//
//  HomeViewController.swift
//  suixinkan
//

import SnapKit
import UIKit

// MARK: - Diffable 标识

/// 首页 section 标识，按角色动态展示工作状态、门店与常用应用网格。
private enum HomeSection: Hashable {
    case workStatus
    case locationReport
    case storeInfo
    case quickActions
    case commonMenus
}

/// 首页 item 标识；工作状态类 item 携带展示数据以支持倒计时 diff 刷新。
private enum HomeItem: Hashable {
    case workStatus(isOnline: Bool, secondsUntilReport: Int, reminderMinutes: Int)
    case locationReport
    case storeInfo(storeID: Int)
    case quickActions(isOnline: Bool)
    case menu(uri: String)
}

/// 首页工作台，展示景区头部、工作状态、位置上报卡片和常用应用网格。
final class HomeViewController: UIViewController {

    private let viewModel = HomeViewModel()
    private let commonMenuStore = HomeCommonMenuStore()
    private var commonURIs: [String] = []
    private var isOnline = false
    private var reminderMinutes = 0
    private var secondsUntilReport = 0
    private var countdownTimer: Timer?

    private let minimalTopRoleIds: Set<Int> = [46, 47, 52, 53, 54]

    private lazy var scenicButton: UIButton = {
        var config = UIButton.Configuration.plain()
        config.baseForegroundColor = UIColor(hex: 0x333333)
        config.image = UIImage(systemName: "chevron.down")?.withConfiguration(
            UIImage.SymbolConfiguration(pointSize: AppMetrics.FontSize.subheadline, weight: .bold)
        )
        config.imagePlacement = .trailing
        config.imagePadding = AppMetrics.Spacing.xSmall
        config.contentInsets = .zero
        let button = UIButton(configuration: config)
        button.contentHorizontalAlignment = .leading
        button.addTarget(self, action: #selector(scenicTapped), for: .touchUpInside)
        return button
    }()

    private lazy var collectionView: UICollectionView = {
        let layout = makeCollectionLayout()
        let collection = UICollectionView(frame: .zero, collectionViewLayout: layout)
        collection.backgroundColor = AppDesignUIKit.pageBackground
        collection.showsVerticalScrollIndicator = false
        collection.delegate = self
        collection.register(HomeWorkStatusCell.self, forCellWithReuseIdentifier: HomeWorkStatusCell.reuseID)
        collection.register(HomeLocationReportCell.self, forCellWithReuseIdentifier: HomeLocationReportCell.reuseID)
        collection.register(HomeStoreInfoCell.self, forCellWithReuseIdentifier: HomeStoreInfoCell.reuseID)
        collection.register(HomeQuickActionsCell.self, forCellWithReuseIdentifier: HomeQuickActionsCell.reuseID)
        collection.register(HomeMenuItemCell.self, forCellWithReuseIdentifier: HomeMenuItemCell.reuseID)
        collection.register(
            CollectionSectionHeaderView.self,
            forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader,
            withReuseIdentifier: CollectionSectionHeaderView.reuseID
        )
        return collection
    }()

    /// Diffable 数据源，驱动多 section 卡片与常用应用网格。
    private var dataSource: UICollectionViewDiffableDataSource<HomeSection, HomeItem>!

    /// 视图加载完成后的 UI 初始化与数据绑定。
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = AppDesignUIKit.pageBackground
        setupTopBar()
        configureDataSource()
        setupCollectionView()
        bindViewModel()
        rebuildMenus()
        observeContextChanges()
    }

    /// 视图即将展示，刷新可见状态。
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        navigationController?.setNavigationBarHidden(true, animated: animated)
        startCountdownTimerIfNeeded()
    }

    /// 视图即将消失，保存或清理临时状态。
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        countdownTimer?.invalidate()
        countdownTimer = nil
    }

    /// 初始化 TopBar 相关 UI 或状态。
    private func setupTopBar() {
        let topBar = UIView()
        topBar.backgroundColor = .white
        view.addSubview(topBar)
        topBar.addSubview(scenicButton)

        topBar.snp.makeConstraints { make in
            make.top.leading.trailing.equalTo(view.safeAreaLayoutGuide)
            make.height.equalTo(78)
        }
        scenicButton.snp.makeConstraints { make in
            make.leading.trailing.equalToSuperview().inset(AppMetrics.Spacing.pageHorizontal)
            make.centerY.equalToSuperview()
        }
        updateScenicTitle()
    }

