Timeline: start refactoring the Interceptor mechanism

vector/src/main/java/im/vector/app/core/epoxy/TimelineEmptyItem.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2019 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 im.vector.app.core.epoxy
+
+import com.airbnb.epoxy.EpoxyAttribute
+import com.airbnb.epoxy.EpoxyModelClass
+import im.vector.app.R
+import im.vector.app.features.home.room.detail.timeline.item.IsEventItem
+
+@EpoxyModelClass(layout = R.layout.item_timeline_empty)
+abstract class TimelineEmptyItem : VectorEpoxyModel<TimelineEmptyItem.Holder>(), IsEventItem {
+
+    @EpoxyAttribute lateinit var eventId: String
+
+    override fun getEventIds(): List<String> {
+        return listOf(eventId)
+    }
+
+    class Holder : VectorEpoxyHolder()
+}

vector/src/main/java/im/vector/app/features/home/room/detail/ScrollOnNewMessageCallback.kt

@@ -20,6 +20,7 @@ import androidx.recyclerview.widget.LinearLayoutManager
 import im.vector.app.core.platform.DefaultListUpdateCallback
 import im.vector.app.features.home.room.detail.timeline.TimelineEventController
 import im.vector.app.features.home.room.detail.timeline.item.BaseEventItem
+import im.vector.app.features.home.room.detail.timeline.item.IsEventItem
 import timber.log.Timber
 import java.util.concurrent.CopyOnWriteArrayList
 
@@ -47,7 +48,7 @@ class ScrollOnNewMessageCallback(private val layoutManager: LinearLayoutManager,
         if (layoutManager.findFirstVisibleItemPosition() != position) {
             return
         }
-        val firstNewItem = timelineEventController.adapter.getModelAtPosition(position) as? BaseEventItem ?: return
+        val firstNewItem = timelineEventController.adapter.getModelAtPosition(position) as? IsEventItem ?: return
         val firstNewItemIds = firstNewItem.getEventIds().firstOrNull()
         val indexOfFirstNewItem = newTimelineEventIds.indexOf(firstNewItemIds)
         if (indexOfFirstNewItem != -1) {

vector/src/main/java/im/vector/app/features/home/room/detail/timeline/TimelineEventController.kt

@@ -38,18 +38,15 @@ import im.vector.app.features.home.room.detail.timeline.factory.MergedHeaderItem
 import im.vector.app.features.home.room.detail.timeline.factory.TimelineItemFactory
 import im.vector.app.features.home.room.detail.timeline.helper.ContentDownloadStateTrackerBinder
 import im.vector.app.features.home.room.detail.timeline.helper.ContentUploadStateTrackerBinder
-import im.vector.app.features.home.room.detail.timeline.helper.ReadMarkerVisibilityStateChangedListener
+import im.vector.app.features.home.room.detail.timeline.helper.TimelineControllerInterceptorHelper
 import im.vector.app.features.home.room.detail.timeline.helper.TimelineEventDiffUtilCallback
 import im.vector.app.features.home.room.detail.timeline.helper.TimelineEventVisibilityStateChangedListener
 import im.vector.app.features.home.room.detail.timeline.helper.TimelineMediaSizeProvider
-import im.vector.app.features.home.room.detail.timeline.item.BaseEventItem
 import im.vector.app.features.home.room.detail.timeline.item.BasedMergedItem
-import im.vector.app.features.home.room.detail.timeline.item.CallTileTimelineItem
 import im.vector.app.features.home.room.detail.timeline.item.DaySeparatorItem
 import im.vector.app.features.home.room.detail.timeline.item.DaySeparatorItem_
 import im.vector.app.features.home.room.detail.timeline.item.MessageInformationData
 import im.vector.app.features.home.room.detail.timeline.item.ReadReceiptData
-import im.vector.app.features.home.room.detail.timeline.item.TimelineReadMarkerItem_
 import im.vector.app.features.home.room.detail.timeline.url.PreviewUrlRetriever
 import im.vector.app.features.media.ImageContentRenderer
 import im.vector.app.features.media.VideoContentRenderer
@@ -194,75 +191,20 @@ class TimelineEventController @Inject constructor(private val dateFormatter: Vec
         }
     }
 
+    private val interceptorHelper = TimelineControllerInterceptorHelper(
+            ::positionOfReadMarker,
+            adapterPositionMapping,
+            vectorPreferences,
+            callManager
+    )
+
     init {
         addInterceptor(this)
         requestModelBuild()
     }
 
