import UIKit

extension Notification.Name {
    static let ironStorageLocalStoreDidChange = Notification.Name(
        "de.rfc1437.ironstorage.local-store-did-change"
    )
    static let ironStorageAuthenticationDidChange = Notification.Name(
        "de.rfc1437.ironstorage.authentication-did-change"
    )
}

@main
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 protocol MobileTabRoot: AnyObject {
    var shellTab: MobileTab { get }
}

@MainActor
private final class AppContext: NSObject, UITabBarControllerDelegate {
    private let tabs = UITabBarController()
    private let authentication = try? mobileAuthentication()
    private var navigationControllers: [UINavigationController] = []
    private var restoreTask: Task<Void, Never>?
    private var authenticationMonitor: Task<Void, Never>?

    deinit {
        restoreTask?.cancel()
        authenticationMonitor?.cancel()
    }

    func makeRootController() -> UIViewController {
        let shell = mobileShellFixture(state: .loading)
        navigationControllers = shell.pages.map { page in
            let root: UIViewController = switch page.tab {
            case .passwords:
                PasswordDirectoryViewController(shellPage: page, authentication: authentication)
            case .preferences:
                PreferencesViewController(page: page, authentication: authentication)
            default:
                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()
        monitorAuthentication()
        return tabs
    }

    func tabBarController(
        _ tabBarController: UITabBarController,
        didSelect viewController: UIViewController
    ) {
        guard
            let navigation = viewController as? UINavigationController,
            let root = navigation.viewControllers.first as? MobileTabRoot
        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 func monitorAuthentication() {
        authenticationMonitor?.cancel()
        guard let authentication else { return }
        authenticationMonitor = Task {
            var wasUnlocked = (try? authentication.state().unlocked) ?? false
            while !Task.isCancelled {
                do {
                    try await Task.sleep(for: .seconds(1))
                } catch {
                    return
                }
                let isUnlocked = (try? authentication.state().unlocked) ?? false
                if isUnlocked != wasUnlocked {
                    wasUnlocked = isUnlocked
                    NotificationCenter.default.post(
                        name: .ironStorageAuthenticationDidChange,
                        object: authentication
                    )
                }
            }
        }
    }
}

@MainActor
private final class ShellViewController: UITableViewController, MobileTabRoot {
    fileprivate let shellTab: MobileTab
    private var page: MobilePage
    private var loadTask: Task<Void, Never>?
    private var loadGeneration = 0
    private var homePage: MobileHomePage?
    private var homeTask: Task<Void, Never>?
    private var homeProgressTask: Task<Void, Never>?
    private var homeOperation: MobileHomeOperation?
    private var homeGeneration = 0
    private var isHomeWorking = false

    private enum HomeSection {
        case summary
        case incoming
        case outgoing
        case empty
        case notice
    }

    private enum HomeRequest: Equatable {
        case refreshIfStale
        case refresh
        case pull
    }

    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)
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(localStoreDidChange),
            name: .ironStorageLocalStoreDidChange,
            object: nil
        )
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) is not supported")
    }

    deinit {
        loadTask?.cancel()
        homeOperation?.cancel()
        homeTask?.cancel()
        homeProgressTask?.cancel()
        NotificationCenter.default.removeObserver(self)
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        apply(page)
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        reloadShell()
        if shellTab == .home, page.state == .ready, homePage != nil {
            runHome(.refreshIfStale)
        }
    }

    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        loadTask?.cancel()
        cancelHomeWork()
    }

    override func numberOfSections(in tableView: UITableView) -> Int {
        guard page.state == .ready else { return 0 }
        if shellTab == .home {
            return homeSections.count
        }
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        guard shellTab == .home else { return 1 }
        switch homeSections[section] {
        case .summary: return homePage?.summaries.count ?? 0
        case .incoming: return homePage?.incoming.count ?? 0
        case .outgoing: return homePage?.outgoing.count ?? 0
        case .empty, .notice: return 1
        }
    }

    override func tableView(
        _ tableView: UITableView,
        titleForHeaderInSection section: Int
    ) -> String? {
        guard shellTab == .home else { return nil }
        switch homeSections[section] {
        case .summary: return "Status"
        case .incoming: return "Incoming Activity"
        case .outgoing: return "Outgoing Activity"
        case .empty: return "Remote Activity"
        case .notice: return "Result"
        }
    }

    override func tableView(
        _ tableView: UITableView,
        titleForFooterInSection section: Int
    ) -> String? {
        guard shellTab == .home, let homePage else { return nil }
        switch homeSections[section] {
        case .summary:
            return freshnessDescription(homePage)
        case .incoming where homePage.incomingTotal > UInt32(homePage.incoming.count):
            return "Showing \(homePage.incoming.count) of \(homePage.incomingTotal) incoming commits."
        case .outgoing where homePage.outgoingTotal > UInt32(homePage.outgoing.count):
            return "Showing \(homePage.outgoing.count) of \(homePage.outgoingTotal) outgoing commits."
        default:
            return nil
        }
    }

    override func tableView(
        _ tableView: UITableView,
        cellForRowAt indexPath: IndexPath
    ) -> UITableViewCell {
        if shellTab == .home {
            return homeCell(at: indexPath)
        }
        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
    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        tableView.deselectRow(at: indexPath, animated: true)
        guard shellTab == .home, let homePage else { return }
        let section = homeSections[indexPath.section]
        let commit: MobileHomeCommit
        let incoming: Bool
        switch section {
        case .incoming:
            commit = homePage.incoming[indexPath.row]
            incoming = true
        case .outgoing:
            commit = homePage.outgoing[indexPath.row]
            incoming = false
        default:
            return
        }
        navigationController?.pushViewController(
            MobileCommitActivityViewController(commit: commit, incoming: incoming),
            animated: true
        )
    }

    @objc private func refreshRequested() {
        if shellTab == .home, page.state == .ready {
            guard !isHomeWorking else {
                refreshControl?.endRefreshing()
                return
            }
            runHome(.pull)
        } else {
            reloadShell()
        }
    }

    @objc private func localStoreDidChange() {
        guard shellTab != .home else { return }
        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
        if page.state == .empty, shellTab == .home {
            navigationItem.rightBarButtonItem = UIBarButtonItem(
                title: "Set Up",
                style: .done,
                target: self,
                action: #selector(setupRequested)
            )
        } else if page.state == .ready, shellTab == .home {
            navigationItem.rightBarButtonItem = UIBarButtonItem(
                image: UIImage(systemName: "arrow.clockwise"),
                style: .plain,
                target: self,
                action: #selector(statusRefreshRequested)
            )
            navigationItem.rightBarButtonItem?.accessibilityLabel = "Refresh remote status"
            navigationItem.rightBarButtonItem?.isEnabled = !isHomeWorking
        } else if page.state == .ready, shellTab == .preferences {
            navigationItem.rightBarButtonItem = UIBarButtonItem(
                title: "Update Token",
                style: .plain,
                target: self,
                action: #selector(tokenUpdateRequested)
            )
        } else {
            navigationItem.rightBarButtonItem = nil
        }
        refreshControl?.endRefreshing()
        tableView.reloadData()

        guard page.state != .ready else {
            contentUnavailableConfiguration = nil
            if shellTab == .home {
                loadHomeIfNeeded()
            }
            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
    }

