QR Code Login Initial view state (#2667)

ElementX/Sources/Screens/QRCodeLoginScreen/QRCodeLoginScreenViewModel.swift

@@ -0,0 +1,50 @@
+//
+// Copyright 2022 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 AVFoundation
+import Combine
+import SwiftUI
+
+typealias QRCodeLoginScreenViewModelType = StateStoreViewModel<QRCodeLoginScreenViewState, QRCodeLoginScreenViewAction>
+
+class QRCodeLoginScreenViewModel: QRCodeLoginScreenViewModelType, QRCodeLoginScreenViewModelProtocol {
+    private let qrCodeLoginService: QRCodeLoginServiceProtocol
+    
+    private let actionsSubject: PassthroughSubject<QRCodeLoginScreenViewModelAction, Never> = .init()
+    var actionsPublisher: AnyPublisher<QRCodeLoginScreenViewModelAction, Never> {
+        actionsSubject.eraseToAnyPublisher()
+    }
+
+    init(qrCodeLoginService: QRCodeLoginServiceProtocol) {
+        self.qrCodeLoginService = qrCodeLoginService
+        super.init(initialViewState: QRCodeLoginScreenViewState())
+    }
+    
+    // MARK: - Public
+    
+    override func process(viewAction: QRCodeLoginScreenViewAction) {
+        switch viewAction {
+        case .cancel:
+            actionsSubject.send(.cancel)
+        case .startScan:
+            Task { await startScanIfPossible() }
+        }
+    }
+    
+    private func startScanIfPossible() async {
+        state.state = await qrCodeLoginService.requestAuthorizationIfNeeded() ? .scanning : .error(.noCameraPermission)
+    }
+}