//
//  TravelAlbumPhotoPreviewViewController.swift
//  suixinkan
//

import CoreImage
import Kingfisher
import SnapKit
import UIKit

/// 相册管理中的单张照片预览页，提供 AI 修图、删除和刷新操作。
final class TravelAlbumPhotoPreviewViewController: UIViewController {
    /// 删除成功后通知相册管理页刷新当前素材列表。
    var onDeleted: (() -> Void)?

    private var previewState: TravelAlbumPhotoPreviewState
    private let api: any TravelAlbumServing
    private let imageView = UIImageView()
    private let bottomBar = UIView()
    private let bottomContentStack = UIStackView()
    private let comparisonBar = UIStackView()
    private let versionControl = UISegmentedControl(items: ["原图", "精修后"])
    private var visibleDisplayModes: [TravelAlbumAIEditResultState.DisplayMode] = [.original, .edited]
    private let highResolutionButton = UIButton(type: .system)
    private let actionStack = UIStackView()
    private let aiEditButton = TravelAlbumPreviewActionButton(
        title: "AI修图",
        icon: UIImage(named: "travel_album_preview_ai_edit") ?? UIImage(systemName: "wand.and.stars")
    )
    private let aiEditResultStore = TravelAlbumAIEditResultStore.shared
    private let previewHeaderView = TravelAlbumPreviewHeaderView()
    private var originalImage: UIImage?
    private var originalImagesByMaterialID: [Int: UIImage] = [:]

    init(materials: [TravelAlbumMaterial], initialIndex: Int, api: any TravelAlbumServing) {
        precondition(!materials.isEmpty, "照片预览至少需要一张素材")
        previewState = TravelAlbumPhotoPreviewState(materials: materials, initialIndex: initialIndex)
        self.api = api
        super.init(nibName: nil, bundle: nil)
        // 与修图样式、封面模板预览保持同一种全屏容器，避免系统导航栏叠加。
        modalPresentationStyle = .fullScreen
        modalTransitionStyle = .crossDissolve
    }

    /// 兼容单张照片入口，并统一复用连续预览实现。
    convenience init(material: TravelAlbumMaterial, api: any TravelAlbumServing) {
        self.init(materials: [material], initialIndex: 0, api: api)
    }

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

    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .black
        setupNavigationBar()
        setupUI()
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(aiEditResultDidChange(_:)),
            name: TravelAlbumAIEditResultStore.didChangeNotification,
            object: aiEditResultStore
        )
        updateAIEditControls()
        loadImage()
    }

    override var preferredStatusBarStyle: UIStatusBarStyle {
        .lightContent
    }

    /// 使用沉浸式自定义头部展示返回入口、文件信息和当前照片位置。
    private func setupNavigationBar() {
        previewHeaderView.onBack = { [weak self] in
            self?.backTapped()
        }
        view.addSubview(previewHeaderView)
        previewHeaderView.snp.makeConstraints { make in
            make.top.equalTo(view.safeAreaLayoutGuide)
            make.leading.trailing.equalToSuperview()
            make.height.equalTo(68)
        }
        updateNavigationTitle()
    }

    private func setupUI() {
        imageView.contentMode = .scaleAspectFit
        imageView.clipsToBounds = true
        imageView.image = UIImage(systemName: "photo")
        imageView.tintColor = UIColor.white.withAlphaComponent(0.5)
        imageView.isUserInteractionEnabled = true
        let previousGesture = UISwipeGestureRecognizer(target: self, action: #selector(photoSwiped(_:)))
        previousGesture.direction = .right
        let nextGesture = UISwipeGestureRecognizer(target: self, action: #selector(photoSwiped(_:)))
        nextGesture.direction = .left
        imageView.addGestureRecognizer(previousGesture)
        imageView.addGestureRecognizer(nextGesture)

        bottomBar.backgroundColor = .black
        bottomBar.layer.borderColor = UIColor.white.withAlphaComponent(0.12).cgColor
        bottomBar.layer.borderWidth = 1 / UIScreen.main.scale
        bottomContentStack.axis = .vertical
        bottomContentStack.spacing = 10
        comparisonBar.axis = .horizontal
        comparisonBar.alignment = .center
        comparisonBar.distribution = .equalSpacing
        comparisonBar.isHidden = true

        versionControl.selectedSegmentIndex = 1
        versionControl.selectedSegmentTintColor = UIColor.white.withAlphaComponent(0.2)
        versionControl.setTitleTextAttributes([.foregroundColor: UIColor.white.withAlphaComponent(0.7)], for: .normal)
        versionControl.setTitleTextAttributes([.foregroundColor: UIColor.white], for: .selected)
        versionControl.addTarget(self, action: #selector(versionChanged), for: .valueChanged)

        highResolutionButton.setTitle("查看高清图", for: .normal)
        highResolutionButton.setTitleColor(.white, for: .normal)
        highResolutionButton.titleLabel?.font = .systemFont(ofSize: 13, weight: .medium)
        highResolutionButton.backgroundColor = UIColor.white.withAlphaComponent(0.18)
        highResolutionButton.layer.cornerRadius = 16
        highResolutionButton.addTarget(self, action: #selector(highResolutionTapped), for: .touchUpInside)

        actionStack.axis = .horizontal
        actionStack.distribution = .fillEqually

        aiEditButton.addTarget(self, action: #selector(aiEditTapped), for: .touchUpInside)
        actionStack.addArrangedSubview(aiEditButton)
        [
            ("删除", "travel_album_preview_delete", "trash", #selector(deleteTapped)),
            ("刷新", "travel_album_preview_refresh", "arrow.clockwise", #selector(refreshTapped)),
        ].forEach { title, assetName, fallbackIcon, action in
            let button = TravelAlbumPreviewActionButton(
                title: title,
                icon: UIImage(named: assetName) ?? UIImage(systemName: fallbackIcon)
            )
            button.addTarget(self, action: action, for: .touchUpInside)
            actionStack.addArrangedSubview(button)
        }

        view.addSubview(imageView)
        view.addSubview(bottomBar)
        bottomBar.addSubview(bottomContentStack)
        bottomContentStack.addArrangedSubview(comparisonBar)
        bottomContentStack.addArrangedSubview(actionStack)
        comparisonBar.addArrangedSubview(versionControl)
        comparisonBar.addArrangedSubview(highResolutionButton)
        bottomBar.snp.makeConstraints { make in
            make.leading.trailing.bottom.equalToSuperview()
        }
        bottomContentStack.snp.makeConstraints { make in
            make.top.equalToSuperview().offset(12)
            make.leading.trailing.equalToSuperview().inset(20)
            make.bottom.equalTo(view.safeAreaLayoutGuide).offset(-10)
        }
        comparisonBar.snp.makeConstraints { make in
            make.height.equalTo(32).priority(.high)
        }
        versionControl.snp.makeConstraints { make in
            make.width.equalTo(124)
            make.height.equalTo(32)
        }
        highResolutionButton.snp.makeConstraints { make in
            make.width.equalTo(112)
            make.height.equalTo(32)
        }
        actionStack.snp.makeConstraints { make in
            make.height.equalTo(58)
        }
        imageView.snp.makeConstraints { make in
            make.top.equalTo(previewHeaderView.snp.bottom)
            make.leading.trailing.equalToSuperview()
            make.bottom.equalTo(bottomBar.snp.top).offset(-20)
        }
    }

