import SnapKit
import UIKit

/// 日清列表条目。
private enum OfflineDailyItem: Hashable {
    case record(OfflineCollectionRecord)
    case empty(String)
}

/// 日清记录在白色列表卡中的圆角位置。
private enum OfflineRecordPosition {
    case single
    case first
    case middle
    case last
}

/// 线下收款日清页，按 9.7 视觉稿展示日历、2×2 汇总、明细和补缴操作。
@MainActor
final class OfflineCollectionDailyViewController: BaseViewController {
    private let viewModel: OfflineCollectionDailyViewModel
    private let tableView = UITableView(frame: .zero, style: .plain)
    private var dataSource: UITableViewDiffableDataSource<Int, OfflineDailyItem>!
    private let headerContainer = UIView()
    private let headerStack = UIStackView()
    private let calendarView = OfflineCollectionCalendarView()
    private let summaryCard = UIView()
    private let summaryDateLabel = UILabel()
    private let totalValue = UILabel()
    private let countValue = UILabel()
    private let settledValue = UILabel()
    private let pendingValue = UILabel()
    private let statusButton = UIButton(type: .system)
    private let bottomContainer = UIView()
    private let settlementButton = OfflineCollectionGradientButton(
        startColor: UIColor(hex: 0xFF8B00),
        endColor: UIColor(hex: 0xFF7200)
    )
    private var feedbackPresented = false
    private var isShowingGlobalLoading = false

    init(
        businessDate: String,
        context: OfflineCollectionContext = .current(),
        api: any OfflineCollectionServing = NetworkServices.shared.offlineCollectionAPI
    ) {
        viewModel = OfflineCollectionDailyViewModel(businessDate: businessDate, context: context, api: api)
        super.init(nibName: nil, bundle: nil)
    }

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

    override func setupNavigationBar() {
        title = "线下收款日清"
    }

    override func setupUI() {
        view.backgroundColor = UIColor(hex: 0xF7FAFF)
        configureTableView()
        configureHeader()
        configureBottomBar()

        view.addSubview(tableView)
        view.addSubview(bottomContainer)
        tableView.snp.makeConstraints { make in
            make.top.leading.trailing.equalTo(view.safeAreaLayoutGuide)
            make.bottom.equalTo(bottomContainer.snp.top)
        }
        bottomContainer.snp.makeConstraints { make in make.leading.trailing.bottom.equalToSuperview() }
    }

    override func bindActions() {
        calendarView.onDateSelected = { [weak self] date in
            guard let self else { return }
            Task { await self.viewModel.selectBusinessDate(date) }
        }
        calendarView.onModeChanged = { [weak self] in self?.resizeHeader() }
        viewModel.onStateChange = { [weak self] in Task { @MainActor in self?.applyState() } }
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        Task { await viewModel.refresh() }
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        setGlobalLoadingVisible(false)
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        resizeHeader()
    }

    private func configureTableView() {
        tableView.backgroundColor = .clear
        tableView.separatorStyle = .none
        tableView.rowHeight = UITableView.automaticDimension
        tableView.estimatedRowHeight = 96
        tableView.showsVerticalScrollIndicator = false
        tableView.contentInset.bottom = 12
        tableView.register(OfflineCollectionRecordCell.self, forCellReuseIdentifier: OfflineCollectionRecordCell.reuseIdentifier)
        tableView.register(OfflineCollectionEmptyCell.self, forCellReuseIdentifier: OfflineCollectionEmptyCell.reuseIdentifier)
        dataSource = makeDataSource()
    }

    private func configureHeader() {
        headerStack.axis = .vertical
        headerStack.spacing = 16
        headerContainer.addSubview(headerStack)
        headerStack.snp.makeConstraints { make in
            make.top.equalToSuperview().offset(12)
            make.bottom.equalToSuperview().inset(10)
            make.leading.trailing.equalToSuperview().inset(16)
        }
        headerStack.addArrangedSubview(calendarView)
        configureSummaryCard()
        headerStack.addArrangedSubview(summaryCard)

