// RDEPUBWebView+FixedLayout.swift
// RDEPUBWebView 的固定版式渲染扩展
// 处理固定版式（Fixed Layout）的加载流程：生成 HTML 模板、
// 计算加载签名（去重）、设置固定版式就绪回退定时器等。

import UIKit
import WebKit

extension RDEPUBWebView {
    /// 便捷方法：加载固定版式的 spread 页面
    public func loadFixedSpread(
        parser: RDEPUBParser,
        spread: EPUBFixedSpread,
        viewportSize: CGSize,
        contentInset: UIEdgeInsets,
        backgroundColor: UIColor?
    ) {
        let request = RDEPUBRenderRequest.fixed(
            RDEPUBFixedRenderRequest(
                spread: spread,
                viewportSize: viewportSize,
                contentInset: contentInset,
                backgroundColorCSS: backgroundColor?.ss_hexString,
                fit: .page,
                searchPresentation: nil
            )
        )
        load(publication: parser.makePublication(), request: request)
    }

    /// 处理固定版式加载：设置状态、生成 HTML、加载到 WebView
    func handleFixedLayoutLoad(
        publication: RDEPUBPublication,
        request: RDEPUBFixedRenderRequest,
        loadSignature: String,
        in webView: WKWebView
    ) {
        currentPageIndex = 0
        currentTotalPagesInChapter = 1
        viewportSize = request.viewportSize
        currentPadding = request.contentInset
        currentFontSize = 16
        currentLineHeightMultiple = 1.5
        currentThemeBackgroundColor = request.backgroundColorCSS
        currentThemeTextColor = nil
        targetLocation = nil
        pendingHighlights = []
        fixedSpread = request.spread
        isFixedLayout = true
        pendingProgressionRequest = false
        currentLoadSignature = loadSignature
        scheduleFixedLayoutReadyFallback()

        let html = RDEPUBFixedLayoutTemplate.html(for: request, publication: publication)
        RDEPUBWebViewDebug.log(debugScope, message: "load fixed spread resources=\(request.spread.resources.map(\.href).joined(separator: ",")) fit=\(request.fit.rawValue)")
        webView.loadHTMLString(
            html,
            baseURL: URL(string: "\(RDEPUBResourceURLSchemeHandler.scheme)://\(RDEPUBResourceURLSchemeHandler.host)/")
        )
    }

    /// 生成固定版式加载签名（用于去重相同请求）
    func fixedLayoutLoadSignature(publicationKey: String, request: RDEPUBFixedRenderRequest) -> String {
        [
            publicationKey,
            "fixed",
            request.spread.resources.map(\.href).joined(separator: "|"),
            String(format: "%.2f", request.viewportSize.width),
            String(format: "%.2f", request.viewportSize.height),
            String(format: "%.2f", request.contentInset.top),
            String(format: "%.2f", request.contentInset.left),
            String(format: "%.2f", request.contentInset.bottom),
            String(format: "%.2f", request.contentInset.right),
            request.backgroundColorCSS ?? "",
            request.fit.rawValue
        ].joined(separator: "#")
    }

    /// 调度固定版式就绪回退定时器（1 秒后如果未收到 ready 消息则手动触发渲染完成）
    func scheduleFixedLayoutReadyFallback() {
        let workItem = DispatchWorkItem { [weak self] in
            RDEPUBWebViewDebug.log(self?.debugScope ?? "ReaderWebView", message: "fixed ready fallback fired")
            self?.applySearchDecorationsIfNeeded {
                self?.rendered()
            }
        }
        fixedLayoutReadyWorkItem = workItem
        DispatchQueue.main.asyncAfter(deadline: .now() + 1.0, execute: workItem)
    }

    /// 取消固定版式就绪回退定时器
    func cancelFixedLayoutReadyFallback() {
        fixedLayoutReadyWorkItem?.cancel()
        fixedLayoutReadyWorkItem = nil
    }
}