    /// 返回相册管理页；照片预览统一使用全屏模态展示。
    @objc private func backTapped() {
        closePreview()
    }

    /// 关闭当前预览；保留导航栈兼容分支，避免旧入口无法返回。
    private func closePreview() {
        if let navigationController,
           navigationController.viewControllers.first !== self {
            navigationController.popViewController(animated: true)
        } else {
            dismiss(animated: true)
        }
    }

    /// 加载当前素材的原图，刷新时始终绕过 Kingfisher 内存缓存。
    private func loadImage(forceRefresh: Bool = false) {
        guard let material = previewState.currentMaterial else { return }
        if let assetName = material.bundledImageAssetName,
           let bundledImage = UIImage(named: assetName) {
            originalImagesByMaterialID[material.id] = bundledImage
            originalImage = bundledImage
            renderCurrentPhoto()
            return
        }
        let imageURL = material.fileUrl.isEmpty ? material.coverUrl : material.fileUrl
        guard let url = URL(string: imageURL), !imageURL.isEmpty else { return }
        let options: KingfisherOptionsInfo = forceRefresh ? [.forceRefresh] : []
        let materialID = material.id
        KingfisherManager.shared.retrieveImage(with: url, options: options) { [weak self] result in
            guard let self, case let .success(value) = result else { return }
            Task { @MainActor in
                self.originalImagesByMaterialID[materialID] = value.image
                guard self.previewState.currentMaterial?.id == materialID else { return }
                self.originalImage = value.image
                self.renderCurrentPhoto()
            }
        }
    }

    /// 响应左右滑动并切换至相邻照片。
    @objc private func photoSwiped(_ gesture: UISwipeGestureRecognizer) {
        let didMove: Bool
        switch gesture.direction {
        case .left:
            didMove = previewState.moveNext()
        case .right:
            didMove = previewState.movePrevious()
        default:
            didMove = false
        }
        guard didMove else { return }
        displayCurrentPhoto()
    }

    /// 更新当前照片的标题、原图和预览内容。
    private func displayCurrentPhoto() {
        guard let material = previewState.currentMaterial else { return }
        originalImage = originalImagesByMaterialID[material.id]
        updateNavigationTitle()
        renderCurrentPhoto()
        updateAIEditControls()
        if originalImage == nil {
            loadImage()
        }
    }

    /// 根据当前照片同步导航栏文件名与大小。
    private func updateNavigationTitle() {
        guard let material = previewState.currentMaterial else { return }
        previewHeaderView.configure(
            title: material.fileName.isEmpty ? "照片预览" : material.fileName,
            subtitle: TravelAlbumDisplayFormatter.fileSizeText(material.fileSize),
            trailingText: "\(previewState.currentIndex + 1)/\(previewState.materials.count)"
        )
    }

    @objc private func aiEditTapped() {
        guard let material = previewState.currentMaterial else { return }
        let state = aiEditResultStore.state(for: material.id)
        guard state.canStartEditing else { return }
        guard let originalImage else {
            showToast("照片加载中，请稍后再试")
            return
        }
        let controller = TravelAlbumAIEditSheetViewController(sourceImage: originalImage, selectedPhotoCount: 1)
        controller.onConfirm = { [weak self] selection in
            guard let self else { return }
            self.startAIEditing(
                materialID: material.id,
                sourceImage: originalImage,
                selection: selection
            )
        }
        present(controller, animated: true)
    }

    /// 启动本地演示修图任务；处理期间禁用入口，完成后用新结果覆盖旧结果。
    private func startAIEditing(
        materialID: Int,
        sourceImage: UIImage,
        selection: TravelAlbumAIEditSelection
    ) {
        let state = aiEditResultStore.state(for: materialID)
        guard state.canStartEditing else { return }
        let existingCoverTemplate = state.appliedCoverTemplateID.flatMap { templateID in
            TravelAlbumCoverTemplate.defaultOptions.first(where: { $0.id == templateID })
        }
        aiEditResultStore.startProcessing(materialIDs: [materialID])
        updateAIEditControls()

        let refinedImage = TravelAlbumAIEditImageProcessor.render(
            effect: selection.refinedPreset.effect,
            source: sourceImage
        )
        let atmosphereImage = selection.atmosphereOption.map { option in
            TravelAlbumAIEditImageProcessor.render(effect: option.effect, source: sourceImage)
        }
        let coverImage = existingCoverTemplate.map { template in
            TravelAlbumCoverTemplateImageProcessor.render(template: template, source: refinedImage)
        }
        let resultStore = aiEditResultStore
        DispatchQueue.main.asyncAfter(deadline: .now() + 1.5) { [weak self] in
            // 即使用户在处理中离开预览页，也要完成任务并让相册缩略图恢复可操作状态。
            if selection.refinedPreset.effect == .original,
               selection.atmosphereOption == nil,
               existingCoverTemplate == nil {
                resultStore.restoreOriginal(materialID: materialID)
            } else {
                resultStore.complete(
                    materialID: materialID,
                    presetID: selection.refinedPreset.id,
                    atmosphereOptionID: selection.atmosphereOption?.id,
                    coverTemplateID: existingCoverTemplate?.id,
                    editedImage: refinedImage,
                    atmosphereImage: atmosphereImage,
                    coverImage: coverImage
                )
            }
            guard let self else { return }
            if self.previewState.currentMaterial?.id == materialID {
                let message: String
                if selection.refinedPreset.effect == .original,
                   selection.atmosphereOption == nil,
                   existingCoverTemplate == nil {
                    message = "已还原为原图"
                } else if selection.atmosphereOption != nil {
                    message = "AI修图完成，已生成 2 个结果"
                } else {
                    message = "AI修图完成"
                }
                self.showToast(message)
            }
        }
    }

    /// 根据当前照片的对比选项展示原图或最新修图结果。
    private func renderCurrentPhoto() {
        guard let material = previewState.currentMaterial else { return }
        let state = aiEditResultStore.state(for: material.id)
        let displayImage: UIImage?
        switch state.displayMode {
        case .original:
            displayImage = originalImagesByMaterialID[material.id]
        case .edited:
            displayImage = aiEditResultStore.editedImage(for: material.id) ?? originalImagesByMaterialID[material.id]
        case .atmosphere:
            displayImage = aiEditResultStore.atmosphereImage(for: material.id)
                ?? aiEditResultStore.editedImage(for: material.id)
                ?? originalImagesByMaterialID[material.id]
        case .cover:
            displayImage = aiEditResultStore.coverImage(for: material.id)
                ?? aiEditResultStore.editedImage(for: material.id)
                ?? originalImagesByMaterialID[material.id]
        }
        UIView.transition(with: imageView, duration: 0.2, options: .transitionCrossDissolve) {
            self.imageView.image = displayImage ?? UIImage(systemName: "photo")
            self.imageView.tintColor = UIColor.white.withAlphaComponent(0.5)
        }
    }

