import UIKit

final class RDEPUBReaderHighlightsViewController: UITableViewController {

    var onSelectHighlight: ((RDEPUBHighlight) -> Void)?

    var onUpdateHighlight: ((RDEPUBHighlight) -> Void)?

    var onDeleteHighlight: ((RDEPUBHighlight) -> Void)?

    private var highlights: [RDEPUBHighlight]

    private let theme: RDEPUBReaderTheme

    private let sectionTitleProvider: (RDEPUBHighlight) -> String?

    private let filterControl = UISegmentedControl(items: ["全部", "注释", "划线"])

    /// 空状态提示。放在 tableView 的子视图而不是 `backgroundView`：
    /// backgroundView 不参与无障碍层级遍历，VoiceOver 与 UI 测试都读不到它。
    private let emptyStateLabel = UILabel()

    private var filteredHighlights: [RDEPUBHighlight] {
        switch filterControl.selectedSegmentIndex {
        case 1:
            return highlights.filter(\.hasNote)
        case 2:
            return highlights.filter { !$0.hasNote }
        default:
            return highlights
        }
    }

    init(
        highlights: [RDEPUBHighlight],
        theme: RDEPUBReaderTheme,
        sectionTitleProvider: @escaping (RDEPUBHighlight) -> String?
    ) {
        self.highlights = highlights.sorted { $0.createdAt > $1.createdAt }
        self.theme = theme
        self.sectionTitleProvider = sectionTitleProvider
        super.init(style: .plain)
        title = "标注"
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        view.accessibilityIdentifier = "epub.reader.highlights.panel"
        tableView.accessibilityIdentifier = "epub.reader.highlights.table"
        tableView.tableFooterView = UIView(frame: .zero)
        tableView.separatorStyle = .none
        tableView.contentInset = UIEdgeInsets(top: 12, left: 0, bottom: 20, right: 0)
        navigationItem.rightBarButtonItem = editButtonItem
        editButtonItem.title = "编辑"
        tableView.allowsMultipleSelectionDuringEditing = false
        configureFilterControl()
        applyTheme()
        updateEmptyState()
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        filteredHighlights.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cellIdentifier = "HighlightCell"
        let cell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier) ?? UITableViewCell(style: .subtitle, reuseIdentifier: cellIdentifier)
        let highlight = filteredHighlights[indexPath.row]

        cell.backgroundColor = .clear
        cell.contentView.backgroundColor = theme.contentBackgroundColor.withAlphaComponent(0.76)
        cell.contentView.layer.cornerRadius = 14
        cell.contentView.layer.masksToBounds = true
        cell.textLabel?.textColor = theme.contentTextColor
        cell.textLabel?.font = UIFont.systemFont(ofSize: 15, weight: .medium)
        cell.textLabel?.numberOfLines = 2
        cell.textLabel?.text = titleText(for: highlight)

        cell.detailTextLabel?.textColor = theme.contentTextColor.withAlphaComponent(0.65)
        cell.detailTextLabel?.font = UIFont.systemFont(ofSize: 12)
        cell.detailTextLabel?.numberOfLines = 3
        cell.detailTextLabel?.text = detailText(for: highlight)
        cell.accessoryType = .none
        return cell
    }

    override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat { 112 }

    override func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
        cell.contentView.frame = cell.bounds.inset(by: UIEdgeInsets(top: 6, left: 18, bottom: 6, right: 18))
    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        guard !tableView.isEditing else { return }
        tableView.deselectRow(at: indexPath, animated: true)
        onSelectHighlight?(filteredHighlights[indexPath.row])
    }

    override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
        true
    }

    override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
        guard editingStyle == .delete else { return }
        deleteHighlight(filteredHighlights[indexPath.row])
    }

    private func configureFilterControl() {
        filterControl.selectedSegmentIndex = 0
        filterControl.accessibilityIdentifier = "epub.reader.highlights.filter"
        filterControl.addTarget(self, action: #selector(filterChangedAction), for: .valueChanged)
        navigationItem.titleView = filterControl
    }

    private func applyTheme() {
        tableView.backgroundColor = theme.toolBackgroundColor
        navigationController?.navigationBar.tintColor = .systemBlue
        navigationController?.navigationBar.barTintColor = tableView.backgroundColor
        navigationController?.navigationBar.titleTextAttributes = [.foregroundColor: theme.toolControlTextColor]
        navigationController?.navigationBar.accessibilityIdentifier = "epub.reader.highlights.navbar"
    }