-    // Update position when we are building new items
     override fun intercept(models: MutableList<EpoxyModel<*>>) = synchronized(modelCache) {
-        positionOfReadMarker = null
-        adapterPositionMapping.clear()
-        val callIds = mutableSetOf<String>()
-        val modelsIterator = models.listIterator()
-        val showHiddenEvents = vectorPreferences.shouldShowHiddenEvents()
-        modelsIterator.withIndex().forEach {
-            val index = it.index
-            val epoxyModel = it.value
-            if (epoxyModel is CallTileTimelineItem) {
-                val callId = epoxyModel.attributes.callId
-                // We should remove the call tile if we already have one for this call or
-                // if this is an active call tile without an actual call (which can happen with permalink)
-                val shouldRemoveCallItem = callIds.contains(callId)
-                        || (!callManager.getAdvertisedCalls().contains(callId) && epoxyModel.attributes.callStatus.isActive())
-                if (shouldRemoveCallItem && !showHiddenEvents) {
-                    modelsIterator.remove()
-                    return@forEach
-                }
-                callIds.add(callId)
-            }
-            if (epoxyModel is BaseEventItem) {
-                epoxyModel.getEventIds().forEach { eventId ->
-                    adapterPositionMapping[eventId] = index
-                }
-            }
-        }
-        val currentUnreadState = this.unreadState
-        if (currentUnreadState is UnreadState.HasUnread) {
-            val position = adapterPositionMapping[currentUnreadState.firstUnreadEventId]?.plus(1)
-            positionOfReadMarker = position
-            if (position != null) {
-                val readMarker = TimelineReadMarkerItem_()
-                        .also {
-                            it.id("read_marker")
-                            it.setOnVisibilityStateChanged(ReadMarkerVisibilityStateChangedListener(callback))
-                        }
-                models.add(position, readMarker)
-            }
-        }
-        val shouldAddBackwardPrefetch = timeline?.hasMoreToLoad(Timeline.Direction.BACKWARDS) ?: false
-        if (shouldAddBackwardPrefetch) {
-            val indexOfPrefetchBackward = (previousModelsSize - 1)
-                    .coerceAtMost(models.size - DEFAULT_PREFETCH_THRESHOLD)
-                    .coerceAtLeast(0)
-
-            val loadingItem = LoadingItem_()
-                    .id("prefetch_backward_loading${System.currentTimeMillis()}")
-                    .showLoader(false)
-                    .setVisibilityStateChangedListener(Timeline.Direction.BACKWARDS)
-
-            models.add(indexOfPrefetchBackward, loadingItem)
-        }
-        val shouldAddForwardPrefetch = timeline?.hasMoreToLoad(Timeline.Direction.FORWARDS) ?: false
-        if (shouldAddForwardPrefetch) {
-            val indexOfPrefetchForward = DEFAULT_PREFETCH_THRESHOLD.coerceAtMost(models.size - 1)
-            val loadingItem = LoadingItem_()
-                    .id("prefetch_forward_loading${System.currentTimeMillis()}")
-                    .showLoader(false)
-                    .setVisibilityStateChangedListener(Timeline.Direction.FORWARDS)
-            models.add(indexOfPrefetchForward, loadingItem)
-        }
-        previousModelsSize = models.size
+        interceptorHelper.intercept(models, unreadState, timeline, callback)
     }
 
     fun update(viewState: RoomDetailViewState) {
@@ -431,6 +373,14 @@ class TimelineEventController @Inject constructor(private val dateFormatter: Vec
         }
     }
 
+    private fun LoadingItem_.setVisibilityStateChangedListener(direction: Timeline.Direction): LoadingItem_ {
+        return onVisibilityStateChanged { _, _, visibilityState ->
+            if (visibilityState == VisibilityState.VISIBLE) {
+                callback?.onLoadMore(direction)
+            }
+        }
+    }
+
     private fun updateUTDStates(event: TimelineEvent, nextEvent: TimelineEvent?) {
         if (vectorPreferences.labShowCompleteHistoryInEncryptedRoom()) {
             return
@@ -461,14 +411,6 @@ class TimelineEventController @Inject constructor(private val dateFormatter: Vec
         return shouldAdd
     }
 
-    private fun LoadingItem_.setVisibilityStateChangedListener(direction: Timeline.Direction): LoadingItem_ {
-        return onVisibilityStateChanged { _, _, visibilityState ->
-            if (visibilityState == VisibilityState.VISIBLE) {
-                callback?.onLoadMore(direction)
-            }
-        }
-    }
-
     fun searchPositionOfEvent(eventId: String?): Int? = synchronized(modelCache) {
         return adapterPositionMapping[eventId]
     }

vector/src/main/java/im/vector/app/features/home/room/detail/timeline/factory/TimelineItemFactory.kt

