsIfNeeded(syncResponse: SyncResponse) {
+        val handlingStrategy = syncResponse.rooms?.join?.let {
+            RoomSyncHandler.HandlingStrategy.JOINED(it)
+        }
+        if (handlingStrategy !is RoomSyncHandler.HandlingStrategy.JOINED) return
+        val eventList = handlingStrategy.data
+                .mapNotNull { (roomId, roomSync) ->
+                    roomSync.timeline?.events?.map {
+                        it.copy(roomId = roomId)
+                    }
+                }.flatten()
+
+        fetchRootThreadEventsIfNeeded(eventList)
+    }
+
+    /**
+     * Fetch root thread events if they are missing from the local storage
+     * @param eventList a list with the events to examine
+     */
+    suspend fun fetchRootThreadEventsIfNeeded(eventList: List<Event>) {
+        if (eventList.isNullOrEmpty()) return
+
+        val threadsToFetch = emptyMap<String, String>().toMutableMap()
+        Realm.getInstance(monarchy.realmConfiguration).use {  realm ->
+            eventList.asSequence()
+                    .filter {
+                        isThreadEvent(it) && it.roomId != null
+                    }.mapNotNull { event ->
+                        getRootThreadEventId(event)?.let {
+                            Pair(it, event.roomId!!)
+                        }
+                    }.forEach { (rootThreadEventId, roomId) ->
+                        EventEntity.where(realm, rootThreadEventId).findFirst() ?: run { threadsToFetch[rootThreadEventId] = roomId }
+                    }
+        }
+        fetchThreadsEvents(threadsToFetch)
+    }
+
+    /**
+     * Fetch multiple unique events using the fetchEvent function
+     */
+    private suspend fun fetchThreadsEvents(threadsToFetch: Map<String, String>) {
+        val eventEntityList = threadsToFetch.mapNotNull { (eventId, roomId) ->
+            fetchEvent(eventId, roomId)?.let {
+                it.toEntity(roomId, SendState.SYNCED, it.ageLocalTs)
+            }
+        }
+
+        if (eventEntityList.isNullOrEmpty()) return
+
+        // Transaction should be done on its own thread, like below
+        monarchy.awaitTransaction { realm ->
+            eventEntityList.forEach {
+                it.copyToRealmOrIgnore(realm, EventInsertType.INCREMENTAL_SYNC)
+            }
+        }
+    }
+
+    /**
+     * This function will fetch the event from the homeserver, this is mandatory when the
+     * initial thread message is too old and is not saved in the device, so in order to
+     * construct the "reply to" format we need to know the event thread.
+     * @return the Event or null otherwise
+     */
+    private suspend fun fetchEvent(eventId: String, roomId: String): Event? {
+        return runCatching {
+            getEventTask.execute(GetEventTask.Params(roomId = roomId, eventId = eventId))
+        }.fold(
+                onSuccess = {
+                    it
+                },
+                onFailure = {
+                    null
+                })
+    }
+
+    /**
+     * Handle events mainly coming from the RoomSyncHandler
+     */
+    fun handleIfNeeded(realm: Realm,
+                       roomId: String,
+                       event: Event) {
+        val payload = transformThreadToReplyIfNeeded(
+                realm = realm,
+                roomId = roomId,
+                event = event,
+                decryptedResult = event.mxDecryptionResult?.payload) ?: return
+
+        event.mxDecryptionResult = event.mxDecryptionResult?.copy(payload = payload)
+    }
+
+    /**
+     * Handle events while they are being decrypted
+     */
+    fun handleIfNeededDuringDecryption(realm: Realm,
+                                       roomId: String?,
+                                       event: Event,
+                                       result: MXEventDecryptionResult): JsonDict? {
+        return transformThreadToReplyIfNeeded(
+                realm = realm,
+                roomId = roomId,
+                event = event,
+                decryptedResult = result.clearEvent)