    private func installEmptyStateLabelIfNeeded() {
        guard emptyStateLabel.superview == nil else { return }
        emptyStateLabel.textAlignment = .center
        emptyStateLabel.numberOfLines = 0
        emptyStateLabel.translatesAutoresizingMaskIntoConstraints = false
        emptyStateLabel.accessibilityIdentifier = "epub.reader.highlights.empty"
        emptyStateLabel.isAccessibilityElement = true
        tableView.addSubview(emptyStateLabel)
        // 固定在可视区域居中，不随内容滚动
        NSLayoutConstraint.activate([
            emptyStateLabel.centerXAnchor.constraint(equalTo: tableView.frameLayoutGuide.centerXAnchor),
            emptyStateLabel.centerYAnchor.constraint(equalTo: tableView.frameLayoutGuide.centerYAnchor),
            emptyStateLabel.leadingAnchor.constraint(greaterThanOrEqualTo: tableView.frameLayoutGuide.leadingAnchor, constant: 24),
            emptyStateLabel.trailingAnchor.constraint(lessThanOrEqualTo: tableView.frameLayoutGuide.trailingAnchor, constant: -24)
        ])
    }

    private func updateEmptyState() {
        installEmptyStateLabelIfNeeded()
        emptyStateLabel.textColor = theme.contentTextColor.withAlphaComponent(0.7)
        emptyStateLabel.text = emptyStateText()
        emptyStateLabel.isHidden = !filteredHighlights.isEmpty
    }

    @objc private func filterChangedAction() {
        tableView.reloadData()
        updateEmptyState()
    }

    private func emptyStateText() -> String {
        switch filterControl.selectedSegmentIndex {
        case 1:
            return "暂无注释"
        case 2:
            return "暂无划线"
        default:
            return "暂无标注"
        }
    }

    private func detailText(for highlight: RDEPUBHighlight) -> String {
        let style = styleDescription(for: highlight)
        let chapter = sectionTitleProvider(highlight)
        let note = normalizedNote(highlight.note)
        let parts = [style, chapter, note].compactMap { $0 }
        if !parts.isEmpty {
            return parts.joined(separator: "\n")
        }
        return highlight.location.href
    }

    private func titleText(for highlight: RDEPUBHighlight) -> String {
        let text = highlight.text.trimmingCharacters(in: .whitespacesAndNewlines)
        if highlight.hasNote {
            return "注释：\(text)"
        }
        return text
    }

    private func styleDescription(for highlight: RDEPUBHighlight) -> String {
        switch highlight.style {
        case .highlight:
            return highlight.hasNote ? "划线注释" : "划线"
        case .underline:
            return highlight.hasNote ? "划线注释" : "划线"
        }
    }

    private func deleteHighlight(_ highlight: RDEPUBHighlight) {
        guard let index = highlights.firstIndex(where: { $0.id == highlight.id }) else { return }
        highlights.remove(at: index)
        tableView.reloadData()
        onDeleteHighlight?(highlight)
        updateEmptyState()
    }

    private func normalizedNote(_ note: String?) -> String? {
        let trimmed = note?.trimmingCharacters(in: .whitespacesAndNewlines) ?? ""
        return trimmed.isEmpty ? nil : trimmed
    }
}

final class RDEPUBReaderBookmarksViewController: UITableViewController {

    var onSelectBookmark: ((RDEPUBBookmark) -> Void)?

    var onDeleteBookmark: ((RDEPUBBookmark) -> Void)?

    private var bookmarks: [RDEPUBBookmark]

    private let theme: RDEPUBReaderTheme

    private let dateFormatter: DateFormatter = {
        let formatter = DateFormatter()
        formatter.dateFormat = "yyyy-MM-dd HH:mm"
        return formatter
    }()

    /// 同 highlights 面板：不能用 `tableView.backgroundView`，那样无障碍读不到。
    private let emptyStateLabel = UILabel()

    init(bookmarks: [RDEPUBBookmark], theme: RDEPUBReaderTheme) {
        self.bookmarks = bookmarks.sorted { $0.createdAt > $1.createdAt }
        self.theme = theme
        super.init(style: .plain)
        title = "书签"
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        view.accessibilityIdentifier = "epub.reader.bookmarks.panel"
        tableView.accessibilityIdentifier = "epub.reader.bookmarks.table"
        tableView.tableFooterView = UIView(frame: .zero)
        tableView.separatorStyle = .none
        tableView.contentInset = UIEdgeInsets(top: 12, left: 0, bottom: 20, right: 0)
        navigationItem.rightBarButtonItem = editButtonItem
        editButtonItem.title = "编辑"
        applyTheme()
        updateEmptyState()
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        bookmarks.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cellIdentifier = "BookmarkCell"
        let cell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier) ?? UITableViewCell(style: .subtitle, reuseIdentifier: cellIdentifier)
        let bookmark = bookmarks[indexPath.row]