@@ -16,7 +16,8 @@
 
 package im.vector.app.features.home.room.detail.timeline.factory
 
-import im.vector.app.core.epoxy.EmptyItem_
+import im.vector.app.core.epoxy.TimelineEmptyItem
+import im.vector.app.core.epoxy.TimelineEmptyItem_
 import im.vector.app.core.epoxy.VectorEpoxyModel
 import im.vector.app.core.resources.UserPreferencesProvider
 import im.vector.app.features.home.room.detail.timeline.TimelineEventController
@@ -114,6 +115,13 @@ class TimelineItemFactory @Inject constructor(private val messageItemFactory: Me
             Timber.e(throwable, "failed to create message item")
             defaultItemFactory.create(event, highlight, callback, throwable)
         }
-        return (computedModel ?: EmptyItem_())
+        return (computedModel ?: buildEmptyItem(event))
     }
+
+    private fun buildEmptyItem(timelineEvent: TimelineEvent): TimelineEmptyItem{
+        return TimelineEmptyItem_()
+                .id(timelineEvent.localId)
+                .eventId(timelineEvent.eventId)
+    }
+
 }

vector/src/main/java/im/vector/app/features/home/room/detail/timeline/helper/TimelineControllerInterceptorHelper.kt

@@ -0,0 +1,154 @@
+/*
+ * Copyright (c) 2021 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 im.vector.app.features.home.room.detail.timeline.helper
+
+import com.airbnb.epoxy.EpoxyModel
+import im.vector.app.features.call.webrtc.WebRtcCallManager
+import im.vector.app.features.home.room.detail.UnreadState
+import im.vector.app.features.home.room.detail.timeline.TimelineEventController
+import im.vector.app.features.home.room.detail.timeline.item.BaseEventItem
+import com.airbnb.epoxy.VisibilityState
+import im.vector.app.features.home.room.detail.timeline.item.CallTileTimelineItem
+import im.vector.app.features.settings.VectorPreferences
+import im.vector.app.features.home.room.detail.timeline.item.TimelineReadMarkerItem_
+import org.matrix.android.sdk.api.session.room.timeline.Timeline
+import im.vector.app.core.epoxy.LoadingItem_
+import im.vector.app.core.epoxy.TimelineEmptyItem_
+import im.vector.app.features.home.room.detail.timeline.item.IsEventItem
+import timber.log.Timber
+import kotlin.reflect.KMutableProperty0
+
+
+private const val DEFAULT_PREFETCH_THRESHOLD = 30
+
+class TimelineControllerInterceptorHelper(private val positionOfReadMarker: KMutableProperty0<Int?>,
+                                          private val adapterPositionMapping: MutableMap<String, Int>,
+                                          private val vectorPreferences: VectorPreferences,
+                                          private val callManager: WebRtcCallManager
+) {
+
+    private var previousModelsSize = 0
+
+    // Update position when we are building new items
+    fun intercept(
+            models: MutableList<EpoxyModel<*>>,
+            unreadState: UnreadState,
+            timeline: Timeline?,
+            callback: TimelineEventController.Callback?
+    ) {
+        positionOfReadMarker.set(null)
+        adapterPositionMapping.clear()
+        val callIds = mutableSetOf<String>()
+
+        // Add some prefetch loader if needed
+        models.addBackwardPrefetchIfNeeded(timeline, callback)
+        models.addForwardPrefetchIfNeeded(timeline, callback)
+
+        val modelsIterator = models.listIterator()
+        val showHiddenEvents = vectorPreferences.shouldShowHiddenEvents()
+        var index = 0
+        val firstUnreadEventId = (unreadState as? UnreadState.HasUnread)?.firstUnreadEventId
+        // Then iterate on models so we have the exact positions in the adapter
+        modelsIterator.forEach { epoxyModel ->
+            Timber.v("Index of model:${epoxyModel::class}: $index")
+            if (epoxyModel is IsEventItem) {
+                epoxyModel.getEventIds().forEach { eventId ->
+                    adapterPositionMapping[eventId] = index
+                    if (eventId == firstUnreadEventId) {
+                        modelsIterator.addReadMarkerItem(callback)
+                        index++
+                        positionOfReadMarker.set(index)
+                    }
+                }
+            }
+            if (epoxyModel is CallTileTimelineItem) {
+                modelsIterator.removeCallItemIfNeeded(epoxyModel, callIds, showHiddenEvents)
+            }
+            index++
+        }
+        previousModelsSize = models.size
+    }
+
+    private fun MutableListIterator<EpoxyModel<*>>.addReadMarkerItem(callback: TimelineEventController.Callback?) {
+        val readMarker = TimelineReadMarkerItem_()
+                .also {
+                    it.id("read_marker")
+                    it.setOnVisibilityStateChanged(ReadMarkerVisibilityStateChangedListener(callback))
+                }
+        add(readMarker)
+    }
+
+    private fun MutableListIterator<EpoxyModel<*>>.removeCallItemIfNeeded(
+            epoxyModel: CallTileTimelineItem,
+            callIds: MutableSet<String>,
+            showHiddenEvents: Boolean
+    ) {
+        val callId = epoxyModel.attributes.callId
+        // We should remove the call tile if we already have one for this call or
+        // if this is an active call tile without an actual call (which can happen with permalink)
+        val shouldRemoveCallItem = callIds.contains(callId)
+                || (!callManager.getAdvertisedCalls().contains(callId) && epoxyModel.attributes.callStatus.isActive())
+        if (shouldRemoveCallItem && !showHiddenEvents) {
+            remove()
+            val emptyItem = TimelineEmptyItem_()
+                    .id(epoxyModel.id())
+                    .eventId(epoxyModel.attributes.informationData.eventId)
+            add(emptyItem)
+        }
+        callIds.add(callId)
+    }
+
+    private fun MutableList<EpoxyModel<*>>.addBackwardPrefetchIfNeeded(timeline: Timeline?, callback: TimelineEventController.Callback?) {
+        val shouldAddBackwardPrefetch = timeline?.hasMoreToLoad(Timeline.Direction.BACKWARDS) ?: false
+        if (shouldAddBackwardPrefetch) {
+            val indexOfPrefetchBackward = (previousModelsSize - 1)
+                    .coerceAtMost(size - DEFAULT_PREFETCH_THRESHOLD)
+                    .coerceAtLeast(0)
+
+            val loadingItem = LoadingItem_()
+                    .id("prefetch_backward_loading${System.currentTimeMillis()}")
+                    .showLoader(false)
+                    .setVisibilityStateChangedListener(Timeline.Direction.BACKWARDS, callback)
+
+            add(indexOfPrefetchBackward, loadingItem)
+        }
+    }
+
+    private fun MutableList<EpoxyModel<*>>.addForwardPrefetchIfNeeded(timeline: Timeline?,callback: TimelineEventController.Callback?) {
+        val shouldAddForwardPrefetch = timeline?.hasMoreToLoad(Timeline.Direction.FORWARDS) ?: false
+        if (shouldAddForwardPrefetch) {
+            val indexOfPrefetchForward = DEFAULT_PREFETCH_THRESHOLD.coerceAtMost(size - 1)
+            val loadingItem = LoadingItem_()
+                    .id("prefetch_forward_loading${System.currentTimeMillis()}")
+                    .showLoader(false)
+                    .setVisibilityStateChangedListener(Timeline.Direction.FORWARDS, callback)
+            add(indexOfPrefetchForward, loadingItem)
+        }
+    }
+
+    private fun LoadingItem_.setVisibilityStateChangedListener(
+            direction: Timeline.Direction,
+            callback: TimelineEventController.Callback?
+    ): LoadingItem_ {
+        return onVisibilityStateChanged { _, _, visibilityState ->
+            if (visibilityState == VisibilityState.VISIBLE) {
+                callback?.onLoadMore(direction)
+            }
+        }
+    }
+
+}