    /// 初始化 CollectionView 布局约束。
    private func setupCollectionView() {
        view.addSubview(collectionView)
        collectionView.snp.makeConstraints { make in
            make.top.equalTo(view.safeAreaLayoutGuide).offset(78)
            make.leading.trailing.bottom.equalToSuperview()
        }
    }

    /// 构建 Compositional Layout，按 section 类型分配全宽卡片或三列网格。
    private func makeCollectionLayout() -> UICollectionViewCompositionalLayout {
        UICollectionViewCompositionalLayout { [weak self] sectionIndex, _ in
            guard let self,
                  let section = self.dataSource?.snapshot().sectionIdentifiers[safe: sectionIndex]
            else {
                return CollectionDiffableLayout.fullWidthSection()
            }
            switch section {
            case .workStatus:
                return CollectionDiffableLayout.fullWidthSection(height: 100)
            case .locationReport:
                return CollectionDiffableLayout.fullWidthSection(height: 148)
            case .storeInfo:
                return CollectionDiffableLayout.fullWidthSection(height: 88)
            case .quickActions:
                return CollectionDiffableLayout.fullWidthSection(height: 118)
            case .commonMenus:
                return CollectionDiffableLayout.addHeader(
                    to: CollectionDiffableLayout.gridSection(itemHeight: 102),
                    height: 36
                )
            }
        }
    }

    /// 注册 Diffable 数据源与 Cell 配置闭包。
    private func configureDataSource() {
        dataSource = UICollectionViewDiffableDataSource<HomeSection, HomeItem>(
            collectionView: collectionView
        ) { [weak self] collectionView, indexPath, item in
            guard let self else { return UICollectionViewCell() }
            switch item {
            case .workStatus(let online, let seconds, let reminder):
                let cell = collectionView.dequeueReusableCell(
                    withReuseIdentifier: HomeWorkStatusCell.reuseID,
                    for: indexPath
                ) as! HomeWorkStatusCell
                cell.configure(
                    isOnline: online,
                    countdownText: self.countdownText(seconds: seconds),
                    reminderText: self.reminderText(minutes: reminder),
                    onOnlineTap: { [weak self] in self?.onlineTapped() },
                    onReminderTap: { [weak self] in self?.reminderTapped() }
                )
                return cell
            case .locationReport:
                let cell = collectionView.dequeueReusableCell(
                    withReuseIdentifier: HomeLocationReportCell.reuseID,
                    for: indexPath
                ) as! HomeLocationReportCell
                cell.configure(onReportTap: { [weak self] in self?.locationReportTapped() })
                return cell
            case .storeInfo(let storeID):
                let cell = collectionView.dequeueReusableCell(
                    withReuseIdentifier: HomeStoreInfoCell.reuseID,
                    for: indexPath
                ) as! HomeStoreInfoCell
                if let store = self.appServices.accountContext.currentStore, store.id == storeID {
                    cell.configure(
                        storeName: store.name,
                        scenicName: self.appServices.accountContext.currentScenic?.name
                    )
                }
                return cell
            case .quickActions(let online):
                let cell = collectionView.dequeueReusableCell(
                    withReuseIdentifier: HomeQuickActionsCell.reuseID,
                    for: indexPath
                ) as! HomeQuickActionsCell
                cell.configure(
                    isOnline: online,
                    onPaymentTap: { [weak self] in self?.paymentTapped() },
                    onTaskCreateTap: { [weak self] in self?.taskCreateTapped() },
                    onOnlineTap: { [weak self] in self?.onlineTapped() }
                )
                return cell
            case .menu(let uri):
                let cell = collectionView.dequeueReusableCell(
                    withReuseIdentifier: HomeMenuItemCell.reuseID,
                    for: indexPath
                ) as! HomeMenuItemCell
                if let menuItem = self.menuItem(for: uri) ?? self.displayMenuItems.first(where: { $0.uri == uri }) {
                    cell.configure(item: menuItem)
                }
                return cell
            }
        }

