// RDEPUBWebView+JavaScriptBridge.swift
// RDEPUBWebView 的 JS 桥接和导航委托扩展
// 实现 WKNavigationDelegate 处理页面加载生命周期，
// 实现 WKScriptMessageHandler 接收 JS 消息（进度/选择/链接/错误/固定版式就绪），
// 并将内部链接和外部链接路由到委托方法。

import Foundation
import WebKit

extension RDEPUBWebView {
    /// 从 URL 解析内部位置（ss-reader:// 协议的链接）
    func internalLocation(from url: URL) -> RDEPUBLocation? {
        let href = url.path.removingPercentEncoding?.trimmingCharacters(in: CharacterSet(charactersIn: "/")) ?? ""
        let fragment = url.fragment
        guard !href.isEmpty || fragment != nil else { return nil }
        return RDEPUBLocation(href: href, progression: 0, fragment: fragment)
    }

    /// 从 JS 消息体中构建当前位置对象
    func currentLocation(from body: [String: Any]) -> RDEPUBLocation {
        let progression = (body["progression"] as? NSNumber)?.doubleValue ?? 0
        let lastProgression = (body["lastProgression"] as? NSNumber)?.doubleValue
        let fragment = body["fragment"] as? String
        return RDEPUBLocation(href: currentHref, progression: progression, lastProgression: lastProgression, fragment: fragment)
    }
}

extension RDEPUBWebView: WKNavigationDelegate {
    public func webView(_ webView: WKWebView, didStartProvisionalNavigation navigation: WKNavigation!) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "didStart", url: webView.url)
    }

    public func webView(_ webView: WKWebView, didCommit navigation: WKNavigation!) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "didCommit", url: webView.url)
    }

    public func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "didFinish", url: webView.url)
        applyPresentation()
    }

    public func webViewWebContentProcessDidTerminate(_ webView: WKWebView) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "processTerminated", url: webView.url)
    }

    public func webView(_ webView: WKWebView, didFail navigation: WKNavigation!, withError error: Error) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "didFail", url: webView.url, error: error)
    }

    public func webView(_ webView: WKWebView, didFailProvisionalNavigation navigation: WKNavigation!, withError error: Error) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "didFailProvisional", url: webView.url, error: error)
    }

    /// 导航策略决策：区分内部链接（ss-reader://）、外部链接（http/https/mailto/tel）和其他导航
    public func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
        RDEPUBWebViewDebug.logNavigationEvent(debugScope, webView: webView, event: "decidePolicy", url: navigationAction.request.url)
        guard navigationAction.navigationType == .linkActivated,
              let url = navigationAction.request.url else {
            decisionHandler(.allow)
            return
        }

        if url.scheme == RDEPUBResourceURLSchemeHandler.scheme,
           let location = internalLocation(from: url) {
            delegate?.epubWebView(self, didActivateInternalLink: location, fromSpineIndex: currentSpineIndex)
            decisionHandler(.cancel)
            return
        }

        if let scheme = url.scheme?.lowercased(), ["http", "https", "mailto", "tel"].contains(scheme) {
            delegate?.epubWebView(self, didActivateExternalLink: url)
            decisionHandler(.cancel)
            return
        }

        decisionHandler(.allow)
    }
}

extension RDEPUBWebView: WKScriptMessageHandler {
    /// 接收 JS 桥接消息，根据消息类型路由到对应的委托方法
    public func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
        RDEPUBWebViewDebug.logMessage(debugScope, webView: message.webView, name: message.name, body: message.body)
        switch message.name {
        case RDEPUBJavaScriptBridgeMessage.progressionChanged.rawValue:
            guard let body = message.body as? [String: Any] else { return }
            delegate?.epubWebView(self, didUpdateLocation: currentLocation(from: body), spineIndex: currentSpineIndex)
        case RDEPUBJavaScriptBridgeMessage.selectionChanged.rawValue:
            if let body = message.body as? [String: Any],
               let text = body["text"] as? String,
               let rangeInfo = body["rangeInfo"] as? String {
                let location = currentLocation(from: body)
                let selection = RDEPUBSelection(location: location, text: text, rangeInfo: rangeInfo)
                delegate?.epubWebView(self, didChangeSelection: selection, spineIndex: currentSpineIndex)
            } else {
                delegate?.epubWebView(self, didChangeSelection: nil, spineIndex: currentSpineIndex)
            }
        case RDEPUBJavaScriptBridgeMessage.internalLink.rawValue:
            guard let body = message.body as? [String: Any],
                  let href = body["href"] as? String else { return }
            let location = RDEPUBLocation(href: href, progression: 0)
            delegate?.epubWebView(self, didActivateInternalLink: location, fromSpineIndex: currentSpineIndex)
        case RDEPUBJavaScriptBridgeMessage.externalLink.rawValue:
            guard let body = message.body as? [String: Any],
                  let urlString = body["url"] as? String,
                  let url = URL(string: urlString) else { return }
            delegate?.epubWebView(self, didActivateExternalLink: url)
        case RDEPUBJavaScriptBridgeMessage.javaScriptError.rawValue:
            delegate?.epubWebView(self, didLogJavaScriptError: "\(message.body)")
        case RDEPUBJavaScriptBridgeMessage.fixedLayoutReady.rawValue:
            applySearchDecorationsIfNeeded {
                self.rendered()
            }
        default:
            break
        }
    }
}