        let listTitle = UILabel()
        listTitle.text = "收款明细"
        listTitle.font = .systemFont(ofSize: 18, weight: .bold)
        listTitle.textColor = UIColor(hex: 0x081739)
        let listTitleContainer = UIView()
        listTitleContainer.addSubview(listTitle)
        listTitle.snp.makeConstraints { make in
            make.leading.equalToSuperview().offset(8)
            make.trailing.centerY.equalToSuperview()
        }
        listTitleContainer.snp.makeConstraints { make in make.height.equalTo(42) }
        headerStack.setCustomSpacing(18, after: summaryCard)
        headerStack.addArrangedSubview(listTitleContainer)

        statusButton.configuration = .plain()
        statusButton.configuration?.baseForegroundColor = AppColor.primary
        statusButton.addTarget(self, action: #selector(retryTapped), for: .touchUpInside)
        statusButton.snp.makeConstraints { make in make.height.greaterThanOrEqualTo(44) }
        statusButton.isHidden = true
        headerStack.addArrangedSubview(statusButton)
        tableView.tableHeaderView = headerContainer
    }

    private func configureSummaryCard() {
        summaryCard.backgroundColor = .white
        summaryCard.layer.cornerRadius = 12
        summaryCard.layer.shadowColor = UIColor(hex: 0x8FA0B8).cgColor
        summaryCard.layer.shadowOpacity = 0.12
        summaryCard.layer.shadowRadius = 10
        summaryCard.layer.shadowOffset = CGSize(width: 0, height: 4)

        summaryDateLabel.font = .systemFont(ofSize: 17, weight: .bold)
        summaryDateLabel.textColor = UIColor(hex: 0x081739)

        let topLeft = metric(title: "线下收款总额", value: totalValue)
        let topRight = metric(title: "登记笔数", value: countValue)
        let bottomLeft = metric(title: "已补缴", value: settledValue)
        let bottomRight = metric(title: "待补缴", value: pendingValue)
        let grid = UIView()
        [topLeft, topRight, bottomLeft, bottomRight].forEach(grid.addSubview)
        topLeft.snp.makeConstraints { make in
            make.top.leading.equalToSuperview()
            make.width.equalToSuperview().multipliedBy(0.5)
            make.height.equalToSuperview().multipliedBy(0.5)
        }
        topRight.snp.makeConstraints { make in
            make.top.trailing.equalToSuperview()
            make.width.height.equalTo(topLeft)
        }
        bottomLeft.snp.makeConstraints { make in
            make.bottom.leading.equalToSuperview()
            make.width.height.equalTo(topLeft)
        }
        bottomRight.snp.makeConstraints { make in
            make.bottom.trailing.equalToSuperview()
            make.width.height.equalTo(topLeft)
        }

        let horizontalDivider = UIView()
        let verticalDivider = UIView()
        [horizontalDivider, verticalDivider].forEach {
            $0.backgroundColor = UIColor(hex: 0xE7EBF1)
            grid.addSubview($0)
        }
        horizontalDivider.snp.makeConstraints { make in
            make.leading.trailing.centerY.equalToSuperview()
            make.height.equalTo(1)
        }
        verticalDivider.snp.makeConstraints { make in
            make.top.bottom.centerX.equalToSuperview()
            make.width.equalTo(1)
        }

        summaryCard.addSubview(summaryDateLabel)
        summaryCard.addSubview(grid)
        summaryDateLabel.snp.makeConstraints { make in
            make.top.equalToSuperview().offset(14)
            make.leading.trailing.equalToSuperview().inset(16)
            make.height.equalTo(22)
        }
        grid.snp.makeConstraints { make in
            make.top.equalTo(summaryDateLabel.snp.bottom).offset(6)
            make.leading.trailing.equalToSuperview().inset(10)
            make.bottom.equalToSuperview().inset(8)
        }
        summaryCard.snp.makeConstraints { make in make.height.equalTo(196) }
    }