    @objc private func setupRequested() {
        navigationController?.pushViewController(OnboardingViewController(), animated: true)
    }

    @objc private func tokenUpdateRequested() {
        navigationController?.pushViewController(TokenUpdateViewController(), animated: true)
    }

    @objc private func statusRefreshRequested() {
        runHome(.refresh)
    }

    private var homeSections: [HomeSection] {
        guard let homePage else { return [] }
        var sections: [HomeSection] = [.summary]
        if !homePage.incoming.isEmpty {
            sections.append(.incoming)
        }
        if !homePage.outgoing.isEmpty {
            sections.append(.outgoing)
        }
        if homePage.incomingTotal == 0, homePage.outgoingTotal == 0 {
            sections.append(.empty)
        }
        if homePage.notice != nil {
            sections.append(.notice)
        }
        return sections
    }

    private func homeCell(at indexPath: IndexPath) -> UITableViewCell {
        let cell = UITableViewCell(style: .subtitle, reuseIdentifier: nil)
        guard let homePage else { return cell }
        var content = cell.defaultContentConfiguration()
        switch homeSections[indexPath.section] {
        case .summary:
            let row = homePage.summaries[indexPath.row]
            content.image = UIImage(systemName: row.systemImage)
            content.text = row.title
            content.secondaryText = row.detail
            cell.selectionStyle = .none
        case .incoming:
            configureCommit(
                homePage.incoming[indexPath.row],
                content: &content,
                cell: cell
            )
        case .outgoing:
            configureCommit(
                homePage.outgoing[indexPath.row],
                content: &content,
                cell: cell
            )
        case .empty:
            content.image = UIImage(systemName: "checkmark.circle")
            content.text = "No Remote Activity"
            content.secondaryText = "There are no commits to pull or push."
            cell.selectionStyle = .none
        case .notice:
            if let notice = homePage.notice {
                content.image = UIImage(systemName: notice.systemImage)
                content.text = notice.title
                content.secondaryText = notice.detail
            }
            content.secondaryTextProperties.numberOfLines = 0
            cell.selectionStyle = .none
        }
        content.secondaryTextProperties.numberOfLines = 0
        cell.contentConfiguration = content
        return cell
    }

    private func configureCommit(
        _ commit: MobileHomeCommit,
        content: inout UIListContentConfiguration,
        cell: UITableViewCell
    ) {
        content.image = UIImage(systemName: commit.systemImage)
        content.text = commit.title
        content.secondaryText = "\(commit.detail)\n\(formattedDate(commit.timestamp))"
        content.secondaryTextProperties.numberOfLines = 0
        cell.accessoryType = .disclosureIndicator
        cell.accessibilityHint = "Shows password-store changes in this commit."
    }

    private func freshnessDescription(_ page: MobileHomePage) -> String {
        let refreshed = page.refreshedAt.map(formattedDate)
        switch page.freshness {
        case .neverRefreshed:
            return "Not refreshed. Pull down to update the local clone or tap Refresh Status."
        case .cached:
            return "Cached · Last refreshed \(refreshed ?? "at an unknown time"). This is not live status."
        case .current:
            return "Current · Refreshed \(refreshed ?? "just now")."
        }
    }

    private func formattedDate(_ timestamp: Int64) -> String {
        Date(timeIntervalSince1970: TimeInterval(timestamp)).formatted(
            date: .abbreviated,
            time: .shortened
        )
    }

    private func loadHomeIfNeeded() {
        guard homePage == nil, homeTask == nil, !isHomeWorking else { return }
        homeGeneration += 1
        let current = homeGeneration
        let operation = mobileHomeOperation()
        homeOperation = operation
        isHomeWorking = true
        navigationItem.rightBarButtonItem?.isEnabled = false
        showHomeLoading()
        homeTask = Task { [weak self] in
            let result = await Task.detached(priority: .userInitiated) {
                do {
                    return Result<MobileHomePage, HomeFailure>.success(try operation.cached())
                } catch let error as MobileHomeFfiError {
                    return .failure(HomeFailure(error))
                } catch {
                    return .failure(.unexpected)
                }
            }.value
            guard let self, current == homeGeneration else { return }
            finishHome(result, request: nil)
            if case .success = result {
                runHome(.refreshIfStale)
            }
        }
    }

    private func runHome(_ request: HomeRequest) {
        guard page.state == .ready, shellTab == .home, !isHomeWorking else { return }
        cancelHomeWork()
        homeGeneration += 1
        let current = homeGeneration
        let operation = mobileHomeOperation()
        homeOperation = operation
        isHomeWorking = true
        navigationItem.rightBarButtonItem?.isEnabled = false
        showHomeProgress(operation.progress())
        homeProgressTask = Task { [weak self] in
            while !Task.isCancelled {
                do {
                    try await Task.sleep(for: .milliseconds(150))
                } catch {
                    return
                }
                guard !Task.isCancelled, let self, current == homeGeneration else { return }
                showHomeProgress(operation.progress())
            }
        }
        homeTask = Task { [weak self] in
            let result = await Task.detached(priority: .userInitiated) {
                do {
                    let page: MobileHomePage = switch request {
                    case .refreshIfStale: try operation.refreshIfStale()
                    case .refresh: try operation.refresh()
                    case .pull: try operation.pull()
                    }
                    return Result<MobileHomePage, HomeFailure>.success(page)
                } catch let error as MobileHomeFfiError {
                    return .failure(HomeFailure(error))
                } catch {
                    return .failure(.unexpected)
                }
            }.value
            guard let self, current == homeGeneration else { return }
            finishHome(result, request: request)
        }
    }

    private func finishHome(
        _ result: Result<MobileHomePage, HomeFailure>,
        request: HomeRequest?
    ) {
        homeProgressTask?.cancel()
        homeProgressTask = nil
        homeTask = nil
        homeOperation = nil
        isHomeWorking = false
        navigationItem.titleView = nil
        navigationItem.prompt = nil
        navigationItem.rightBarButtonItem?.isEnabled = true
        refreshControl?.endRefreshing()
        switch result {
        case let .success(homePage):
            self.homePage = homePage
            contentUnavailableConfiguration = nil
            tableView.reloadData()
            if request == .pull {
                NotificationCenter.default.post(name: .ironStorageLocalStoreDidChange, object: nil)
                if let notice = homePage.notice {
                    UIAccessibility.post(notification: .announcement, argument: notice.title)
                }
            }
        case let .failure(failure):
            tableView.reloadData()
            if homePage == nil {
                showHomeFailure(failure)
            } else if failure.kind != .interrupted {
                presentHomeFailure(failure)
            }
        }
    }