    /// 刷新修图对比栏和 AI 按钮的可用状态。
    private func updateAIEditControls() {
        guard let material = previewState.currentMaterial else { return }
        let state = aiEditResultStore.state(for: material.id)
        comparisonBar.isHidden = !state.hasEditedResult
        updateVersionControl(for: state)
        aiEditButton.isEnabled = state.canStartEditing
        aiEditButton.alpha = state.canStartEditing ? 1 : 0.35
        UIView.animate(withDuration: 0.2) {
            self.view.layoutIfNeeded()
        }
    }

    @objc private func versionChanged() {
        guard let material = previewState.currentMaterial,
              visibleDisplayModes.indices.contains(versionControl.selectedSegmentIndex) else { return }
        aiEditResultStore.selectDisplayMode(
            visibleDisplayModes[versionControl.selectedSegmentIndex],
            materialID: material.id
        )
        renderCurrentPhoto()
    }

    /// 根据当前实际结果动态展示原图、精修后、氛围感和封面切换项。
    private func updateVersionControl(for state: TravelAlbumAIEditResultState) {
        var modes: [TravelAlbumAIEditResultState.DisplayMode] = [.original, .edited]
        if state.hasAtmosphereResult {
            modes.append(.atmosphere)
        }
        if state.isCover {
            modes.append(.cover)
        }
        if visibleDisplayModes != modes {
            visibleDisplayModes = modes
            versionControl.removeAllSegments()
            modes.enumerated().forEach { index, mode in
                let title: String
                switch mode {
                case .original: title = "原图"
                case .edited: title = "精修后"
                case .atmosphere: title = "氛围感"
                case .cover: title = "封面"
                }
                versionControl.insertSegment(withTitle: title, at: index, animated: false)
            }
            let width: CGFloat
            switch modes.count {
            case 4: width = 220
            case 3: width = 180
            default: width = 124
            }
            versionControl.snp.updateConstraints { make in
                make.width.equalTo(width)
            }
        }
        versionControl.selectedSegmentIndex = visibleDisplayModes.firstIndex(of: state.displayMode) ?? 1
    }

    @objc private func aiEditResultDidChange(_ notification: Notification) {
        guard let materialID = notification.userInfo?[TravelAlbumAIEditResultStore.materialIDUserInfoKey] as? Int,
              previewState.currentMaterial?.id == materialID else { return }
        renderCurrentPhoto()
        updateAIEditControls()
    }

    @objc private func highResolutionTapped() {
        guard let image = imageView.image else { return }
        let controller = TravelAlbumImagePreviewViewController(image: image, title: "高清图")
        controller.modalPresentationStyle = .fullScreen
        controller.modalTransitionStyle = .crossDissolve
        present(controller, animated: true)
    }

    @objc private func deleteTapped() {
        guard let material = previewState.currentMaterial else { return }
        guard !material.isPurchased else {
            showToast("已购照片不可删除")
            return
        }
        let alert = UIAlertController(title: "删除照片", message: "删除后无法恢复，确定删除这张照片吗？", preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "取消", style: .cancel))
        alert.addAction(UIAlertAction(title: "删除", style: .destructive) { [weak self] _ in
            guard let self else { return }
            Task {
                do {
                    try await self.api.deleteMaterial(id: material.id)
                    await MainActor.run {
                        self.originalImagesByMaterialID.removeValue(forKey: material.id)
                        self.aiEditResultStore.remove(materialID: material.id)
                        self.onDeleted?()
                        if self.previewState.removeCurrent() {
                            self.displayCurrentPhoto()
                        } else {
                            self.closePreview()
                        }
                    }
                } catch {
                    await MainActor.run {
                        self.showToast(error.localizedDescription.isEmpty ? "删除失败" : error.localizedDescription)
                    }
                }
            }
        })
        present(alert, animated: true)
    }

    @objc private func refreshTapped() {
        guard let material = previewState.currentMaterial else { return }
        imageView.image = UIImage(systemName: "arrow.triangle.2.circlepath")
        imageView.tintColor = UIColor.white.withAlphaComponent(0.5)
        originalImage = nil
        originalImagesByMaterialID.removeValue(forKey: material.id)
        loadImage(forceRefresh: true)
    }

    private func showToast(_ message: String) {
        let alert = UIAlertController(title: nil, message: message, preferredStyle: .alert)
        present(alert, animated: true)
        DispatchQueue.main.asyncAfter(deadline: .now() + 1.2) { [weak alert] in
            alert?.dismiss(animated: true)
        }
    }
}

/// 全屏预览页底部的图文操作按钮。
private final class TravelAlbumPreviewActionButton: UIButton {
    init(title: String, icon: UIImage?) {
        super.init(frame: .zero)
        var configuration = UIButton.Configuration.plain()
        configuration.image = icon
        configuration.title = title
        configuration.imagePlacement = .top
        configuration.imagePadding = 6
        configuration.baseForegroundColor = .white
        configuration.titleTextAttributesTransformer = UIConfigurationTextAttributesTransformer { attributes in
            var attributes = attributes
            attributes.font = .systemFont(ofSize: 13)
            return attributes
        }
        self.configuration = configuration
    }

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

/// 相册预览统一头部，提供单一返回入口、两行标题和可选的右侧状态信息。
private final class TravelAlbumPreviewHeaderView: UIView {
    var onBack: (() -> Void)?

    private let backButton = UIButton(type: .system)
    private let titleLabel = UILabel()
    private let subtitleLabel = UILabel()
    private let titleStack = UIStackView()
    private let trailingLabel = UILabel()

    override init(frame: CGRect) {
        super.init(frame: frame)
        setupUI()
    }