    private func metric(title: String, value: UILabel) -> UIView {
        let titleLabel = UILabel()
        titleLabel.text = title
        titleLabel.font = .systemFont(ofSize: 12)
        titleLabel.textColor = UIColor(hex: 0x7B8494)
        titleLabel.textAlignment = .center

        value.font = .systemFont(ofSize: 20, weight: .bold)
        value.textColor = UIColor(hex: 0x081739)
        value.textAlignment = .center
        value.adjustsFontSizeToFitWidth = true
        value.minimumScaleFactor = 0.72

        let stack = UIStackView(arrangedSubviews: [titleLabel, value])
        stack.axis = .vertical
        stack.alignment = .fill
        stack.spacing = 6

        let container = UIView()
        container.addSubview(stack)
        stack.snp.makeConstraints { make in
            make.center.equalToSuperview()
            make.leading.trailing.equalToSuperview().inset(12)
        }
        return container
    }

    private func configureBottomBar() {
        bottomContainer.backgroundColor = .white
        bottomContainer.layer.shadowColor = UIColor(hex: 0x8090A8).cgColor
        bottomContainer.layer.shadowOpacity = 0.12
        bottomContainer.layer.shadowRadius = 12
        bottomContainer.layer.shadowOffset = CGSize(width: 0, height: -3)
        settlementButton.setTitle("当日暂无待补缴", for: .normal)
        settlementButton.setTitleColor(.white, for: .normal)
        settlementButton.titleLabel?.font = .systemFont(ofSize: 17, weight: .semibold)
        settlementButton.layer.cornerRadius = 10
        settlementButton.clipsToBounds = true
        settlementButton.accessibilityIdentifier = "offlineCollection.settle"
        settlementButton.addTarget(self, action: #selector(settlementTapped), for: .touchUpInside)
        bottomContainer.addSubview(settlementButton)
        settlementButton.snp.makeConstraints { make in
            make.top.equalToSuperview().offset(14)
            make.leading.trailing.equalToSuperview().inset(16)
            make.height.equalTo(54)
            make.bottom.equalTo(bottomContainer.safeAreaLayoutGuide).inset(14)
        }
    }

    @MainActor private func applyState() {
        let processing = viewModel.settlementState == .processing
        setGlobalLoadingVisible(viewModel.isLoading || processing)
        calendarView.apply(
            selectedDate: viewModel.businessDate,
            maximumDate: viewModel.serverToday,
            pendingDates: viewModel.pendingDates
        )
        summaryDateLabel.text = formattedSummaryDate()
        totalValue.text = OfflineCollectionMoney.display(viewModel.summary.totalAmountFen)
        countValue.text = "\(viewModel.summary.totalCount)笔"
        settledValue.text = OfflineCollectionMoney.display(viewModel.summary.settledAmountFen)
        pendingValue.text = OfflineCollectionMoney.display(viewModel.summary.pendingAmountFen)
        pendingValue.textColor = viewModel.summary.pendingCount > 0 ? UIColor(hex: 0xFF7600) : UIColor(hex: 0x081739)

        if let error = viewModel.errorMessage, !viewModel.isLoading {
            statusButton.isHidden = false
            statusButton.isUserInteractionEnabled = true
            statusButton.configuration?.title = "\(error)  点击重试"
            UIAccessibility.post(notification: .announcement, argument: error)
        } else {
            statusButton.isHidden = true
        }

        settlementButton.isEnabled = viewModel.canSettle && !processing
        if processing {
            settlementButton.setTitle("补缴中", for: .normal)
        } else if viewModel.summary.totalCount > 0 && viewModel.summary.pendingCount == 0 {
            settlementButton.setTitle("本日已全部补缴", for: .normal)
        } else if viewModel.summary.pendingCount == 0 {
            settlementButton.setTitle("当日暂无待补缴", for: .normal)
        } else {
            settlementButton.setTitle(
                "补缴本日全部 \(OfflineCollectionMoney.display(viewModel.summary.pendingAmountFen))",
                for: .normal
            )
        }
        settlementButton.alpha = viewModel.canSettle || processing ? 1 : 0.45
        applySnapshot()
        resizeHeader()
        presentFeedbackIfNeeded()
    }

