111 lines
4.0 KiB
Swift
111 lines
4.0 KiB
Swift
import Foundation
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struct RDEPUBLocationConverter {
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// MARK: - 主路径：先构建目标章，拿到真实长度后再精确转换
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/// 旧版 RDEPUBLocation -> 新版 RDEPUBChapterLocation
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/// 主迁移路径：要求先构建目标章，用真实 chapterLength 做精确转换
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/// 仅在无法获取章节长度时才降级到粗估 fallback
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static func convert(
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legacy location: RDEPUBLocation,
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parser: RDEPUBParser,
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publication: RDEPUBPublication,
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chapterLengthProvider: ((Int) -> Int?)? = nil
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) -> RDEPUBChapterLocation? {
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// 1. 从 href 找到 spineIndex
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guard let spineItem = publication.spine.first(where: {
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$0.href == location.href || $0.href.contains(location.href)
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}) else { return nil }
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let spineIndex = publication.spine.firstIndex(of: spineItem) ?? 0
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// 2. 优先用 fragmentID 定位（最精确，不受 progression 精度影响）
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if let fragmentID = location.fragment {
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return RDEPUBChapterLocation(
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spineIndex: spineIndex,
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chapterOffset: 0, // fragmentID 由 chapterOffsetMap 精确解析
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fragmentID: fragmentID,
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progressionInChapter: location.progression
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)
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}
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// 3. 有 chapterLength 时做精确转换
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if let provider = chapterLengthProvider,
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let chapterLength = provider(spineIndex), chapterLength > 0 {
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return convert(
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legacy: location,
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spineIndex: spineIndex,
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chapterLength: chapterLength
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)
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}
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// 4. Fallback：无法获取章节长度时的粗估（仅作临时降级）
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let estimatedOffset = Int(location.progression * 10000)
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return RDEPUBChapterLocation(
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spineIndex: spineIndex,
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chapterOffset: estimatedOffset,
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fragmentID: nil,
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progressionInChapter: location.progression,
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schemaVersion: 1 // 标记为降级结果，后续可被精确值覆盖
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)
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}
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/// 精确转换：已知章节实际长度
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static func convert(
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legacy location: RDEPUBLocation,
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spineIndex: Int,
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chapterLength: Int
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) -> RDEPUBChapterLocation? {
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let offset = Int(location.progression * Double(chapterLength))
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return RDEPUBChapterLocation(
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spineIndex: spineIndex,
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chapterOffset: offset,
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fragmentID: location.fragment,
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progressionInChapter: location.progression,
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schemaVersion: 2
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)
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}
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/// 从已构建的 RDEPUBRuntimeChapter 做精确转换（推荐迁移路径）
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static func convert(
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legacy location: RDEPUBLocation,
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chapter: RDEPUBRuntimeChapter
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) -> RDEPUBChapterLocation? {
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// 优先用 fragmentID
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if let fragmentID = location.fragment,
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let fragmentOffset = chapter.chapterOffsetMap.chapterOffset(forFragmentID: fragmentID) {
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return RDEPUBChapterLocation(
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spineIndex: chapter.spineIndex,
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chapterOffset: fragmentOffset,
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fragmentID: fragmentID,
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progressionInChapter: nil,
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schemaVersion: 2
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)
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}
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// 用 progression + 真实长度
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let chapterLength = chapter.typesetAttributedString.length
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return convert(
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legacy: location,
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spineIndex: chapter.spineIndex,
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chapterLength: chapterLength
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)
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}
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/// 新版 -> 旧版（兼容外部接口）
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static func toLegacy(
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chapterLocation: RDEPUBChapterLocation,
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href: String,
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chapterLength: Int
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) -> RDEPUBLocation {
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let progression = chapterLength > 0
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? Double(chapterLocation.chapterOffset) / Double(chapterLength)
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: 0
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return RDEPUBLocation(
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href: href,
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progression: min(max(progression, 0), 1),
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fragment: chapterLocation.fragmentID
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)
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}
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} |