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

    /// 刷新头部标题、辅助说明和右侧状态。
    func configure(title: String, subtitle: String?, trailingText: String?) {
        titleLabel.text = title
        subtitleLabel.text = subtitle
        subtitleLabel.isHidden = subtitle?.isEmpty != false
        trailingLabel.text = trailingText
        trailingLabel.isHidden = trailingText?.isEmpty != false
    }

    private func setupUI() {
        backgroundColor = .black

        var backConfiguration = UIButton.Configuration.plain()
        backConfiguration.image = UIImage(
            systemName: "chevron.left",
            withConfiguration: UIImage.SymbolConfiguration(pointSize: 17, weight: .semibold)
        )
        backConfiguration.baseForegroundColor = .white
        backConfiguration.contentInsets = .zero
        backButton.configuration = backConfiguration
        backButton.backgroundColor = UIColor.white.withAlphaComponent(0.10)
        backButton.layer.cornerRadius = 20
        backButton.accessibilityLabel = "返回"
        backButton.addTarget(self, action: #selector(backTapped), for: .touchUpInside)

        titleLabel.textColor = .white
        titleLabel.font = .systemFont(ofSize: 17, weight: .semibold)
        titleLabel.textAlignment = .center
        titleLabel.lineBreakMode = .byTruncatingMiddle

        subtitleLabel.textColor = UIColor.white.withAlphaComponent(0.55)
        subtitleLabel.font = .systemFont(ofSize: 12, weight: .regular)
        subtitleLabel.textAlignment = .center

        titleStack.axis = .vertical
        titleStack.alignment = .fill
        titleStack.spacing = 3
        titleStack.addArrangedSubview(titleLabel)
        titleStack.addArrangedSubview(subtitleLabel)

        trailingLabel.textColor = UIColor.white.withAlphaComponent(0.78)
        trailingLabel.font = .monospacedDigitSystemFont(ofSize: 12, weight: .medium)
        trailingLabel.textAlignment = .center
        trailingLabel.backgroundColor = UIColor.white.withAlphaComponent(0.10)
        trailingLabel.layer.cornerRadius = 14
        trailingLabel.clipsToBounds = true

        addSubview(backButton)
        addSubview(titleStack)
        addSubview(trailingLabel)
        backButton.snp.makeConstraints { make in
            make.leading.equalToSuperview().offset(16)
            make.centerY.equalToSuperview()
            make.width.height.equalTo(40)
        }
        trailingLabel.snp.makeConstraints { make in
            make.trailing.equalToSuperview().offset(-16)
            make.centerY.equalToSuperview()
            make.width.greaterThanOrEqualTo(44)
            make.height.equalTo(28)
        }
        titleStack.snp.makeConstraints { make in
            make.center.equalToSuperview()
            make.leading.greaterThanOrEqualTo(backButton.snp.trailing).offset(12)
            make.trailing.lessThanOrEqualTo(trailingLabel.snp.leading).offset(-12)
            make.width.lessThanOrEqualTo(230)
        }
    }

    @objc private func backTapped() {
        onBack?()
    }
}

/// 图片统一大图预览页，支持双指缩放并沿用相册预览的沉浸式头部。
private final class TravelAlbumImagePreviewViewController: UIViewController, UIScrollViewDelegate {
    private let image: UIImage
    private let previewTitle: String
    private let previewHeaderView = TravelAlbumPreviewHeaderView()
    private let scrollView = UIScrollView()
    private let imageView = UIImageView()

    init(image: UIImage, title: String = "高清图") {
        self.image = image
        previewTitle = title
        super.init(nibName: nil, bundle: nil)
    }

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

    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .black
        previewHeaderView.configure(
            title: previewTitle,
            subtitle: "双指缩放查看细节",
            trailingText: nil
        )
        previewHeaderView.onBack = { [weak self] in
            self?.dismiss(animated: true)
        }

        scrollView.delegate = self
        scrollView.minimumZoomScale = 1
        scrollView.maximumZoomScale = 4
        scrollView.showsHorizontalScrollIndicator = false
        scrollView.showsVerticalScrollIndicator = false
        imageView.image = image
        imageView.contentMode = .scaleAspectFit

        view.addSubview(previewHeaderView)
        view.addSubview(scrollView)
        scrollView.addSubview(imageView)
        previewHeaderView.snp.makeConstraints { make in
            make.top.equalTo(view.safeAreaLayoutGuide)
            make.leading.trailing.equalToSuperview()
            make.height.equalTo(68)
        }
        scrollView.snp.makeConstraints { make in
            make.top.equalTo(previewHeaderView.snp.bottom)
            make.leading.trailing.bottom.equalToSuperview()
        }
        imageView.snp.makeConstraints { make in
            make.edges.equalTo(scrollView.contentLayoutGuide)
            make.width.height.equalTo(scrollView.frameLayoutGuide)
        }
    }

    func viewForZooming(in scrollView: UIScrollView) -> UIView? {
        imageView
    }

    override var preferredStatusBarStyle: UIStatusBarStyle {
        .lightContent
    }
}

/// AI 修图底部弹窗，统一选择原图精修、可选氛围感修图和封面模板。
final class TravelAlbumAIEditSheetViewController: UIViewController {
    var onConfirm: ((TravelAlbumAIEditSelection) -> Void)?

    private let sourceImage: UIImage?
    private let selectedPhotoCount: Int
    private let presets = TravelAlbumEditPreset.defaultOptions
    private let atmosphereOptions = TravelAlbumAtmosphereEditOption.defaultOptions
    private let coverTemplates = TravelAlbumCoverTemplate.defaultOptions
    private let showsCoverTemplates: Bool
    private var selectedPresetID = TravelAlbumEditPreset.defaultOptions[0].id
    private var selectedAtmosphereOptionID: String?
    private var selectedCoverTemplateID: String?
    private let scrollView = UIScrollView()
    private let contentView = UIView()
    private let tipsContainerView = UIView()
    private let tipsLabel = UILabel()
    private let quotaInfoView = UIView()
    private var collectionView: UICollectionView!
    private var dataSource: UICollectionViewDiffableDataSource<Int, TravelAlbumEditPreset>!
    private var atmosphereCollectionView: UICollectionView!
    private var atmosphereDataSource: UICollectionViewDiffableDataSource<Int, TravelAlbumAtmosphereEditOption>!
    private var coverCollectionView: UICollectionView!
    private var coverDataSource: UICollectionViewDiffableDataSource<Int, TravelAlbumCoverTemplate>!

    init(sourceImage: UIImage?, selectedPhotoCount: Int) {
        self.sourceImage = sourceImage
        self.selectedPhotoCount = max(selectedPhotoCount, 1)
        showsCoverTemplates = TravelAlbumCoverTemplate.shouldShow(for: selectedPhotoCount)
        selectedCoverTemplateID = showsCoverTemplates ? TravelAlbumCoverTemplate.defaultOptions.first?.id : nil
        super.init(nibName: nil, bundle: nil)
        modalPresentationStyle = .pageSheet
        if let sheetPresentationController {
            let contentIdentifier = UISheetPresentationController.Detent.Identifier("aiEditContent")
            let desiredHeight: CGFloat = showsCoverTemplates ? 920 : 770
            let contentDetent = UISheetPresentationController.Detent.custom(identifier: contentIdentifier) { context in
                return min(desiredHeight, context.maximumDetentValue)
            }
            sheetPresentationController.detents = [contentDetent, .large()]
            sheetPresentationController.selectedDetentIdentifier = contentIdentifier
            sheetPresentationController.prefersGrabberVisible = true
        }
    }