    private func formattedSummaryDate() -> String {
        guard let date = OfflineCollectionDate.date(from: viewModel.businessDate) else { return viewModel.businessDate }
        let calendar = OfflineCollectionDate.calendar
        let text = "\(calendar.component(.month, from: date))月\(calendar.component(.day, from: date))日"
        return viewModel.businessDate == viewModel.serverToday ? "\(text) · 今日" : text
    }

    private func setGlobalLoadingVisible(_ visible: Bool) {
        guard visible != isShowingGlobalLoading else { return }
        isShowingGlobalLoading = visible
        visible ? showLoading() : hideLoading()
    }

    @MainActor private func applySnapshot() {
        var snapshot = NSDiffableDataSourceSnapshot<Int, OfflineDailyItem>()
        snapshot.appendSections([0])
        if viewModel.records.isEmpty {
            let text = viewModel.errorMessage == nil && !viewModel.isLoading ? "本日暂无线下收款记录" : ""
            snapshot.appendItems([.empty(text)])
        } else {
            snapshot.appendItems(viewModel.records.map(OfflineDailyItem.record))
        }
        dataSource.apply(snapshot, animatingDifferences: false)
    }

    private func makeDataSource() -> UITableViewDiffableDataSource<Int, OfflineDailyItem> {
        UITableViewDiffableDataSource(tableView: tableView) { [weak self] tableView, indexPath, item in
            switch item {
            case let .record(record):
                let cell = tableView.dequeueReusableCell(
                    withIdentifier: OfflineCollectionRecordCell.reuseIdentifier,
                    for: indexPath
                ) as! OfflineCollectionRecordCell
                let count = self?.viewModel.records.count ?? 1
                let position: OfflineRecordPosition
                if count == 1 { position = .single }
                else if indexPath.row == 0 { position = .first }
                else if indexPath.row == count - 1 { position = .last }
                else { position = .middle }
                cell.apply(record, position: position)
                return cell
            case let .empty(text):
                let cell = tableView.dequeueReusableCell(
                    withIdentifier: OfflineCollectionEmptyCell.reuseIdentifier,
                    for: indexPath
                ) as! OfflineCollectionEmptyCell
                cell.apply(text)
                return cell
            }
        }
    }

    private func resizeHeader() {
        guard tableView.bounds.width > 0 else { return }
        headerContainer.frame.size.width = tableView.bounds.width
        headerContainer.setNeedsLayout()
        headerContainer.layoutIfNeeded()
        let height = headerContainer.systemLayoutSizeFitting(
            CGSize(width: tableView.bounds.width, height: UIView.layoutFittingCompressedSize.height),
            withHorizontalFittingPriority: .required,
            verticalFittingPriority: .fittingSizeLevel
        ).height
        guard abs(headerContainer.frame.height - height) > 0.5 else { return }
        headerContainer.frame.size.height = height
        tableView.tableHeaderView = headerContainer
    }

    @MainActor private func presentFeedbackIfNeeded() {
        guard !feedbackPresented else { return }
        switch viewModel.settlementState {
        case .idle, .processing:
            return
        case let .success(result):
            feedbackPresented = true
            let alert = UIAlertController(
                title: "补缴成功",
                message: "营业日：\(result.date)\n共结清 \(result.updatedCount) 笔",
                preferredStyle: .alert
            )
            alert.addAction(UIAlertAction(title: "完成", style: .default) { [weak self] _ in self?.finishFeedback() })
            present(alert, animated: true)
        case let .failed(message, canRetry):
            feedbackPresented = true
            let alert = UIAlertController(title: "补缴失败", message: message, preferredStyle: .alert)
            alert.addAction(UIAlertAction(title: "暂不处理", style: .cancel) { [weak self] _ in
                self?.viewModel.cancelPreparedSettlement()
                self?.finishFeedback()
            })
            if canRetry {
                alert.addAction(UIAlertAction(title: "重新补缴", style: .default) { [weak self] _ in
                    guard let self else { return }
                    self.feedbackPresented = false
                    Task { await self.viewModel.confirmSettlement() }
                })
            }
            present(alert, animated: true)
        }
    }

    private func finishFeedback() {
        feedbackPresented = false
        viewModel.clearSettlementFeedback()
    }