    private func showHomeLoading() {
        var configuration = UIContentUnavailableConfiguration.loading()
        configuration.text = "Loading Activity"
        configuration.secondaryText = "Reading cached remote-branch state from storage."
        contentUnavailableConfiguration = configuration
    }

    private func showHomeFailure(_ failure: HomeFailure) {
        var configuration = UIContentUnavailableConfiguration.empty()
        configuration.image = UIImage(systemName: "exclamationmark.triangle")
        configuration.text = failure.title
        configuration.secondaryText = failure.detail
        contentUnavailableConfiguration = configuration
    }

    private func presentHomeFailure(_ failure: HomeFailure) {
        let alert = UIAlertController(
            title: failure.title,
            message: failure.detail,
            preferredStyle: .alert
        )
        if failure.kind == .authentication || failure.kind == .secureStorage {
            alert.addAction(UIAlertAction(title: "Preferences", style: .default) { [weak self] _ in
                self?.tabBarController?.selectedIndex = 3
            })
        }
        alert.addAction(UIAlertAction(title: "OK", style: .cancel))
        present(alert, animated: true)
    }

    private func showHomeProgress(_ progress: MobileHomeProgress) {
        let spinner = UIActivityIndicatorView(style: .medium)
        spinner.startAnimating()
        spinner.accessibilityLabel = "In progress"
        let label = UILabel()
        label.text = progress.title
        label.font = .preferredFont(forTextStyle: .headline)
        label.adjustsFontForContentSizeCategory = true
        let stack = UIStackView(arrangedSubviews: [spinner, label])
        stack.spacing = 8
        navigationItem.titleView = stack
        navigationItem.prompt = progress.detail
    }

    private func cancelHomeWork() {
        homeGeneration += 1
        homeOperation?.cancel()
        homeOperation = nil
        homeTask?.cancel()
        homeTask = nil
        homeProgressTask?.cancel()
        homeProgressTask = nil
        isHomeWorking = false
        navigationItem.titleView = nil
        navigationItem.prompt = nil
        refreshControl?.endRefreshing()
        navigationItem.rightBarButtonItem?.isEnabled = true
    }

    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"
        }
    }
}

@MainActor
private final class PreferencesViewController: UITableViewController, MobileTabRoot {
    fileprivate let shellTab = MobileTab.preferences
    private var page: MobilePage
    private let authentication: MobileAuthentication?
    private var state: MobileAuthenticationState?
    private var preferenceTask: Task<Void, Never>?
    private var loadTask: Task<Void, Never>?
    private var loadGeneration = 0

    init(page: MobilePage, authentication: MobileAuthentication?) {
        self.page = page
        self.authentication = authentication
        super.init(style: .insetGrouped)
        title = page.title
        navigationItem.largeTitleDisplayMode = .always
        navigationItem.rightBarButtonItem = UIBarButtonItem(
            title: "Update Token",
            style: .plain,
            target: self,
            action: #selector(tokenUpdateRequested)
        )
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(authenticationDidChange),
            name: .ironStorageAuthenticationDidChange,
            object: nil
        )
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) is not supported")
    }

    deinit {
        preferenceTask?.cancel()
        loadTask?.cancel()
        NotificationCenter.default.removeObserver(self)
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        reloadShell()
    }

    override func numberOfSections(in tableView: UITableView) -> Int {
        page.state == .ready ? 2 : 0
    }

    override func tableView(
        _ tableView: UITableView,
        numberOfRowsInSection section: Int
    ) -> Int {
        section == 0 ? 1 : 2
    }

    override func tableView(
        _ tableView: UITableView,
        titleForHeaderInSection section: Int
    ) -> String? {
        section == 0 ? "Secure Unlock" : "Authentication Session"
    }

    override func tableView(
        _ tableView: UITableView,
        titleForFooterInSection section: Int
    ) -> String? {
        if section == 0 {
            return "When enabled, the GPG passphrase is device-only, requires a device passcode, and is invalidated when enrolled biometrics change."
        }
        return "Manual lock and inactivity expiry immediately revoke the shared Rust authentication lease."
    }

    override func tableView(
        _ tableView: UITableView,
        cellForRowAt indexPath: IndexPath
    ) -> UITableViewCell {
        let cell = UITableViewCell(style: .subtitle, reuseIdentifier: nil)
        var content = cell.defaultContentConfiguration()
        if indexPath.section == 0 {
            content.image = UIImage(systemName: "faceid")
            content.text = "Biometric Unlock"
            content.secondaryText = state?.biometricUnlockEnabled == true
                ? "Protected passphrase enrolled"
                : "Manual passphrase required"
            let toggle = UISwitch()
            toggle.isOn = state?.biometricUnlockEnabled == true
            toggle.isEnabled = authentication != nil
            toggle.addTarget(self, action: #selector(biometricToggleChanged(_:)), for: .valueChanged)
            toggle.accessibilityLabel = "Biometric Unlock"
            cell.accessoryView = toggle
            cell.selectionStyle = .none
        } else if indexPath.row == 0 {
            let unlocked = state?.unlocked == true
            content.image = UIImage(systemName: unlocked ? "lock.open.fill" : "lock.fill")
            content.text = unlocked ? "Unlocked" : "Locked"
            content.secondaryText = unlocked
                ? "Locks in \(state?.remainingSeconds ?? 0) seconds without activity"
                : "Protected content is masked"
            cell.selectionStyle = .none
        } else {
            content.image = UIImage(systemName: "lock.fill")
            content.text = "Lock Now"
            content.textProperties.color = .systemRed
            content.secondaryText = "Revoke all active authentication handles"
            cell.accessoryType = .disclosureIndicator
            cell.isUserInteractionEnabled = state?.unlocked == true
            cell.contentView.alpha = state?.unlocked == true ? 1 : 0.45
        }
        content.secondaryTextProperties.numberOfLines = 0
        cell.contentConfiguration = content
        return cell
    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        tableView.deselectRow(at: indexPath, animated: true)
        guard indexPath.section == 1, indexPath.row == 1, let authentication else { return }
        do {
            try authentication.manualLock()
            refreshState()
            NotificationCenter.default.post(
                name: .ironStorageAuthenticationDidChange,
                object: authentication
            )
            UIAccessibility.post(notification: .announcement, argument: "IronStorage locked")
        } catch let error as MobileAuthenticationFfiError {
            presentAuthenticationFailure(AuthenticationFailure(error))
        } catch {
            presentAuthenticationFailure(.unexpected)
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        apply(page)
    }

    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 == .preferences })
            else { return }
            apply(page)
        }
    }

    private func apply(_ page: MobilePage) {
        self.page = page
        title = page.title
        guard page.state == .ready else {
            var configuration = UIContentUnavailableConfiguration.empty()
            configuration.image = UIImage(systemName: "gearshape")
            configuration.text = page.stateTitle
            configuration.secondaryText = page.stateDetail
            contentUnavailableConfiguration = configuration
            tableView.reloadData()
            return
        }
        contentUnavailableConfiguration = nil
        refreshState()
    }