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

    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = AppColor.pageBackground
        setupUI()
        applySnapshot()
    }

    private func setupUI() {
        let titleLabel = UILabel()
        titleLabel.text = "AI修图"
        titleLabel.font = .systemFont(ofSize: 18, weight: .semibold)
        titleLabel.textColor = AppColor.textPrimary
        titleLabel.textAlignment = .center

        let countLabel = UILabel()
        countLabel.text = "已选择 \(selectedPhotoCount) 张照片"
        countLabel.font = .systemFont(ofSize: 15)
        countLabel.textColor = AppColor.textSecondary
        countLabel.textAlignment = .center

        tipsContainerView.backgroundColor = UIColor(hex: 0xEAF2FF)
        tipsContainerView.layer.cornerRadius = 10
        tipsLabel.font = .systemFont(ofSize: 13)
        tipsLabel.textColor = UIColor(hex: 0x43617F)
        tipsLabel.numberOfLines = 0
        tipsContainerView.addSubview(tipsLabel)
        tipsLabel.snp.makeConstraints { make in
            make.edges.equalToSuperview().inset(12)
        }

        let presetTitleLabel = UILabel()
        presetTitleLabel.text = "原图精修"
        presetTitleLabel.font = .systemFont(ofSize: 15, weight: .semibold)
        presetTitleLabel.textColor = AppColor.textPrimary

        let layout = UICollectionViewFlowLayout()
        layout.scrollDirection = .horizontal
        layout.minimumLineSpacing = 12
        layout.itemSize = CGSize(width: 116, height: 142)
        collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
        collectionView.backgroundColor = .clear
        collectionView.showsHorizontalScrollIndicator = false
        collectionView.delegate = self
        collectionView.register(TravelAlbumEditPresetCell.self, forCellWithReuseIdentifier: TravelAlbumEditPresetCell.reuseIdentifier)
        dataSource = UICollectionViewDiffableDataSource<Int, TravelAlbumEditPreset>(collectionView: collectionView) { [weak self] collectionView, indexPath, preset in
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: TravelAlbumEditPresetCell.reuseIdentifier, for: indexPath) as! TravelAlbumEditPresetCell
            cell.apply(preset: preset, sourceImage: self?.sourceImage, selected: self?.selectedPresetID == preset.id)
            cell.onPreview = { [weak self] in
                guard let self else { return }
                let previewImage = self.sourceImage.map {
                    TravelAlbumAIEditImageProcessor.render(effect: preset.effect, source: $0)
                }
                self.presentStylePreview(title: preset.title, image: previewImage)
            }
            return cell
        }

        let atmosphereHeaderView = UIView()
        let atmosphereTitleLabel = UILabel()
        atmosphereTitleLabel.text = "氛围感修图"
        atmosphereTitleLabel.font = .systemFont(ofSize: 15, weight: .semibold)
        atmosphereTitleLabel.textColor = AppColor.textPrimary
        let optionalLabel = UILabel()
        optionalLabel.text = "选填"
        optionalLabel.font = .systemFont(ofSize: 12, weight: .medium)
        optionalLabel.textColor = AppColor.primary
        optionalLabel.backgroundColor = UIColor(hex: 0xEAF2FF)
        optionalLabel.textAlignment = .center
        optionalLabel.layer.cornerRadius = 13
        optionalLabel.clipsToBounds = true
        atmosphereHeaderView.addSubview(atmosphereTitleLabel)
        atmosphereHeaderView.addSubview(optionalLabel)
        atmosphereTitleLabel.snp.makeConstraints { make in
            make.leading.centerY.equalToSuperview()
        }
        optionalLabel.snp.makeConstraints { make in
            make.leading.equalTo(atmosphereTitleLabel.snp.trailing).offset(8)
            make.centerY.equalToSuperview()
            make.width.equalTo(48)
            make.height.equalTo(26)
        }

        let atmosphereLayout = UICollectionViewFlowLayout()
        atmosphereLayout.scrollDirection = .horizontal
        atmosphereLayout.minimumLineSpacing = 12
        atmosphereLayout.itemSize = CGSize(width: 116, height: 142)
        atmosphereCollectionView = UICollectionView(frame: .zero, collectionViewLayout: atmosphereLayout)
        atmosphereCollectionView.backgroundColor = .clear
        atmosphereCollectionView.showsHorizontalScrollIndicator = false
        atmosphereCollectionView.delegate = self
        atmosphereCollectionView.register(
            TravelAlbumEditPresetCell.self,
            forCellWithReuseIdentifier: TravelAlbumEditPresetCell.reuseIdentifier
        )
        atmosphereDataSource = UICollectionViewDiffableDataSource<Int, TravelAlbumAtmosphereEditOption>(
            collectionView: atmosphereCollectionView
        ) { [weak self] collectionView, indexPath, option in
            let cell = collectionView.dequeueReusableCell(
                withReuseIdentifier: TravelAlbumEditPresetCell.reuseIdentifier,
                for: indexPath
            ) as! TravelAlbumEditPresetCell
            cell.apply(
                atmosphereOption: option,
                sourceImage: self?.sourceImage,
                selected: self?.selectedAtmosphereOptionID == option.id
            )
            cell.onPreview = { [weak self] in
                guard let self else { return }
                let previewImage = self.sourceImage.map {
                    TravelAlbumAIEditImageProcessor.render(effect: option.effect, source: $0)
                }
                self.presentStylePreview(title: option.title, image: previewImage)
            }
            return cell
        }
        updateAtmosphereSelection()

        let coverHeaderView = UIView()
        coverHeaderView.isHidden = !showsCoverTemplates
        let coverTitleLabel = UILabel()
        coverTitleLabel.text = "封面风格模板"
        coverTitleLabel.font = .systemFont(ofSize: 15, weight: .semibold)
        coverTitleLabel.textColor = AppColor.textPrimary
        let freeGiftLabel = UILabel()
        freeGiftLabel.text = "赠送 · 不占精修张数"
        freeGiftLabel.font = .systemFont(ofSize: 12, weight: .medium)
        freeGiftLabel.textColor = UIColor(hex: 0xF29A38)
        freeGiftLabel.backgroundColor = UIColor(hex: 0xFFF3DE)
        freeGiftLabel.textAlignment = .center
        freeGiftLabel.layer.cornerRadius = 13
        freeGiftLabel.clipsToBounds = true
        coverHeaderView.addSubview(coverTitleLabel)
        coverHeaderView.addSubview(freeGiftLabel)
        coverTitleLabel.snp.makeConstraints { make in
            make.leading.centerY.equalToSuperview()
        }
        freeGiftLabel.snp.makeConstraints { make in
            make.trailing.centerY.equalToSuperview()
            make.height.equalTo(26)
            make.width.equalTo(148)
        }

