// RDEPUBReaderController+DataSource.swift
// EPUB 阅读器数据源与代理实现
// 实现 RDReaderDataSource 和 RDReaderDelegate 协议，为阅读器视图提供页面数量、
// 页面内容视图、页码变化通知、屏幕方向变化处理等核心数据与事件支持。

import UIKit

/// RDEPUBReaderController 数据源与代理扩展
///
/// 本文件实现 RDReaderDataSource 和 RDReaderDelegate 协议，为阅读器视图提供页面数量、
/// 页面内容视图、页码变化通知、屏幕方向变化处理等核心数据与事件支持。

// MARK: - RDReaderView 数据源与代理

extension RDEPUBReaderController: RDReaderDataSource, RDReaderDelegate {
    /// 返回阅读器总页数
    public func pageCountOfReaderView(readerView: RDReaderView) -> Int {
        readerContext.bookPageMap?.totalPages ?? textBook?.pages.count ?? activePages.count
    }

    /// 为指定页码创建或复用内容视图（优先文本渲染，回退 Web 渲染）
    public func pageContentView(readerView: RDReaderView, pageNum: Int, containerView: UIView?) -> UIView {
        if readerContext.bookPageMap != nil {
            _ = runtime.prepareOnDemandChapter(forAbsolutePageNumber: pageNum + 1)
            if let resolvedPage = runtime.pageResolver.resolvePage(absolutePageIndex: pageNum) {
                let contentView = (containerView as? RDEPUBTextContentView) ?? RDEPUBTextContentView()
                contentView.delegate = self
                contentView.configure(
                    page: resolvedPage.page,
                    pageNumber: pageNum + 1,
                    totalPages: pageCountOfReaderView(readerView: readerView),
                    configuration: configuration,
                    highlights: textHighlights(for: resolvedPage.page),
                    searchState: searchState
                )
                return contentView
            }
        }

        if let textBook, let page = textBook.page(at: pageNum + 1) {
            let contentView = (containerView as? RDEPUBTextContentView) ?? RDEPUBTextContentView()
            contentView.delegate = self
            contentView.configure(
                page: page,
                pageNumber: pageNum + 1,
                totalPages: textBook.pages.count,
                configuration: configuration,
                highlights: textHighlights(for: page),
                searchState: searchState
            )
            return contentView
        }

        guard let publication,
              let request = request(for: pageNum) else {
            return containerView ?? UIView()
        }

        let contentView = (containerView as? RDEPUBWebContentView) ?? RDEPUBWebContentView()
        contentView.delegate = self
        contentView.configure(
            publication: publication,
            request: request,
            pageNumber: pageNum + 1,
            totalPages: activePages.count,
            theme: configuration.theme
        )
        return contentView
    }

    /// 返回页面内容视图的重用标识符（区分文本与 Web 渲染）
    public func pageIdentifier(readerView: RDReaderView, pageNum: Int) -> String? {
        (textBook == nil && readerContext.bookPageMap == nil)
            ? NSStringFromClass(RDEPUBWebContentView.self)
            : NSStringFromClass(RDEPUBTextContentView.self)
    }

    /// 获取指定文本页面上的高亮标注列表
    private func textHighlights(for page: RDEPUBTextPage) -> [RDEPUBHighlight] {
        if let textBook,
           let chapterData = textBook.chapterData(for: page.href) {
            return chapterData.highlights(on: page, from: activeHighlights)
        }

        guard let publication else {
            return activeHighlights.filter { $0.location.href == page.href }
        }
        let pageHref = publication.resourceResolver.normalizedHref(page.href) ?? page.href
        return activeHighlights.filter {
            (publication.resourceResolver.normalizedHref($0.location.href) ?? $0.location.href) == pageHref
        }
    }

    /// 根据规范化 href 获取文本章节数据
    func textChapterData(forNormalizedHref href: String) -> RDEPUBChapterData? {
        readerContext.textChapterData(forNormalizedHref: href)
    }

    /// 返回阅读器顶部工具视图
    public func topToolView(readerView: RDReaderView) -> UIView? {
        topToolView
    }

    /// 返回阅读器底部工具视图
    public func bottomToolView(readerView: RDReaderView) -> UIView? {
        bottomToolView
    }

    /// 页码变化回调：清除选区、同步阅读状态、检测到达末尾
    public func pageNum(readerView: RDReaderView, pageNum: Int) {
        readerContext.markUserNavigationActivity()
        updateCurrentSelection(nil)
        reconcileTextPaginationSizeIfNeeded(for: pageNum)

        // 用户开始导航时，应用后台解析完成的完整 map
        runtime.applyPendingFullPageMapIfNeeded()

        if readerContext.bookPageMap != nil {
            _ = runtime.prepareOnDemandChapter(forAbsolutePageNumber: pageNum + 1)
            runtime.extendPartialBookPageMapIfNeeded(currentPageNumber: pageNum + 1)
        }

        let totalPages = pageCountOfReaderView(readerView: readerView)
        if totalPages > 0, pageNum == totalPages - 1 {
            delegate?.epubReaderDidReachEnd(self)
        }

        if (textBook != nil || readerContext.bookPageMap != nil),
           let location = resolvedTextLocation(forPageNumber: pageNum + 1) {
            persist(location: location)
            synchronizeTextReadingState(pageNumber: pageNum + 1, location: location)
            return
        }

        if let location = fallbackLocation(for: pageNum) {
            persist(location: location)
        }
        if readingSession?.navigatorState == .jumping || readingSession?.navigatorState == .moving {
            readingSession?.transition(to: .idle)
        }
    }

    /// 屏幕方向即将变化回调，捕获待恢复的展示位置
    public func readerViewOrientationWillChange(readerView: RDReaderView, isLandscape: Bool) {
        _ = isLandscape
        runtime.viewportMonitor.capturePendingPresentationRestoreLocation()
    }

    /// 检测页面尺寸变化并触发重新分页（避免布局错乱）
    private func reconcileTextPaginationSizeIfNeeded(for pageNum: Int) {
        guard textBook != nil || readerContext.bookPageMap != nil,
              !isRepaginating,
              !isReconcilingTextPaginationSize,
              pageNum >= 0,
              let lastTextPaginationPageSize else {
            return
        }

        let resolvedSize = readerView.resolvedSinglePageSize(pageNum: pageNum)
        guard resolvedSize.width > 0,
              resolvedSize.height > 0 else {
            return
        }

        let sizeChanged = abs(resolvedSize.width - lastTextPaginationPageSize.width) > 0.5
            || abs(resolvedSize.height - lastTextPaginationPageSize.height) > 0.5
        guard sizeChanged else {
            return
        }

        isReconcilingTextPaginationSize = true
        DispatchQueue.main.async { [weak self] in
            guard let self else { return }
            self.isReconcilingTextPaginationSize = false
            guard (self.textBook != nil || self.readerContext.bookPageMap != nil), !self.isRepaginating else { return }
            self.repaginatePreservingCurrentLocation()
        }
    }
}