    @objc private func tokenUpdateRequested() {
        navigationController?.pushViewController(TokenUpdateViewController(), animated: true)
    }

    @objc private func authenticationDidChange() {
        refreshState()
    }

    @objc private func biometricToggleChanged(_ sender: UISwitch) {
        guard let authentication else {
            sender.setOn(false, animated: true)
            presentAuthenticationFailure(.unavailable)
            return
        }
        sender.isEnabled = false
        let enabled = sender.isOn
        preferenceTask?.cancel()
        preferenceTask = Task { [weak self, weak sender] in
            let result = await Task.detached(priority: .userInitiated) {
                do {
                    return Result<MobileAuthenticationState, AuthenticationFailure>.success(
                        try authentication.setBiometricUnlock(enabled: enabled)
                    )
                } catch let error as MobileAuthenticationFfiError {
                    return .failure(AuthenticationFailure(error))
                } catch {
                    return .failure(.unexpected)
                }
            }.value
            guard !Task.isCancelled, let self else { return }
            sender?.isEnabled = true
            switch result {
            case let .success(state):
                self.state = state
                tableView.reloadData()
                NotificationCenter.default.post(
                    name: .ironStorageAuthenticationDidChange,
                    object: authentication
                )
            case let .failure(failure):
                sender?.setOn(!enabled, animated: true)
                presentAuthenticationFailure(failure)
            }
        }
    }

    private func refreshState() {
        state = try? authentication?.state()
        tableView.reloadData()
    }
}

@MainActor
private final class PasswordDirectoryViewController: UITableViewController, MobileTabRoot {
    fileprivate let shellTab = MobileTab.passwords
    private let path: String?
    private let authentication: MobileAuthentication?
    private var shellPage: MobilePage?
    private var directoryPage: MobilePasswordPage?
    private var loadTask: Task<Void, Never>?
    private var loadGeneration = 0

    init(
        shellPage: MobilePage,
        authentication: MobileAuthentication?,
        path: String? = nil
    ) {
        self.shellPage = shellPage
        self.authentication = authentication
        self.path = path
        super.init(style: .insetGrouped)
        title = shellPage.title
        navigationItem.largeTitleDisplayMode = path == nil ? .always : .never
        refreshControl = UIRefreshControl()
        refreshControl?.addTarget(self, action: #selector(refreshRequested), for: .valueChanged)
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(localStoreDidChange),
            name: .ironStorageLocalStoreDidChange,
            object: nil
        )
    }

    private init(path: String, title: String, authentication: MobileAuthentication?) {
        self.path = path
        self.authentication = authentication
        shellPage = nil
        super.init(style: .insetGrouped)
        self.title = title
        navigationItem.largeTitleDisplayMode = .never
        refreshControl = UIRefreshControl()
        refreshControl?.addTarget(self, action: #selector(refreshRequested), for: .valueChanged)
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(localStoreDidChange),
            name: .ironStorageLocalStoreDidChange,
            object: nil
        )
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) is not supported")
    }

    deinit {
        loadTask?.cancel()
        NotificationCenter.default.removeObserver(self)
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        if let shellPage {
            apply(shellPage)
        } else {
            showLoading()
        }
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        reload()
    }

    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        loadGeneration += 1
        loadTask?.cancel()
        refreshControl?.endRefreshing()
    }

    override func numberOfSections(in tableView: UITableView) -> Int {
        directoryPage?.rows.isEmpty == false ? 1 : 0
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        directoryPage?.rows.count ?? 0
    }

    override func tableView(
        _ tableView: UITableView,
        cellForRowAt indexPath: IndexPath
    ) -> UITableViewCell {
        let cell = UITableViewCell(style: .subtitle, reuseIdentifier: nil)
        guard let row = directoryPage?.rows[indexPath.row] else { return cell }
        var content = cell.defaultContentConfiguration()
        content.image = UIImage(systemName: row.systemImage)
        content.text = row.title
        content.secondaryText = row.detail
        content.textProperties.numberOfLines = 2
        content.secondaryTextProperties.numberOfLines = 1
        cell.contentConfiguration = content
        cell.accessoryType = .disclosureIndicator
        cell.accessibilityLabel = "\(row.title), \(row.detail)"
        cell.accessibilityHint = row.kind == .directory
            ? "Opens this password folder."
            : "Opens the locked password viewer."
        return cell
    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        guard let row = directoryPage?.rows[indexPath.row] else { return }
        let controller: UIViewController = switch row.kind {
        case .directory:
            PasswordDirectoryViewController(
                path: row.path,
                title: row.title,
                authentication: authentication
            )
        case .entry:
            LockedPasswordViewController(entry: row, authentication: authentication)
        }
        navigationController?.pushViewController(controller, animated: true)
    }

    @objc private func refreshRequested() {
        reload()
    }

    @objc private func localStoreDidChange() {
        guard viewIfLoaded?.window != nil else { return }
        reload()
    }

    private func reload() {
        loadGeneration += 1
        let generation = loadGeneration
        let selectedID = tableView.indexPathForSelectedRow.flatMap {
            directoryPage?.rows[$0.row].id
        }
        loadTask?.cancel()
        loadTask = Task { [weak self] in
            guard let self else { return }
            if path == nil {
                let shell = await Task.detached(priority: .userInitiated) { mobileShell() }.value
                guard
                    !Task.isCancelled,
                    generation == loadGeneration,
                    let page = shell.pages.first(where: { $0.tab == .passwords })
                else { return }
                apply(page)
                guard page.state == .ready else { return }
            } else {
                showLoading()
            }
            let path = self.path
            let result = await Task.detached(priority: .userInitiated) {
                do {
                    return Result<MobilePasswordPage, PasswordFailure>.success(
                        try mobilePasswordPage(path: path)
                    )
                } catch let error as MobilePasswordFfiError {
                    return .failure(PasswordFailure(error))
                } catch {
                    return .failure(.unexpected)
                }
            }.value
            guard !Task.isCancelled, generation == loadGeneration else { return }
            finish(result, selectedID: selectedID)
        }
    }

    private func apply(_ page: MobilePage) {
        shellPage = page
        title = page.title
        guard page.state == .ready else {
            directoryPage = nil
            tableView.reloadData()
            refreshControl?.endRefreshing()
            var configuration = page.state == .loading
                ? UIContentUnavailableConfiguration.loading()
                : UIContentUnavailableConfiguration.empty()
            configuration.image = page.state == .loading
                ? nil
                : UIImage(systemName: page.state == .error ? "exclamationmark.triangle" : "lock.shield")
            configuration.text = page.stateTitle
            configuration.secondaryText = page.stateDetail
            contentUnavailableConfiguration = configuration
            return
        }
        showLoading()
    }