        let coverLayout = UICollectionViewFlowLayout()
        coverLayout.scrollDirection = .horizontal
        coverLayout.minimumLineSpacing = 12
        coverLayout.itemSize = CGSize(width: 116, height: 142)
        coverCollectionView = UICollectionView(frame: .zero, collectionViewLayout: coverLayout)
        coverCollectionView.backgroundColor = .clear
        coverCollectionView.showsHorizontalScrollIndicator = false
        coverCollectionView.isHidden = !showsCoverTemplates
        coverCollectionView.delegate = self
        coverCollectionView.register(
            TravelAlbumCoverTemplateCell.self,
            forCellWithReuseIdentifier: TravelAlbumCoverTemplateCell.reuseIdentifier
        )
        coverDataSource = UICollectionViewDiffableDataSource<Int, TravelAlbumCoverTemplate>(
            collectionView: coverCollectionView
        ) { [weak self] collectionView, indexPath, template in
            let cell = collectionView.dequeueReusableCell(
                withReuseIdentifier: TravelAlbumCoverTemplateCell.reuseIdentifier,
                for: indexPath
            ) as! TravelAlbumCoverTemplateCell
            cell.apply(
                template: template,
                sourceImage: self?.sourceImage,
                selected: self?.selectedCoverTemplateID == template.id
            )
            cell.onPreview = { [weak self] in
                guard let self else { return }
                let previewImage = TravelAlbumCoverTemplateImageProcessor.render(
                    template: template,
                    source: self.sourceImage
                )
                self.presentStylePreview(title: template.title, image: previewImage)
            }
            return cell
        }

        let modeTitleLabel = UILabel()
        modeTitleLabel.text = "修图模式"
        modeTitleLabel.font = .systemFont(ofSize: 15)
        modeTitleLabel.textColor = AppColor.textSecondary

        quotaInfoView.backgroundColor = .white
        quotaInfoView.layer.cornerRadius = 12
        quotaInfoView.accessibilityLabel = "AI精修按张收费，剩余9张"
        quotaInfoView.accessibilityTraits = .staticText
        let modeLabel = UILabel()
        modeLabel.text = "AI精修 · 按张收费"
        modeLabel.font = .systemFont(ofSize: 16, weight: .medium)
        modeLabel.textColor = AppColor.textPrimary
        let quotaLabel = UILabel()
        quotaLabel.text = "剩余 9 张"
        quotaLabel.font = .systemFont(ofSize: 14, weight: .medium)
        quotaLabel.textColor = AppColor.primary
        quotaLabel.backgroundColor = UIColor(hex: 0xEAF2FF)
        quotaLabel.textAlignment = .center
        quotaLabel.layer.cornerRadius = 15
        quotaLabel.clipsToBounds = true
        quotaInfoView.addSubview(modeLabel)
        quotaInfoView.addSubview(quotaLabel)
        modeLabel.snp.makeConstraints { make in
            make.leading.equalToSuperview().offset(16)
            make.centerY.equalToSuperview()
        }
        quotaLabel.snp.makeConstraints { make in
            make.trailing.equalToSuperview().offset(-16)
            make.centerY.equalToSuperview()
            make.width.equalTo(82)
            make.height.equalTo(30)
        }

        let cancelButton = makeBottomButton(title: "取消", isPrimary: false)
        cancelButton.addTarget(self, action: #selector(cancelTapped), for: .touchUpInside)
        let confirmButton = makeBottomButton(title: "确定", isPrimary: true)
        confirmButton.addTarget(self, action: #selector(confirmTapped), for: .touchUpInside)
        let buttonStack = UIStackView(arrangedSubviews: [cancelButton, confirmButton])
        buttonStack.axis = .horizontal
        buttonStack.spacing = 12
        buttonStack.distribution = .fillEqually

        view.addSubview(scrollView)
        view.addSubview(buttonStack)
        scrollView.addSubview(contentView)
        [
            titleLabel,
            countLabel,
            tipsContainerView,
            presetTitleLabel,
            collectionView,
            atmosphereHeaderView,
            atmosphereCollectionView,
            coverHeaderView,
            coverCollectionView,
            modeTitleLabel,
            quotaInfoView,
        ].forEach(contentView.addSubview)
        scrollView.showsVerticalScrollIndicator = false
        scrollView.alwaysBounceVertical = showsCoverTemplates
        scrollView.snp.makeConstraints { make in
            make.top.leading.trailing.equalToSuperview()
            make.bottom.equalTo(buttonStack.snp.top).offset(-12)
        }
        contentView.snp.makeConstraints { make in
            make.edges.equalTo(scrollView.contentLayoutGuide)
            make.width.equalTo(scrollView.frameLayoutGuide)
        }
        buttonStack.snp.makeConstraints { make in
            make.leading.trailing.equalToSuperview().inset(20)
            make.bottom.equalTo(view.safeAreaLayoutGuide).offset(-16)
            make.height.equalTo(48)
        }
        titleLabel.snp.makeConstraints { make in
            make.top.equalToSuperview().offset(28)
            make.leading.trailing.equalToSuperview().inset(24)
        }
        countLabel.snp.makeConstraints { make in
            make.top.equalTo(titleLabel.snp.bottom).offset(12)
            make.leading.trailing.equalTo(titleLabel)
        }
        tipsContainerView.snp.makeConstraints { make in
            make.top.equalTo(countLabel.snp.bottom).offset(14)
            make.leading.trailing.equalToSuperview().inset(20)
        }
        presetTitleLabel.snp.makeConstraints { make in
            make.top.equalTo(tipsContainerView.snp.bottom).offset(20)
            make.leading.equalToSuperview().offset(20)
        }
        collectionView.snp.makeConstraints { make in
            make.top.equalTo(presetTitleLabel.snp.bottom).offset(12)
            make.leading.trailing.equalToSuperview().inset(20)
            make.height.equalTo(142)
        }
        atmosphereHeaderView.snp.makeConstraints { make in
            make.top.equalTo(collectionView.snp.bottom).offset(20)
            make.leading.trailing.equalToSuperview().inset(20)
            make.height.equalTo(26)
        }
        atmosphereCollectionView.snp.makeConstraints { make in
            make.top.equalTo(atmosphereHeaderView.snp.bottom).offset(12)
            make.leading.trailing.equalToSuperview().inset(20)
            make.height.equalTo(142)
        }
        coverHeaderView.snp.makeConstraints { make in
            make.top.equalTo(atmosphereCollectionView.snp.bottom).offset(showsCoverTemplates ? 20 : 0)
            make.leading.trailing.equalToSuperview().inset(20)
            make.height.equalTo(showsCoverTemplates ? 26 : 0)
        }
        coverCollectionView.snp.makeConstraints { make in
            make.top.equalTo(coverHeaderView.snp.bottom).offset(showsCoverTemplates ? 12 : 0)
            make.leading.trailing.equalToSuperview().inset(20)
            make.height.equalTo(showsCoverTemplates ? 142 : 0)
        }
        modeTitleLabel.snp.makeConstraints { make in
            make.top.equalTo(coverCollectionView.snp.bottom).offset(20)
            make.leading.equalToSuperview().offset(20)
        }
        quotaInfoView.snp.makeConstraints { make in
            make.top.equalTo(modeTitleLabel.snp.bottom).offset(12)
            make.leading.trailing.equalToSuperview().inset(20)
            make.height.equalTo(62)
            make.bottom.equalToSuperview().offset(-20)
        }
    }