        dataSource.supplementaryViewProvider = { [weak self] collectionView, kind, indexPath in
            guard let self,
                  kind == UICollectionView.elementKindSectionHeader,
                  let section = self.dataSource.snapshot().sectionIdentifiers[safe: indexPath.section],
                  section == .commonMenus,
                  let header = collectionView.dequeueReusableSupplementaryView(
                      ofKind: kind,
                      withReuseIdentifier: CollectionSectionHeaderView.reuseID,
                      for: indexPath
                  ) as? CollectionSectionHeaderView
            else { return nil }
            header.configure(title: "常用应用")
            return header
        }
    }

    /// 根据当前角色与状态构建 snapshot 并应用 diff 更新。
    private func applySnapshot(animated: Bool = true) {
        var snapshot = NSDiffableDataSourceSnapshot<HomeSection, HomeItem>()

        if shouldShowWorkStatus {
            snapshot.appendSections([.workStatus, .locationReport])
            snapshot.appendItems(
                [.workStatus(isOnline: isOnline, secondsUntilReport: secondsUntilReport, reminderMinutes: reminderMinutes)],
                toSection: .workStatus
            )
            snapshot.appendItems([.locationReport], toSection: .locationReport)
        }

        if isStoreManager, let store = appServices.accountContext.currentStore {
            snapshot.appendSections([.storeInfo])
            snapshot.appendItems([.storeInfo(storeID: store.id)], toSection: .storeInfo)
        }

        if shouldShowWorkStatus {
            snapshot.appendSections([.quickActions])
            snapshot.appendItems([.quickActions(isOnline: isOnline)], toSection: .quickActions)
        }

        snapshot.appendSections([.commonMenus])
        snapshot.appendItems(
            displayMenuItems.map { HomeItem.menu(uri: $0.uri) },
            toSection: .commonMenus
        )

        dataSource.apply(snapshot, animatingDifferences: animated)
    }

    /// 绑定 ViewModel 回调或数据。
    private func bindViewModel() {
        viewModel.onChange = { [weak self] in
            self?.applySnapshot()
        }
    }

    /// 监听权限与账号上下文变化并刷新菜单。
    private func observeContextChanges() {
        let services = appServices
        services.permissionContext.onChange = { [weak self] in
            self?.rebuildMenus()
        }
        services.accountContext.onChange = { [weak self] in
            self?.updateScenicTitle()
            self?.applySnapshot()
        }
    }

    /// 按当前角色权限重建首页菜单与常用应用。
    private func rebuildMenus() {
        let services = appServices
        viewModel.buildMenus(
            from: services.permissionContext.rolePermissions,
            currentRoleId: services.permissionContext.currentRole?.id
        )
        commonURIs = commonMenuStore.load(menuItems: viewModel.menuItems)
        applySnapshot()
    }

    /// 刷新顶部景区名称展示。
    private func updateScenicTitle() {
        let name = appServices.accountContext.currentScenic?.name ?? "请选择景区"
        scenicButton.configuration?.attributedTitle = AttributedString(
            name,
            attributes: AttributeContainer([
                .font: UIFont.systemFont(ofSize: AppMetrics.FontSize.title3, weight: .semibold)
            ])
        )
    }

    /// 当前登录角色 ID。
    private var currentRoleId: Int? {
        appServices.permissionContext.currentRole?.id
    }

    /// 部分精简角色不展示工作状态与位置上报区块。
    private var shouldShowWorkStatus: Bool {
        guard let currentRoleId else { return true }
        return !minimalTopRoleIds.contains(currentRoleId)
    }

    /// 是否为门店管理员角色（roleId = 46）。
    private var isStoreManager: Bool {
        currentRoleId == 46
    }

    /// 常用应用展示项：优先用户自定义，不足 3 个时取权限菜单前 3 项，末尾固定「更多功能」。
    private var displayMenuItems: [HomeMenuItem] {
        let selected = commonURIs.compactMap { menuItem(for: $0) }
        let fallback = selected.isEmpty ? Array(viewModel.menuItems.prefix(3)) : selected
        return fallback + [HomeMenuItem(title: "更多功能", uri: "more_functions", iconSrc: nil)]
    }