    @objc private func retryTapped() {
        Task { await viewModel.refresh() }
    }

    @objc private func settlementTapped() {
        do {
            let request = try viewModel.prepareSettlement()
            let message = "营业日：\(request.businessDate)\n待补缴记录：\(request.pendingCount) 笔\n本次补缴金额：\(OfflineCollectionMoney.display(request.amountFen))"
            let alert = UIAlertController(title: "确认补缴", message: message, preferredStyle: .alert)
            alert.addAction(UIAlertAction(title: "取消", style: .cancel) { [weak self] _ in
                self?.viewModel.cancelPreparedSettlement()
            })
            alert.addAction(UIAlertAction(title: "确认补缴", style: .default) { [weak self] _ in
                guard let self else { return }
                Task { await self.viewModel.confirmSettlement() }
            })
            present(alert, animated: true)
        } catch {
            showToast(error.localizedDescription)
        }
    }
}

/// 日清页的一笔收款记录行，纯展示支付方式、编号、金额、状态与时间。
private final class OfflineCollectionRecordCell: UITableViewCell {
    static let reuseIdentifier = "OfflineCollectionRecordCell"

    private let card = UIView()
    private let iconView = UIImageView()
    private let titleLabel = UILabel()
    private let idLabel = UILabel()
    private let amountLabel = UILabel()
    private let statusLabel = UILabel()
    private let timeLabel = UILabel()
    private let separator = UIView()

    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        selectionStyle = .none
        backgroundColor = .clear
        contentView.backgroundColor = .clear

        card.backgroundColor = .white
        iconView.contentMode = .scaleAspectFit
        titleLabel.font = .systemFont(ofSize: 15, weight: .semibold)
        titleLabel.textColor = UIColor(hex: 0x081739)

        idLabel.font = .systemFont(ofSize: 9.5, weight: .medium)
        idLabel.textColor = UIColor(hex: 0x6F7B8F)
        idLabel.textAlignment = .left
        idLabel.numberOfLines = 0
        idLabel.lineBreakMode = .byCharWrapping
        idLabel.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
        idLabel.setContentCompressionResistancePriority(.required, for: .vertical)

        amountLabel.font = .systemFont(ofSize: 16, weight: .bold)
        amountLabel.textColor = UIColor(hex: 0x081739)
        amountLabel.textAlignment = .right
        amountLabel.adjustsFontSizeToFitWidth = true
        amountLabel.minimumScaleFactor = 0.72

        statusLabel.font = .systemFont(ofSize: 11, weight: .medium)
        statusLabel.textAlignment = .center
        statusLabel.layer.cornerRadius = 7
        statusLabel.clipsToBounds = true

        timeLabel.font = .systemFont(ofSize: 12)
        timeLabel.textColor = UIColor(hex: 0x7B8494)
        timeLabel.textAlignment = .right
        separator.backgroundColor = UIColor(hex: 0xE7EBF1)

        let idContainer = UIView()
        idContainer.backgroundColor = UIColor(hex: 0xF0F2F6)
        idContainer.layer.cornerRadius = 5
        idContainer.clipsToBounds = true
        idContainer.addSubview(idLabel)
        idLabel.snp.makeConstraints { make in
            make.edges.equalToSuperview().inset(UIEdgeInsets(top: 3, left: 6, bottom: 3, right: 6))
        }

        card.addSubview(iconView)
        card.addSubview(titleLabel)
        card.addSubview(idContainer)
        card.addSubview(amountLabel)
        card.addSubview(statusLabel)
        card.addSubview(timeLabel)
        card.addSubview(separator)
        contentView.addSubview(card)

