//
//  CloudDriveListViewController.swift
//  suixinkan
//

import Kingfisher
import PhotosUI
import SnapKit
import UIKit
import UniformTypeIdentifiers

/// 相册云盘列表页，对齐 Android `CloudStorageListScreen`。
final class CloudDriveListViewController: BaseViewController {
    private let viewModel = CloudDriveListViewModel()
    private let api: any CloudDriveServing
    private let transferManager: CloudTransferManager

    private let pathScrollView = UIScrollView()
    private let pathStackView = UIStackView()
    private let searchContainer = UIView()
    private let searchIconView = UIImageView(image: CloudDriveAsset.image(named: "icon_cloud_storage_file_search", fallbackSystemName: "magnifyingglass"))
    private let searchField = UITextField()
    private let sortButton = UIButton(type: .system)
    private let filterButton = UIButton(type: .system)
    private let displayModeButton = UIButton(type: .system)
    private var collectionView: UICollectionView!
    private var dataSource: UICollectionViewDiffableDataSource<Int, CloudFile>!
    private let uploadButton = AppButton(title: "上传")
    private let bottomBar = UIView()

    /// 初始化相册云盘列表页。
    init(
        api: (any CloudDriveServing)? = nil,
        transferManager: CloudTransferManager = .shared
    ) {
        self.api = api ?? NetworkServices.shared.cloudDriveAPI
        self.transferManager = transferManager
        super.init(nibName: nil, bundle: nil)
    }

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

    override func setupNavigationBar() {
        title = "相册云盘"
        navigationItem.rightBarButtonItem = UIBarButtonItem(
            image: CloudDriveAsset.image(named: "icon_cloud_storage_transit", fallbackSystemName: "arrow.up.arrow.down.circle"),
            style: .plain,
            target: self,
            action: #selector(openTransferManager)
        )
    }

    override func setupUI() {
        view.backgroundColor = .white

        pathScrollView.showsHorizontalScrollIndicator = false
        pathStackView.axis = .horizontal
        pathStackView.alignment = .center
        pathStackView.spacing = AppSpacing.xs
        pathScrollView.addSubview(pathStackView)

        searchContainer.backgroundColor = AppColor.inputBackground
        searchContainer.layer.cornerRadius = AppRadius.xs
        searchIconView.tintColor = AppColor.textTertiary
        searchField.placeholder = "搜索文件名称"
        searchField.font = .app(.body)
        searchField.textColor = AppColor.textPrimary
        searchField.returnKeyType = .search
        searchField.delegate = self
        searchContainer.addSubview(searchIconView)
        searchContainer.addSubview(searchField)

        configureFilterButton(sortButton)
        configureFilterButton(filterButton)
        displayModeButton.tintColor = AppColor.textPrimary
        displayModeButton.backgroundColor = .white
        displayModeButton.layer.cornerRadius = AppRadius.xs

        collectionView = UICollectionView(frame: .zero, collectionViewLayout: makeLayout())
        collectionView.backgroundColor = .white
        collectionView.alwaysBounceVertical = true
        collectionView.delegate = self
        collectionView.register(CloudDriveFileCell.self, forCellWithReuseIdentifier: CloudDriveFileCell.reuseIdentifier)
        dataSource = UICollectionViewDiffableDataSource<Int, CloudFile>(collectionView: collectionView) { [weak self] collectionView, indexPath, file in
            let cell = collectionView.dequeueReusableCell(
                withReuseIdentifier: CloudDriveFileCell.reuseIdentifier,
                for: indexPath
            ) as! CloudDriveFileCell
            cell.apply(file: file, mode: self?.viewModel.displayMode ?? .grid)
            cell.onDetails = { [weak self] in self?.showControlSheet(for: file) }
            return cell
        }

        bottomBar.backgroundColor = .white
        bottomBar.layer.borderColor = AppColor.border.cgColor
        bottomBar.layer.borderWidth = 0.5

        view.addSubview(pathScrollView)
        view.addSubview(searchContainer)
        view.addSubview(sortButton)
        view.addSubview(filterButton)
        view.addSubview(displayModeButton)
        view.addSubview(collectionView)
        view.addSubview(bottomBar)
        bottomBar.addSubview(uploadButton)
    }

