import SnapKit
import UIKit

/// 业务根页面之前核验注销状态；冷静期提供明确撤销，未知状态只允许查询和主动退出。
@MainActor
final class StoreAccountDeregistrationAccessViewController: BaseViewController {
    /// 冻结的门店身份，用于 Scene 对旧请求的隔离。
    let identity: StoreAccountDeregistrationIdentity?
    private let api: (any StoreAccountDeregistrationServing)?
    private let session: AppSessionStore
    private let onAllowed: (StoreAccountDeregistrationAccessViewController) -> Void
    private let onAccessDenied: () -> Void
    private let viewModel: StoreAccountDeregistrationAccessViewModel
    private let hasInitialResult: Bool
    private typealias Style = StoreAccountDeregistrationStyle
    private let scrollView = UIScrollView()
    private let refreshControl = UIRefreshControl()
    private let stack = UIStackView()
    private let bottomBar = UIView()
    private let titleLabel = Style.label(size: 24, weight: .semibold)
    private let stateIcon = Style.icon("lock", size: 36)
    private let stateIconBadge = UIView()
    private let deadlineLabel = Style.label(size: 19, weight: .semibold)
    private let infoLabel = Style.label("重新登录该身份自动撤销申请", size: 13, color: Style.textSecondary)
    private var deadlineCard = UIView()
    private var infoCard = UIView()
    private let messageLabel = UILabel()
    private let retryButton = UIButton(type: .system)
    private let cancelButton = UIButton(type: .system)
    private let logoutButton = UIButton(type: .system)
    private var queryTask: Task<Void, Never>?
    private var needsForegroundRefresh = false
    private var previousPopGestureEnabled: Bool?

    /// 显式注入会话与 API；身份构造失败时仍展示错误，不自动退出或重新登录。
    init(identity: StoreAccountDeregistrationIdentity?, api: (any StoreAccountDeregistrationServing)?,
         session: AppSessionStore, requiresSubmissionReconciliation: Bool = false,
         submissionStore: (any StoreAccountDeregistrationSubmissionTracking)? = nil,
         initialViewModel: StoreAccountDeregistrationAccessViewModel? = nil,
         onAccessDenied: @escaping () -> Void = {},
         onAllowed: @escaping (StoreAccountDeregistrationAccessViewController) -> Void) {
        self.identity = identity
        self.api = api
        self.session = session
        self.onAllowed = onAllowed
        self.onAccessDenied = onAccessDenied
        hasInitialResult = initialViewModel != nil
        viewModel = initialViewModel ?? StoreAccountDeregistrationAccessViewModel(
            requiresSubmissionReconciliation: requiresSubmissionReconciliation, submissionStore: submissionStore)
        super.init(nibName: nil, bundle: nil)
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") }

    override func setupNavigationBar() {
        title = "注销账号"
        navigationItem.hidesBackButton = true
    }

    override func setupUI() {
        view.backgroundColor = Style.pageBackground
        view.addSubview(scrollView)
        scrollView.alwaysBounceVertical = true
        refreshControl.accessibilityIdentifier = "deregister.access.refresh"
        refreshControl.accessibilityLabel = "下拉刷新"
        refreshControl.tintColor = .clear
        refreshControl.addTarget(self, action: #selector(retryTapped), for: .valueChanged)
        scrollView.refreshControl = refreshControl
        scrollView.addSubview(stack)
        stack.axis = .vertical
        stack.spacing = 18
        stateIconBadge.backgroundColor = Style.infoBackground
        stateIconBadge.layer.cornerRadius = 44
        stateIconBadge.addSubview(stateIcon)
        stateIconBadge.snp.makeConstraints { $0.width.height.equalTo(88) }
        stateIcon.snp.makeConstraints { $0.center.equalToSuperview(); $0.width.height.equalTo(44) }
        titleLabel.textAlignment = .center
        messageLabel.numberOfLines = 0
        messageLabel.font = .systemFont(ofSize: 15)
        messageLabel.textColor = Style.textSecondary
        messageLabel.textAlignment = .center
        let iconRow = UIView()
        iconRow.addSubview(stateIconBadge)
        stateIconBadge.snp.makeConstraints { $0.top.bottom.centerX.equalToSuperview() }
        let hero = Style.stack([iconRow, titleLabel, messageLabel], spacing: 12)
        stack.addArrangedSubview(hero)
        deadlineLabel.accessibilityIdentifier = "deregister.access.deadline"
        let deadlineIcon = Style.icon("calendar", size: 22)
        deadlineIcon.snp.makeConstraints { $0.width.equalTo(28) }
        let deadlineText = Style.stack([
            Style.label("冷静期截止时间", size: 13, color: Style.textSecondary), deadlineLabel
        ], spacing: 8)
        let deadlineRow = UIStackView(arrangedSubviews: [deadlineIcon, deadlineText])
        deadlineRow.axis = .horizontal
        deadlineRow.alignment = .center
        deadlineRow.spacing = 12
        deadlineCard = Style.card(deadlineRow)
        stack.addArrangedSubview(deadlineCard)
        let infoIcon = Style.icon("info.circle", size: 17)
        infoIcon.snp.makeConstraints { $0.width.equalTo(22) }
        let infoRow = UIStackView(arrangedSubviews: [infoIcon, infoLabel])
        infoRow.axis = .horizontal
        infoRow.alignment = .center
        infoRow.spacing = 8
        infoCard = Style.card(infoRow, background: Style.infoBackground)
        stack.addArrangedSubview(infoCard)