vector/src/main/java/im/vector/app/features/home/room/detail/timeline/item/BaseEventItem.kt

@@ -32,7 +32,7 @@ import im.vector.app.core.utils.DimensionConverter
 /**
  * Children must override getViewType()
  */
-abstract class BaseEventItem<H : BaseEventItem.BaseHolder> : VectorEpoxyModel<H>() {
+abstract class BaseEventItem<H : BaseEventItem.BaseHolder> : VectorEpoxyModel<H>(), IsEventItem {
 
     // To use for instance when opening a permalink with an eventId
     @EpoxyAttribute
@@ -53,12 +53,6 @@ abstract class BaseEventItem<H : BaseEventItem.BaseHolder> : VectorEpoxyModel<H>
         holder.checkableBackground.isChecked = highlighted
     }
 
-    /**
-     * Returns the eventIds associated with the EventItem.
-     * Will generally get only one, but it handles the merging items.
-     */
-    abstract fun getEventIds(): List<String>
-
     abstract class BaseHolder(@IdRes val stubId: Int) : VectorEpoxyHolder() {
         val leftGuideline by bind<View>(R.id.messageStartGuideline)
         val checkableBackground by bind<CheckableView>(R.id.messageSelectedBackground)

vector/src/main/java/im/vector/app/features/home/room/detail/timeline/item/IsEventItem.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019 New Vector Ltd
+ * Copyright (c) 2021 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.
@@ -14,12 +14,12 @@
  * limitations under the License.
  */
 
-package im.vector.app.core.epoxy
+package im.vector.app.features.home.room.detail.timeline.item
 
-import com.airbnb.epoxy.EpoxyModelClass
-import im.vector.app.R
-
-@EpoxyModelClass(layout = R.layout.item_empty)
-abstract class EmptyItem : VectorEpoxyModel<EmptyItem.Holder>() {
-    class Holder : VectorEpoxyHolder()
+interface IsEventItem {
+    /**
+     * Returns the eventIds associated with the EventItem.
+     * Will generally get only one, but it handles the merging items.
+     */
+    fun getEventIds(): List<String>
 }