Add a service and flow coordinator for the LinkNewDevice feature. (#4859)

* Add a LinkNewDeviceService that exposes the SDK's grant QR code login methods.

* Add a flow coordinator for linking a new device.

Changes the presentation too.

ElementX/Sources/Screens/LinkNewDeviceScreen/LinkNewDeviceScreenCoordinator.swift

@@ -9,7 +9,7 @@ import Combine
 import SwiftUI
 
 enum LinkNewDeviceScreenCoordinatorAction {
-    case linkMobileDevice
+    case linkMobileDevice(LinkNewDeviceService.GenerateProgressPublisher)
     case linkDesktopComputer
     case dismiss
 }
@@ -38,8 +38,8 @@ final class LinkNewDeviceScreenCoordinator: CoordinatorProtocol {
             
             guard let self else { return }
             switch action {
-            case .linkMobileDevice:
-                actionsSubject.send(.linkMobileDevice)
+            case .linkMobileDevice(let progressPublisher):
+                actionsSubject.send(.linkMobileDevice(progressPublisher))
             case .linkDesktopComputer:
                 actionsSubject.send(.linkDesktopComputer)
             case .dismiss:

ElementX/Sources/Screens/LinkNewDeviceScreen/LinkNewDeviceScreenModels.swift

@@ -8,7 +8,7 @@
 import Foundation
 
 enum LinkNewDeviceScreenViewModelAction {
-    case linkMobileDevice
+    case linkMobileDevice(LinkNewDeviceService.GenerateProgressPublisher)
     case linkDesktopComputer
     case dismiss
 }

ElementX/Sources/Screens/LinkNewDeviceScreen/LinkNewDeviceScreenViewModel.swift

@@ -6,6 +6,7 @@
 //
 
 import Combine
+import MatrixRustSDK
 import SwiftUI
 
 typealias LinkNewDeviceScreenViewModelType = StateStoreViewModelV2<LinkNewDeviceScreenViewState, LinkNewDeviceScreenViewAction>
@@ -33,7 +34,7 @@ class LinkNewDeviceScreenViewModel: LinkNewDeviceScreenViewModelType, LinkNewDev
         
         switch viewAction {
         case .linkMobileDevice:
-            linkMobileDevice()
+            Task { await linkMobileDevice() }
         case .linkDesktopComputer:
             actionsSubject.send(.linkDesktopComputer)
         case .dismiss:
@@ -51,11 +52,27 @@ class LinkNewDeviceScreenViewModel: LinkNewDeviceScreenViewModelType, LinkNewDev
         }
     }
     
-    private func linkMobileDevice() {
+    private func linkMobileDevice() async {
         state.mode = .readyToLink(isGeneratingCode: true)
         
-        // TODO: Generate a QR code.
+        let linkNewDeviceService = clientProxy.linkNewDeviceService()
         
-        actionsSubject.send(.linkMobileDevice)
+        let progressPublisher = linkNewDeviceService.generateQRCode()
+        
+        do {
+            _ = try await progressPublisher.values
+                .first { progress in
+                    switch progress {
+                    case .qrReady: true
+                    default: false
+                    }
+                }
+            
+            actionsSubject.send(.linkMobileDevice(progressPublisher))
+            state.mode = .readyToLink(isGeneratingCode: false)
+        } catch {
+            #warning("Needs some form of re-usable error handling, will handle with the next screen.")
+            state.mode = .notSupported
+        }
     }
 }

ElementX/Sources/Screens/LinkNewDeviceScreen/View/LinkNewDeviceScreen.swift

@@ -21,6 +21,7 @@ struct LinkNewDeviceScreen: View {
         .backgroundStyle(.compound.bgSubtleSecondary)
         .navigationTitle(L10n.commonLinkNewDevice)
         .navigationBarTitleDisplayMode(.inline)
+        .toolbar { toolbar }
     }
     
     @ViewBuilder
@@ -86,11 +87,13 @@ struct LinkNewDeviceScreen: View {
                     }
                 }
                 .buttonStyle(.compound(.primary))
+                .accessibilityIdentifier(A11yIdentifiers.linkNewDeviceScreen.mobileDevice)
                 
                 Button { context.send(viewAction: .linkDesktopComputer) } label: {
                     Label(L10n.screenLinkNewDeviceRootDesktopComputer, icon: \.computer)
                 }
                 .buttonStyle(.compound(.primary))
+                .accessibilityIdentifier(A11yIdentifiers.linkNewDeviceScreen.desktopComputer)
             }
             .disabled(isGeneratingCode)
         case .notSupported:
@@ -100,6 +103,15 @@ struct LinkNewDeviceScreen: View {
             .buttonStyle(.compound(.primary))
         }
     }
+    
+    var toolbar: some ToolbarContent {
+        ToolbarItem(placement: .cancellationAction) {
+            Button(L10n.actionCancel) {
+                context.send(viewAction: .dismiss)
+            }
+            .accessibilityIdentifier(A11yIdentifiers.linkNewDeviceScreen.cancel)
+        }
+    }
 }
 
 // MARK: - Previews
@@ -148,6 +160,7 @@ struct LinkNewDeviceScreen_Previews: PreviewProvider, TestablePreview {
                 return false
             }
         }
+        clientProxy.linkNewDeviceServiceReturnValue = .init(handler: GrantLoginWithQrCodeHandlerSDKMock(.init(generateDelay: .seconds(20))))
         
         let viewModel = LinkNewDeviceScreenViewModel(clientProxy: clientProxy)