375 lines
17 KiB
Swift
375 lines
17 KiB
Swift
import UIKit
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import Foundation
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/// 内容块构建器
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/// 职责：将 [ContentBlock] 数组转换为单个 NSAttributedString
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struct ContentBlockBuilder {
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// MARK: - 样式常量（与 VerticalScreenPlayerView 保持一致）
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private static let bodyFontSize: CGFloat = 19 // ✅ 优化：17 → 19，提升阅读舒适度
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private static let bodyLineSpacing: CGFloat = 10 // ✅ 优化：调整为黄金比例 1.72倍行高 (19*1.72≈32.7, lineSpacing≈10)
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private static let paragraphSpacing: CGFloat = 24 // ✅ 优化：22 → 24，段落间距随正文字号增大
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// MARK: - 核心方法
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/// 将 ContentBlock 数组转换为单个 NSAttributedString（向后兼容）
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/// - Parameters:
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/// - blocks: ContentBlock 数组
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/// - accentColor: 高亮色（与进度条主题色一致），nil 时用 brandVital
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/// - Returns: 合并后的 NSAttributedString
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static func buildAttributedString(from blocks: [ContentBlock], accentColor: UIColor? = nil) -> NSAttributedString {
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let result = NSMutableAttributedString()
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appendBlocks(blocks, to: result, accentColor: accentColor)
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return result
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}
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/// 将 ContentBlock 数组转换为单个 NSAttributedString（包含头部信息）
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///
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/// 【极简主义重构说明 - 给 Gemini】
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/// 本次重构移除了头部冗余信息，实现极简阅读体验：
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/// 1. 移除问候语："作者，你好" 文案已删除
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/// 2. 移除简介：headerInfo.intro 不再显示
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/// 3. 只保留标题：标题样式调整为紧凑布局（paragraphSpacing = 24, paragraphSpacingBefore = 10）
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/// 4. 标题去重：如果正文第一个 block 是标题且内容相同，自动跳过避免重复
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///
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/// 注意：标题保留在 NSAttributedString 中，确保笔记的 NSRange 索引依然有效
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///
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/// - Parameters:
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/// - blocks: ContentBlock 数组
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/// - headerInfo: 课程详情（用于构建标题）
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/// - accentColor: 高亮色（与进度条主题色一致），nil 时用 brandVital
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/// - Returns: 合并后的 NSAttributedString（只包含标题和正文）
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static func buildAttributedString(
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from blocks: [ContentBlock],
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headerInfo: LessonDetail,
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accentColor: UIColor? = nil
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) -> NSAttributedString {
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let result = NSMutableAttributedString()
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// ==========================================
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// 1. 头部构建（极简版：只保留标题）
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// ==========================================
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// 主标题 (30pt Heavy, 醒目) ✅ 优化：28 → 30，随正文字号调整
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let titleAttrs: [NSAttributedString.Key: Any] = [
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.font: UIFont.systemFont(ofSize: 30, weight: .heavy), // ✅ 优化：28 → 30
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.foregroundColor: UIColor.inkPrimary,
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.paragraphStyle: {
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let style = NSMutableParagraphStyle()
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style.lineHeightMultiple = 1.1
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style.paragraphSpacing = 36 // ✅ 优化：32 → 36，标题与正文间距加大
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style.paragraphSpacingBefore = 10
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style.alignment = .left
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return style
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}(),
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.kern: 0.5
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]
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result.append(NSAttributedString(string: headerInfo.title + "\n", attributes: titleAttrs))
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// ❌ 已移除：问候语和简介（"作者，你好" 和 intro 文案）
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// ==========================================
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// 2. 正文构建
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// ==========================================
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// ✅ 标题去重逻辑：防止正文第一个 block 重复显示标题
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var blocksToAppend = blocks
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if !blocks.isEmpty,
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let firstBlock = blocks.first,
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firstBlock.type == .heading1 {
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let firstBlockContent = firstBlock.content.trimmingCharacters(in: .whitespacesAndNewlines)
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let headerTitle = headerInfo.title.trimmingCharacters(in: .whitespacesAndNewlines)
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// 精确匹配：如果第一个 block 是标题且内容相同，则跳过
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if firstBlockContent == headerTitle {
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blocksToAppend = Array(blocks.dropFirst())
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}
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}
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appendBlocks(blocksToAppend, to: result, accentColor: accentColor)
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return result
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}
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// MARK: - Private Helpers
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/// 复用块拼接逻辑：用「段后间距」保证段间松（paragraphSpacingAfter 比段前+换行更稳定）
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private static func appendBlocks(_ blocks: [ContentBlock], to result: NSMutableAttributedString, accentColor: UIColor? = nil) {
