import UIKit
import WebKit

public protocol RDEPUBWebViewDelegate: AnyObject {

    func epubWebView(_ webView: RDEPUBWebView, didUpdateLocation location: RDEPUBLocation, spineIndex: Int)

    func epubWebView(_ webView: RDEPUBWebView, didChangeSelection selection: RDEPUBSelection?, spineIndex: Int)

    func epubWebView(_ webView: RDEPUBWebView, didRequestSelectionAction action: RDEPUBAnnotationMenuAction)

    func epubWebView(_ webView: RDEPUBWebView, didActivateInternalLink location: RDEPUBLocation, fromSpineIndex: Int)

    func epubWebView(_ webView: RDEPUBWebView, didActivateExternalLink url: URL)

    func epubWebView(_ webView: RDEPUBWebView, didLogJavaScriptError message: String)

    func epubWebViewDidFinishRendering(_ webView: RDEPUBWebView)

    func epubWebView(_ webView: RDEPUBWebView, didTapImageWithSource src: String, sourceRect: CGRect?)

    func epubWebView(_ webView: RDEPUBWebView, didTapFootnoteWithAltText altText: String, sourceRect: CGRect?)
}

public extension RDEPUBWebViewDelegate {
    func epubWebView(_ webView: RDEPUBWebView, didRequestSelectionAction action: RDEPUBAnnotationMenuAction) {}
    func epubWebView(_ webView: RDEPUBWebView, didTapImageWithSource src: String, sourceRect: CGRect?) {}
    func epubWebView(_ webView: RDEPUBWebView, didTapFootnoteWithAltText altText: String, sourceRect: CGRect?) {}
}

final class RDEPUBAnnotationWebView: WKWebView {

    var onSelectionAction: ((RDEPUBAnnotationMenuAction) -> Void)?

    // M-15: Backing store for UIEditMenuInteraction (iOS 16+).
    // Stored as Any? to avoid @available on stored property restriction.
    var _editMenuInteraction: Any?

    override var canBecomeFirstResponder: Bool {
        true
    }

    override func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
        switch action {
        case #selector(rd_copy(_:)),
             #selector(rd_highlight(_:)),
             #selector(rd_annotate(_:)):
            return true
        default:
            return false
        }
    }

    @objc func rd_copy(_ sender: Any?) {
        onSelectionAction?(.copy)
    }

    @objc func rd_highlight(_ sender: Any?) {
        onSelectionAction?(.highlight)
    }

    @objc func rd_annotate(_ sender: Any?) {
        onSelectionAction?(.annotate)
    }
}

// MARK: - UIEditMenuInteractionDelegate (iOS 16+)

@available(iOS 16.0, *)
extension RDEPUBAnnotationWebView: UIEditMenuInteractionDelegate {
    func editMenuInteraction(
        _ interaction: UIEditMenuInteraction,
        menuFor configuration: UIEditMenuConfiguration
    ) -> UIMenu {
        UIMenu(children: [
            UICommand(title: "复制", action: #selector(rd_copy(_:))),
            UICommand(title: "划线", action: #selector(rd_highlight(_:))),
            UICommand(title: "注释", action: #selector(rd_annotate(_:)))
        ])
    }

    func editMenuInteraction(
        _ interaction: UIEditMenuInteraction,
        targetRectFor configuration: UIEditMenuConfiguration
    ) -> CGRect {
        bounds
    }
}

public final class RDEPUBWebView: UIView {

    public weak var delegate: RDEPUBWebViewDelegate?

    public var onRendered: (() -> Void)?

    var onDecorationsResolved: (([RDEPUBTextOverlayDecoration]) -> Void)?

        var publication: RDEPUBPublication?

        var currentRenderRequest: RDEPUBRenderRequest?

        var webView: WKWebView?

        var schemeHandler: RDEPUBResourceURLSchemeHandler?

        var configuredPublicationKey: String?

        var currentLoadSignature: String?

        var currentSpineIndex = 0

        var currentHref = ""

        var currentPageIndex = 0

        var currentTotalPagesInChapter = 1

        var viewportSize: CGSize = .zero

        var currentPadding: UIEdgeInsets = .zero

        var currentFontSize: CGFloat = 16

        var currentLineHeightMultiple: CGFloat = 1.5

        var currentThemeBackgroundColor: String?

        var currentThemeTextColor: String?

        var targetLocation: RDEPUBLocation?

        var pendingHighlights: [RDEPUBHighlight] = []

        var fixedSpread: EPUBFixedSpread?