    private func finish(
        _ result: Result<MobilePasswordPage, PasswordFailure>,
        selectedID: String?
    ) {
        refreshControl?.endRefreshing()
        switch result {
        case let .success(page):
            directoryPage = page
            title = page.title
            contentUnavailableConfiguration = nil
            tableView.reloadData()
            if page.rows.isEmpty {
                var configuration = UIContentUnavailableConfiguration.empty()
                configuration.image = UIImage(systemName: "folder")
                configuration.text = "Empty Folder"
                configuration.secondaryText = "This password folder contains no entries."
                contentUnavailableConfiguration = configuration
            } else if let selectedID,
                      let row = page.rows.firstIndex(where: { $0.id == selectedID }) {
                tableView.selectRow(at: IndexPath(row: row, section: 0), animated: false, scrollPosition: .none)
            }
        case let .failure(failure):
            if failure.kind == .directoryMissing, path != nil {
                UIAccessibility.post(
                    notification: .announcement,
                    argument: "The password folder no longer exists."
                )
                navigationController?.popViewController(animated: true)
                return
            }
            directoryPage = nil
            tableView.reloadData()
            var configuration = UIContentUnavailableConfiguration.empty()
            configuration.image = UIImage(systemName: "exclamationmark.triangle")
            configuration.text = failure.title
            configuration.secondaryText = failure.detail
            contentUnavailableConfiguration = configuration
        }
    }

    private func showLoading() {
        var configuration = UIContentUnavailableConfiguration.loading()
        configuration.text = "Loading Passwords"
        configuration.secondaryText = "Reading the locked folder model from storage."
        contentUnavailableConfiguration = configuration
    }
}

private struct PasswordFailure: Error, Sendable {
    let kind: MobilePasswordErrorKind
    let title: String
    let detail: String

    init(_ error: MobilePasswordFfiError) {
        switch error {
        case let .Failed(kind, title, detail):
            self.kind = kind
            self.title = title
            self.detail = detail
        }
    }

    static let unexpected = PasswordFailure(
        kind: .repository,
        title: "Passwords Are Unavailable",
        detail: "IronStorage could not load the storage-provided folder."
    )

    private init(kind: MobilePasswordErrorKind, title: String, detail: String) {
        self.kind = kind
        self.title = title
        self.detail = detail
    }
}

@MainActor
private final class LockedPasswordViewController: UIViewController {
    private let entry: MobilePasswordRow
    private let authentication: MobileAuthentication?
    private let imageView = UIImageView()
    private let titleLabel = UILabel()
    private let detailLabel = UILabel()
    private let unlockButton = UIButton(type: .system)
    private var unlockTask: Task<Void, Never>?
    private var state: MobileAuthenticationState?

    init(entry: MobilePasswordRow, authentication: MobileAuthentication?) {
        self.entry = entry
        self.authentication = authentication
        super.init(nibName: nil, bundle: nil)
        title = entry.title
        navigationItem.largeTitleDisplayMode = .never
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) is not supported")
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .systemGroupedBackground
        imageView.preferredSymbolConfiguration = UIImage.SymbolConfiguration(pointSize: 44)
        imageView.tintColor = .secondaryLabel
        titleLabel.font = .preferredFont(forTextStyle: .title2)
        titleLabel.adjustsFontForContentSizeCategory = true
        titleLabel.textAlignment = .center
        detailLabel.font = .preferredFont(forTextStyle: .body)
        detailLabel.adjustsFontForContentSizeCategory = true
        detailLabel.textAlignment = .center
        detailLabel.textColor = .secondaryLabel
        detailLabel.numberOfLines = 0
        unlockButton.configuration = .filled()
        unlockButton.configuration?.cornerStyle = .capsule
        unlockButton.addTarget(self, action: #selector(unlockRequested), for: .touchUpInside)
        let stack = UIStackView(arrangedSubviews: [imageView, titleLabel, detailLabel, unlockButton])
        stack.axis = .vertical
        stack.alignment = .center
        stack.spacing = 12
        stack.setCustomSpacing(24, after: detailLabel)
        stack.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(stack)
        NSLayoutConstraint.activate([
            stack.centerYAnchor.constraint(equalTo: view.safeAreaLayoutGuide.centerYAnchor),
            stack.leadingAnchor.constraint(greaterThanOrEqualTo: view.layoutMarginsGuide.leadingAnchor),
            stack.trailingAnchor.constraint(lessThanOrEqualTo: view.layoutMarginsGuide.trailingAnchor),
            detailLabel.widthAnchor.constraint(lessThanOrEqualToConstant: 360),
            unlockButton.widthAnchor.constraint(greaterThanOrEqualToConstant: 140),
        ])
        view.accessibilityIdentifier = entry.id
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(authenticationDidChange),
            name: .ironStorageAuthenticationDidChange,
            object: nil
        )
        render()
    }

    deinit {
        unlockTask?.cancel()
        NotificationCenter.default.removeObserver(self)
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        refreshState()
    }

    @objc private func authenticationDidChange() {
        refreshState()
    }

    @objc private func unlockRequested() {
        if state?.unlocked == true, let authentication {
            do {
                try authentication.touchUserActivity()
                refreshState()
                UIAccessibility.post(notification: .announcement, argument: "Unlock extended")
            } catch let error as MobileAuthenticationFfiError {
                presentAuthenticationFailure(AuthenticationFailure(error))
            } catch {
                presentAuthenticationFailure(.unexpected)
            }
            return
        }
        unlock(passphrase: nil)
    }

    @objc private func lockRequested() {
        guard let authentication else { return }
        do {
            try authentication.manualLock()
            state = try authentication.state()
            NotificationCenter.default.post(
                name: .ironStorageAuthenticationDidChange,
                object: authentication
            )
            render()
        } catch let error as MobileAuthenticationFfiError {
            presentAuthenticationFailure(AuthenticationFailure(error))
        } catch {
            presentAuthenticationFailure(.unexpected)
        }
    }

    private func refreshState() {
        state = try? authentication?.state()
        render()
    }

    private func unlock(passphrase: String?) {
        guard let authentication else {
            presentAuthenticationFailure(.unavailable)
            return
        }
        unlockTask?.cancel()
        unlockButton.isEnabled = false
        unlockButton.configuration?.showsActivityIndicator = true
        let path = entry.path
        unlockTask = Task { [weak self] in
            let result = await Task.detached(priority: .userInitiated) {
                do {
                    return Result<MobileAuthenticationState, AuthenticationFailure>.success(
                        try authentication.unlockEntry(path: path, passphrase: passphrase)
                    )
                } catch let error as MobileAuthenticationFfiError {
                    return .failure(AuthenticationFailure(error))
                } catch {
                    return .failure(.unexpected)
                }
            }.value
            guard !Task.isCancelled, let self else { return }
            unlockButton.isEnabled = true
            unlockButton.configuration?.showsActivityIndicator = false
            switch result {
            case let .success(state):
                self.state = state
                NotificationCenter.default.post(
                    name: .ironStorageAuthenticationDidChange,
                    object: authentication
                )
                render()
                UIAccessibility.post(notification: .announcement, argument: "Password unlocked")
            case let .failure(failure):
                if passphrase == nil,
                   failure.kind == .passphraseRequired || failure.kind == .biometryUnavailable {
                    promptForPassphrase(message: failure.detail)
                } else if failure.kind != .cancelled {
                    presentAuthenticationFailure(failure)
                }
            }
        }
    }

