Add App Lock settings screen (#1917)

ElementX/Sources/Screens/AppLock/AppLockScreen/AppLockScreenViewModel.swift

@@ -0,0 +1,51 @@
+//
+// 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 Combine
+import SwiftUI
+
+typealias AppLockScreenViewModelType = StateStoreViewModel<AppLockScreenViewState, AppLockScreenViewAction>
+
+class AppLockScreenViewModel: AppLockScreenViewModelType, AppLockScreenViewModelProtocol {
+    private let appLockService: AppLockServiceProtocol
+    private var actionsSubject: PassthroughSubject<AppLockScreenViewModelAction, Never> = .init()
+    
+    var actions: AnyPublisher<AppLockScreenViewModelAction, Never> {
+        actionsSubject.eraseToAnyPublisher()
+    }
+
+    init(appLockService: AppLockServiceProtocol) {
+        self.appLockService = appLockService
+        
+        super.init(initialViewState: AppLockScreenViewState(bindings: .init()))
+    }
+    
+    // MARK: - Public
+    
+    override func process(viewAction: AppLockScreenViewAction) {
+        MXLog.info("View model: received view action: \(viewAction)")
+        
+        switch viewAction {
+        case .submitPINCode(let pinCode):
+            guard appLockService.unlock(with: pinCode) else {
+                MXLog.warning("Invalid PIN code entered.")
+                // Indicate failure here.
+                return
+            }
+            actionsSubject.send(.appUnlocked)
+        }
+    }
+}