        card.snp.makeConstraints { make in
            make.top.bottom.equalToSuperview()
            make.leading.trailing.equalToSuperview().inset(16)
            make.height.greaterThanOrEqualTo(90)
        }
        iconView.snp.makeConstraints { make in
            make.leading.equalToSuperview().offset(12)
            make.top.equalToSuperview().offset(10)
            make.width.height.equalTo(38)
        }
        titleLabel.snp.makeConstraints { make in
            make.leading.equalTo(iconView.snp.trailing).offset(10)
            make.centerY.equalTo(iconView)
        }
        amountLabel.snp.makeConstraints { make in
            make.leading.greaterThanOrEqualTo(titleLabel.snp.trailing).offset(4)
            make.centerY.equalTo(iconView)
            make.width.equalTo(68)
        }
        statusLabel.snp.makeConstraints { make in
            make.leading.equalTo(amountLabel.snp.trailing).offset(4)
            make.trailing.equalToSuperview().inset(12)
            make.centerY.equalTo(iconView)
            make.width.equalTo(50)
            make.height.equalTo(27)
        }
        timeLabel.snp.makeConstraints { make in
            make.trailing.equalToSuperview().inset(12)
            make.centerY.equalTo(idContainer)
            make.width.equalTo(40)
        }
        idContainer.snp.makeConstraints { make in
            make.leading.equalTo(iconView)
            make.top.equalTo(iconView.snp.bottom).offset(6)
            make.trailing.lessThanOrEqualTo(timeLabel.snp.leading).offset(-8)
            make.bottom.equalToSuperview().inset(10)
        }
        separator.snp.makeConstraints { make in
            make.leading.equalToSuperview().offset(12)
            make.trailing.equalToSuperview().inset(8)
            make.bottom.equalToSuperview()
            make.height.equalTo(1 / UIScreen.main.scale)
        }
    }

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

    func apply(_ record: OfflineCollectionRecord, position: OfflineRecordPosition) {
        iconView.image = UIImage(named: record.paymentMethod.assetName)
        titleLabel.text = record.paymentMethod == .wechat ? "微信收款" : record.paymentMethod.displayName
        idLabel.text = "编号 \(record.collectNo)"
        amountLabel.text = OfflineCollectionMoney.display(record.amountFen)
        let settled = record.status == .settled
        statusLabel.text = settled ? "已补缴" : "未补缴"
        statusLabel.textColor = settled ? UIColor(hex: 0x16A34A) : UIColor(hex: 0xFF7600)
        statusLabel.backgroundColor = settled ? UIColor(hex: 0xEAF8EF) : UIColor(hex: 0xFFF0E2)
        timeLabel.text = record.timeText
        separator.isHidden = position == .single || position == .last

        card.layer.cornerRadius = 12
        switch position {
        case .single:
            card.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner, .layerMinXMaxYCorner, .layerMaxXMaxYCorner]
        case .first:
            card.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
        case .middle:
            card.layer.maskedCorners = []
        case .last:
            card.layer.maskedCorners = [.layerMinXMaxYCorner, .layerMaxXMaxYCorner]
        }
        accessibilityLabel = "\(titleLabel.text ?? "")，编号 \(record.collectNo)，\(amountLabel.text ?? "")，\(statusLabel.text ?? "")，\(record.timeText)"
    }
}

/// 日清页空数据占位。
private final class OfflineCollectionEmptyCell: UITableViewCell {
    static let reuseIdentifier = "OfflineCollectionEmptyCell"
    private let label = UILabel()

    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        selectionStyle = .none
        backgroundColor = .clear
        label.font = .systemFont(ofSize: 14)
        label.textColor = UIColor(hex: 0x7B8494)
        label.textAlignment = .center
        contentView.addSubview(label)
        label.snp.makeConstraints { make in make.edges.equalToSuperview().inset(36) }
    }

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

    func apply(_ text: String) {
        label.text = text
    }
}