import UIKit
import WebKit

extension RDEPUBWebView {

    func configureWebViewIfNeeded(publication: RDEPUBPublication) {
        let parser = publication.parser
        let publicationKey = parser.opfURL?.path ?? parser.extractionRootURL?.path ?? UUID().uuidString
        if publicationKey == configuredPublicationKey, webView != nil {
            return
        }

        teardownWebView()

        let userContentController = WKUserContentController()
        let messageHandlerProxy = RDEPUBWeakScriptMessageHandler(target: self)
        RDEPUBJavaScriptBridge.messageNames.forEach {
            userContentController.add(messageHandlerProxy, name: $0)
        }
        userContentController.addUserScript(
            WKUserScript(
                source: RDEPUBJavaScriptBridge.userScript,
                injectionTime: .atDocumentEnd,
                forMainFrameOnly: true
            )
        )

        let configuration = WKWebViewConfiguration()
        configuration.websiteDataStore = .nonPersistent()
        configuration.userContentController = userContentController
        let schemeHandler = RDEPUBResourceURLSchemeHandler(parser: parser)
        configuration.setURLSchemeHandler(schemeHandler, forURLScheme: RDEPUBResourceURLSchemeHandler.scheme)

        let webView = RDEPUBAnnotationWebView(frame: bounds, configuration: configuration)
        webView.onSelectionAction = { [weak self] action in
            guard let self else { return }
            self.handleSelectionMenuAction(action)
        }
        // M-15: Use UIEditMenuInteraction on iOS 16+ to replace deprecated UIMenuController
        if #available(iOS 16.0, *) {
            let interaction = UIEditMenuInteraction(delegate: webView)
            webView.addInteraction(interaction)
            webView._editMenuInteraction = interaction
        } else {
            UIMenuController.shared.menuItems = [
                UIMenuItem(title: "拷贝", action: #selector(RDEPUBAnnotationWebView.rd_copy(_:))),
                UIMenuItem(title: "高亮", action: #selector(RDEPUBAnnotationWebView.rd_highlight(_:))),
                UIMenuItem(title: "批注", action: #selector(RDEPUBAnnotationWebView.rd_annotate(_:)))
            ]
        }
        webView.navigationDelegate = self
        // 安全区自适应会把 Web 布局视口缩小（横屏左右各 59pt、底部 21pt），
        // 固定布局页面随之按缩小后的视口适配，产生大边距/中缝。
        // 阅读区域的安全区避让统一由 fixedContentInset / 排版 CSS 负责。
        webView.scrollView.contentInsetAdjustmentBehavior = .never
        webView.scrollView.isScrollEnabled = false
        webView.scrollView.showsHorizontalScrollIndicator = false
        webView.scrollView.showsVerticalScrollIndicator = false
        webView.scrollView.bounces = false
        webView.scrollView.alwaysBounceHorizontal = false
        webView.scrollView.alwaysBounceVertical = false
        webView.scrollView.clipsToBounds = true
        webView.scrollView.panGestureRecognizer.isEnabled = false
        webView.scrollView.pinchGestureRecognizer?.isEnabled = false
        webView.isOpaque = false
        webView.backgroundColor = .clear
        webView.clipsToBounds = true
        if #available(iOS 16.4, *) {
            webView.isInspectable = RDEPUBWebViewDebug.isInspectableEnabled
        }

        addSubview(webView)
        webView.frame = bounds
        webView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

        self.schemeHandler = schemeHandler
        self.webView = webView
        self.configuredPublicationKey = publicationKey
        RDEPUBWebViewDebug.log(debugScope, message: "configured webView=\(RDEPUBWebViewDebug.webViewID(webView)) publicationKey=\(publicationKey)")
    }

    func handleSelectionMenuAction(_ action: RDEPUBAnnotationMenuAction) {
        delegate?.epubWebView(self, didRequestSelectionAction: action)
        clearWebSelection()
    }

    func clearWebSelection() {
        webView?.evaluateJavaScript("window.getSelection && window.getSelection().removeAllRanges();")
    }

    func teardownWebView() {
        cancelFixedLayoutReadyFallback()
        if let webView {
            RDEPUBWebViewDebug.log(debugScope, message: "teardown webView=\(RDEPUBWebViewDebug.webViewID(webView))")
        }
        // M-15: Clean up UIEditMenuInteraction on iOS 16+
        if #available(iOS 16.0, *), let interaction = (webView as? RDEPUBAnnotationWebView)?._editMenuInteraction as? UIEditMenuInteraction {
            webView?.removeInteraction(interaction)
        }
        webView?.navigationDelegate = nil
        if let userContentController = webView?.configuration.userContentController {
            RDEPUBJavaScriptBridge.messageNames.forEach {
                userContentController.removeScriptMessageHandler(forName: $0)
            }
        }
        (webView as? RDEPUBAnnotationWebView)?.onSelectionAction = nil
        webView?.removeFromSuperview()
        webView = nil
        schemeHandler = nil
        configuredPublicationKey = nil
        currentLoadSignature = nil
    }
}

/// M-08: WKUserContentController 强持有注册的 script message handler。
/// 直接注册 RDEPUBWebView 自身会形成保留环
/// （webView → userContentController → RDEPUBWebView → webView），
/// 被丢弃的页面 WebView 将永远无法释放。本代理弱持有真实 handler，
/// 保留环从一开始就不成立，RDEPUBWebView 可随最后一个持有者正常 deinit。
private final class RDEPUBWeakScriptMessageHandler: NSObject, WKScriptMessageHandler {

    private weak var target: WKScriptMessageHandler?

    init(target: WKScriptMessageHandler) {
        self.target = target
    }

    func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
        target?.userContentController(userContentController, didReceive: message)
    }
}