    /// 按 URI 解析并返回可用菜单项。
    private func menuItem(for uri: String) -> HomeMenuItem? {
        let availableURIs = Set(viewModel.menuItems.map(\.uri))
        let resolvedUri = HomeMenuRouter.canonicalURI(for: uri, availableURIs: availableURIs)
        guard let existing = viewModel.menuItems.first(where: { $0.uri == resolvedUri }) else { return nil }
        return HomeMenuItem(
            title: HomeMenuRouter.displayTitle(for: resolvedUri, fallback: existing.title),
            uri: resolvedUri,
            iconSrc: existing.iconSrc
        )
    }

    /// 格式化倒计时展示文本。
    private func countdownText(seconds: Int) -> String {
        let hours = seconds / 3_600
        let minutes = (seconds % 3_600) / 60
        let secs = seconds % 60
        return "\(hours):\(String(format: "%02d", minutes)):\(String(format: "%02d", secs))"
    }

    /// 格式化提前提醒展示文本。
    private func reminderText(minutes: Int) -> String {
        minutes == 0 ? "不提醒" : "提前\(minutes)分钟"
    }

    /// 在线状态下启动位置上报倒计时。
    private func startCountdownTimerIfNeeded() {
        countdownTimer?.invalidate()
        guard isOnline else { return }
        countdownTimer = Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { [weak self] _ in
            guard let self, self.isOnline, self.secondsUntilReport > 0 else { return }
            self.secondsUntilReport -= 1
            self.applySnapshot(animated: false)
        }
    }

    /// 点击景区名称，跳转景区选择页。
    @objc private func scenicTapped() {
        HomeMenuRouting.push(.scenicSelection, from: self)
    }

    /// 切换在线 / 离线状态。
    @objc private func onlineTapped() {
        let message = isOnline
            ? "是否确认切换为离线状态？离线后将暂停位置上报。"
            : "是否确认切换为在线状态？在线后将开始位置上报和计时。"
        let alert = UIAlertController(title: "切换在线状态", message: message, preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "取消", style: .cancel))
        alert.addAction(UIAlertAction(title: "确定", style: .default) { [weak self] _ in
            guard let self else { return }
            self.isOnline.toggle()
            if self.isOnline {
                self.secondsUntilReport = 7_200
                self.startCountdownTimerIfNeeded()
            } else {
                self.countdownTimer?.invalidate()
            }
            self.applySnapshot()
        })
        present(alert, animated: true)
    }

    /// 选择位置上报提前提醒时间。
    @objc private func reminderTapped() {
        let sheet = UIAlertController(title: "提前提醒时间", message: nil, preferredStyle: .actionSheet)
        for minute in [0, 5, 10, 15, 30] {
            let title = minute == 0 ? "不提醒" : "\(minute)分钟"
            sheet.addAction(UIAlertAction(title: title, style: .default) { [weak self] _ in
                self?.reminderMinutes = minute
                self?.applySnapshot()
            })
        }
        sheet.addAction(UIAlertAction(title: "取消", style: .cancel))
        present(sheet, animated: true)
    }

    /// 跳转位置上报页面。
    @objc private func locationReportTapped() {
        HomeMenuRouting.openRoute(HomeMenuRouter.resolve(uri: "location_report", title: "位置上报"), from: self)
    }

    /// 跳转立即收款页面。
    @objc private func paymentTapped() {
        HomeMenuRouting.openRoute(HomeMenuRouter.resolve(uri: "payment_collection", title: "立即收款"), from: self)
    }

    /// 跳转提交任务页面。
    @objc private func taskCreateTapped() {
        HomeMenuRouting.openRoute(HomeMenuRouter.resolve(uri: "task_create", title: "提交任务"), from: self)
    }
}

// MARK: - UICollectionViewDelegate

extension HomeViewController: UICollectionViewDelegate {
    /// 点击常用应用网格项，执行菜单路由。
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        guard let item = dataSource.itemIdentifier(for: indexPath),
              case .menu(let uri) = item,
              let menuItem = displayMenuItems.first(where: { $0.uri == uri })
        else { return }
        HomeMenuRouting.openMenu(menuItem, from: self)
    }
}