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for (index, block) in blocks.enumerated() {
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let isLastBlock = (index == blocks.count - 1)
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let spacingAfter: CGFloat? = isLastBlock ? nil : paragraphSpacing
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let blockContent = buildBlockContent(block, accentColor: accentColor, paragraphSpacingAfter: spacingAfter)
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result.append(blockContent)
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if !isLastBlock {
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result.append(NSAttributedString(string: "\n", attributes: [:]))
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}
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}
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}
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// MARK: - Block 内容构建
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/// 根据 Block 类型构建 NSAttributedString；paragraphSpacingAfter 用于段间松（仅对 paragraph 等生效）
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/// 正文内：### / #### / ## 直接删掉不做样式；行首 - 或 - 后直接跟字 统一成 •
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private static func buildBlockContent(_ block: ContentBlock, accentColor: UIColor? = nil, paragraphSpacingAfter: CGFloat? = nil) -> NSAttributedString {
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switch block.type {
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case .heading1:
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return buildHeading1(block.content)
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case .heading2:
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return buildHeading2(block.content)
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case .paragraph:
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let raw = block.content
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let withoutHeading = stripMarkdownHeadingPrefix(raw)
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let contentWithBullets = replaceLineStartHyphenWithBullet(withoutHeading)
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return buildParagraph(contentWithBullets, accentColor: accentColor, spacingAfter: paragraphSpacingAfter)
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case .quote:
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return buildQuote(block.content)
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case .highlight:
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return buildHighlight(block.content, accentColor: accentColor)
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case .list:
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return buildList(block.content)
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}
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}
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// MARK: - 各类型 Block 的构建方法
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/// Heading1: 26pt bold, 上下间距 28pt/10pt ✅ 优化：24 → 26
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private static func buildHeading1(_ content: String) -> NSAttributedString {
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let paragraphStyle = NSMutableParagraphStyle()
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paragraphStyle.paragraphSpacingBefore = 28
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paragraphStyle.paragraphSpacing = 10
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let attributes: [NSAttributedString.Key: Any] = [
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.font: UIFont.systemFont(ofSize: 26, weight: .bold), // ✅ 优化：24 → 26
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.foregroundColor: UIColor.inkPrimary,
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.paragraphStyle: paragraphStyle
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]
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return NSAttributedString(string: content, attributes: attributes)
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}
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/// Heading2: 22pt bold, 上下间距 20pt/8pt ✅ 优化：20 → 22
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private static func buildHeading2(_ content: String) -> NSAttributedString {
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let paragraphStyle = NSMutableParagraphStyle()
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paragraphStyle.paragraphSpacingBefore = 20
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paragraphStyle.paragraphSpacing = 8
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let attributes: [NSAttributedString.Key: Any] = [
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.font: UIFont.systemFont(ofSize: 22, weight: .bold), // ✅ 优化：20 → 22
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.foregroundColor: UIColor.inkPrimary,
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.paragraphStyle: paragraphStyle
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]
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return NSAttributedString(string: content, attributes: attributes)
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}
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/// Paragraph: 17pt, 行高 29.3pt (1.72倍), 字间距 0.5pt；spacingAfter 为段后间距（段间松）
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private static func buildParagraph(_ content: String, accentColor: UIColor? = nil, spacingAfter: CGFloat? = nil) -> NSAttributedString {
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return parseHTMLContent(content, baseAttributes: getParagraphAttributes(spacingAfter: spacingAfter), accentColor: accentColor)
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}
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/// 去掉段首的 #### / ### / ## / # 前缀，不改变样式（直接删掉）
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private static func stripMarkdownHeadingPrefix(_ content: String) -> String {
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let trimmed = content.trimmingCharacters(in: .whitespacesAndNewlines)
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if trimmed.hasPrefix("#### ") {
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return String(trimmed.dropFirst(5))
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}
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if trimmed.hasPrefix("### ") {
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return String(trimmed.dropFirst(4))
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}
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if trimmed.hasPrefix("## ") {
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return String(trimmed.dropFirst(3))
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}
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if trimmed.hasPrefix("# ") {
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return String(trimmed.dropFirst(2))
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}
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return content
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}
