quick and dirty /join command (#3288)

Co-authored-by: Mauro Romito <mauro.romito@element.io>
Co-authored-by: Mauro <34335419+Velin92@users.noreply.github.com>

ElementX/Sources/Screens/Timeline/TimelineModels.swift

@@ -72,6 +72,7 @@ enum TimelineViewAction {
     case hasSwitchedTimeline
     
     case hasScrolled(direction: ScrollDirection)
+    case setOpenURLAction(OpenURLAction)
 }
 
 enum TimelineComposerAction {
@@ -101,6 +102,9 @@ struct TimelineViewState: BindableState {
     // It's updated from the room info, so it's faster than using the timeline
     var pinnedEventIDs: Set<String> = []
     
+    /// an openURL closure which opens URLs first using the App's environment rather than skipping out to external apps
+    var openURL: OpenURLAction?
+    
     var bindings: TimelineViewStateBindings
     
     /// A closure providing the associated audio player state for an item in the timeline.

ElementX/Sources/Screens/Timeline/TimelineViewModel.swift

@@ -7,6 +7,7 @@
 
 import Algorithms
 import Combine
+import MatrixRustSDK
 import OrderedCollections
 import SwiftUI
 
@@ -167,6 +168,8 @@ class TimelineViewModel: TimelineViewModelType, TimelineViewModelProtocol {
             Task { state.timelineViewState.isSwitchingTimelines = false }
         case let .hasScrolled(direction):
             actionsSubject.send(.hasScrolled(direction: direction))
+        case .setOpenURLAction(let action):
+            state.openURL = action
         }
     }
 
@@ -560,7 +563,27 @@ class TimelineViewModel: TimelineViewModelType, TimelineViewModelProtocol {
             displayAlert(.encryptionAuthenticity(authenticityMessage))
         }
     }
+    
+    private func slashCommand(message: String) -> SlashCommand? {
+        for command in SlashCommand.allCases {
+            if message.starts(with: command.rawValue) {
+                return command
+            }
+        }
+        return nil
+    }
 
+    private func handleJoinCommand(message: String) {
+        guard let alias = String(message.dropFirst(SlashCommand.join.rawValue.count))
+            .components(separatedBy: .whitespacesAndNewlines)
+            .first,
+            let urlString = try? matrixToRoomAliasPermalink(roomAlias: alias),
+            let url = URL(string: urlString) else {
+            return
+        }
+        state.openURL?(url)
+    }
+    
     private func sendCurrentMessage(_ message: String, html: String?, mode: ComposerMode, intentionalMentions: IntentionalMentions) async {
         guard !message.isEmpty else {
             fatalError("This message should never be empty")
@@ -580,9 +603,14 @@ class TimelineViewModel: TimelineViewModelType, TimelineViewModelProtocol {
                                           html: html,
                                           intentionalMentions: intentionalMentions)
         case .default:
-            await timelineController.sendMessage(message,
-                                                 html: html,
-                                                 intentionalMentions: intentionalMentions)
+            switch slashCommand(message: message) {
+            case .join:
+                handleJoinCommand(message: message)
+            case .none:
+                await timelineController.sendMessage(message,
+                                                     html: html,
+                                                     intentionalMentions: intentionalMentions)
+            }
         case .recordVoiceMessage, .previewVoiceMessage:
             fatalError("invalid composer mode.")
         }
@@ -862,3 +890,7 @@ extension EnvironmentValues {
         set { self[FocussedEventID.self] = newValue }
     }
 }
+
+private enum SlashCommand: String, CaseIterable {
+    case join = "/join "
+}

ElementX/Sources/Screens/Timeline/View/TimelineView.swift

@@ -11,11 +11,16 @@ import WysiwygComposer
 /// A table view wrapper that displays the timeline of a room.
 struct TimelineView: UIViewControllerRepresentable {
     @EnvironmentObject private var viewModelContext: TimelineViewModel.Context
-    
+    @Environment(\.openURL) var openURL
+
     func makeUIViewController(context: Context) -> TimelineTableViewController {
         let tableViewController = TimelineTableViewController(coordinator: context.coordinator,
                                                               isScrolledToBottom: $viewModelContext.isScrolledToBottom,
                                                               scrollToBottomPublisher: viewModelContext.viewState.timelineViewState.scrollToBottomPublisher)
+        // Needs to be dispatched on main asynchronously otherwise we get a runtime warning
+        DispatchQueue.main.async {
+            viewModelContext.send(viewAction: .setOpenURLAction(openURL))
+        }
         return tableViewController
     }