// MARK: - Card Cells

/// 在线状态卡片 Cell，展示在线切换、倒计时与提醒设置。
private final class HomeWorkStatusCell: UICollectionViewCell {
    static let reuseID = "HomeWorkStatusCell"

    private let cardView = UIView()
    private let onlineButton = UIButton(type: .system)
    private let clockLabel = UILabel()
    private let reminderButton = UIButton(type: .system)

    /// 初始化实例。
    override init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = .clear
        cardView.backgroundColor = .white
        cardView.layer.cornerRadius = 8
        contentView.addSubview(cardView)

        onlineButton.titleLabel?.font = .systemFont(ofSize: AppMetrics.FontSize.caption, weight: .medium)
        onlineButton.layer.cornerRadius = 4
        onlineButton.contentEdgeInsets = UIEdgeInsets(top: 6, left: 12, bottom: 6, right: 12)

        clockLabel.font = .systemFont(ofSize: AppMetrics.FontSize.body, weight: .medium)
        clockLabel.textColor = AppDesignUIKit.primary

        reminderButton.titleLabel?.font = .systemFont(ofSize: AppMetrics.FontSize.body, weight: .medium)
        reminderButton.setTitleColor(AppDesignUIKit.primary, for: .normal)

        let stack = UIStackView(arrangedSubviews: [onlineButton, clockLabel, reminderButton])
        stack.axis = .horizontal
        stack.distribution = .equalSpacing
        stack.alignment = .center
        cardView.addSubview(stack)

        cardView.snp.makeConstraints { make in
            make.edges.equalToSuperview()
        }
        stack.snp.makeConstraints { make in
            make.edges.equalToSuperview().inset(15)
        }
    }

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

    /// 配置在线状态、倒计时与提醒，并绑定点击回调。
    func configure(
        isOnline: Bool,
        countdownText: String,
        reminderText: String,
        onOnlineTap: @escaping () -> Void,
        onReminderTap: @escaping () -> Void
    ) {
        onlineButton.setTitle(isOnline ? "在线" : "离线", for: .normal)
        onlineButton.setTitleColor(isOnline ? UIColor(hex: 0xF0FDF4) : UIColor(hex: 0x7B8EAA), for: .normal)
        onlineButton.backgroundColor = isOnline ? UIColor(hex: 0x22C55E) : UIColor(hex: 0xF4F4F4)
        clockLabel.text = "  \(countdownText)"
        reminderButton.setTitle(" \(reminderText)", for: .normal)

        onlineButton.removeAction(identifiedBy: UIAction.Identifier("online"), for: .touchUpInside)
        reminderButton.removeAction(identifiedBy: UIAction.Identifier("reminder"), for: .touchUpInside)
        onlineButton.addAction(UIAction(identifier: UIAction.Identifier("online")) { _ in onOnlineTap() }, for: .touchUpInside)
        reminderButton.addAction(UIAction(identifier: UIAction.Identifier("reminder")) { _ in onReminderTap() }, for: .touchUpInside)
    }
}

/// 位置上报卡片 Cell，展示打卡范围提示与立即上报入口。
private final class HomeLocationReportCell: UICollectionViewCell {
    static let reuseID = "HomeLocationReportCell"

    private let cardView = UIView()
    private let actionButton = UIButton(type: .system)

    /// 初始化实例。
    override init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = .clear
        cardView.backgroundColor = .white
        cardView.layer.cornerRadius = 8
        contentView.addSubview(cardView)

        let titleLabel = UILabel()
        titleLabel.text = "立即上报"
        titleLabel.font = .systemFont(ofSize: 22, weight: .bold)
        titleLabel.textColor = UIColor(hex: 0x333333)

        let subtitleLabel = UILabel()
        subtitleLabel.text = "您已进入打卡范围"
        subtitleLabel.font = .systemFont(ofSize: 15)
        subtitleLabel.textColor = UIColor(hex: 0x999999)