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/// 将正文中「行首 - 」或「行首 - 后直接跟字」统一成「• 」，用于支持 AI 输出的 Markdown 列表
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private static func replaceLineStartHyphenWithBullet(_ content: String) -> String {
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let lines = content.components(separatedBy: "\n")
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let processed = lines.map { line -> String in
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let dropCount = line.prefix(while: { $0.isWhitespace }).count
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let rest = line.dropFirst(dropCount)
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if rest.hasPrefix("- ") {
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let indent = String(line.prefix(dropCount))
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return indent + "• " + rest.dropFirst(2)
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}
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if rest.hasPrefix("-") {
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let indent = String(line.prefix(dropCount))
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if rest.count == 1 {
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return indent + "• "
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}
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if !(rest.dropFirst(1).first?.isWhitespace ?? true) {
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return indent + "• " + rest.dropFirst(1)
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}
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}
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return line
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}
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return processed.joined(separator: "\n")
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}
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/// Quote: 17pt medium, 左侧竖线, 灰色文字, 行距 8pt
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private static func buildQuote(_ content: String) -> NSAttributedString {
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let paragraphStyle = NSMutableParagraphStyle()
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paragraphStyle.lineSpacing = 8
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paragraphStyle.firstLineHeadIndent = 12 // 左侧留出竖线空间
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paragraphStyle.headIndent = 12
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let attributes: [NSAttributedString.Key: Any] = [
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.font: UIFont.systemFont(ofSize: bodyFontSize, weight: .medium),
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.foregroundColor: UIColor.inkSecondary,
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.paragraphStyle: paragraphStyle
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]
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// TODO: 左侧竖线可以通过 NSTextAttachment 或自定义绘制实现
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// 这里先用文本缩进模拟
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let quoteContent = "│ " + content // 临时方案：使用字符模拟竖线
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return NSAttributedString(string: quoteContent, attributes: attributes)
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}
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/// Highlight: 20pt bold, 背景色, 圆角, 内边距 ✅ 优化：18 → 20
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private static func buildHighlight(_ content: String, accentColor: UIColor? = nil) -> NSAttributedString {
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let color = accentColor ?? UIColor.brandVital
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let paragraphStyle = NSMutableParagraphStyle()
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paragraphStyle.lineSpacing = bodyLineSpacing + 2
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let attributes: [NSAttributedString.Key: Any] = [
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.font: UIFont.systemFont(ofSize: 20, weight: .bold), // ✅ 优化：18 → 20
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.foregroundColor: color,
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.paragraphStyle: paragraphStyle,
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.backgroundColor: color.withAlphaComponent(0.08)
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]
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return NSAttributedString(string: content, attributes: attributes)
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}
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/// List: 项目符号 "• ", 17pt
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private static func buildList(_ content: String) -> NSAttributedString {
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let paragraphStyle = NSMutableParagraphStyle()
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paragraphStyle.firstLineHeadIndent = 0
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paragraphStyle.headIndent = 20 // 项目符号后的缩进
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let attributes: [NSAttributedString.Key: Any] = [
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.font: UIFont.systemFont(ofSize: bodyFontSize),
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.foregroundColor: UIColor.inkBody,
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.paragraphStyle: paragraphStyle,
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.kern: 0.5
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]
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let listContent = "• " + content
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return NSAttributedString(string: listContent, attributes: attributes)
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}
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// MARK: - 样式辅助方法
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/// 获取段落基础样式；spacingAfter 为段后间距（段间松），nil 表示不额外加
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private static func getParagraphAttributes(spacingAfter: CGFloat? = nil) -> [NSAttributedString.Key: Any] {
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let paragraphStyle = NSMutableParagraphStyle()
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paragraphStyle.lineBreakMode = .byWordWrapping
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if let after = spacingAfter {
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paragraphStyle.paragraphSpacing = after
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}
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let font = UIFont.systemFont(ofSize: bodyFontSize)
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let lineSpacing: CGFloat = bodyLineSpacing
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let baseLineHeight = font.lineHeight
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paragraphStyle.minimumLineHeight = baseLineHeight + lineSpacing
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paragraphStyle.maximumLineHeight = baseLineHeight + lineSpacing
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paragraphStyle.lineSpacing = 0
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return [
