Render state items in the timeline and as the last message on the home screen. (#473)

* State events in the timeline WIP
* Implement membership change strings.
* Add other state event types and use in RoomSummaryProvider.

Co-authored-by: Stefan Ceriu <stefanc@matrix.org>

ElementX/Sources/Services/Room/RoomSummary/RoomEventStringBuilder.swift

@@ -0,0 +1,84 @@
+//
+// Copyright 2023 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 RoomEventStringBuilder {
+    private let roomStateStringBuilder: RoomStateStringBuilder
+    
+    /// The Matrix ID of the current user.
+    private let userID: String
+    
+    init(userID: String, roomStateStringBuilder: RoomStateStringBuilder) {
+        self.userID = userID
+        self.roomStateStringBuilder = roomStateStringBuilder
+    }
+    
+    // swiftlint:disable:next cyclomatic_complexity
+    func buildAttributedString(for eventItemProxy: EventTimelineItemProxy) -> AttributedString? {
+        let sender = eventItemProxy.sender
+        let isOutgoing = eventItemProxy.isOwn
+        
+        switch eventItemProxy.content.kind() {
+        case .unableToDecrypt:
+            return prefix(ElementL10n.encryptionInformationDecryptionError, with: sender)
+        case .redactedMessage:
+            return prefix(ElementL10n.eventRedacted, with: sender)
+        case .sticker:
+            return prefix(ElementL10n.sendASticker, with: sender)
+        case .failedToParseMessageLike, .failedToParseState:
+            return prefix(ElementL10n.roomTimelineItemUnsupported, with: sender)
+        case .message:
+            guard let messageContent = eventItemProxy.content.asMessage() else { fatalError("Invalid message timeline item: \(eventItemProxy)") }
+            
+            let message: String
+            switch messageContent.msgtype() {
+            // Message types that don't need a prefix.
+            case .emote(content: let content):
+                let senderDisplayName = sender.displayName ?? sender.id
+                return AttributedString("* \(senderDisplayName) \(content.body)")
+            // Message types that should be prefixed with the sender's name.
+            case .image:
+                message = ElementL10n.sentAnImage
+            case .video:
+                message = ElementL10n.sentAVideo
+            case .file:
+                message = ElementL10n.sentAFile
+            default:
+                message = messageContent.body()
+            }
+            return prefix(message, with: sender)
+        case .state(let stateKey, let state):
+            return roomStateStringBuilder
+                .buildString(for: state, stateKey: stateKey, sender: sender, isOutgoing: isOutgoing)
+                .map(AttributedString.init)
+        case .roomMembership(userId: let userID, change: let change):
+            return roomStateStringBuilder
+                .buildString(for: change, member: userID, sender: sender, isOutgoing: isOutgoing)
+                .map(AttributedString.init)
+        }
+    }
+    
+    func prefix(_ eventSummary: String, with sender: TimelineItemSender) -> AttributedString {
+        if let senderDisplayName = sender.displayName,
+           let attributedSenderDisplayName = try? AttributedString(markdown: "**\(senderDisplayName)**") {
+            // Don't include the message body in the markdown otherwise it makes tappable links.
+            return attributedSenderDisplayName + ": " + AttributedString(eventSummary)
+        } else {
+            return AttributedString(eventSummary)
+        }
+    }
+}

ElementX/Sources/Services/Room/RoomSummary/RoomSummaryProvider.swift

@@ -21,6 +21,7 @@ import MatrixRustSDK
 class RoomSummaryProvider: RoomSummaryProviderProtocol {
     private let slidingSyncViewProxy: SlidingSyncViewProxy
     private let serialDispatchQueue: DispatchQueue
+    private let eventStringBuilder: RoomEventStringBuilder
     
     private var cancellables = Set<AnyCancellable>()
     
@@ -34,9 +35,10 @@ class RoomSummaryProvider: RoomSummaryProviderProtocol {
         }
     }
     
-    init(slidingSyncViewProxy: SlidingSyncViewProxy) {
+    init(slidingSyncViewProxy: SlidingSyncViewProxy, eventStringBuilder: RoomEventStringBuilder) {
         self.slidingSyncViewProxy = slidingSyncViewProxy
         serialDispatchQueue = DispatchQueue(label: "io.element.elementx.roomsummaryprovider")
+        self.eventStringBuilder = eventStringBuilder
         
         rooms = slidingSyncViewProxy.currentRoomsList().map { roomListEntry in
             buildSummaryForRoomListEntry(roomListEntry)
@@ -151,16 +153,8 @@ class RoomSummaryProvider: RoomSummaryProviderProtocol {
         DispatchQueue.global(qos: .default).sync {
             if let latestRoomMessage = room.latestRoomMessage() {
                 let lastMessage = EventTimelineItemProxy(item: latestRoomMessage)
-                
                 lastMessageTimestamp = lastMessage.timestamp
-                
-                if let senderDisplayName = lastMessage.sender.displayName,
-                   let attributedSenderDisplayName = try? AttributedString(markdown: "**\(senderDisplayName)**") {
-                    // Don't include the message body in the markdown otherwise it makes tappable links.
-                    attributedLastMessage = attributedSenderDisplayName + ": " + AttributedString(lastMessage.body ?? "")
-                } else if let body = lastMessage.body {
-                    attributedLastMessage = AttributedString(body)
-                }
+                attributedLastMessage = eventStringBuilder.buildAttributedString(for: lastMessage)
             }
         }