        view.addSubview(bottomBar)
        bottomBar.backgroundColor = .white
        Style.configure(retryButton, title: "重新查询状态")
        Style.configure(logoutButton, title: "退出登录")
        Style.configure(cancelButton, title: "撤销注销申请", primary: false)
        let actions = Style.stack([retryButton, logoutButton, cancelButton], spacing: 12)
        bottomBar.addSubview(actions)
        actions.snp.makeConstraints { $0.edges.equalToSuperview().inset(UIEdgeInsets(top: 12, left: 16, bottom: 12, right: 16)) }
        for button in [retryButton, logoutButton, cancelButton] {
            button.snp.makeConstraints { $0.height.greaterThanOrEqualTo(50) }
        }
        retryButton.addTarget(self, action: #selector(retryTapped), for: .touchUpInside)
        cancelButton.addTarget(self, action: #selector(cancelTapped), for: .touchUpInside)
        logoutButton.addTarget(self, action: #selector(logoutTapped), for: .touchUpInside)
        messageLabel.accessibilityIdentifier = "deregister.access.message"
        titleLabel.accessibilityIdentifier = "deregister.access.title"
        retryButton.accessibilityIdentifier = "deregister.access.retry"
        cancelButton.accessibilityIdentifier = "deregister.access.cancel"
        logoutButton.accessibilityIdentifier = "deregister.access.logout"
    }

    override func setupConstraints() {
        bottomBar.snp.makeConstraints {
            $0.leading.trailing.equalToSuperview()
            $0.bottom.equalTo(view.safeAreaLayoutGuide)
        }
        scrollView.snp.makeConstraints {
            $0.top.leading.trailing.equalTo(view.safeAreaLayoutGuide)
            $0.bottom.equalTo(bottomBar.snp.top)
        }
        stack.snp.makeConstraints {
            $0.top.equalTo(scrollView.contentLayoutGuide).offset(24)
            $0.leading.trailing.bottom.equalTo(scrollView.contentLayoutGuide).inset(16)
            $0.width.equalTo(scrollView.frameLayoutGuide).offset(-32)
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        if hasInitialResult { applyViewModel() } else { retryTapped() }
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        previousPopGestureEnabled = navigationController?.interactivePopGestureRecognizer?.isEnabled
        navigationItem.hidesBackButton = true
        navigationController?.interactivePopGestureRecognizer?.isEnabled = false
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        if let previousPopGestureEnabled {
            navigationController?.interactivePopGestureRecognizer?.isEnabled = previousPopGestureEnabled
        }
    }

    /// 在途旧查询不能覆盖刚收到的受限信号；之后由用户主动重新查询。
    func recordRestriction() {
        viewModel.recordRestriction()
        onAccessDenied()
        if isViewLoaded { applyViewModel() }
    }

