import IQKeyboardCore
import IQKeyboardManagerSwift
import SnapKit
import UIKit

/// 简洁两步注销页面；一次确认两项资产，短信和实际申请仍由用户主动操作。
@MainActor
final class StoreAccountDeregistrationViewController: BaseViewController {
    private typealias Style = StoreAccountDeregistrationStyle
    private let viewModel: StoreAccountDeregistrationViewModel
    private let api: any StoreAccountDeregistrationServing
    private let identityName: String
    private let readOnly: Bool
    private let onUnresolvedSubmission: (() -> Void)?
    private let onSubmissionAccepted: () -> Void
    private var didHandleAcceptedSubmission = false
    private let scrollView = UIScrollView()
    private let refreshControl = UIRefreshControl()
    private let content = UIStackView()
    private let bottomBar = UIView()
    private let steps = UIStackView()
    private let firstStep = Style.label("1  确认资产", size: 13, weight: .semibold)
    private let secondStep = Style.label("2  手机验证", size: 13, weight: .semibold)
    private let heading = Style.label(size: 24, weight: .semibold)
    private let subtitle = Style.label(size: 14, color: AppColor.textSecondary)
    private let conditionStack = UIStackView()
    private let verificationStack = UIStackView()
    private let walletAmount = Style.label("—", size: 28, weight: .semibold)
    private let pointsAmount = Style.label("—", size: 28, weight: .semibold)
    private let walletState = Style.label(size: 12, color: AppColor.textSecondary)
    private let pointsState = Style.label(size: 12, color: AppColor.textSecondary)
    private let assetHint = Style.label(size: 13, color: AppColor.textSecondary)
    private let blockersLabel = Style.label(size: 14, color: AppColor.textSecondary)
    private let riskLabel = Style.label(size: 13, color: AppColor.warning)
    private let statusLabel = Style.label(size: 13, color: AppColor.textSecondary)
    private let errorLabel = Style.label(size: 14, color: AppColor.danger)
    private let codeField = UITextField()
    private let reasonField = UITextField()
    private let smsButton = UIButton(type: .system)
    private let continueButton = Style.button("确认资产并继续", id: "deregister.continue")
    private let submitButton = Style.button("提交注销申请", id: "deregister.submit")
    private let backButton = UIButton(type: .system)
    private let footerHint = Style.label(size: 12, color: AppColor.textSecondary)
    private var blockersCard = UIView()
    private var errorCard = UIView()
    private var actionTask: Task<Void, Never>?
    private var previousPopGestureEnabled: Bool?
    private var previousViewportHeight: CGFloat = 0

    /// 注入当前身份及旧接口，不读取任意手机号，也不自动确认资产。
    init(identityName: String, viewModel: StoreAccountDeregistrationViewModel,
         api: any StoreAccountDeregistrationServing, readOnly: Bool = false,
         onUnresolvedSubmission: (() -> Void)? = nil,
         onSubmissionAccepted: @escaping () -> Void = {
             NotificationCenter.default.post(name: NotificationName.userDidLogout, object: nil)
         }) {
        self.identityName = identityName
        self.viewModel = viewModel
        self.api = api
        self.readOnly = readOnly
        self.onUnresolvedSubmission = onUnresolvedSubmission
        self.onSubmissionAccepted = onSubmissionAccepted
        super.init(nibName: nil, bundle: nil)
    }

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

    override func setupNavigationBar() {
        title = readOnly ? "注销条件" : "注销账号"
    }