    private func makeBottomButton(title: String, isPrimary: Bool) -> UIButton {
        let button = UIButton(type: .system)
        button.setTitle(title, for: .normal)
        button.setTitleColor(isPrimary ? .white : AppColor.textPrimary, for: .normal)
        button.titleLabel?.font = .systemFont(ofSize: 16, weight: .semibold)
        button.backgroundColor = isPrimary ? AppColor.primary : .white
        button.layer.cornerRadius = 10
        button.layer.borderWidth = isPrimary ? 0 : 1
        button.layer.borderColor = UIColor(hex: 0xD5D5D5).cgColor
        return button
    }

    private func applySnapshot() {
        var snapshot = NSDiffableDataSourceSnapshot<Int, TravelAlbumEditPreset>()
        snapshot.appendSections([0])
        snapshot.appendItems(presets)
        dataSource.apply(snapshot, animatingDifferences: false)

        var atmosphereSnapshot = NSDiffableDataSourceSnapshot<Int, TravelAlbumAtmosphereEditOption>()
        atmosphereSnapshot.appendSections([0])
        atmosphereSnapshot.appendItems(atmosphereOptions)
        atmosphereDataSource.apply(atmosphereSnapshot, animatingDifferences: false)

        guard showsCoverTemplates else { return }
        var coverSnapshot = NSDiffableDataSourceSnapshot<Int, TravelAlbumCoverTemplate>()
        coverSnapshot.appendSections([0])
        coverSnapshot.appendItems(coverTemplates)
        coverDataSource.apply(coverSnapshot, animatingDifferences: false)
    }

    @objc private func cancelTapped() {
        dismiss(animated: true)
    }

    /// 刷新氛围感修图的可选状态，并用 Tips 明确不同组合会生成几个结果。
    private func updateAtmosphereSelection() {
        let isAtmosphereSelected = selectedAtmosphereOptionID != nil
        if showsCoverTemplates {
            tipsLabel.text = isAtmosphereSelected
                ? "Tips：本次显示 3 类风格。每张照片生成「精修后 + 氛围感」2 个结果，第一张照片另生成所选封面结果。"
                : "Tips：氛围感修图为选填，可横向选择一种样式；选中后每张照片会额外生成 1 个独立结果，第一张照片仍另生成封面。"
        } else {
            tipsLabel.text = isAtmosphereSelected
                ? "Tips：已同时选择原图精修和氛围感修图，每张照片会生成「精修后 + 氛围感」2 个独立结果。"
                : "Tips：原图精修、氛围感修图为两类独立模板；同时选择这两种模板时，同一张原图将并行生成两份不同的修图成品。"
        }
    }

    /// 展示当前样式的大图预览；原图尚未加载时给出明确提示，不改变当前选择。
    private func presentStylePreview(title: String, image: UIImage?) {
        guard let image else {
            let alert = UIAlertController(
                title: "暂时无法预览",
                message: "当前照片仍在加载，请稍后再试。",
                preferredStyle: .alert
            )
            alert.addAction(UIAlertAction(title: "知道了", style: .default))
            present(alert, animated: true)
            return
        }
        let controller = TravelAlbumImagePreviewViewController(image: image, title: title)
        controller.modalPresentationStyle = .fullScreen
        controller.modalTransitionStyle = .crossDissolve
        present(controller, animated: true)
    }

    @objc private func confirmTapped() {
        guard let preset = presets.first(where: { $0.id == selectedPresetID }) else { return }
        let coverTemplate = selectedCoverTemplateID.flatMap { selectedID in
            coverTemplates.first(where: { $0.id == selectedID })
        }
        let atmosphereOption = selectedAtmosphereOptionID.flatMap { selectedID in
            atmosphereOptions.first(where: { $0.id == selectedID })
        }
        let selection = TravelAlbumAIEditSelection(
            refinedPreset: preset,
            atmosphereOption: atmosphereOption,
            coverTemplate: coverTemplate
        )
        onConfirm?(selection)
        dismiss(animated: true)
    }
}

extension TravelAlbumAIEditSheetViewController: UICollectionViewDelegate {
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        if collectionView === coverCollectionView {
            guard let template = coverDataSource.itemIdentifier(for: indexPath) else { return }
            selectedCoverTemplateID = template.id
            collectionView.visibleCells.compactMap { $0 as? TravelAlbumCoverTemplateCell }.forEach { cell in
                guard let visiblePath = collectionView.indexPath(for: cell),
                      let visibleTemplate = coverDataSource.itemIdentifier(for: visiblePath) else { return }
                cell.setSelected(visibleTemplate.id == selectedCoverTemplateID)
            }
            return
        }

        if collectionView === atmosphereCollectionView {
            guard let option = atmosphereDataSource.itemIdentifier(for: indexPath) else { return }
            // 氛围感为非必选项，再次点击当前样式即可取消本次氛围感结果。
            selectedAtmosphereOptionID = selectedAtmosphereOptionID == option.id ? nil : option.id
            collectionView.visibleCells.compactMap { $0 as? TravelAlbumEditPresetCell }.forEach { cell in
                guard let visiblePath = collectionView.indexPath(for: cell),
                      let visibleOption = atmosphereDataSource.itemIdentifier(for: visiblePath) else { return }
                cell.setSelected(visibleOption.id == selectedAtmosphereOptionID)
            }
            updateAtmosphereSelection()
            return
        }

        guard let preset = dataSource.itemIdentifier(for: indexPath) else { return }
        selectedPresetID = preset.id
        collectionView.visibleCells.compactMap { $0 as? TravelAlbumEditPresetCell }.forEach { cell in
            guard let visiblePath = collectionView.indexPath(for: cell), let visiblePreset = dataSource.itemIdentifier(for: visiblePath) else { return }
            cell.setSelected(visiblePreset.id == selectedPresetID)
        }
    }
}

/// 带效果缩略图的修图预设单元格。
private final class TravelAlbumEditPresetCell: UICollectionViewCell {
    static let reuseIdentifier = "TravelAlbumEditPresetCell"

    var onPreview: (() -> Void)?

