import UIKit

protocol RDEPUBWebContentViewDelegate: AnyObject {

    func epubWebContentView(_ contentView: RDEPUBWebContentView, didUpdateLocation location: RDEPUBLocation, spineIndex: Int)

    func epubWebContentView(_ contentView: RDEPUBWebContentView, didChangeSelection selection: RDEPUBSelection?, spineIndex: Int)

    func epubWebContentView(_ contentView: RDEPUBWebContentView, didRequestSelectionAction action: RDEPUBAnnotationMenuAction)

    func epubWebContentView(_ contentView: RDEPUBWebContentView, didActivateInternalLink location: RDEPUBLocation, fromSpineIndex: Int)

    func epubWebContentView(_ contentView: RDEPUBWebContentView, didActivateExternalLink url: URL)

    func epubWebContentView(_ contentView: RDEPUBWebContentView, didLogJavaScriptError message: String)

    func epubWebContentView(_ contentView: RDEPUBWebContentView, didTapImageWithSource src: String, sourceRect: CGRect?)

    func epubWebContentView(_ contentView: RDEPUBWebContentView, didTapFootnoteWithAltText altText: String, sourceRect: CGRect?)
}

final class RDEPUBWebContentView: UIView, RDEpubReaderPageResourceReleasing, RDEpubReaderPageVisibilityHandling {
    weak var delegate: RDEPUBWebContentViewDelegate?

    /// The current href of the loaded chapter (exposed for image resolution).
    var currentHref: String {
        epubWebView.currentHref
    }

    private let epubWebView = RDEPUBWebView()
    private let decorationOverlayView = RDEPUBWebDecorationOverlayView()
    private let pageNumberLabel: UILabel = {
        let label = UILabel()
        label.font = UIFont.systemFont(ofSize: 13)
        return label
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)
        clipsToBounds = true
        layer.masksToBounds = true

        addSubview(epubWebView)
        addSubview(decorationOverlayView)
        addSubview(pageNumberLabel)
        epubWebView.delegate = self
        epubWebView.onDecorationsResolved = { [weak self] decorations in
            self?.decorationOverlayView.applyDecorations(decorations)
        }
    }

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

    override func layoutSubviews() {
        super.layoutSubviews()
        epubWebView.frame = bounds
        decorationOverlayView.frame = bounds

        let labelSize = pageNumberLabel.sizeThatFits(CGSize(width: bounds.width, height: 20))
        pageNumberLabel.frame = CGRect(
            x: bounds.width - labelSize.width - 24,
            y: bounds.height - labelSize.height - 20,
            width: labelSize.width,
            height: labelSize.height
        )
    }

    func configure(
        publication: RDEPUBPublication,
        request: RDEPUBRenderRequest,
        pageNumber: Int,
        totalPages: Int,
        theme: RDEPUBReaderTheme
    ) {
        backgroundColor = theme.contentBackgroundColor
        pageNumberLabel.textColor = theme.contentTextColor
        pageNumberLabel.text = "\(pageNumber) / \(totalPages)"
        decorationOverlayView.applyDecorations([])
        epubWebView.load(publication: publication, request: request)
        setNeedsLayout()
    }

    func releaseResources() {
        decorationOverlayView.applyDecorations([])
        epubWebView.reset()
        epubWebView.delegate = self
        epubWebView.onDecorationsResolved = { [weak self] decorations in
            self?.decorationOverlayView.applyDecorations(decorations)
        }
    }

    func readerPageVisibilityDidChange(isVisible: Bool) {
        epubWebView.setReaderPageVisible(isVisible)
    }
}

extension RDEPUBWebContentView: RDEPUBWebViewDelegate {
    func epubWebView(_ webView: RDEPUBWebView, didUpdateLocation location: RDEPUBLocation, spineIndex: Int) {
        delegate?.epubWebContentView(self, didUpdateLocation: location, spineIndex: spineIndex)
    }

    func epubWebView(_ webView: RDEPUBWebView, didChangeSelection selection: RDEPUBSelection?, spineIndex: Int) {
        delegate?.epubWebContentView(self, didChangeSelection: selection, spineIndex: spineIndex)
    }

    func epubWebView(_ webView: RDEPUBWebView, didRequestSelectionAction action: RDEPUBAnnotationMenuAction) {
        delegate?.epubWebContentView(self, didRequestSelectionAction: action)
    }

    func epubWebView(_ webView: RDEPUBWebView, didActivateInternalLink location: RDEPUBLocation, fromSpineIndex: Int) {
        delegate?.epubWebContentView(self, didActivateInternalLink: location, fromSpineIndex: fromSpineIndex)
    }

    func epubWebView(_ webView: RDEPUBWebView, didActivateExternalLink url: URL) {
        delegate?.epubWebContentView(self, didActivateExternalLink: url)
    }

    func epubWebView(_ webView: RDEPUBWebView, didLogJavaScriptError message: String) {
        delegate?.epubWebContentView(self, didLogJavaScriptError: message)
    }
    func epubWebViewDidFinishRendering(_ webView: RDEPUBWebView) {}
    func epubWebView(_ webView: RDEPUBWebView, didTapImageWithSource src: String, sourceRect: CGRect?) {
        delegate?.epubWebContentView(self, didTapImageWithSource: src, sourceRect: sourceRect)
    }
    func epubWebView(_ webView: RDEPUBWebView, didTapFootnoteWithAltText altText: String, sourceRect: CGRect?) {
        delegate?.epubWebContentView(self, didTapFootnoteWithAltText: altText, sourceRect: sourceRect)
    }
}

extension RDEPUBWebContentViewDelegate {
    func epubWebContentView(_ contentView: RDEPUBWebContentView, didTapImageWithSource src: String, sourceRect: CGRect?) {
        // Default: no-op. Implementors can present an image viewer.
    }
    func epubWebContentView(_ contentView: RDEPUBWebContentView, didTapFootnoteWithAltText altText: String, sourceRect: CGRect?) {
        // Default: no-op. Implementors can present a footnote tooltip.
    }
}