    override func setupConstraints() {
        pathScrollView.snp.makeConstraints { make in
            make.top.equalTo(view.safeAreaLayoutGuide)
            make.leading.trailing.equalToSuperview().inset(AppSpacing.md)
            make.height.equalTo(52)
        }
        pathStackView.snp.makeConstraints { make in
            make.edges.equalToSuperview()
            make.height.equalToSuperview()
        }
        searchContainer.snp.makeConstraints { make in
            make.top.equalTo(pathScrollView.snp.bottom).offset(2)
            make.leading.trailing.equalToSuperview().inset(AppSpacing.md)
            make.height.equalTo(36)
        }
        searchIconView.snp.makeConstraints { make in
            make.leading.equalToSuperview().offset(AppSpacing.sm)
            make.centerY.equalToSuperview()
            make.width.height.equalTo(16)
        }
        searchField.snp.makeConstraints { make in
            make.leading.equalTo(searchIconView.snp.trailing).offset(AppSpacing.sm)
            make.top.bottom.trailing.equalToSuperview().inset(AppSpacing.xs)
        }
        sortButton.snp.makeConstraints { make in
            make.top.equalTo(searchContainer.snp.bottom).offset(AppSpacing.md)
            make.leading.equalToSuperview().offset(AppSpacing.md)
            make.height.equalTo(36)
        }
        filterButton.snp.makeConstraints { make in
            make.top.width.height.equalTo(sortButton)
            make.leading.equalTo(sortButton.snp.trailing).offset(AppSpacing.sm)
        }
        displayModeButton.snp.makeConstraints { make in
            make.centerY.equalTo(sortButton)
            make.leading.equalTo(filterButton.snp.trailing).offset(AppSpacing.sm)
            make.trailing.equalToSuperview().inset(6)
            make.width.height.equalTo(36)
        }
        sortButton.snp.makeConstraints { make in
            make.width.equalTo(filterButton)
        }
        bottomBar.snp.makeConstraints { make in
            make.leading.trailing.bottom.equalToSuperview()
        }
        uploadButton.snp.makeConstraints { make in
            make.top.leading.trailing.equalToSuperview().inset(AppSpacing.md)
            make.bottom.equalTo(view.safeAreaLayoutGuide).inset(AppSpacing.md)
        }
        collectionView.snp.makeConstraints { make in
            make.top.equalTo(sortButton.snp.bottom).offset(AppSpacing.md)
            make.leading.trailing.equalToSuperview()
            make.bottom.equalTo(bottomBar.snp.top)
        }
    }

    override func bindActions() {
        uploadButton.addTarget(self, action: #selector(uploadTapped), for: .touchUpInside)
        displayModeButton.addTarget(self, action: #selector(displayModeTapped), for: .touchUpInside)
        viewModel.onStateChange = { [weak self] in
            Task { @MainActor in self?.applyViewModel() }
        }
        viewModel.onShowMessage = { [weak self] message in
            Task { @MainActor in self?.showToast(message) }
        }
        transferManager.onUploadCompleted = { [weak self] folderId in
            guard let self else { return }
            Task { await self.viewModel.handleUploadCompleted(parentFolderId: folderId, api: self.api) }
        }
        transferManager.onShowMessage = { [weak self] message in
            Task { @MainActor in self?.showToast(message) }
        }
        configureMenus()
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        Task { await viewModel.refresh(api: api, showLoading: true) }
    }

    @MainActor
    private func applyViewModel() {
        rebuildBreadcrumb()
        searchField.text = viewModel.searchText
        sortButton.setTitle(viewModel.sortType.title, for: .normal)
        filterButton.setTitle(viewModel.filterType.title, for: .normal)
        let displayIconName = viewModel.displayMode == .grid ? "icon_cloud_storage_show_type_list" : "icon_cloud_storage_show_type_table"
        let displayFallback = viewModel.displayMode == .grid ? "list.bullet" : "square.grid.2x2"
        displayModeButton.setImage(CloudDriveAsset.image(named: displayIconName, fallbackSystemName: displayFallback), for: .normal)
        sortButton.setImage(CloudDriveAsset.image(named: "icon_cloud_storage_list_sort", fallbackSystemName: "arrow.up.arrow.down"), for: .normal)
        filterButton.setImage(CloudDriveAsset.image(named: "icon_cloud_storage_file_filter", fallbackSystemName: "line.3.horizontal.decrease.circle"), for: .normal)
        collectionView.setCollectionViewLayout(makeLayout(), animated: false)

        var snapshot = NSDiffableDataSourceSnapshot<Int, CloudFile>()
        snapshot.appendSections([0])
        snapshot.appendItems(viewModel.files)
        dataSource.apply(snapshot, animatingDifferences: true)

        if viewModel.isLoading && viewModel.files.isEmpty {
            showLoading()
        } else {
            hideLoading()
        }
    }

