// RDEPUBWebView.swift
// EPUB WebView 主类
// 封装 WKWebView 的 EPUB 渲染能力，是 Resource View 层的核心组件。
// 统一管理固定版式和重排模式的加载流程，持有当前渲染状态（spineIndex、pageIndex、
// 主题色、高亮等），并通过委托模式通知上层页面渲染和交互事件。
// 具体逻辑分散在 +Configuration、+FixedLayout、+Reflowable、+JavaScriptBridge、+Search 扩展中。

import UIKit
import WebKit

/// RDEPUBWebView 委托协议，定义 WebView 向上层通知的事件
public protocol RDEPUBWebViewDelegate: AnyObject {
    /// 阅读位置更新事件
    func epubWebView(_ webView: RDEPUBWebView, didUpdateLocation location: RDEPUBLocation, spineIndex: Int)
    /// 文本选择变化事件
    func epubWebView(_ webView: RDEPUBWebView, didChangeSelection selection: RDEPUBSelection?, spineIndex: Int)
    /// 选择菜单动作请求事件
    func epubWebView(_ webView: RDEPUBWebView, didRequestSelectionAction action: RDEPUBAnnotationMenuAction)
    /// 内部链接点击事件
    func epubWebView(_ webView: RDEPUBWebView, didActivateInternalLink location: RDEPUBLocation, fromSpineIndex: Int)
    /// 外部链接点击事件
    func epubWebView(_ webView: RDEPUBWebView, didActivateExternalLink url: URL)
    /// JavaScript 错误事件
    func epubWebView(_ webView: RDEPUBWebView, didLogJavaScriptError message: String)
    /// 页面渲染完成事件
    func epubWebViewDidFinishRendering(_ webView: RDEPUBWebView)
}

/// 委托协议的默认实现（选择菜单动作为可选）
public extension RDEPUBWebViewDelegate {
    func epubWebView(_ webView: RDEPUBWebView, didRequestSelectionAction action: RDEPUBAnnotationMenuAction) {}
}

/// 自定义 WKWebView 子类，支持拷贝/高亮/批注选择菜单
final class RDEPUBAnnotationWebView: WKWebView {
    /// 选择菜单动作回调
    var onSelectionAction: ((RDEPUBAnnotationMenuAction) -> Void)?

    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)
    }
}

/// EPUB WebView 主类，封装 WKWebView 的 EPUB 渲染能力
/// Resource View 层核心组件，统一管理固定版式和重排模式的渲染
public final class RDEPUBWebView: UIView {
    /// 委托对象，接收渲染和交互事件
    public weak var delegate: RDEPUBWebViewDelegate?
    /// 渲染完成回调（与 delegate 并行使用）
    public var onRendered: (() -> Void)?

        /// 当前关联的出版物
        var publication: RDEPUBPublication?
        /// 当前渲染请求
        var currentRenderRequest: RDEPUBRenderRequest?
        /// 内部 WKWebView 实例
        var webView: WKWebView?
        /// URL Scheme 处理器
        var schemeHandler: RDEPUBResourceURLSchemeHandler?
        /// 已配置的出版物标识（用于判断是否需要重建 WebView）
        var configuredPublicationKey: String?
        /// 当前加载签名（用于去重相同请求）
        var currentLoadSignature: String?
        /// 当前 spine 索引
        var currentSpineIndex = 0
        /// 当前资源 href
        var currentHref = ""
        /// 当前页码（从 0 开始）
        var currentPageIndex = 0
        /// 当前章节总页数
        var currentTotalPagesInChapter = 1
        /// 当前视口尺寸
        var viewportSize: CGSize = .zero
        /// 当前内容内边距
        var currentPadding: UIEdgeInsets = .zero
        /// 当前字号
        var currentFontSize: CGFloat = 16
        /// 当前行高倍数
        var currentLineHeightMultiple: CGFloat = 1.5
        /// 当前主题背景色
        var currentThemeBackgroundColor: String?
        /// 当前主题文字色
        var currentThemeTextColor: String?
        /// 目标跳转位置
        var targetLocation: RDEPUBLocation?
        /// 待应用的高亮列表
        var pendingHighlights: [RDEPUBHighlight] = []
        /// 当前固定版式 spread（固定版式时非空）
        var fixedSpread: EPUBFixedSpread?
        /// 是否为固定版式模式
        var isFixedLayout = false
        /// 是否有待处理的进度汇报请求
        var pendingProgressionRequest = false
        /// 固定版式就绪回退定时器
        var fixedLayoutReadyWorkItem: DispatchWorkItem?
        /// 当前请求是否已完成渲染
        var didRenderCurrentRequest = false
        /// 调试日志作用域
        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")
    }

    deinit {
        teardownWebView()
    }

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

    /// 重置所有状态并销毁 WebView
    public func reset() {
        delegate = nil
        onRendered = 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
        pendingProgressionRequest = false
        didRenderCurrentRequest = false
        teardownWebView()
    }

    /// 加载渲染请求：配置 WebView、生成签名、分发到固定版式或重排处理
    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)
        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)
        }
    }

    /// 生成页面加载签名
    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)
        }
    }

    /// 标记渲染完成：通知委托和回调，延迟 100ms 确保布局稳定
    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?()
        }
    }
}