        let textStack = UIStackView(arrangedSubviews: [titleLabel, subtitleLabel])
        textStack.axis = .vertical
        textStack.spacing = AppMetrics.Spacing.xxSmall

        actionButton.setImage(UIImage(systemName: "hand.tap.fill"), for: .normal)
        actionButton.tintColor = .white
        actionButton.backgroundColor = AppDesignUIKit.primary
        actionButton.layer.cornerRadius = 46

        cardView.addSubview(textStack)
        cardView.addSubview(actionButton)
        cardView.snp.makeConstraints { make in
            make.edges.equalToSuperview()
        }
        textStack.snp.makeConstraints { make in
            make.leading.top.bottom.equalToSuperview().inset(15)
            make.trailing.lessThanOrEqualTo(actionButton.snp.leading).offset(-12)
        }
        actionButton.snp.makeConstraints { make in
            make.trailing.equalToSuperview().inset(15)
            make.centerY.equalToSuperview()
            make.width.height.equalTo(92)
        }
    }

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

    /// 配置立即上报按钮点击回调。
    func configure(onReportTap: @escaping () -> Void) {
        actionButton.removeAction(identifiedBy: UIAction.Identifier("report"), for: .touchUpInside)
        actionButton.addAction(UIAction(identifier: UIAction.Identifier("report")) { _ in onReportTap() }, for: .touchUpInside)
    }
}

/// 门店信息卡片 Cell，展示当前门店名称与营业状态。
private final class HomeStoreInfoCell: UICollectionViewCell {
    static let reuseID = "HomeStoreInfoCell"

    private let cardView = UIView()
    private let nameLabel = UILabel()
    private let scenicLabel = UILabel()

    /// 初始化实例。
    override init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = .clear
        cardView.backgroundColor = .white
        cardView.layer.cornerRadius = 8
        contentView.addSubview(cardView)

        nameLabel.font = .systemFont(ofSize: AppMetrics.FontSize.title2, weight: .bold)

        scenicLabel.font = .systemFont(ofSize: AppMetrics.FontSize.subheadline)
        scenicLabel.textColor = UIColor(hex: 0x7B8EAA)
        scenicLabel.numberOfLines = 2

        let statusLabel = UILabel()
        statusLabel.text = "营业中"
        statusLabel.font = .systemFont(ofSize: AppMetrics.FontSize.caption)
        statusLabel.textColor = UIColor(hex: 0x22C55E)
        statusLabel.backgroundColor = UIColor(hex: 0xF0FDF4)
        statusLabel.layer.cornerRadius = 4
        statusLabel.clipsToBounds = true
        statusLabel.textAlignment = .center

        let textStack = UIStackView(arrangedSubviews: [nameLabel, scenicLabel])
        textStack.axis = .vertical
        textStack.spacing = AppMetrics.Spacing.xSmall

        cardView.addSubview(textStack)
        cardView.addSubview(statusLabel)
        cardView.snp.makeConstraints { make in
            make.edges.equalToSuperview()
        }
        textStack.snp.makeConstraints { make in
            make.leading.top.bottom.equalToSuperview().inset(AppMetrics.Spacing.medium)
            make.trailing.lessThanOrEqualTo(statusLabel.snp.leading).offset(-8)
        }
        statusLabel.snp.makeConstraints { make in
            make.trailing.top.equalToSuperview().inset(AppMetrics.Spacing.medium)
            make.width.greaterThanOrEqualTo(52)
            make.height.equalTo(22)
        }
    }

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

    /// 配置门店名称与所属景区。
    func configure(storeName: String, scenicName: String?) {
        nameLabel.text = storeName
        scenicLabel.text = scenicName
    }
}

/// 快捷操作行 Cell，展示收款、任务与在线状态入口。
private final class HomeQuickActionsCell: UICollectionViewCell {
    static let reuseID = "HomeQuickActionsCell"

    private let stackView = UIStackView()

    /// 初始化实例。
    override init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = .clear
        stackView.axis = .horizontal
        stackView.spacing = AppMetrics.Spacing.small
        stackView.distribution = .fillEqually
        contentView.addSubview(stackView)
        stackView.snp.makeConstraints { make in
            make.edges.equalToSuperview()
        }
    }