        cell.backgroundColor = .clear
        cell.contentView.backgroundColor = theme.contentBackgroundColor.withAlphaComponent(0.76)
        cell.contentView.layer.cornerRadius = 14
        cell.contentView.layer.masksToBounds = true
        cell.textLabel?.textColor = theme.contentTextColor
        cell.textLabel?.font = UIFont.systemFont(ofSize: 15, weight: .medium)
        cell.textLabel?.numberOfLines = 2
        cell.textLabel?.text = titleText(for: bookmark)

        cell.detailTextLabel?.textColor = theme.contentTextColor.withAlphaComponent(0.65)
        cell.detailTextLabel?.font = UIFont.systemFont(ofSize: 12)
        cell.detailTextLabel?.numberOfLines = 3
        cell.detailTextLabel?.text = detailText(for: bookmark)
        cell.accessoryType = .none
        return cell
    }

    override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat { 104 }

    override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
        guard editingStyle == .delete else { return }
        deleteBookmark(bookmarks[indexPath.row])
    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        tableView.deselectRow(at: indexPath, animated: true)
        onSelectBookmark?(bookmarks[indexPath.row])
    }

    private func applyTheme() {
        tableView.backgroundColor = theme.toolBackgroundColor
        navigationController?.navigationBar.tintColor = .systemBlue
        navigationController?.navigationBar.barTintColor = tableView.backgroundColor
        navigationController?.navigationBar.titleTextAttributes = [.foregroundColor: theme.toolControlTextColor]
        navigationController?.navigationBar.accessibilityIdentifier = "epub.reader.bookmarks.navbar"
    }

    private func installEmptyStateLabelIfNeeded() {
        guard emptyStateLabel.superview == nil else { return }
        emptyStateLabel.text = "暂无书签"
        emptyStateLabel.textAlignment = .center
        emptyStateLabel.numberOfLines = 0
        emptyStateLabel.translatesAutoresizingMaskIntoConstraints = false
        emptyStateLabel.accessibilityIdentifier = "epub.reader.bookmarks.empty"
        emptyStateLabel.isAccessibilityElement = true
        tableView.addSubview(emptyStateLabel)
        NSLayoutConstraint.activate([
            emptyStateLabel.centerXAnchor.constraint(equalTo: tableView.frameLayoutGuide.centerXAnchor),
            emptyStateLabel.centerYAnchor.constraint(equalTo: tableView.frameLayoutGuide.centerYAnchor),
            emptyStateLabel.leadingAnchor.constraint(greaterThanOrEqualTo: tableView.frameLayoutGuide.leadingAnchor, constant: 24),
            emptyStateLabel.trailingAnchor.constraint(lessThanOrEqualTo: tableView.frameLayoutGuide.trailingAnchor, constant: -24)
        ])
    }

    private func updateEmptyState() {
        installEmptyStateLabelIfNeeded()
        emptyStateLabel.textColor = theme.contentTextColor.withAlphaComponent(0.7)
        emptyStateLabel.isHidden = !bookmarks.isEmpty
    }

    private func titleText(for bookmark: RDEPUBBookmark) -> String {
        if let chapterTitle = bookmark.chapterTitle, !chapterTitle.isEmpty {
            return chapterTitle
        }
        return bookmark.location.href
    }

    private func detailText(for bookmark: RDEPUBBookmark) -> String {
        let parts = [
            dateFormatter.string(from: bookmark.createdAt),
            bookmark.note?.trimmingCharacters(in: .whitespacesAndNewlines),
            bookmark.location.href
        ].compactMap { value -> String? in
            guard let value, !value.isEmpty else { return nil }
            return value
        }
        return parts.joined(separator: "\n")
    }

    private func deleteBookmark(_ bookmark: RDEPUBBookmark) {
        guard let index = bookmarks.firstIndex(where: { $0.id == bookmark.id }) else { return }
        bookmarks.remove(at: index)
        tableView.reloadData()
        onDeleteBookmark?(bookmark)
        updateEmptyState()
    }
}