import UIKit

final class RDEPUBReaderBottomToolView: RDEPUBReaderToolView {

    var onShowTableOfContents: (() -> Void)?

    var onShowBookmarks: (() -> Void)?

    var onShowHighlights: (() -> Void)?

    var onAddHighlight: (() -> Void)?

    var onShowSettings: (() -> Void)?

    private let stackView: UIStackView = {
        let view = UIStackView()
        view.axis = .horizontal
        view.distribution = .fillEqually
        view.alignment = .fill
        view.spacing = 16
        return view
    }()

    private let chapterButton = RDEPUBReaderTintButton(type: .system)

    private let bookmarksButton = RDEPUBReaderTintButton(type: .system)

    private let highlightsButton = RDEPUBReaderTintButton(type: .system)

    private let addHighlightButton = RDEPUBReaderTintButton(type: .system)

    private let settingsButton = RDEPUBReaderTintButton(type: .system)

    override init(frame: CGRect) {
        super.init(frame: frame)
        accessibilityIdentifier = "epub.reader.bottomToolbar"

        addSubview(stackView)
        stackView.translatesAutoresizingMaskIntoConstraints = false
        stackView.addArrangedSubview(chapterButton)
        stackView.addArrangedSubview(bookmarksButton)
        stackView.addArrangedSubview(highlightsButton)
        stackView.addArrangedSubview(addHighlightButton)
        stackView.addArrangedSubview(settingsButton)

        NSLayoutConstraint.activate([
            stackView.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 16),
            stackView.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -16),
            stackView.topAnchor.constraint(equalTo: topAnchor),
            stackView.bottomAnchor.constraint(equalTo: safeAreaLayoutGuide.bottomAnchor)
        ])

        configureButton(chapterButton, systemName: "list.bullet", fallbackTitle: "目录")
        configureButton(bookmarksButton, systemName: "bookmark", fallbackTitle: "书签")
        configureButton(highlightsButton, systemName: "note.text", fallbackTitle: "批注")
        configureButton(addHighlightButton, systemName: "highlighter", fallbackTitle: "标注")
        configureButton(settingsButton, systemName: "textformat.size", fallbackTitle: "设置")
        chapterButton.accessibilityIdentifier = "epub.reader.toc"
        bookmarksButton.accessibilityIdentifier = "epub.reader.bookmarks"
        highlightsButton.accessibilityIdentifier = "epub.reader.highlights"
        addHighlightButton.accessibilityIdentifier = "epub.reader.add-highlight"
        settingsButton.accessibilityIdentifier = "epub.reader.settings"

        [chapterButton, bookmarksButton, highlightsButton, addHighlightButton, settingsButton].forEach { button in
            button.heightAnchor.constraint(greaterThanOrEqualToConstant: 44).isActive = true
        }

        chapterButton.addTarget(self, action: #selector(chapterAction), for: .touchUpInside)
        bookmarksButton.addTarget(self, action: #selector(bookmarksAction), for: .touchUpInside)
        highlightsButton.addTarget(self, action: #selector(highlightsAction), for: .touchUpInside)
        addHighlightButton.addTarget(self, action: #selector(highlightAction), for: .touchUpInside)
        settingsButton.addTarget(self, action: #selector(settingsAction), for: .touchUpInside)
    }

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

    override func lineFrame(in bounds: CGRect) -> CGRect {
        CGRect(x: 0, y: 0, width: bounds.width, height: 0.5)
    }

    override func apply(theme: RDEPUBReaderTheme) {
        super.apply(theme: theme)
        [chapterButton, bookmarksButton, highlightsButton, addHighlightButton, settingsButton].forEach { button in
            button.tintColor = .black
            button.setTitleColor(.black, for: .normal)
        }
    }

    func setAddHighlightEnabled(_ isEnabled: Bool) {
        addHighlightButton.isEnabled = isEnabled
        addHighlightButton.alpha = isEnabled ? 1 : 0.45
    }

    func setHighlightsEnabled(_ isEnabled: Bool) {
        highlightsButton.isEnabled = isEnabled
        highlightsButton.alpha = isEnabled ? 1 : 0.45
    }

    func setBookmarksEnabled(_ isEnabled: Bool) {
        bookmarksButton.isEnabled = isEnabled
        bookmarksButton.alpha = isEnabled ? 1 : 0.45
    }

    func updateVisibility(
        showsTableOfContents: Bool,
        allowsHighlights: Bool,
        showsSettingsPanel: Bool
    ) {
        chapterButton.isHidden = !showsTableOfContents
        bookmarksButton.isHidden = false
        highlightsButton.isHidden = !allowsHighlights
        addHighlightButton.isHidden = !allowsHighlights
        settingsButton.isHidden = !showsSettingsPanel
    }

    private func configureButton(_ button: UIButton, systemName: String, fallbackTitle: String) {
        button.titleLabel?.font = UIFont.systemFont(ofSize: 14, weight: .medium)
        if #available(iOS 13.0, *), let image = UIImage(systemName: systemName) {
            button.setImage(image.withRenderingMode(.alwaysTemplate), for: .normal)
        } else {
            button.setTitle(fallbackTitle, for: .normal)
        }
    }

    @objc private func chapterAction() {
        onShowTableOfContents?()
    }

    @objc private func bookmarksAction() {
        onShowBookmarks?()
    }

    @objc private func highlightsAction() {
        onShowHighlights?()
    }

    @objc private func highlightAction() {
        onAddHighlight?()
    }

    @objc private func settingsAction() {
        onShowSettings?()
    }
}