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.font: font,
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.foregroundColor: UIColor.inkBody,
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.paragraphStyle: paragraphStyle,
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.kern: 0.5
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]
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}
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/// 解析 HTML 内容（处理 <span class='highlight'>、<b>、<br> 标签）
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private static func parseHTMLContent(_ rawString: String, baseAttributes: [NSAttributedString.Key: Any], accentColor: UIColor? = nil) -> NSAttributedString {
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let cleanString = rawString.replacingOccurrences(of: "<br>", with: "\n")
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let result = NSMutableAttributedString()
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let highlightColor = accentColor ?? UIColor.brandVital
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var highlightAttributes = baseAttributes
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highlightAttributes[.foregroundColor] = highlightColor
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highlightAttributes[.font] = UIFont.systemFont(ofSize: bodyFontSize, weight: .bold)
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// 分割 <span class='highlight'>
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let parts = cleanString.components(separatedBy: "<span class='highlight'>")
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for (index, part) in parts.enumerated() {
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if index == 0 {
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// 开头普通文本（含 <b> 需解析）
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result.append(parseBoldTags(part, baseAttributes: baseAttributes))
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} else {
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let subParts = part.components(separatedBy: "</span>")
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if !subParts.isEmpty {
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// 高亮部分（可能内含 <b>，解析后统一为高亮样式即可，主要去掉 <b> 字面量）
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result.append(parseBoldTags(subParts[0], baseAttributes: highlightAttributes))
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// 剩余普通部分（含 <b> 需解析）
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if subParts.count > 1 {
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result.append(parseBoldTags(subParts[1], baseAttributes: baseAttributes))
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}
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} else {
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result.append(parseBoldTags(part, baseAttributes: baseAttributes))
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}
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}
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}
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return result
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}
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/// 解析 <b>...</b>，将加粗区间应用粗体，其余用 baseAttributes；未闭合的 <b> 视作到文末加粗，多余 </b> 舍弃。
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private static func parseBoldTags(_ s: String, baseAttributes: [NSAttributedString.Key: Any]) -> NSAttributedString {
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let res = NSMutableAttributedString()
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let baseFont = baseAttributes[.font] as? UIFont ?? UIFont.systemFont(ofSize: bodyFontSize)
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var boldAttrs = baseAttributes
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boldAttrs[.font] = UIFont.systemFont(ofSize: baseFont.pointSize, weight: .bold)
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let openTag = "<b>"
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let closeTag = "</b>"
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var i = s.startIndex
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while i < s.endIndex {
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if let openRange = s.range(of: openTag, range: i..<s.endIndex) {
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// <b> 前的普通文本
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res.append(NSAttributedString(string: String(s[i..<openRange.lowerBound]), attributes: baseAttributes))
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let afterOpen = openRange.upperBound
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if let closeRange = s.range(of: closeTag, range: afterOpen..<s.endIndex) {
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res.append(NSAttributedString(string: String(s[afterOpen..<closeRange.lowerBound]), attributes: boldAttrs))
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i = closeRange.upperBound
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} else {
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// 未闭合 <b>，到文末为粗体
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res.append(NSAttributedString(string: String(s[afterOpen...]), attributes: boldAttrs))
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i = s.endIndex
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}
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} else {
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// 无 <b>：若有孤儿 </b> 则跳过，其余为普通
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if let closeRange = s.range(of: closeTag, range: i..<s.endIndex) {
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res.append(NSAttributedString(string: String(s[i..<closeRange.lowerBound]), attributes: baseAttributes))
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i = closeRange.upperBound
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} else {
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res.append(NSAttributedString(string: String(s[i...]), attributes: baseAttributes))
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break
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}
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}
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}
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return res
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}
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/// 创建段落样式（用于段落间距）
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private static func createParagraphStyle(spacingBefore: CGFloat) -> NSParagraphStyle {
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let style = NSMutableParagraphStyle()
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style.paragraphSpacingBefore = spacingBefore
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return style
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}
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}
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// MARK: - 注意
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// UIColor 扩展已在 DesignSystem+UIKit.swift 中定义，无需重复定义
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