Prioritise joining rooms by alias if available and letting the homeserver do the right thing

ElementX/Sources/Mocks/Generated/GeneratedMocks.swift

@@ -2523,6 +2523,74 @@ class ClientProxyMock: ClientProxyProtocol {
             return joinRoomViaReturnValue
         }
     }
+    //MARK: - joinRoomAlias
+
+    var joinRoomAliasUnderlyingCallsCount = 0
+    var joinRoomAliasCallsCount: Int {
+        get {
+            if Thread.isMainThread {
+                return joinRoomAliasUnderlyingCallsCount
+            } else {
+                var returnValue: Int? = nil
+                DispatchQueue.main.sync {
+                    returnValue = joinRoomAliasUnderlyingCallsCount
+                }
+
+                return returnValue!
+            }
+        }
+        set {
+            if Thread.isMainThread {
+                joinRoomAliasUnderlyingCallsCount = newValue
+            } else {
+                DispatchQueue.main.sync {
+                    joinRoomAliasUnderlyingCallsCount = newValue
+                }
+            }
+        }
+    }
+    var joinRoomAliasCalled: Bool {
+        return joinRoomAliasCallsCount > 0
+    }
+    var joinRoomAliasReceivedRoomAlias: String?
+    var joinRoomAliasReceivedInvocations: [String] = []
+
+    var joinRoomAliasUnderlyingReturnValue: Result<Void, ClientProxyError>!
+    var joinRoomAliasReturnValue: Result<Void, ClientProxyError>! {
+        get {
+            if Thread.isMainThread {
+                return joinRoomAliasUnderlyingReturnValue
+            } else {
+                var returnValue: Result<Void, ClientProxyError>? = nil
+                DispatchQueue.main.sync {
+                    returnValue = joinRoomAliasUnderlyingReturnValue
+                }
+
+                return returnValue!
+            }
+        }
+        set {
+            if Thread.isMainThread {
+                joinRoomAliasUnderlyingReturnValue = newValue
+            } else {
+                DispatchQueue.main.sync {
+                    joinRoomAliasUnderlyingReturnValue = newValue
+                }
+            }
+        }
+    }
+    var joinRoomAliasClosure: ((String) async -> Result<Void, ClientProxyError>)?
+
+    func joinRoomAlias(_ roomAlias: String) async -> Result<Void, ClientProxyError> {
+        joinRoomAliasCallsCount += 1
+        joinRoomAliasReceivedRoomAlias = roomAlias
+        joinRoomAliasReceivedInvocations.append(roomAlias)
+        if let joinRoomAliasClosure = joinRoomAliasClosure {
+            return await joinRoomAliasClosure(roomAlias)
+        } else {
+            return joinRoomAliasReturnValue
+        }
+    }
     //MARK: - uploadMedia
 
     var uploadMediaUnderlyingCallsCount = 0

ElementX/Sources/Screens/JoinRoomScreen/JoinRoomScreenViewModel.swift

@@ -92,14 +92,25 @@ class JoinRoomScreenViewModel: JoinRoomScreenViewModelType, JoinRoomScreenViewMo
             hideLoadingIndicator()
         }
         
+        // Prioritise joining by the alias and letting the homeserver do the right thing
+        if let alias = state.roomDetails?.canonicalAlias {
+            switch await clientProxy.joinRoomAlias(alias) {
+            case .success:
+                actionsSubject.send(.joined)
+            case .failure(let error):
+                MXLog.error("Failed joining room alias: \(alias) with error: \(error)")
+                userIndicatorController.submitIndicator(.init(title: L10n.errorUnknown))
+            }
+        } else {
             switch await clientProxy.joinRoom(roomID, via: via) {
             case .success:
                 actionsSubject.send(.joined)
             case .failure(let error):
-            MXLog.error("Failed joining room with error: \(error)")
+                MXLog.error("Failed joining room id: \(roomID) with error: \(error)")
                 userIndicatorController.submitIndicator(.init(title: L10n.errorUnknown))
             }
         }
+    }
     
     private func showDeclineInviteConfirmationAlert() {
         guard let roomDetails = state.roomDetails else {

ElementX/Sources/Services/Client/ClientProxy.swift

@@ -385,6 +385,20 @@ class ClientProxy: ClientProxyProtocol {
         }
     }
     
+    func joinRoomAlias(_ roomAlias: String) async -> Result<Void, ClientProxyError> {
+        do {
+            let room = try await client.joinRoomByIdOrAlias(roomIdOrAlias: roomAlias, serverNames: [])
+            
+            // Wait for the room to appear in the room lists to avoid issues downstream
+            let _ = await waitForRoomSummary(with: .success(room.id()), name: nil, timeout: 30)
+            
+            return .success(())
+        } catch {
+            MXLog.error("Failed joining roomAlias: \(roomAlias) with error: \(error)")
+            return .failure(.sdkError(error))
+        }
+    }
+    
     func uploadMedia(_ media: MediaInfo) async -> Result<String, ClientProxyError> {
         guard let mimeType = media.mimeType else {
             MXLog.error("Failed uploading media, invalid mime type: \(media)")

ElementX/Sources/Services/Client/ClientProxyProtocol.swift

@@ -131,6 +131,8 @@ protocol ClientProxyProtocol: AnyObject, MediaLoaderProtocol {
     
     func joinRoom(_ roomID: String, via: [String]) async -> Result<Void, ClientProxyError>
     
+    func joinRoomAlias(_ roomAlias: String) async -> Result<Void, ClientProxyError>
+    
     func uploadMedia(_ media: MediaInfo) async -> Result<String, ClientProxyError>
     
     func roomForIdentifier(_ identifier: String) async -> RoomProxyProtocol?