    override func setupUI() {
        view.backgroundColor = AppColor.pageBackground
        view.addSubview(scrollView)
        refreshControl.accessibilityIdentifier = "deregister.refresh"
        refreshControl.accessibilityLabel = "下拉刷新"
        refreshControl.tintColor = .clear
        refreshControl.addTarget(self, action: #selector(refreshTapped), for: .valueChanged)
        scrollView.refreshControl = refreshControl
        scrollView.addSubview(content)
        content.axis = .vertical
        content.spacing = 16
        content.addArrangedSubview(steps)
        steps.axis = .horizontal
        steps.distribution = .fillEqually
        steps.addArrangedSubview(firstStep)
        steps.addArrangedSubview(secondStep)
        steps.isHidden = readOnly
        content.addArrangedSubview(Style.stack([heading, subtitle], spacing: 8))
        let identityText = Style.stack([
            Style.label("当前门店身份", size: 12, color: AppColor.textSecondary),
            Style.label(identityName, size: 17, weight: .semibold)
        ], spacing: 5)
        let identityRow = UIStackView(arrangedSubviews: [Style.icon("person.crop.circle"), identityText])
        identityRow.axis = .horizontal
        identityRow.alignment = .center
        identityRow.spacing = 12
        content.addArrangedSubview(Style.card(identityRow))
        conditionStack.axis = .vertical
        conditionStack.spacing = 16
        verificationStack.axis = .vertical
        verificationStack.spacing = 16
        buildConditions()
        buildVerification()
        content.addArrangedSubview(conditionStack)
        content.addArrangedSubview(verificationStack)
        errorCard = Style.card(errorLabel)
        errorCard.backgroundColor = AppColor.dangerBackground
        content.addArrangedSubview(errorCard)
        content.addArrangedSubview(statusLabel)
        statusLabel.accessibilityIdentifier = "deregister.status"
        errorLabel.accessibilityIdentifier = "deregister.error"

        view.addSubview(bottomBar)
        bottomBar.backgroundColor = .white
        footerHint.textAlignment = .center
        let actions = Style.stack([continueButton, submitButton, footerHint], spacing: 10)
        bottomBar.addSubview(actions)
        actions.snp.makeConstraints { $0.edges.equalToSuperview().inset(UIEdgeInsets(top: 12, left: 16, bottom: 12, right: 16)) }
        bottomBar.isHidden = readOnly
        continueButton.addTarget(self, action: #selector(continueTapped), for: .touchUpInside)
        submitButton.addTarget(self, action: #selector(submitTapped), for: .touchUpInside)
        scrollView.keyboardDismissMode = .onDrag
        scrollView.alwaysBounceVertical = true
    }

    private func buildConditions() {
        let columns = UIStackView()
        columns.axis = .horizontal
        columns.distribution = .fillEqually
        columns.spacing = 16
        columns.addArrangedSubview(Style.stack([
            Style.label("现金余额", size: 13, color: AppColor.textSecondary), walletAmount, walletState
        ], spacing: 8))
        columns.addArrangedSubview(Style.stack([
            Style.label("积分", size: 13, color: AppColor.textSecondary), pointsAmount, pointsState
        ], spacing: 8))
        walletAmount.adjustsFontSizeToFitWidth = true
        walletAmount.minimumScaleFactor = 0.6
        walletAmount.numberOfLines = 1
        pointsAmount.adjustsFontSizeToFitWidth = true
        pointsAmount.minimumScaleFactor = 0.6
        pointsAmount.numberOfLines = 1
        walletState.accessibilityIdentifier = "deregister.wallet.state"
        pointsState.accessibilityIdentifier = "deregister.points.state"
        let assets = Style.card(Style.stack([
            Style.label("账号资产", size: 16, weight: .semibold), columns, assetHint
        ], spacing: 16))
        assets.accessibilityIdentifier = "deregister.assets"
        conditionStack.addArrangedSubview(assets)
        blockersLabel.accessibilityIdentifier = "deregister.blockers"
        blockersCard = Style.card(Style.stack([
            Style.label("待处理事项", size: 16, weight: .semibold), blockersLabel, riskLabel
        ]))
        conditionStack.addArrangedSubview(blockersCard)
        let notices = Style.stack([
            Style.label("注销须知", size: 16, weight: .semibold),
            notice("person.crop.circle", title: "仅注销当前身份", detail: "同手机号的其他身份不受影响。"),
            notice("clock", title: "7 天冷静期", detail: "提交后可撤销申请，到期由服务端复核。"),
            notice("exclamationmark.shield", title: "正式完成后不可恢复", detail: "历史订单、财务及审计记录按规则保留。")
        ], spacing: 16)
        conditionStack.addArrangedSubview(Style.card(notices))
    }

