import UIKit

final class RDEPUBNotePopupViewController: UIViewController {

    private let note: RDEPUBResolvedNote
    private let theme: RDEPUBReaderTheme
    private let onReturnToSource: (() -> Void)?
    private let onOpenNoteLocation: (() -> Void)?

    private let textView = UITextView()
    private let actionsStackView = UIStackView()

    init(
        note: RDEPUBResolvedNote,
        theme: RDEPUBReaderTheme,
        onReturnToSource: (() -> Void)? = nil,
        onOpenNoteLocation: (() -> Void)? = nil
    ) {
        self.note = note
        self.theme = theme
        self.onReturnToSource = onReturnToSource
        self.onOpenNoteLocation = onOpenNoteLocation
        super.init(nibName: nil, bundle: nil)
        title = note.title ?? "注释"
    }

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

    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = theme.toolBackgroundColor
        navigationItem.rightBarButtonItem = UIBarButtonItem(
            barButtonSystemItem: .done,
            target: self,
            action: #selector(close)
        )

        textView.translatesAutoresizingMaskIntoConstraints = false
        textView.isEditable = false
        textView.alwaysBounceVertical = true
        textView.backgroundColor = .clear
        textView.textContainerInset = UIEdgeInsets(top: 18, left: 18, bottom: 24, right: 18)
        textView.attributedText = attributedContent()
        textView.accessibilityIdentifier = "epub.reader.note.text"
        actionsStackView.translatesAutoresizingMaskIntoConstraints = false
        actionsStackView.axis = .horizontal
        actionsStackView.spacing = 12
        actionsStackView.distribution = .fillEqually
        actionsStackView.accessibilityIdentifier = "epub.reader.note.actions"
        configureActionButtons()

        view.addSubview(actionsStackView)
        view.addSubview(textView)

        NSLayoutConstraint.activate([
            actionsStackView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 18),
            actionsStackView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -18),
            actionsStackView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 12),
            actionsStackView.heightAnchor.constraint(equalToConstant: actionsStackView.arrangedSubviews.isEmpty ? 0 : 36),
            textView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            textView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            textView.topAnchor.constraint(equalTo: actionsStackView.bottomAnchor, constant: actionsStackView.arrangedSubviews.isEmpty ? 0 : 8),
            textView.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        ])
    }

    private func configureActionButtons() {
        if note.sourceLocation != nil, onReturnToSource != nil {
            actionsStackView.addArrangedSubview(
                makeActionButton(title: "返回原文", action: #selector(returnToSource))
            )
        }
        if onOpenNoteLocation != nil {
            actionsStackView.addArrangedSubview(
                makeActionButton(title: "打开注释原文", action: #selector(openNoteLocation))
            )
        }
        actionsStackView.isHidden = actionsStackView.arrangedSubviews.isEmpty
    }

    private func makeActionButton(title: String, action: Selector) -> UIButton {
        let button = UIButton(type: .system)
        var configuration = UIButton.Configuration.filled()
        configuration.cornerStyle = .medium
        configuration.title = title
        configuration.baseBackgroundColor = theme.toolControlTextColor.withAlphaComponent(0.10)
        configuration.baseForegroundColor = theme.toolControlTextColor
        button.configuration = configuration
        if title == "返回原文" {
            button.accessibilityIdentifier = "epub.reader.note.return"
        } else if title == "打开注释原文" {
            button.accessibilityIdentifier = "epub.reader.note.open"
        }
        button.addTarget(self, action: action, for: .touchUpInside)
        return button
    }

    private func attributedContent() -> NSAttributedString {
        let html = """
        <html>
        <head>
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <style>
        body {
          font: -apple-system-body;
          color: \(theme.themeTextColorCSS);
          line-height: 1.55;
        }
        a { color: #3b6ea8; }
        img, svg, table { max-width: 100%; height: auto; }
        </style>
        </head>
        <body>\(note.html)</body>
        </html>
        """
        guard let data = html.data(using: .utf8),
              let attributed = try? NSMutableAttributedString(
                data: data,
                options: [
                    .documentType: NSAttributedString.DocumentType.html,
                    .characterEncoding: String.Encoding.utf8.rawValue
                ],
                documentAttributes: nil
              ) else {
            return NSAttributedString(string: note.plainText)
        }
        return attributed
    }

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

    @objc private func returnToSource() {
        dismiss(animated: true) { [onReturnToSource] in
            onReturnToSource?()
        }
    }

    @objc private func openNoteLocation() {
        dismiss(animated: true) { [onOpenNoteLocation] in
            onOpenNoteLocation?()
        }
    }
}