+    }
+
+    /**
+     * If the event is a thread event then transform/enhance it to a visual Reply Event,
+     * If the event is not a thread event, null value will be returned
+     * If there is an error (ex. the root/origin thread event is not found), null willl be returend
+     */
+    private fun transformThreadToReplyIfNeeded(realm: Realm, roomId: String?, event: Event, decryptedResult: JsonDict?): JsonDict? {
+        roomId ?: return null
+        if (!isThreadEvent(event)) return null
+        val rootThreadEventId = getRootThreadEventId(event) ?: return null
+        val payload = decryptedResult?.toMutableMap() ?: return null
+        val body = getValueFromPayload(payload, "body") ?: return null
+        val msgType = getValueFromPayload(payload, "msgtype") ?: return null
+        val rootThreadEvent = getEventFromDB(realm, rootThreadEventId) ?: return null
+        val rootThreadEventSenderId = rootThreadEvent.senderId ?: return null
+
+        decryptIfNeeded(rootThreadEvent, roomId)
+
+        val rootThreadEventBody = getValueFromPayload(rootThreadEvent.mxDecryptionResult?.payload?.toMutableMap(), "body")
+
+        val permalink = permalinkFactory.createPermalink(roomId, rootThreadEventId, false)
+        val userLink = permalinkFactory.createPermalink(rootThreadEventSenderId, false) ?: ""
+
+        val replyFormatted = LocalEchoEventFactory.REPLY_PATTERN.format(
+                permalink,
+                userLink,
+                rootThreadEventSenderId,
+                // Remove inner mx_reply tags if any
+                rootThreadEventBody,
+                body)
+
+        val messageTextContent = MessageTextContent(
+                msgType = msgType,
+                format = MessageFormat.FORMAT_MATRIX_HTML,
+                body = body,
+                formattedBody = replyFormatted
+        ).toContent()
+
+        payload["content"] = messageTextContent
+
+        return payload
+    }
+
+    /**
+     * Decrypt the event
+     */
+
+    private fun decryptIfNeeded(event: Event, roomId: String) {
+        try {
+            if (!event.isEncrypted() || event.mxDecryptionResult != null) return
+
+            // Event from sync does not have roomId, so add it to the event first
+            val result = cryptoService.decryptEvent(event.copy(roomId = roomId), "")
+            event.mxDecryptionResult = OlmDecryptionResult(
+                    payload = result.clearEvent,
+                    senderKey = result.senderCurve25519Key,
+                    keysClaimed = result.claimedEd25519Key?.let { k -> mapOf("ed25519" to k) },
+                    forwardingCurve25519KeyChain = result.forwardingCurve25519KeyChain
+            )
+        } catch (e: MXCryptoError) {
+            if (e is MXCryptoError.Base) {
+                event.mCryptoError = e.errorType
+                event.mCryptoErrorReason = e.technicalMessage.takeIf { it.isNotEmpty() } ?: e.detailedErrorDescription
+            }
+        }
+    }
+
+    /**
+     * Try to get the event form the local DB, if the event does not exist null
+     * will be returned
+     */
+    private fun getEventFromDB(realm: Realm, eventId: String): Event? {
+        val eventEntity = EventEntity.where(realm, eventId = eventId).findFirst() ?: return null
+        return EventMapper.map(eventEntity)
+    }
+
+    /**
+     * Returns True if the event is a thread
+     * @param event
+     */
+    private fun isThreadEvent(event: Event): Boolean =
+            event.content.toModel<MessageRelationContent>()?.relatesTo?.type == RelationType.THREAD
+
+    /**
+     * Returns the root thread eventId or null otherwise
+     * @param event
+     */
+    private fun getRootThreadEventId(event: Event): String? =
+            event.content.toModel<MessageRelationContent>()?.relatesTo?.eventId
+
+    @Suppress("UNCHECKED_CAST")
+    private fun getValueFromPayload(payload: JsonDict?, key: String): String? {
+        val content = payload?.get("content") as? JsonDict
+        return content?.get(key) as? String
+    }
+}