    private func notice(_ icon: String, title: String, detail: String) -> UIView {
        let image = Style.icon(icon, size: 18)
        image.snp.makeConstraints { $0.width.equalTo(22) }
        let row = UIStackView(arrangedSubviews: [image, Style.stack([
            Style.label(title, size: 14, weight: .medium),
            Style.label(detail, size: 13, color: AppColor.textSecondary)
        ], spacing: 4)])
        row.axis = .horizontal
        row.alignment = .top
        row.spacing = 10
        return row
    }

    private func buildVerification() {
        codeField.placeholder = "请输入短信验证码"
        codeField.keyboardType = .numberPad
        codeField.textContentType = .oneTimeCode
        codeField.accessibilityIdentifier = "deregister.code"
        codeField.accessibilityLabel = "短信验证码"
        reasonField.placeholder = "请输入注销原因"
        reasonField.accessibilityIdentifier = "deregister.reason"
        reasonField.accessibilityLabel = "注销原因"
        for field in [codeField, reasonField] {
            field.font = .systemFont(ofSize: 16)
            field.autocorrectionType = .no
            // 本页通过keyboardLayoutGuide和滚动区域避让，避免全局键盘库重复抬升整页。
            field.iq.enableMode = .disabled
            field.addTarget(self, action: #selector(inputChanged), for: .editingChanged)
            field.addTarget(self, action: #selector(revealFocusedInput), for: .editingDidBegin)
            field.snp.makeConstraints { $0.height.equalTo(48) }
        }
        smsButton.setTitle("获取验证码", for: .normal)
        smsButton.titleLabel?.font = .systemFont(ofSize: 14, weight: .medium)
        smsButton.accessibilityIdentifier = "deregister.sms"
        smsButton.setContentHuggingPriority(.required, for: .horizontal)
        smsButton.setContentCompressionResistancePriority(.required, for: .horizontal)
        smsButton.addTarget(self, action: #selector(smsTapped), for: .touchUpInside)
        smsButton.snp.makeConstraints { $0.height.greaterThanOrEqualTo(44) }
        let codeRow = UIStackView(arrangedSubviews: [codeField, smsButton])
        codeRow.axis = .horizontal
        codeRow.spacing = 12
        verificationStack.addArrangedSubview(Style.card(Style.stack([
            Style.label("短信验证", size: 16, weight: .semibold), codeRow,
            Style.label("验证码将发送至当前身份绑定的手机号。", size: 13, color: AppColor.textSecondary)
        ], spacing: 8)))
        verificationStack.addArrangedSubview(Style.card(Style.stack([
            Style.label("注销原因", size: 16, weight: .semibold), reasonField
        ], spacing: 8)))
        backButton.setTitle("返回查看资产与须知", for: .normal)
        backButton.titleLabel?.font = .systemFont(ofSize: 14)
        backButton.accessibilityIdentifier = "deregister.back"
        backButton.addTarget(self, action: #selector(backTapped), for: .touchUpInside)
        backButton.snp.makeConstraints { $0.height.greaterThanOrEqualTo(44) }
        verificationStack.addArrangedSubview(backButton)
    }

    override func setupConstraints() {
        bottomBar.snp.makeConstraints {
            $0.leading.trailing.equalToSuperview()
            $0.bottom.equalTo(view.keyboardLayoutGuide.snp.top)
        }
        scrollView.snp.makeConstraints {
            $0.top.leading.trailing.equalTo(view.safeAreaLayoutGuide)
            if readOnly { $0.bottom.equalTo(view.safeAreaLayoutGuide) }
            else { $0.bottom.equalTo(bottomBar.snp.top) }
        }
        content.snp.makeConstraints {
            $0.edges.equalTo(scrollView.contentLayoutGuide).inset(16)
            $0.width.equalTo(scrollView.frameLayoutGuide).offset(-32)
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        applyViewModel()
        refreshTapped()
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        previousPopGestureEnabled = navigationController?.interactivePopGestureRecognizer?.isEnabled
        applyViewModel()
    }