    private func promptForPassphrase(message: String) {
        let alert = UIAlertController(
            title: "GPG Key Passphrase",
            message: message,
            preferredStyle: .alert
        )
        alert.addTextField { field in
            field.isSecureTextEntry = true
            field.textContentType = .password
            field.placeholder = "Passphrase"
            field.returnKeyType = .go
        }
        alert.addAction(UIAlertAction(title: "Cancel", style: .cancel))
        alert.addAction(UIAlertAction(title: "Unlock", style: .default) { [weak self, weak alert] _ in
            guard let field = alert?.textFields?.first, let value = field.text, !value.isEmpty else {
                return
            }
            field.text = nil
            self?.unlock(passphrase: value)
        })
        present(alert, animated: true)
    }

    private func render() {
        let unlocked = state?.unlocked == true
        imageView.image = UIImage(systemName: unlocked ? "lock.open.fill" : "lock.fill")
        titleLabel.text = unlocked ? "Key Unlocked" : "Locked Password"
        detailLabel.text = if unlocked {
            "The GPG key is available for protected operations for up to \(state?.remainingSeconds ?? 0) seconds."
        } else {
            "Authenticate to unlock this password entry. Browsing remains available while locked."
        }
        unlockButton.configuration?.title = unlocked ? "Extend Unlock" : "Unlock"
        navigationItem.rightBarButtonItem = unlocked
            ? UIBarButtonItem(
                image: UIImage(systemName: "lock.fill"),
                style: .plain,
                target: self,
                action: #selector(lockRequested)
            )
            : nil
        navigationItem.rightBarButtonItem?.accessibilityLabel = "Lock IronStorage"
        unlockButton.accessibilityHint = unlocked
            ? "Extends access after authentication."
            : "Requests biometric authentication or the GPG key passphrase."
    }
}

private struct AuthenticationFailure: Error, Sendable {
    let kind: MobileAuthenticationErrorKind
    let title: String
    let detail: String

    init(_ error: MobileAuthenticationFfiError) {
        switch error {
        case let .Failed(kind, title, detail):
            self.kind = kind
            self.title = title
            self.detail = detail
        }
    }

    static let unexpected = AuthenticationFailure(
        kind: .secureStorage,
        title: "Unlock Failed",
        detail: "IronStorage could not complete authentication."
    )

    static let unavailable = AuthenticationFailure(
        kind: .configuration,
        title: "Authentication Is Unavailable",
        detail: "Finish password-store setup before unlocking entries."
    )

    private init(kind: MobileAuthenticationErrorKind, title: String, detail: String) {
        self.kind = kind
        self.title = title
        self.detail = detail
    }
}

@MainActor
private extension UIViewController {
    func presentAuthenticationFailure(_ failure: AuthenticationFailure) {
        let alert = UIAlertController(
            title: failure.title,
            message: failure.detail,
            preferredStyle: .alert
        )
        alert.addAction(UIAlertAction(title: "OK", style: .default))
        present(alert, animated: true)
    }
}

private struct HomeFailure: Error, Sendable {
    let kind: MobileHomeErrorKind
    let title: String
    let detail: String

    init(_ error: MobileHomeFfiError) {
        switch error {
        case let .Failed(kind, title, detail):
            self.kind = kind
            self.title = title
            self.detail = detail
        }
    }

    static let unexpected = HomeFailure(
        kind: .repository,
        title: "Remote Activity Failed",
        detail: "IronStorage could not load the storage-provided Home page."
    )

    private init(kind: MobileHomeErrorKind, title: String, detail: String) {
        self.kind = kind
        self.title = title
        self.detail = detail
    }
}

@MainActor
private final class MobileCommitActivityViewController: UITableViewController {
    private let commit: MobileHomeCommit

    init(commit: MobileHomeCommit, incoming: Bool) {
        self.commit = commit
        super.init(style: .insetGrouped)
        title = incoming ? "Incoming Commit" : "Outgoing Commit"
        navigationItem.largeTitleDisplayMode = .never
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) is not supported")
    }

    override func numberOfSections(in tableView: UITableView) -> Int { 2 }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        section == 0 ? 1 : max(commit.changes.count, 1)
    }

    override func tableView(
        _ tableView: UITableView,
        titleForHeaderInSection section: Int
    ) -> String? {
        section == 0 ? "Commit" : "Password Store Changes"
    }

    override func tableView(
        _ tableView: UITableView,
        cellForRowAt indexPath: IndexPath
    ) -> UITableViewCell {
        let cell = UITableViewCell(style: .subtitle, reuseIdentifier: nil)
        var content = cell.defaultContentConfiguration()
        if indexPath.section == 0 {
            content.image = UIImage(systemName: commit.systemImage)
            content.text = commit.title
            content.secondaryText = "\(commit.detail)\n\(formattedDate)"
        } else if commit.changes.isEmpty {
            content.image = UIImage(systemName: "minus.circle")
            content.text = "No File Changes"
            content.secondaryText = "This commit does not change password-store files."
        } else {
            let change = commit.changes[indexPath.row]
            content.image = UIImage(systemName: change.systemImage)
            content.text = change.title
            content.secondaryText = change.detail
        }
        content.secondaryTextProperties.numberOfLines = 0
        cell.contentConfiguration = content
        cell.selectionStyle = .none
        return cell
    }

    private var formattedDate: String {
        Date(timeIntervalSince1970: TimeInterval(commit.timestamp)).formatted(
            date: .abbreviated,
            time: .shortened
        )
    }
}

