Build native iPhone application shell

apple/Sources/App/IronStorageApp.swift

@@ -1,20 +1,195 @@
-import SwiftUI
+import UIKit
 
 @main
-struct IronStorageApp: App {
-    var body: some Scene {
-        WindowGroup {
-            ContentView()
+final class AppDelegate: UIResponder, UIApplicationDelegate {
+    var window: UIWindow?
+    private var context: AppContext?
+
+    func application(
+        _ application: UIApplication,
+        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]? = nil
+    ) -> Bool {
+        let window = UIWindow(frame: UIScreen.main.bounds)
+        let context = AppContext()
+        self.context = context
+        window.rootViewController = context.makeRootController()
+        window.makeKeyAndVisible()
+        self.window = window
+        return true
+    }
+}
+
+@MainActor
+private final class AppContext: NSObject, UITabBarControllerDelegate {
+    private let tabs = UITabBarController()
+    private var navigationControllers: [UINavigationController] = []
+    private var restoreTask: Task<Void, Never>?
+
+    func makeRootController() -> UIViewController {
+        let shell = mobileShellFixture(state: .loading)
+        navigationControllers = shell.pages.map { page in
+            let root = ShellViewController(page: page)
+            let navigation = UINavigationController(rootViewController: root)
+            navigation.navigationBar.prefersLargeTitles = true
+            navigation.tabBarItem = UITabBarItem(
+                title: page.title,
+                image: UIImage(systemName: page.systemImage),
+                selectedImage: UIImage(systemName: page.selectedSystemImage)
+            )
+            return navigation
+        }
+        tabs.viewControllers = navigationControllers
+        tabs.delegate = self
+        restoreSelectedTab()
+        return tabs
+    }
+
+    func tabBarController(
+        _ tabBarController: UITabBarController,
+        didSelect viewController: UIViewController
+    ) {
+        guard
+            let navigation = viewController as? UINavigationController,
+            let root = navigation.viewControllers.first as? ShellViewController
+        else {
+            return
+        }
+        do {
+            try setSelectedMobileTab(tab: root.shellTab)
+        } catch {
+            let alert = UIAlertController(
+                title: "Selection Was Not Saved",
+                message: error.localizedDescription,
+                preferredStyle: .alert
+            )
+            alert.addAction(UIAlertAction(title: "OK", style: .default))
+            tabs.present(alert, animated: true)
+        }
+    }
+
+    private func restoreSelectedTab() {
+        restoreTask?.cancel()
+        restoreTask = Task { [weak self] in
+            let shell = await Task.detached(priority: .userInitiated) { mobileShell() }.value
+            guard !Task.isCancelled, let self else { return }
+            if let index = shell.pages.firstIndex(where: { $0.tab == shell.selectedTab }) {
+                tabs.selectedIndex = index
+            }
         }
     }
 }
 
-private struct ContentView: View {
-    var body: some View {
-        ContentUnavailableView(
-            "No Password Store",
-            systemImage: "lock.shield",
-            description: Text("Open or clone a store in \(productName()) to begin.")
-        )
+@MainActor
+private final class ShellViewController: UITableViewController {
+    fileprivate let shellTab: MobileTab
+    private var page: MobilePage
+    private var loadTask: Task<Void, Never>?
+    private var loadGeneration = 0
+
+    init(page: MobilePage) {
+        shellTab = page.tab
+        self.page = page
+        super.init(style: .insetGrouped)
+        title = page.title
+        navigationItem.largeTitleDisplayMode = .always
+        refreshControl = UIRefreshControl()
+        refreshControl?.addTarget(self, action: #selector(refreshRequested), for: .valueChanged)
+    }
+
+    @available(*, unavailable)
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) is not supported")
+    }
+
+    deinit {
+        loadTask?.cancel()
+    }
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        apply(page)
+    }
+
+    override func viewWillAppear(_ animated: Bool) {
+        super.viewWillAppear(animated)
+        reloadShell()
+    }
+
+    override func viewDidDisappear(_ animated: Bool) {
+        super.viewDidDisappear(animated)
+        loadTask?.cancel()
+    }
+
+    override func numberOfSections(in tableView: UITableView) -> Int {
+        page.state == .ready ? 1 : 0
+    }
+
+    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
+        1
+    }
+
+    override func tableView(
+        _ tableView: UITableView,
+        cellForRowAt indexPath: IndexPath
+    ) -> UITableViewCell {
+        let cell = UITableViewCell(style: .subtitle, reuseIdentifier: nil)
+        var content = cell.defaultContentConfiguration()
+        content.image = UIImage(systemName: page.systemImage)
+        content.text = page.stateTitle
+        content.secondaryText = page.stateDetail
+        content.secondaryTextProperties.numberOfLines = 0
+        cell.contentConfiguration = content
+        cell.selectionStyle = .none
+        cell.accessibilityLabel = "\(page.stateTitle). \(page.stateDetail)"
+        return cell
+    }
+
+    @objc private func refreshRequested() {
+        reloadShell()
+    }
+
+    private func reloadShell() {
+        loadGeneration += 1
+        let generation = loadGeneration
+        loadTask?.cancel()
+        loadTask = Task { [weak self] in
+            let shell = await Task.detached(priority: .userInitiated) { mobileShell() }.value
+            guard
+                !Task.isCancelled,
+                let self,
+                generation == loadGeneration,
+                let page = shell.pages.first(where: { $0.tab == self.shellTab })
+            else { return }
+            apply(page)
+        }
+    }
+
+    private func apply(_ page: MobilePage) {
+        self.page = page
+        title = page.title
+        refreshControl?.endRefreshing()
+        tableView.reloadData()
+
+        guard page.state != .ready else {
+            contentUnavailableConfiguration = nil
+            return
+        }
+        var configuration = page.state == .loading
+            ? UIContentUnavailableConfiguration.loading()
+            : UIContentUnavailableConfiguration.empty()
+        configuration.text = page.stateTitle
+        configuration.secondaryText = page.stateDetail
+        configuration.image = UIImage(systemName: stateImage(page.state))
+        contentUnavailableConfiguration = configuration
+    }
+
+    private func stateImage(_ state: MobileShellState) -> String {
+        switch state {
+        case .loading: "hourglass"
+        case .empty: "lock.shield"
+        case .ready: page.systemImage
+        case .locked: "lock.fill"
+        case .error: "exclamationmark.triangle"
+        }
     }
 }