    private func rebuildBreadcrumb() {
        pathStackView.arrangedSubviews.forEach { $0.removeFromSuperview() }
        let homeButton = UIButton(type: .system)
        homeButton.setImage(CloudDriveAsset.image(named: "icon_cloud_storage_go_home", fallbackSystemName: "house.fill"), for: .normal)
        homeButton.tintColor = AppColor.textPrimary
        homeButton.addTarget(self, action: #selector(homeTapped), for: .touchUpInside)
        homeButton.snp.makeConstraints { make in
            make.width.height.equalTo(24)
        }
        pathStackView.addArrangedSubview(homeButton)

        for (index, item) in viewModel.pathStack.enumerated() {
            if index > 0 {
                let arrow = UIImageView(image: CloudDriveAsset.image(named: "icon_cloud_storage_current_path_arrow", fallbackSystemName: "chevron.right"))
                arrow.tintColor = AppColor.textTertiary
                arrow.snp.makeConstraints { make in
                    make.width.equalTo(8)
                }
                pathStackView.addArrangedSubview(arrow)
            }
            let button = UIButton(type: .system)
            button.setTitle(item.name, for: .normal)
            button.titleLabel?.font = .app(index == viewModel.pathStack.count - 1 ? .body : .caption)
            button.setTitleColor(index == viewModel.pathStack.count - 1 ? .black : AppColor.textSecondary, for: .normal)
            button.tag = index
            button.addTarget(self, action: #selector(pathTapped(_:)), for: .touchUpInside)
            pathStackView.addArrangedSubview(button)
        }
    }

    private func configureMenus() {
        sortButton.menu = UIMenu(children: CloudDriveSortType.allCases.map { type in
            UIAction(title: type.title) { [weak self] _ in
                guard let self else { return }
                Task { await self.viewModel.chooseSortType(type, api: self.api) }
            }
        })
        sortButton.showsMenuAsPrimaryAction = true

        filterButton.menu = UIMenu(children: CloudDriveFilterType.allCases.map { type in
            UIAction(title: type.title) { [weak self] _ in
                guard let self else { return }
                Task { await self.viewModel.chooseFilterType(type, api: self.api) }
            }
        })
        filterButton.showsMenuAsPrimaryAction = true
    }

    private func configureFilterButton(_ button: UIButton) {
        button.backgroundColor = AppColor.inputBackground
        button.layer.cornerRadius = AppRadius.xs
        button.titleLabel?.font = .app(.caption)
        button.setTitleColor(AppColor.textPrimary, for: .normal)
        button.contentHorizontalAlignment = .left
        button.imageView?.contentMode = .scaleAspectFit
        button.tintColor = AppColor.textPrimary
        button.semanticContentAttribute = .forceLeftToRight
        button.imageEdgeInsets = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: AppSpacing.xs)
        button.contentEdgeInsets = UIEdgeInsets(top: 0, left: AppSpacing.sm, bottom: 0, right: AppSpacing.sm)
    }

    private func makeLayout() -> UICollectionViewCompositionalLayout {
        UICollectionViewCompositionalLayout { [weak self] _, environment in
            let mode = self?.viewModel.displayMode ?? .grid
            switch mode {
            case .grid:
                let columns = 2
                let spacing: CGFloat = 15
                let horizontalInset: CGFloat = 12
                let availableWidth = environment.container.effectiveContentSize.width - horizontalInset * 2
                let itemWidth = (availableWidth - spacing) / CGFloat(columns)
                let itemSize = NSCollectionLayoutSize(widthDimension: .absolute(itemWidth), heightDimension: .absolute(itemWidth * 0.82))
                let item = NSCollectionLayoutItem(layoutSize: itemSize)
                let groupSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1), heightDimension: .absolute(itemWidth * 0.82))
                let group = NSCollectionLayoutGroup.horizontal(layoutSize: groupSize, repeatingSubitem: item, count: columns)
                group.interItemSpacing = .fixed(spacing)
                let section = NSCollectionLayoutSection(group: group)
                section.contentInsets = NSDirectionalEdgeInsets(top: 12, leading: horizontalInset, bottom: 12, trailing: horizontalInset)
                section.interGroupSpacing = spacing
                return section
            case .list:
                let itemSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1), heightDimension: .absolute(72))
                let item = NSCollectionLayoutItem(layoutSize: itemSize)
                let group = NSCollectionLayoutGroup.vertical(layoutSize: itemSize, subitems: [item])
                let section = NSCollectionLayoutSection(group: group)
                section.contentInsets = NSDirectionalEdgeInsets(top: 0, leading: AppSpacing.md, bottom: AppSpacing.md, trailing: AppSpacing.md)
                return section
            }
        }
    }