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

    /// 配置三个快捷操作按钮与点击回调。
    func configure(
        isOnline: Bool,
        onPaymentTap: @escaping () -> Void,
        onTaskCreateTap: @escaping () -> Void,
        onOnlineTap: @escaping () -> Void
    ) {
        stackView.arrangedSubviews.forEach { $0.removeFromSuperview() }
        stackView.addArrangedSubview(quickActionCard(
            icon: "qrcode",
            title: "立即收款",
            active: false,
            action: onPaymentTap
        ))
        stackView.addArrangedSubview(quickActionCard(
            icon: "checklist.checked",
            title: "提交任务",
            active: false,
            action: onTaskCreateTap
        ))
        stackView.addArrangedSubview(quickActionCard(
            icon: isOnline ? "wifi" : "wifi.slash",
            title: isOnline ? "在线" : "离线",
            active: isOnline,
            action: onOnlineTap
        ))
    }

    /// 构建单个快捷操作卡片。
    private func quickActionCard(
        icon: String,
        title: String,
        active: Bool,
        action: @escaping () -> Void
    ) -> UIView {
        let card = UIView()
        card.backgroundColor = active ? UIColor(hex: 0xE3F2FD) : .white
        card.layer.cornerRadius = 8

        let iconView = UIImageView(image: UIImage(systemName: icon))
        iconView.tintColor = AppDesignUIKit.primary
        iconView.contentMode = .scaleAspectFit

        let label = UILabel()
        label.text = title
        label.font = .systemFont(ofSize: AppMetrics.FontSize.body)
        label.textAlignment = .center

        let innerStack = UIStackView(arrangedSubviews: [iconView, label])
        innerStack.axis = .vertical
        innerStack.spacing = AppMetrics.Spacing.xSmall
        innerStack.alignment = .center
        card.addSubview(innerStack)
        innerStack.snp.makeConstraints { make in
            make.center.equalToSuperview()
        }
        iconView.snp.makeConstraints { make in
            make.height.equalTo(34)
        }

        let button = UIButton(type: .custom)
        button.addAction(UIAction { _ in action() }, for: .touchUpInside)
        card.addSubview(button)
        button.snp.makeConstraints { make in
            make.edges.equalToSuperview()
        }
        card.snp.makeConstraints { make in
            make.height.equalTo(102)
        }
        return card
    }
}

/// 首页菜单网格单项 Cell，负责图标与标题展示。
private final class HomeMenuItemCell: UICollectionViewCell {
    static let reuseID = "HomeMenuItemCell"

    private let iconView = UIImageView()
    private let titleLabel = UILabel()

    /// 初始化实例。
    override init(frame: CGRect) {
        super.init(frame: frame)
        contentView.backgroundColor = .white
        contentView.layer.cornerRadius = 8

        titleLabel.font = .systemFont(ofSize: AppMetrics.FontSize.body)
        titleLabel.textColor = UIColor(hex: 0x4B5563)
        titleLabel.textAlignment = .center
        titleLabel.numberOfLines = 1
        titleLabel.adjustsFontSizeToFitWidth = true

        let stack = UIStackView(arrangedSubviews: [iconView, titleLabel])
        stack.axis = .vertical
        stack.spacing = AppMetrics.Spacing.small
        stack.alignment = .center
        contentView.addSubview(stack)
        stack.snp.makeConstraints { make in
            make.center.equalToSuperview()
            make.leading.trailing.equalToSuperview().inset(4)
        }
        iconView.snp.makeConstraints { make in
            make.width.height.equalTo(30)
        }
        iconView.contentMode = .scaleAspectFit
    }

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

    /// 配置菜单项图标与标题。
    func configure(item: HomeMenuItem) {
        titleLabel.text = item.title
        let symbol = UIImage(systemName: HomeIconCatalog.iconName(for: item.uri))
        iconView.loadRemoteImage(urlString: item.iconSrc, contentMode: .scaleAspectFit, placeholder: symbol)
        iconView.tintColor = AppDesign.primary
    }
}

/// 安全下标，避免 section 越界。
private extension Array {
    subscript(safe index: Int) -> Element? {
        indices.contains(index) ? self[index] : nil
    }
}