230 lines
9.8 KiB
Swift
230 lines
9.8 KiB
Swift
import Foundation
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import CryptoKit
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// MARK: - 分页缓存数据模型（WXRead 模式：只缓存页范围，不缓存富文本）
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/// 单个章节的分页元数据缓存，用于磁盘持久化。
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///
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/// 对标 WXRead 的 WRChapterPageCount 缓存策略：只存储每页的 NSRange + 分页原因，
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/// 不缓存完整的 NSAttributedString。缓存命中时重新渲染 HTML，但跳过 CoreText 分页步骤。
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public struct RDEPUBTextChapterPaginationCache: Equatable {
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/// 章节文件相对路径
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public var href: String
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/// 每页在章节富文本中的字符范围
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public var pageRanges: [NSRange]
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/// 每页的分页原因（语义边界、帧限制等）
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public var breakReasons: [RDEPUBTextPageBreakReason]
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public var semanticHints: [RDEPUBTextSemanticHint]
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public init(
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href: String,
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pageRanges: [NSRange],
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breakReasons: [RDEPUBTextPageBreakReason],
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semanticHints: [RDEPUBTextSemanticHint]
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) {
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self.href = href
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self.pageRanges = pageRanges
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self.breakReasons = breakReasons
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self.semanticHints = semanticHints
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}
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}
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// MARK: - NSCoding 归档层（只使用字符串和整数类型）
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/// 整本书的分页缓存归档，用于 NSKeyedArchiver 序列化。
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/// 包含所有章节的分页归档数据。
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final class PaginationCacheArchive: NSObject, NSSecureCoding {
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static var supportsSecureCoding: Bool { true }
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let chapters: [ChapterPaginationArchive]
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init(chapters: [ChapterPaginationArchive]) {
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self.chapters = chapters
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}
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func encode(with coder: NSCoder) {
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coder.encode(chapters, forKey: "chapters")
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}
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required init?(coder: NSCoder) {
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guard let chapters = coder.decodeObject(of: [NSArray.self, ChapterPaginationArchive.self], forKey: "chapters") as? [ChapterPaginationArchive] else { return nil }
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self.chapters = chapters
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}
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}
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/// 单个章节的分页归档，将 NSRange 拆分为 location/length 数组以便 NSSecureCoding 编码。
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final class ChapterPaginationArchive: NSObject, NSSecureCoding {
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static var supportsSecureCoding: Bool { true }
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let href: String
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/// 页范围的起始位置数组（与 rangeLengths 一一对应）
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let rangeLocations: [NSNumber]
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/// 页范围的长度数组
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let rangeLengths: [NSNumber]
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/// 分页原因的原始字符串数组
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let breakReasons: [String]
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/// 语义提示的原始字符串数组
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let semanticHints: [String]
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/// 从缓存模型构建归档对象
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init(from cache: RDEPUBTextChapterPaginationCache) {
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self.href = cache.href
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self.rangeLocations = cache.pageRanges.map { NSNumber(value: $0.location) }
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self.rangeLengths = cache.pageRanges.map { NSNumber(value: $0.length) }
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self.breakReasons = cache.breakReasons.map(\.rawValue)
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self.semanticHints = cache.semanticHints.map(\.rawValue)
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}
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func encode(with coder: NSCoder) {
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coder.encode(href, forKey: "href")
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coder.encode(rangeLocations, forKey: "rangeLocations")
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coder.encode(rangeLengths, forKey: "rangeLengths")
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coder.encode(breakReasons, forKey: "breakReasons")
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coder.encode(semanticHints, forKey: "semanticHints")
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}
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required init?(coder: NSCoder) {
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guard let href = coder.decodeObject(of: NSString.self, forKey: "href") as String?,
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let rangeLocations = coder.decodeObject(of: [NSArray.self, NSNumber.self], forKey: "rangeLocations") as? [NSNumber],
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let rangeLengths = coder.decodeObject(of: [NSArray.self, NSNumber.self], forKey: "rangeLengths") as? [NSNumber],
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let breakReasons = coder.decodeObject(of: [NSArray.self, NSString.self], forKey: "breakReasons") as? [String],
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let semanticHints = coder.decodeObject(of: [NSArray.self, NSString.self], forKey: "semanticHints") as? [String] else {
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return nil
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}
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self.href = href
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self.rangeLocations = rangeLocations
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self.rangeLengths = rangeLengths
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self.breakReasons = breakReasons
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self.semanticHints = semanticHints
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}
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/// 将归档数据转换回缓存模型
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func toCache() -> RDEPUBTextChapterPaginationCache {
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let pageRanges = zip(rangeLocations, rangeLengths).map { loc, len in
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NSRange(location: loc.intValue, length: len.intValue)
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}
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return RDEPUBTextChapterPaginationCache(
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href: href,
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pageRanges: pageRanges,
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breakReasons: breakReasons.compactMap(RDEPUBTextPageBreakReason.init(rawValue:)),
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semanticHints: semanticHints.compactMap(RDEPUBTextSemanticHint.init(rawValue:))
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)
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}
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}
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// MARK: - 分页缓存管理器
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/// 磁盘持久化的分页缓存层，对标 WXRead 的 WRChapterPageCount 缓存模式。
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///
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/// 缓存策略：
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/// - 缓存键 = SHA256(书籍ID + 字号 + 行距 + 内边距 + 页面尺寸 + schema版本)
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/// - 缓存值 = 每章的页 NSRange 列表 + 分页原因（NSKeyedArchiver 序列化）
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/// - 富文本不缓存：缓存命中时重新渲染 HTML，但跳过 CoreText 分页步骤
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/// - 线程安全：所有读写操作通过 serial DispatchQueue 串行执行
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public final class RDEPUBTextBookCache {
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/// 缓存模式版本号，变更时旧缓存自动失效
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// 分页算法调整后需要提升版本，避免继续复用旧页范围缓存。
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public var schemaVersion: Int = 6
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/// 串行队列，保证缓存读写的线程安全
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private let queue = DispatchQueue(label: "com.rdreader.textbookcache", qos: .utility)
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/// 缓存文件目录
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private let cacheDirectory: URL
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/// 初始化缓存管理器，自动创建缓存目录
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/// - Parameter subdirectory: Caches 目录下的子目录名
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public init(subdirectory: String = "RDEPUBTextBookCache") {
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let baseURL = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask).first?