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

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        guard scrollView.bounds.height != previousViewportHeight else { return }
        previousViewportHeight = scrollView.bounds.height
        revealFocusedInput()
    }

    @objc private func revealFocusedInput() {
        guard let field = [codeField, reasonField].first(where: \.isFirstResponder) else { return }
        let rect = field.convert(field.bounds, to: scrollView).insetBy(dx: 0, dy: -12)
        scrollView.scrollRectToVisible(rect, animated: false)
    }

    private func applyViewModel() {
        let busy = actionTask != nil || viewModel.isBusy
        let verifying = viewModel.step == .verification && !readOnly
        let unresolved = viewModel.step == .unresolvedRequest && !readOnly
        heading.text = readOnly ? "当前注销条件" : (verifying ? "验证绑定手机号" : "注销前，请确认")
        subtitle.text = verifying ? "完成验证后，即可提交注销申请。" : "仅注销此身份，其他身份不受影响。"
        firstStep.textColor = verifying ? AppColor.textSecondary : AppColor.primary
        secondStep.textColor = verifying ? AppColor.primary : AppColor.textSecondary
        conditionStack.isHidden = verifying || unresolved
        verificationStack.isHidden = !verifying
        continueButton.isHidden = verifying || readOnly
        submitButton.isHidden = !verifying
        continueButton.configuration?.title = viewModel.requiresAssetConfirmation ? "确认资产并继续" : "下一步"
        continueButton.isEnabled = !busy && viewModel.canConfirmAssetsAndContinue
        submitButton.isEnabled = !busy && viewModel.canContinue && hasVerificationInput
        smsButton.isEnabled = !busy && viewModel.canContinue
        codeField.isEnabled = !busy
        reasonField.isEnabled = !busy
        backButton.isEnabled = !busy
        refreshControl.isEnabled = !busy
        footerHint.text = verifying ? "7 天内可撤销，正式完成后不可恢复" : "请确认资产及注销须知后继续"
        errorLabel.text = viewModel.errorMessage
        errorCard.isHidden = viewModel.errorMessage == nil

        if let value = viewModel.eligibility {
            walletAmount.text = "¥\(value.walletBalance)"
            pointsAmount.text = "\(value.pointsBalance)"
            walletState.text = value.walletWaived ? "已确认放弃" : "待确认放弃"
            pointsState.text = value.pointsWaived ? "已确认放弃" : "待确认放弃"
            walletState.textColor = value.walletWaived ? AppColor.primary : AppColor.textSecondary
            pointsState.textColor = value.pointsWaived ? AppColor.primary : AppColor.textSecondary
            let assetIssues = value.blockers.filter(\.isAssetConfirmation)
            assetHint.text = readOnly ? "以当前查询结果为准，冷静期内不能再次确认资产。"
                : (assetIssues.contains { $0.code == "WAIVER_STALE" }
                   ? "资产已变化，请按最新金额重新确认。"
                   : "正式注销时，将清空已确认放弃的现金和积分。")
            blockersCard.isHidden = value.businessBlockers.isEmpty
            blockersLabel.text = value.businessBlockers.map { "• \($0.message)\n  \($0.guidance)" }.joined(separator: "\n\n")
            riskLabel.text = value.eligibleAt.map { "业务风险期预计结束：\($0)" }
            riskLabel.isHidden = value.eligibleAt == nil
        } else {
            walletAmount.text = "—"
            pointsAmount.text = "—"
            walletState.text = "待查询"
            pointsState.text = "待查询"
            assetHint.text = busy ? "正在查询资产与注销条件…" : "暂未获取到资产，请刷新重试。"
            blockersCard.isHidden = true
        }
        statusLabel.text = unresolved ? "申请状态待确认，请刷新后重试，暂勿重复提交。"
            : (viewModel.status?.isCancelled == true ? "上次申请已撤销，可重新申请。" : nil)
        statusLabel.isHidden = statusLabel.text == nil
        let preventsBack = busy || unresolved || (!readOnly && viewModel.submissionAttempted)
        navigationItem.hidesBackButton = preventsBack
        if view.window != nil {
            navigationController?.interactivePopGestureRecognizer?.isEnabled = !preventsBack && (previousPopGestureEnabled ?? true)
        }
    }