    /// 从后台回来只读重查；废弃后台前的在途结果，不重发申请或撤销操作。
    func refreshAfterBackground() {
        viewModel.recordRestriction()
        navigationController?.popToRootViewController(animated: false)
        if presentedViewController is UIAlertController { dismiss(animated: false) }
        if queryTask != nil {
            needsForegroundRefresh = true
            applyViewModel()
        } else {
            retryTapped()
        }
    }

    private func applyViewModel() {
        let busy = queryTask != nil
        let cooling = viewModel.decision == .cooling
        retryButton.isEnabled = !busy && api != nil
        retryButton.isHidden = cooling
        refreshControl.isEnabled = !busy && api != nil
        cancelButton.isHidden = !cooling
        cancelButton.isEnabled = !busy && api != nil
        logoutButton.isEnabled = !busy
        Style.configure(logoutButton, title: "退出登录", primary: cooling)
        deadlineCard.isHidden = !cooling
        infoCard.isHidden = !cooling
        deadlineLabel.text = viewModel.status?.coolingUntil ?? "—"
        guard identity != nil, api != nil else {
            titleLabel.text = "暂时无法查询"
            messageLabel.text = "当前身份信息不完整，请联系管理员。"
            stateIcon.image = UIImage(systemName: "exclamationmark.circle")
            return
        }
        var symbol = "clock"
        switch viewModel.decision {
        case .notChecked, .checking:
            titleLabel.text = nil
            messageLabel.text = nil
        case .allowed:
            titleLabel.text = "当前身份可正常使用"
            messageLabel.text = "正在返回首页"
            symbol = "checkmark.circle"
        case .cooling:
            titleLabel.text = "注销申请已提交"
            messageLabel.text = "当前身份：\(identity?.displayName ?? "当前身份")"
            symbol = "lock"
        case .unresolved:
            titleLabel.text = "注销状态待确认"
            messageLabel.text = "暂时未获取到明确结果，请刷新重试。\n请勿重复提交；如持续出现，请联系管理员。"
            symbol = "questionmark.circle"
        case .failed:
            titleLabel.text = "暂时无法查询"
            messageLabel.text = "请检查网络后重试。\n查询失败不会撤销你的注销申请。"
            symbol = "wifi.exclamationmark"
        case .obsolete:
            titleLabel.text = "当前身份已变化"
            messageLabel.text = "请返回当前账号后重试。"
            symbol = "person.crop.circle.badge.exclamationmark"
        }
        stateIcon.image = UIImage(systemName: symbol,
                                  withConfiguration: UIImage.SymbolConfiguration(pointSize: 36, weight: .medium))
        navigationItem.hidesBackButton = true
        navigationController?.interactivePopGestureRecognizer?.isEnabled = false
    }

    @objc private func cancelTapped() {
        guard queryTask == nil, let identity, let api, identity.matches(session: session),
              viewModel.decision == .cooling else { return }
        let alert = UIAlertController(title: "撤销当前身份的注销申请？",
            message: "将撤销“\(identity.displayName)”的申请，服务端确认后恢复使用。其他身份不受影响。",
            preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "保留注销申请", style: .cancel))
        alert.addAction(UIAlertAction(title: "确认撤销", style: .destructive) { [weak self] _ in
            guard let self, self.queryTask == nil else { return }
            self.queryTask = Task { @MainActor [weak self] in
                guard let self else { return }
                self.showLoading()
                await self.viewModel.cancel(api: api) { [session = self.session] in identity.matches(session: session) }
                self.hideLoading()
                self.finishQuery()
            }
            self.applyViewModel()
        })
        present(alert, animated: true)
    }

    @objc private func retryTapped() {
        guard queryTask == nil, let identity, let api else {
            refreshControl.endRefreshing()
            applyViewModel()
            return
        }
        queryTask = Task { @MainActor [weak self] in
            guard let self else { return }
            self.showLoading()
            await self.viewModel.verify(api: api) { [session = self.session] in identity.matches(session: session) }
            self.hideLoading()
            self.finishQuery()
        }
        applyViewModel()
    }

    private func finishQuery() {
        queryTask = nil
        refreshControl.endRefreshing()
        if needsForegroundRefresh {
            needsForegroundRefresh = false
            retryTapped()
            return
        }
        applyViewModel()
        if viewModel.decision == .allowed, identity?.matches(session: session) == true {
            onAllowed(self)
        } else {
            onAccessDenied()
        }
    }

    @objc private func logoutTapped() {
        let alert = UIAlertController(title: "退出登录？", message:
            "退出本身不会撤销申请，但会清除本机登录凭证。再次登录或选中此身份会自动撤销尚未完成的申请。", preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "继续保留查询", style: .cancel))
        alert.addAction(UIAlertAction(title: "退出登录", style: .destructive) { _ in
            NotificationCenter.default.post(name: NotificationName.userDidLogout, object: nil)
        })
        present(alert, animated: true)
    }
}