@MainActor
private final class TokenUpdateViewController: UITableViewController {
    private let accountField = UITextField()
    private let tokenField = UITextField()
    private var updateTask: Task<Void, Never>?
    private var generation = 0
    private var isWorking = false

    init() {
        super.init(style: .insetGrouped)
        title = "Update Token"
        navigationItem.largeTitleDisplayMode = .never
        for field in [accountField, tokenField] {
            field.borderStyle = .none
            field.clearButtonMode = .whileEditing
            field.autocorrectionType = .no
            field.autocapitalizationType = .none
            field.adjustsFontForContentSizeCategory = true
            field.font = .preferredFont(forTextStyle: .body)
        }
        accountField.placeholder = "Account name"
        tokenField.placeholder = "New application token"
        tokenField.textContentType = .oneTimeCode
        tokenField.isSecureTextEntry = true
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) is not supported")
    }

    deinit {
        updateTask?.cancel()
    }

    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        generation += 1
        updateTask?.cancel()
    }

    override func numberOfSections(in tableView: UITableView) -> Int { 2 }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        section == 0 ? 2 : 1
    }

    override func tableView(
        _ tableView: UITableView,
        titleForHeaderInSection section: Int
    ) -> String? {
        section == 0 ? "HTTPS Credential" : nil
    }

    override func tableView(
        _ tableView: UITableView,
        titleForFooterInSection section: Int
    ) -> String? {
        section == 0
            ? "The existing token is never displayed. Updating replaces it only in protected system storage."
            : nil
    }

    override func tableView(
        _ tableView: UITableView,
        cellForRowAt indexPath: IndexPath
    ) -> UITableViewCell {
        let cell = UITableViewCell(style: .default, reuseIdentifier: nil)
        if indexPath.section == 1 {
            cell.textLabel?.text = isWorking ? "Updating…" : "Replace Token"
            cell.textLabel?.textColor = isWorking ? .secondaryLabel : view.tintColor
            cell.textLabel?.textAlignment = .center
            cell.isUserInteractionEnabled = !isWorking
            return cell
        }
        let field = indexPath.row == 0 ? accountField : tokenField
        field.translatesAutoresizingMaskIntoConstraints = false
        field.isEnabled = !isWorking
        cell.contentView.addSubview(field)
        NSLayoutConstraint.activate([
            field.leadingAnchor.constraint(equalTo: cell.contentView.layoutMarginsGuide.leadingAnchor),
            field.trailingAnchor.constraint(equalTo: cell.contentView.layoutMarginsGuide.trailingAnchor),
            field.topAnchor.constraint(equalTo: cell.contentView.topAnchor, constant: 10),
            field.bottomAnchor.constraint(equalTo: cell.contentView.bottomAnchor, constant: -10)
        ])
        return cell
    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        tableView.deselectRow(at: indexPath, animated: true)
        guard indexPath.section == 1, !isWorking else { return }
        replaceToken()
    }

    private func replaceToken() {
        generation += 1
        let current = generation
        isWorking = true
        navigationItem.prompt = "Saving in protected system storage."
        tableView.reloadData()
        let account = accountField.text ?? ""
        let token = tokenField.text ?? ""
        updateTask = Task { [weak self] in
            let result = await Task.detached(priority: .userInitiated) {
                do {
                    try replaceConfiguredMobileApplicationToken(
                        account: account,
                        applicationToken: token
                    )
                    return Result<Void, OnboardingFailure>.success(())
                } catch let error as MobileOnboardingFfiError {
                    return .failure(OnboardingFailure(error))
                } catch {
                    return .failure(.unexpected)
                }
            }.value
            guard let self, current == generation else { return }
            isWorking = false
            navigationItem.prompt = nil
            tableView.reloadData()
            switch result {
            case .success:
                tokenField.text = nil
                let alert = UIAlertController(
                    title: "Token Updated",
                    message: "The new application token is ready for HTTPS Git operations.",
                    preferredStyle: .alert
                )
                alert.addAction(UIAlertAction(title: "Done", style: .default) { [weak self] _ in
                    self?.navigationController?.popViewController(animated: true)
                })
                present(alert, animated: true)
            case let .failure(failure):
                let alert = UIAlertController(
                    title: failure.title,
                    message: failure.detail,
                    preferredStyle: .alert
                )
                alert.addAction(UIAlertAction(title: "OK", style: .cancel))
                present(alert, animated: true)
            }
        }
    }
}

@MainActor
private final class OnboardingViewController: UITableViewController {
    private let serverField = UITextField()
    private let accountField = UITextField()
    private let repositoryField = UITextField()
    private let tokenField = UITextField()
    private var branches: [String] = []
    private var selectedBranch = 0
    private var operation: MobileOnboardingOperation?
    private var workTask: Task<Void, Never>?
    private var progressTask: Task<Void, Never>?
    private var generation = 0
    private var isWorking = false

    init() {
        super.init(style: .insetGrouped)
        title = "Connect Store"
        navigationItem.largeTitleDisplayMode = .never
        configureFields()
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) is not supported")
    }

    deinit {
        operation?.cancel()
        workTask?.cancel()
        progressTask?.cancel()
    }

    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        cancelWork()
    }

    override func numberOfSections(in tableView: UITableView) -> Int {
        branches.isEmpty ? 2 : 3
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        switch section {
        case 0: 4
        case 1: 1
        default: 2
        }
    }

    override func tableView(
        _ tableView: UITableView,
        titleForHeaderInSection section: Int
    ) -> String? {
        switch section {
        case 0: "HTTPS Repository"
        case 1: branches.isEmpty ? nil : "Remote"
        default: "Local Clone"
        }
    }

    override func tableView(
        _ tableView: UITableView,
        titleForFooterInSection section: Int
    ) -> String? {
        section == 0 ? "The application token is stored in protected system storage, never in configuration." : nil
    }

    override func tableView(
        _ tableView: UITableView,
        cellForRowAt indexPath: IndexPath
    ) -> UITableViewCell {
        if indexPath.section == 0 {
            return fieldCell(indexPath.row)
        }
        let cell = UITableViewCell(style: .value1, reuseIdentifier: nil)
        if branches.isEmpty {
            cell.textLabel?.text = "Discover Branches"
            cell.textLabel?.textColor = view.tintColor
            cell.accessoryType = .disclosureIndicator
        } else if indexPath.section == 1 {
            cell.textLabel?.text = "Branch"
            cell.detailTextLabel?.text = branches[selectedBranch]
            cell.accessoryType = .disclosureIndicator
        } else if indexPath.row == 0 {
            cell.textLabel?.text = "Clone Password Store"
            cell.textLabel?.textColor = view.tintColor
        } else {
            cell.textLabel?.text = "Use Existing Clone"
            cell.textLabel?.textColor = .secondaryLabel
        }
        cell.isUserInteractionEnabled = !isWorking
        return cell
    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        tableView.deselectRow(at: indexPath, animated: true)
        guard !isWorking else { return }
        if branches.isEmpty, indexPath.section == 1 {
            discoverBranches()
        } else if indexPath.section == 1 {
            chooseBranch(from: tableView.cellForRow(at: indexPath))
        } else if indexPath.section == 2 {
            runSetup(useExisting: indexPath.row == 1)
        }
    }

    private func configureFields() {
        for field in [serverField, accountField, repositoryField, tokenField] {
            field.borderStyle = .none
            field.clearButtonMode = .whileEditing
            field.autocorrectionType = .no
            field.returnKeyType = .next
            field.adjustsFontForContentSizeCategory = true
            field.font = .preferredFont(forTextStyle: .body)
        }
        serverField.placeholder = "https://git.example.com"
        serverField.textContentType = .URL
        serverField.keyboardType = .URL
        serverField.autocapitalizationType = .none
        accountField.placeholder = "Account name"
        accountField.autocapitalizationType = .none
        repositoryField.placeholder = "owner/password-store"
        repositoryField.autocapitalizationType = .none
        tokenField.placeholder = "Application token"
        tokenField.textContentType = .oneTimeCode
        tokenField.isSecureTextEntry = true
    }