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.appendingPathComponent(subdirectory, isDirectory: true)
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?? FileManager.default.temporaryDirectory.appendingPathComponent(subdirectory, isDirectory: true)
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self.cacheDirectory = baseURL
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try? FileManager.default.createDirectory(at: cacheDirectory, withIntermediateDirectories: true)
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}
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// MARK: - 缓存键生成
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// 对标 WRChapterPageCount.currentCacheKeyWithBookId：
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// 编码 bookID + fontSize + lineHeightMultiple + contentInsets + pageSize
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/// 生成缓存文件名（SHA256 哈希 + ".cache" 后缀）。
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///
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/// 任意布局参数变更都会导致缓存键不同，从而自动失效。
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public func cacheKey(
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bookID: String,
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fontSize: CGFloat,
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lineHeightMultiple: CGFloat,
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contentInsets: UIEdgeInsets,
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pageSize: CGSize,
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layoutConfigSignature: String = RDEPUBTextLayoutConfig.default.cacheSignature
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) -> String {
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let raw = "\(bookID)_\(fontSize)_\(lineHeightMultiple)_\(contentInsets.top)_\(contentInsets.left)_\(contentInsets.bottom)_\(contentInsets.right)_\(pageSize.width)_\(pageSize.height)_\(layoutConfigSignature)_v\(schemaVersion)"
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let digest = SHA256.hash(data: Data(raw.utf8))
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let hex = digest.map { String(format: "%02x", $0) }.joined()
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return hex + ".cache"
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}
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// MARK: - 加载/保存（只缓存分页元数据）
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/// 从磁盘加载缓存的分页元数据，返回以章节 href 为键的字典。
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/// 缓存未命中或反序列化失败时返回 nil。
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public func load(key: String) -> [String: RDEPUBTextChapterPaginationCache]? {
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queue.sync {
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let fileURL = cacheDirectory.appendingPathComponent(key)
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guard FileManager.default.fileExists(atPath: fileURL.path) else {
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print("[Cache] load MISS key=\(key)")
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return nil
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}
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do {
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let data = try Data(contentsOf: fileURL)
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guard let archive = try NSKeyedUnarchiver.unarchivedObject(
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ofClass: PaginationCacheArchive.self,
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from: data
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) else {
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print("[Cache] load MISS key=\(key) (unarchive returned nil)")
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return nil
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}
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var result: [String: RDEPUBTextChapterPaginationCache] = [:]
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for chapter in archive.chapters {
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result[chapter.href] = chapter.toCache()
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}
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print("[Cache] load HIT key=\(key) chapters=\(result.count)")
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return result
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} catch {
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print("[Cache] load MISS key=\(key) error=\(error)")
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return nil
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}
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}
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}
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/// 将分页元数据保存到磁盘（原子写入，防止损坏）
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public func save(_ chapters: [RDEPUBTextChapterPaginationCache], key: String) {
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queue.sync {
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let fileURL = cacheDirectory.appendingPathComponent(key)
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do {
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let archives = chapters.map { ChapterPaginationArchive(from: $0) }
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let bookArchive = PaginationCacheArchive(chapters: archives)
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let data = try NSKeyedArchiver.archivedData(withRootObject: bookArchive, requiringSecureCoding: true)
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try data.write(to: fileURL, options: .atomic)
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print("[Cache] save key=\(key) chapters=\(chapters.count)")
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} catch {
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print("[Cache] save FAILED key=\(key) error=\(error)")
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}
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}
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}
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// MARK: - 缓存失效
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/// 清除所有缓存文件
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public func invalidateAll() {
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queue.sync {
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let fileManager = FileManager.default
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guard let contents = try? fileManager.contentsOfDirectory(at: cacheDirectory, includingPropertiesForKeys: nil) else {
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return
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}
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for file in contents {
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try? fileManager.removeItem(at: file)
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}
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print("[Cache] invalidateAll")
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}
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}
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}
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