    private let imageView = UIImageView()
    private let titleLabel = UILabel()
    private let selectionView = UIImageView(image: UIImage(systemName: "checkmark.circle.fill"))
    private let previewButton = UIButton(type: .system)

    override init(frame: CGRect) {
        super.init(frame: frame)
        contentView.backgroundColor = .white
        contentView.layer.cornerRadius = 10
        contentView.clipsToBounds = true
        imageView.contentMode = .scaleAspectFill
        imageView.clipsToBounds = true
        imageView.backgroundColor = UIColor(hex: 0xEAF2FF)
        titleLabel.font = .systemFont(ofSize: 12, weight: .medium)
        titleLabel.textColor = AppColor.textPrimary
        titleLabel.textAlignment = .center
        titleLabel.numberOfLines = 2
        selectionView.tintColor = AppColor.primary
        selectionView.backgroundColor = .white
        selectionView.layer.cornerRadius = 10
        selectionView.clipsToBounds = true
        previewButton.setTitle("预览", for: .normal)
        previewButton.setTitleColor(.white, for: .normal)
        previewButton.titleLabel?.font = .systemFont(ofSize: 11, weight: .medium)
        previewButton.backgroundColor = UIColor.black.withAlphaComponent(0.58)
        previewButton.layer.cornerRadius = 12
        previewButton.addTarget(self, action: #selector(previewTapped), for: .touchUpInside)
        contentView.addSubview(imageView)
        contentView.addSubview(titleLabel)
        contentView.addSubview(selectionView)
        contentView.addSubview(previewButton)
        imageView.snp.makeConstraints { make in
            make.top.leading.trailing.equalToSuperview()
            make.height.equalTo(96)
        }
        titleLabel.snp.makeConstraints { make in
            make.top.equalTo(imageView.snp.bottom).offset(6)
            make.leading.trailing.equalToSuperview().inset(5)
            make.bottom.lessThanOrEqualToSuperview().offset(-5)
        }
        selectionView.snp.makeConstraints { make in
            make.top.trailing.equalToSuperview().inset(6)
            make.size.equalTo(20)
        }
        previewButton.snp.makeConstraints { make in
            make.trailing.bottom.equalTo(imageView).inset(6)
            make.width.equalTo(46)
            make.height.equalTo(24)
        }
    }

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

    func apply(preset: TravelAlbumEditPreset, sourceImage: UIImage?, selected: Bool) {
        apply(
            title: preset.title,
            effect: preset.effect,
            sourceImage: sourceImage,
            selected: selected
        )
    }

    /// 更新氛围感样式的效果图、名称和单选状态。
    func apply(
        atmosphereOption: TravelAlbumAtmosphereEditOption,
        sourceImage: UIImage?,
        selected: Bool
    ) {
        apply(
            title: atmosphereOption.title,
            effect: atmosphereOption.effect,
            sourceImage: sourceImage,
            selected: selected
        )
        accessibilityHint = "再次点击已选样式可取消，点击预览按钮查看大图"
    }

    private func apply(
        title: String,
        effect: TravelAlbumEditPreset.Effect,
        sourceImage: UIImage?,
        selected: Bool
    ) {
        titleLabel.text = title
        imageView.image = sourceImage.map {
            TravelAlbumAIEditImageProcessor.render(effect: effect, source: $0)
        } ?? UIImage(systemName: "photo")
        setSelected(selected)
        accessibilityLabel = title
        accessibilityValue = selected ? "已选中" : "未选中"
    }

    func setSelected(_ selected: Bool) {
        contentView.layer.borderWidth = selected ? 2 : 0
        contentView.layer.borderColor = selected ? AppColor.primary.cgColor : UIColor.clear.cgColor
        selectionView.isHidden = !selected
        accessibilityValue = selected ? "已选中" : "未选中"
    }

    override func prepareForReuse() {
        super.prepareForReuse()
        onPreview = nil
        accessibilityHint = nil
    }

    @objc private func previewTapped() {
        onPreview?()
    }
}

/// 带本地排版效果图的封面模板单元格。
private final class TravelAlbumCoverTemplateCell: UICollectionViewCell {
    static let reuseIdentifier = "TravelAlbumCoverTemplateCell"

    var onPreview: (() -> Void)?

    private let imageView = UIImageView()
    private let titleLabel = UILabel()
    private let selectionView = UIImageView(image: UIImage(systemName: "checkmark.circle.fill"))
    private let previewButton = UIButton(type: .system)

    override init(frame: CGRect) {
        super.init(frame: frame)
        contentView.backgroundColor = .white
        contentView.layer.cornerRadius = 10
        contentView.clipsToBounds = true

        imageView.contentMode = .scaleAspectFill
        imageView.clipsToBounds = true
        imageView.backgroundColor = UIColor(hex: 0xEAF2FF)
        titleLabel.font = .systemFont(ofSize: 12, weight: .medium)
        titleLabel.textColor = AppColor.textPrimary
        titleLabel.textAlignment = .center
        selectionView.tintColor = AppColor.primary
        selectionView.backgroundColor = .white
        selectionView.layer.cornerRadius = 10
        selectionView.clipsToBounds = true
        previewButton.setTitle("预览", for: .normal)
        previewButton.setTitleColor(.white, for: .normal)
        previewButton.titleLabel?.font = .systemFont(ofSize: 11, weight: .medium)
        previewButton.backgroundColor = UIColor.black.withAlphaComponent(0.58)
        previewButton.layer.cornerRadius = 12
        previewButton.addTarget(self, action: #selector(previewTapped), for: .touchUpInside)

        contentView.addSubview(imageView)
        contentView.addSubview(titleLabel)
        contentView.addSubview(selectionView)
        contentView.addSubview(previewButton)
        imageView.snp.makeConstraints { make in
            make.top.leading.trailing.equalToSuperview()
            make.height.equalTo(104)
        }
        titleLabel.snp.makeConstraints { make in
            make.top.equalTo(imageView.snp.bottom).offset(6)
            make.leading.trailing.equalToSuperview().inset(5)
            make.bottom.lessThanOrEqualToSuperview().offset(-5)
        }
        selectionView.snp.makeConstraints { make in
            make.top.trailing.equalToSuperview().inset(6)
            make.size.equalTo(20)
        }
        previewButton.snp.makeConstraints { make in
            make.trailing.bottom.equalTo(imageView).inset(6)
            make.width.equalTo(46)
            make.height.equalTo(24)
        }
    }

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

    /// 更新模板效果图与单选状态。
    func apply(template: TravelAlbumCoverTemplate, sourceImage: UIImage?, selected: Bool) {
        titleLabel.text = template.title
        imageView.image = TravelAlbumCoverTemplateImageProcessor.render(
            template: template,
            source: sourceImage,
            targetSize: CGSize(width: 232, height: 208)
        )
        setSelected(selected)
        accessibilityLabel = "\(template.title)封面模板"
        accessibilityValue = selected ? "已选中" : "未选中"
        accessibilityHint = "点击预览按钮查看完整模板样式"
    }

    /// 刷新当前模板的选中描边和勾选标识。
    func setSelected(_ selected: Bool) {
        contentView.layer.borderWidth = selected ? 2 : 0
        contentView.layer.borderColor = selected ? AppColor.primary.cgColor : UIColor.clear.cgColor
        selectionView.isHidden = !selected
        accessibilityValue = selected ? "已选中" : "未选中"
    }

    override func prepareForReuse() {
        super.prepareForReuse()
        onPreview = nil
    }

    @objc private func previewTapped() {
        onPreview?()
    }
}