    private func fieldCell(_ row: Int) -> UITableViewCell {
        let field = [serverField, accountField, repositoryField, tokenField][row]
        let cell = UITableViewCell(style: .default, reuseIdentifier: nil)
        field.translatesAutoresizingMaskIntoConstraints = false
        cell.contentView.addSubview(field)
        NSLayoutConstraint.activate([
            field.leadingAnchor.constraint(equalTo: cell.contentView.layoutMarginsGuide.leadingAnchor),
            field.trailingAnchor.constraint(equalTo: cell.contentView.layoutMarginsGuide.trailingAnchor),
            field.topAnchor.constraint(equalTo: cell.contentView.topAnchor, constant: 10),
            field.bottomAnchor.constraint(equalTo: cell.contentView.bottomAnchor, constant: -10)
        ])
        return cell
    }

    private func makeOperation() throws -> MobileOnboardingOperation {
        try mobileOnboardingOperation(
            serverUrl: serverField.text ?? "",
            account: accountField.text ?? "",
            repositoryPath: repositoryField.text ?? "",
            applicationToken: tokenField.text ?? ""
        )
    }

    private func discoverBranches() {
        do {
            let operation = try makeOperation()
            begin(operation, title: "Checking Repository") { operation in
                let discovery = try operation.discover()
                return .discovered(discovery)
            }
        } catch {
            present(error)
        }
    }

    private func runSetup(useExisting: Bool) {
        guard branches.indices.contains(selectedBranch) else { return }
        do {
            let operation = try makeOperation()
            let branch = branches[selectedBranch]
            begin(operation, title: useExisting ? "Opening Store" : "Cloning Store") { operation in
                let outcome = try operation.setup(branch: branch, useExisting: useExisting)
                return .completed(outcome)
            }
        } catch {
            present(error)
        }
    }

    private func begin(
        _ operation: MobileOnboardingOperation,
        title: String,
        work: @escaping @Sendable (MobileOnboardingOperation) throws -> WorkResult
    ) {
        cancelWork()
        generation += 1
        let current = generation
        self.operation = operation
        isWorking = true
        showProgress(title: title, detail: "Preparing secure storage.")
        tableView.reloadData()
        progressTask = Task { [weak self] in
            while !Task.isCancelled {
                do {
                    try await Task.sleep(for: .milliseconds(150))
                } catch {
                    return
                }
                guard !Task.isCancelled, let self, current == generation else { return }
                let progress = operation.progress()
                showProgress(title: progress.title, detail: progress.detail)
            }
        }
        workTask = Task { [weak self] in
            let result = await Task.detached(priority: .userInitiated) {
                do {
                    return Result<WorkResult, OnboardingFailure>.success(try work(operation))
                } catch let error as MobileOnboardingFfiError {
                    return .failure(OnboardingFailure(error))
                } catch {
                    return .failure(.unexpected)
                }
            }.value
            guard let self, current == generation else { return }
            finish(result)
        }
    }

    private func finish(_ result: Result<WorkResult, OnboardingFailure>) {
        progressTask?.cancel()
        progressTask = nil
        operation = nil
        isWorking = false
        navigationItem.titleView = nil
        navigationItem.prompt = nil
        switch result {
        case let .success(.discovered(discovery)):
            branches = discovery.branches
            selectedBranch = min(Int(discovery.selectedBranch), max(branches.count - 1, 0))
            tableView.reloadData()
        case let .success(.completed(outcome)):
            tokenField.text = nil
            let alert = UIAlertController(title: outcome.title, message: outcome.detail, preferredStyle: .alert)
            alert.addAction(UIAlertAction(title: "Done", style: .default) { [weak self] _ in
                self?.navigationController?.popViewController(animated: true)
            })
            present(alert, animated: true)
        case let .failure(failure):
            tableView.reloadData()
            present(failure)
        }
    }

    private func chooseBranch(from source: UIView?) {
        let sheet = UIAlertController(title: "Branch", message: nil, preferredStyle: .actionSheet)
        for (index, branch) in branches.enumerated() {
            sheet.addAction(UIAlertAction(title: branch, style: .default) { [weak self] _ in
                self?.selectedBranch = index
                self?.tableView.reloadSections(IndexSet(integer: 1), with: .automatic)
            })
        }
        sheet.addAction(UIAlertAction(title: "Cancel", style: .cancel))
        sheet.popoverPresentationController?.sourceView = source
        sheet.popoverPresentationController?.sourceRect = source?.bounds ?? .zero
        present(sheet, animated: true)
    }

    private func present(_ error: Error) {
        if let error = error as? MobileOnboardingFfiError {
            present(OnboardingFailure(error))
        } else {
            present(.unexpected)
        }
    }

    private func present(_ failure: OnboardingFailure) {
        let alert = UIAlertController(title: failure.title, message: failure.detail, preferredStyle: .alert)
        if failure.kind == .existingClone, !branches.isEmpty {
            alert.addAction(UIAlertAction(title: "Use Existing", style: .default) { [weak self] _ in
                self?.runSetup(useExisting: true)
            })
        }
        alert.addAction(UIAlertAction(title: "OK", style: .cancel))
        present(alert, animated: true)
    }

    private func showProgress(title: String, detail: String) {
        let spinner = UIActivityIndicatorView(style: .medium)
        spinner.startAnimating()
        spinner.accessibilityLabel = "In progress"
        let label = UILabel()
        label.text = title
        label.font = .preferredFont(forTextStyle: .headline)
        label.adjustsFontForContentSizeCategory = true
        let stack = UIStackView(arrangedSubviews: [spinner, label])
        stack.spacing = 8
        navigationItem.titleView = stack
        navigationItem.prompt = detail
    }

    private func cancelWork() {
        generation += 1
        operation?.cancel()
        operation = nil
        workTask?.cancel()
        workTask = nil
        progressTask?.cancel()
        progressTask = nil
        navigationItem.prompt = nil
        navigationItem.titleView = nil
        isWorking = false
    }
}

private enum WorkResult: Sendable {
    case discovered(MobileOnboardingDiscovery)
    case completed(MobileOnboardingOutcome)
}

private struct OnboardingFailure: Error, Sendable {
    let kind: MobileOnboardingErrorKind?
    let title: String
    let detail: String

    init(_ error: MobileOnboardingFfiError) {
        switch error {
        case let .Failed(kind, title, detail):
            self.kind = kind
            self.title = title
            self.detail = detail
        }
    }

    static let unexpected = OnboardingFailure(
        kind: nil,
        title: "Setup Failed",
        detail: "IronStorage could not complete setup."
    )

    private init(kind: MobileOnboardingErrorKind?, title: String, detail: String) {
        self.kind = kind
        self.title = title
        self.detail = detail
    }
}