Add timeline day separators and read markers (#383)

* Add timeline day separators and read markers

ElementX/Sources/Services/Timeline/TimelineController/RoomTimelineController.swift

@@ -235,6 +235,22 @@ class RoomTimelineController: RoomTimelineControllerProtocol {
             case .event(let eventItem):
                 newTimelineItems.append(timelineItemFactory.buildTimelineItemFor(eventItemProxy: eventItem,
                                                                                  inGroupState: inGroupState))
+            case .virtual(let virtualItem):
+                switch virtualItem {
+                case .dayDivider(let year, let month, let day):
+                    // These components will be replaced by a timestamp in upcoming releases
+                    let dateComponents = DateComponents(calendar: .current, year: Int(year), month: Int(month), day: Int(day))
+                    if let dateString = dateComponents.date?.formatted(date: .complete, time: .omitted) {
+                        newTimelineItems.append(SeparatorRoomTimelineItem(id: UUID().uuidString, text: dateString))
+                    } else {
+                        MXLog.error("Failed formatting separator date")
+                    }
+                case .readMarker:
+                    // Don't show the read marker if it's the last item in the timeline
+                    if index != timelineProvider.itemsPublisher.value.indices.last {
+                        newTimelineItems.append(ReadMarkerRoomTimelineItem(id: UUID().uuidString))
+                    }
+                }
             default:
                 break
             }

ElementX/Sources/Services/Timeline/TimelineItems/Items/ReadMarkerRoomTimelineItem.swift

@@ -0,0 +1,21 @@
+//
+// Copyright 2022 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.
+//
+
+import Foundation
+
+struct ReadMarkerRoomTimelineItem: DecorationTimelineItemProtocol, Identifiable, Hashable {
+    let id: String
+}

ElementX/Sources/Services/Timeline/TimelineItems/RoomTimelineViewFactory.swift

@@ -17,6 +17,7 @@
 import Foundation
 
 struct RoomTimelineViewFactory: RoomTimelineViewFactoryProtocol {
+    // swiftlint:disable:next cyclomatic_complexity
     func buildTimelineViewFor(timelineItem: RoomTimelineItemProtocol) -> RoomTimelineViewProvider {
         switch timelineItem {
         case let item as TextRoomTimelineItem:
@@ -37,6 +38,8 @@ struct RoomTimelineViewFactory: RoomTimelineViewFactoryProtocol {
             return .redacted(item)
         case let item as EncryptedRoomTimelineItem:
             return .encrypted(item)
+        case let item as ReadMarkerRoomTimelineItem:
+            return .readMarker(item)
         default:
             fatalError("Unknown timeline item")
         }

ElementX/Sources/Services/Timeline/TimelineItems/RoomTimelineViewProvider.swift

@@ -27,6 +27,7 @@ enum RoomTimelineViewProvider: Identifiable, Hashable {
     case notice(NoticeRoomTimelineItem)
     case redacted(RedactedRoomTimelineItem)
     case encrypted(EncryptedRoomTimelineItem)
+    case readMarker(ReadMarkerRoomTimelineItem)
     case backPaginationIndicator(Bool)
     
     var id: String {
@@ -49,6 +50,8 @@ enum RoomTimelineViewProvider: Identifiable, Hashable {
             return item.id
         case .encrypted(let item):
             return item.id
+        case .readMarker(let item):
+            return item.id
         case .backPaginationIndicator:
             return "BackpaginationLoadingIndicator"
         }
@@ -76,6 +79,8 @@ extension RoomTimelineViewProvider: View {
             RedactedRoomTimelineView(timelineItem: item)
         case .encrypted(let item):
             EncryptedRoomTimelineView(timelineItem: item)
+        case .readMarker(let item):
+            ReadMarkerRoomTimelineView(timelineItem: item)
         case .backPaginationIndicator(let isBackPaginating):
             ProgressView()
                 .frame(maxWidth: .infinity)