    private func showControlSheet(for file: CloudFile) {
        viewModel.setControlFile(file)
        let sheet = CloudDriveActionSheetViewController(title: "请选择", items: [
            CloudDriveActionSheetViewController.Item(
                title: "删除",
                image: CloudDriveAsset.image(named: "icon_cloud_storage_file_delete", fallbackSystemName: "trash"),
                isDestructive: true
            ) { [weak self] in self?.confirmDelete() },
            CloudDriveActionSheetViewController.Item(
                title: "下载",
                image: CloudDriveAsset.image(named: "icon_cloud_storage_file_download", fallbackSystemName: "arrow.down.circle"),
                isDestructive: false
            ) { [weak self] in self?.download(file) },
            CloudDriveActionSheetViewController.Item(
                title: "移动",
                image: CloudDriveAsset.image(named: "icon_cloud_storage_file_move", fallbackSystemName: "folder"),
                isDestructive: false
            ) { [weak self] in self?.showMoveDialog() },
            CloudDriveActionSheetViewController.Item(
                title: "详情",
                image: CloudDriveAsset.image(named: "icon_cloud_storage_file_item_details", fallbackSystemName: "info.circle"),
                isDestructive: false
            ) { [weak self] in self?.showDetailDialog(file) }
        ])
        present(sheet, animated: true)
    }

    private func confirmDelete() {
        showAlert(title: "删除确认", message: "删除后无法恢复，确认删除吗？") { [weak self] in
            guard let self else { return }
            Task { await self.viewModel.deleteCurrentFile(api: self.api) }
        }
    }

    private func download(_ file: CloudFile) {
        guard file.isSelectableMedia else {
            showToast("当前类型不支持下载")
            return
        }
        guard !file.fileUrl.isEmpty else {
            showToast("文件地址不存在")
            return
        }
        transferManager.addDownloadTask(fileURL: file.fileUrl, fileName: file.name, fileType: file.type, fileSize: file.fileSize)
    }

    private func showMoveDialog() {
        let items = viewModel.moveTargetFolders().map { folder in
            CloudDriveActionSheetViewController.Item(
                title: folder.name,
                image: CloudDriveAsset.image(named: "icon_cloud_storage_file_type_folder", fallbackSystemName: "folder"),
                isDestructive: false
            ) { [weak self] in
                guard let self else { return }
                Task { await self.viewModel.moveCurrentFile(targetFolderId: folder.id, api: self.api) }
            }
        }
        present(CloudDriveActionSheetViewController(title: "移动到", items: items), animated: true)
    }

    private func showDetailDialog(_ file: CloudFile) {
        let sheet = CloudDriveDetailSheetViewController(file: file) { [weak self] name in
            guard let self else { return }
            Task { await self.viewModel.saveCurrentFileName(name, api: self.api) }
        }
        present(sheet, animated: true)
    }

    @objc private func uploadTapped() {
        let sheet = CloudDriveActionSheetViewController(title: "选择上传类型", items: [
            CloudDriveActionSheetViewController.Item(
                title: "上传图片",
                image: CloudDriveAsset.image(named: "icon_cloud_storage_add_photo", fallbackSystemName: "photo"),
                isDestructive: false
            ) { [weak self] in self?.beginPick(type: 1) },
            CloudDriveActionSheetViewController.Item(
                title: "上传视频",
                image: CloudDriveAsset.image(named: "icon_cloud_storage_add_video", fallbackSystemName: "video"),
                isDestructive: false
            ) { [weak self] in self?.beginPick(type: 2) },
            CloudDriveActionSheetViewController.Item(
                title: "新建文件夹",
                image: CloudDriveAsset.image(named: "icon_cloud_storage_add_folder", fallbackSystemName: "folder.badge.plus"),
                isDestructive: false
            ) { [weak self] in self?.showCreateFolderDialog() }
        ])
        present(sheet, animated: true)
    }

    private func beginPick(type: Int) {
        Task {
            guard await viewModel.checkCanUpload(api: api) else { return }
            await MainActor.run {
                var configuration = PHPickerConfiguration(photoLibrary: .shared())
                configuration.selectionLimit = 1
                configuration.filter = type == 1 ? .images : .videos
                let picker = PHPickerViewController(configuration: configuration)
                picker.delegate = self
                picker.view.tag = type
                present(picker, animated: true)
            }
        }
    }

    private func showCreateFolderDialog() {
        guard viewModel.pathStack.count < 5 else {
            showToast("不能创建更深的文件夹")
            return
        }
        let alert = UIAlertController(title: "新建文件夹", message: nil, preferredStyle: .alert)
        alert.addTextField { textField in
            textField.placeholder = "请输入文件夹名称"
        }
        alert.addAction(UIAlertAction(title: "取消", style: .cancel))
        alert.addAction(UIAlertAction(title: "确定", style: .default) { [weak self, weak alert] _ in
            guard let self else { return }
            let name = alert?.textFields?.first?.text ?? ""
            Task { await self.viewModel.addFolder(name: name, api: self.api) }
        })
        present(alert, animated: true)
    }