    private var hasVerificationInput: Bool {
        !(codeField.text ?? "").trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
            && !(reasonField.text ?? "").trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
    }

    private func run(_ operation: @escaping @MainActor () async -> Void) {
        guard actionTask == nil, !didHandleAcceptedSubmission else {
            refreshControl.endRefreshing()
            return
        }
        actionTask = Task { @MainActor [weak self] in
            guard let self else { return }
            self.showLoading()
            await operation()
            self.hideLoading()
            self.refreshControl.endRefreshing()
            self.actionTask = nil
            if !self.readOnly, self.viewModel.submissionAccepted {
                self.didHandleAcceptedSubmission = true
                self.onSubmissionAccepted()
                return
            }
            self.applyViewModel()
            if !self.readOnly, self.viewModel.submissionAttempted || self.viewModel.status?.isCooling == true {
                self.onUnresolvedSubmission?()
            }
        }
        applyViewModel()
    }

    @objc private func inputChanged() { applyViewModel() }
    @objc private func refreshTapped() { run { [self] in await self.viewModel.refresh(api: self.api) } }

    @objc private func continueTapped() {
        guard !readOnly, viewModel.canConfirmAssetsAndContinue, let snapshot = viewModel.eligibility else { return }
        if !viewModel.requiresAssetConfirmation {
            run { [self] in await self.viewModel.confirmAssetsAndContinue(snapshot: snapshot, api: self.api) }
            return
        }
        let alert = UIAlertController(title: "确认放弃账号资产？", message:
            "当前身份：\(identityName)\n\n现金余额：¥\(snapshot.walletBalance)\n积分：\(snapshot.pointsBalance)\n\n我确认自愿放弃以上现金余额，并确认自愿放弃以上积分。正式注销时将按规则清零。", preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "暂不确认", style: .cancel))
        alert.addAction(UIAlertAction(title: "确认并继续", style: .destructive) { [weak self] _ in
            guard let self else { return }
            self.run { [self] in await self.viewModel.confirmAssetsAndContinue(snapshot: snapshot, api: self.api) }
        })
        present(alert, animated: true)
    }

    @objc private func backTapped() {
        view.endEditing(true)
        viewModel.returnToConditions()
        applyViewModel()
    }

    @objc private func smsTapped() {
        guard !readOnly else { return }
        run { [self] in
            if await self.viewModel.sendSMS(api: self.api) { showToast("验证码已发送至当前身份绑定手机号") }
        }
    }

    @objc private func submitTapped() {
        guard !readOnly, viewModel.canContinue, hasVerificationInput else { return }
        let code = codeField.text ?? ""
        let reason = reasonField.text ?? ""
        view.endEditing(true)
        let alert = UIAlertController(title: "提交注销申请？", message:
            "仅注销“\(identityName)”。提交成功后将退出登录，并进入 7 天冷静期，最终由服务端复核；正式完成不可恢复。\n\n重新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: "暂不提交", style: .cancel))
        alert.addAction(UIAlertAction(title: "确认提交申请", style: .destructive) { [weak self] _ in
            self?.submitConfirmedApplication(smsCode: code, reason: reason)
        })
        present(alert, animated: true)
    }

    /// 用户确认最终弹窗后提交；仅明确成功触发一次退出，未知结果仍进入核验流程。
    func submitConfirmedApplication(smsCode: String, reason: String) {
        guard !readOnly else { return }
        run { [self] in await viewModel.submit(smsCode: smsCode, reason: reason, api: api) }
    }
}