Add a workaround to include some via parameters for room v12 tombstone links. (#4413)

Without them, following the link fails as previously the server could use the server name from the room ID (which in and of itself seems somewhat error prone).

Author: pixlwave

ElementX/Sources/FlowCoordinators/RoomFlowCoordinator.swift

@@ -627,9 +627,9 @@ class RoomFlowCoordinator: FlowCoordinatorProtocol {
                     stateMachine.tryEvent(.presentKnockRequestsListScreen)
                 case .presentThread(let itemID):
                     stateMachine.tryEvent(.presentThread(itemID: itemID))
-                case .presentRoom(roomID: let roomID):
+                case .presentRoom(let roomID, let via):
                     stateMachine.tryEvent(.startChildFlow(roomID: roomID,
-                                                          via: [],
+                                                          via: via,
                                                           entryPoint: .room))
                 }
             }

ElementX/Sources/Screens/RoomScreen/RoomScreenCoordinator.swift

@@ -46,7 +46,7 @@ enum RoomScreenCoordinatorAction {
     case presentResolveSendFailure(failure: TimelineItemSendFailure.VerifiedUser, sendHandle: SendHandleProxy)
     case presentKnockRequestsList
     case presentThread(itemID: TimelineItemIdentifier)
-    case presentRoom(roomID: String)
+    case presentRoom(roomID: String, via: [String])
 }
 
 final class RoomScreenCoordinator: CoordinatorProtocol {
@@ -148,8 +148,8 @@ final class RoomScreenCoordinator: CoordinatorProtocol {
                     composerViewModel.process(timelineAction: action)
                 case .hasScrolled(direction: let direction):
                     roomViewModel.timelineHasScrolled(direction: direction)
-                case .displayRoom(let roomID):
-                    actionsSubject.send(.presentRoom(roomID: roomID))
+                case .displayRoom(let roomID, let via):
+                    actionsSubject.send(.presentRoom(roomID: roomID, via: via))
                 case .viewInRoomTimeline:
                     fatalError("The action: \(action) should not be sent to this coordinator")
                 }
@@ -181,8 +181,8 @@ final class RoomScreenCoordinator: CoordinatorProtocol {
                     composerViewModel.process(timelineAction: .removeFocus)
                 case .displayKnockRequests:
                     actionsSubject.send(.presentKnockRequestsList)
-                case .displayRoom(let roomID):
-                    actionsSubject.send(.presentRoom(roomID: roomID))
+                case .displayRoom(let roomID, let via):
+                    actionsSubject.send(.presentRoom(roomID: roomID, via: via))
                 }
             }
             .store(in: &cancellables)

ElementX/Sources/Screens/RoomScreen/RoomScreenModels.swift

@@ -15,7 +15,7 @@ enum RoomScreenViewModelAction: Equatable {
     case displayCall
     case removeComposerFocus
     case displayKnockRequests
-    case displayRoom(roomID: String)
+    case displayRoom(roomID: String, via: [String])
 }
 
 enum RoomScreenViewAction {

ElementX/Sources/Screens/RoomScreen/RoomScreenViewModel.swift

@@ -5,6 +5,7 @@
 // Please see LICENSE files in the repository root for full details.
 //
 
+import Algorithms
 import Combine
 import Foundation
 import MatrixRustSDK
@@ -117,7 +118,8 @@ class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol
             actionsSubject.send(.displayKnockRequests)
         case .displaySuccessorRoom:
             guard let successorID = roomProxy.infoPublisher.value.successor?.roomId else { return }
-            actionsSubject.send(.displayRoom(roomID: successorID))
+            let serverNames = roomProxy.knownServerNames(maxCount: 50) // Limit to the same number used by ClientProxy.resolveRoomAlias(_:)
+            actionsSubject.send(.displayRoom(roomID: successorID, via: Array(serverNames)))
         }
     }
 

ElementX/Sources/Screens/Timeline/TimelineModels.swift

@@ -28,7 +28,7 @@ enum TimelineViewModelAction {
     case composer(action: TimelineComposerAction)
     case hasScrolled(direction: ScrollDirection)
     case viewInRoomTimeline(eventID: String)
-    case displayRoom(roomID: String)
+    case displayRoom(roomID: String, via: [String])
 }
 
 enum TimelineViewPollAction {

ElementX/Sources/Screens/Timeline/TimelineViewModel.swift

@@ -214,7 +214,8 @@ class TimelineViewModel: TimelineViewModelType, TimelineViewModelProtocol {
             guard let predecessorID = roomProxy.predecessorRoom?.roomId else {
                 fatalError("Predecessor room should exist if this action is triggered.")
             }
-            actionsSubject.send(.displayRoom(roomID: predecessorID))
+            let serverNames = roomProxy.knownServerNames(maxCount: 50) // Limit to the same number used by ClientProxy.resolveRoomAlias(_:)
+            actionsSubject.send(.displayRoom(roomID: predecessorID, via: Array(serverNames)))
         }
     }
 

ElementX/Sources/Services/Room/RoomProxyProtocol.swift

@@ -200,4 +200,13 @@ extension JoinedRoomProxyProtocol {
         await updateMembers()
         return membersPublisher.value
     }
+    
+    // This is a horrible workaround for not having any server names available when using tombstone links with v12 room IDs.
+    func knownServerNames(maxCount: Int) -> any Sequence<String> {
+        membersPublisher.value
+            .prefix(1000) // No need to go crazy here…
+            .compactMap { $0.userID.split(separator: ":").last.map(String.init) }
+            .uniqued()
+            .prefix(maxCount)
+    }
 }