    @objc private func displayModeTapped() {
        viewModel.toggleDisplayMode()
    }

    @objc private func openTransferManager() {
        navigationController?.pushViewController(CloudDriveTransferViewController(manager: transferManager), animated: true)
    }

    @objc private func homeTapped() {
        Task { await viewModel.goHome(api: api) }
    }

    @objc private func pathTapped(_ sender: UIButton) {
        Task { await viewModel.navigateToPathIndex(sender.tag, api: api) }
    }

    private func openPreview(file: CloudFile) {
        navigationController?.pushViewController(CloudDrivePreviewViewController(file: file), animated: true)
    }

    private func stagePickedFile(result: PHPickerResult, fileType: Int) {
        let provider = result.itemProvider
        let typeIdentifier = fileType == 2 ? UTType.image.identifier : UTType.movie.identifier
        provider.loadFileRepresentation(forTypeIdentifier: typeIdentifier) { [weak self] url, error in
            guard let self else { return }
            if let error {
                Task { @MainActor in self.showToast(error.localizedDescription) }
                return
            }
            guard let url else { return }
            do {
                let stagedURL = try Self.copyPickedFileToStage(url: url, suggestedName: provider.suggestedName, fileType: fileType)
                let size = (try? FileManager.default.attributesOfItem(atPath: stagedURL.path)[.size] as? NSNumber)?.int64Value ?? 0
                Task { @MainActor in
                    self.transferManager.addUploadTask(
                        localFileURL: stagedURL,
                        fileName: stagedURL.lastPathComponent,
                        fileType: fileType,
                        fileSize: size,
                        parentFolderId: self.viewModel.currentFolderID
                    )
                }
            } catch {
                Task { @MainActor in self.showToast(error.localizedDescription) }
            }
        }
    }

    private static func copyPickedFileToStage(url: URL, suggestedName: String?, fileType: Int) throws -> URL {
        let directory = FileManager.default.temporaryDirectory.appendingPathComponent("cloud_drive_uploads", isDirectory: true)
        try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
        let ext = url.pathExtension.isEmpty ? (fileType == 2 ? "jpg" : "mp4") : url.pathExtension
        let baseName = CloudTransferFileName.sanitized(suggestedName ?? "cloud_upload")
        let fileName = baseName.lowercased().hasSuffix(".\(ext.lowercased())") ? baseName : "\(baseName).\(ext)"
        let destination = directory.appendingPathComponent("\(UUID().uuidString.replacingOccurrences(of: "-", with: ""))_\(fileName)")
        if FileManager.default.fileExists(atPath: destination.path) {
            try FileManager.default.removeItem(at: destination)
        }
        try FileManager.default.copyItem(at: url, to: destination)
        return destination
    }
}

extension CloudDriveListViewController: UITextFieldDelegate {
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        viewModel.updateSearchText(textField.text ?? "")
        textField.resignFirstResponder()
        Task { await viewModel.refresh(api: api, showLoading: true) }
        return true
    }
}

extension CloudDriveListViewController: UICollectionViewDelegate {
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        guard let file = dataSource.itemIdentifier(for: indexPath) else { return }
        Task {
            if let preview = await viewModel.handleFileTap(file, api: api) {
                await MainActor.run { self.openPreview(file: preview) }
            }
        }
    }

    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        let offsetY = scrollView.contentOffset.y
        let contentHeight = scrollView.contentSize.height
        let frameHeight = scrollView.frame.size.height
        if offsetY > contentHeight - frameHeight - 120 {
            let lastIndex = max(0, viewModel.files.count - 1)
            Task { await viewModel.loadMoreIfNeeded(lastVisibleIndex: lastIndex, api: api) }
        }
    }
}

extension CloudDriveListViewController: PHPickerViewControllerDelegate {
    func picker(_ picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) {
        let type = picker.view.tag
        picker.dismiss(animated: true)
        guard let result = results.first else { return }
        stagePickedFile(result: result, fileType: type == 2 ? 1 : 2)
    }
}