        var isFixedLayout = false

        var isReaderPageVisible = true

        var hasReaderPageBeenVisible = false

        var needsReaderPagePlaybackRestart = false

        var appliedNativeMediaPlaybackSuspended = false

        var isNativeMediaPlaybackOperationInFlight = false

        var nativeMediaPlaybackOperationGeneration: UInt = 0

        var nativeMediaPlaybackRequests: [(suspended: Bool, completion: () -> Void)] = []

        var isWaitingForReaderPageMediaNavigation = false

        var pendingReaderPageMediaNavigation: WKNavigation?

        var isReaderPageMediaActivationBlocked = false

        var pendingProgressionRequest = false

        var fixedLayoutReadyWorkItem: DispatchWorkItem?

        var didRenderCurrentRequest = false

        let debugScope = "ReaderWebView"

    public override init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = .clear
    }

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

    // M-08: script message handler 经 RDEPUBWeakScriptMessageHandler 弱代理注册
    // （见 configureWebViewIfNeeded），webView → userContentController → self
    // 的保留环不再成立，deinit 会随最后一个持有者释放而正常触发。
    // reset() 仍可用于在丢弃路径上提前拆除 WKWebView（不必等 dealloc）。
    deinit {
        teardownWebView()
    }

    public override func layoutSubviews() {
        super.layoutSubviews()
        webView?.frame = bounds
    }

    public func reset() {
        delegate = nil
        onRendered = nil
        onDecorationsResolved = nil
        publication = nil
        currentRenderRequest = nil
        currentSpineIndex = 0
        currentHref = ""
        currentPageIndex = 0
        currentTotalPagesInChapter = 1
        viewportSize = .zero
        currentPadding = .zero
        currentFontSize = 16
        currentLineHeightMultiple = 1.5
        currentThemeBackgroundColor = nil
        currentThemeTextColor = nil
        targetLocation = nil
        pendingHighlights = []
        fixedSpread = nil
        isFixedLayout = false
        isReaderPageVisible = true
        hasReaderPageBeenVisible = false
        needsReaderPagePlaybackRestart = false
        isWaitingForReaderPageMediaNavigation = false
        pendingReaderPageMediaNavigation = nil
        isReaderPageMediaActivationBlocked = false
        pendingProgressionRequest = false
        didRenderCurrentRequest = false
        teardownWebView()
    }

    public func load(publication: RDEPUBPublication, request: RDEPUBRenderRequest) {
        configureWebViewIfNeeded(publication: publication)
        guard let webView else { return }

        self.publication = publication
        self.currentRenderRequest = request
        self.currentSpineIndex = request.primarySpineIndex
        self.currentHref = request.primaryHref
        self.didRenderCurrentRequest = false
        cancelFixedLayoutReadyFallback()

        let publicationKey = publication.parser.opfURL?.path ?? publication.parser.extractionRootURL?.path ?? ""
        let loadSignature = pageLoadSignature(publicationKey: publicationKey, request: request)
        if request.isFixedLayout {
            // A fixed-layout load replaces the whole Hype document. Keep WebKit
            // suspended until navigation finishes so the outgoing page cannot
            // overlap the new page's zero-second narration.
            hasReaderPageBeenVisible = false
            needsReaderPagePlaybackRestart = false
            isWaitingForReaderPageMediaNavigation = true
            setNativeReaderPageMediaPlaybackSuspended(true)
        }
        RDEPUBWebViewDebug.log(
            debugScope,
            message: "load request=\(request.isFixedLayout ? "fixed" : "reflowable") signature=\(loadSignature) webView=\(RDEPUBWebViewDebug.webViewID(webView))"
        )

        switch request {
        case .reflowable(let reflowableRequest):
            handleReflowableLoad(publication: publication, request: reflowableRequest, loadSignature: loadSignature, in: webView)
        case .fixed(let fixedRequest):
            handleFixedLayoutLoad(publication: publication, request: fixedRequest, loadSignature: loadSignature, in: webView)
        }
    }

    func pageLoadSignature(
        publicationKey: String,
        request: RDEPUBRenderRequest
    ) -> String {
        switch request {
        case .reflowable(let request):
            return reflowableLoadSignature(publicationKey: publicationKey, request: request)
        case .fixed(let request):
            return fixedLayoutLoadSignature(publicationKey: publicationKey, request: request)
        }
    }

    func rendered() {
        guard !didRenderCurrentRequest else { return }
        didRenderCurrentRequest = true
        cancelFixedLayoutReadyFallback()
        RDEPUBWebViewDebug.log(debugScope, message: "rendered spine=\(currentSpineIndex) href=\(currentHref) fixed=\(isFixedLayout)")
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
            guard let self else { return }
            self.delegate?.epubWebViewDidFinishRendering(self)
            self.onRendered?()
        }
    }
}