add chinese subtitles

ios/OralTrainer/Views/RootView.swift

@@ -9,6 +9,10 @@ struct RootView: View {
     @StateObject private var historyManager = TrainingHistoryManager()
     @State private var activeModule: Module = .course
     @State private var continuousPlayback = false
+    @State private var showChineseSubtitles = false
+    @State private var chineseTranslationLoading = false
+    @State private var chineseTranslationError = ""
+    @State private var chineseTranslationTask: Task<Void, Never>?
     @State private var showImporter = false
     @State private var showFullscreenPlayer = false
     @State private var courses: [Course] = []
@@ -53,6 +57,8 @@ struct RootView: View {
                         controller: controller,
                         catalogVM: catalogVM,
                         continuousPlayback: $continuousPlayback,
+                        showChineseSubtitles: $showChineseSubtitles,
+                        chineseSubtitlePlaceholder: chineseSubtitlePlaceholder,
                         onFullscreen: enterFullscreen
                     )
                 case .test:
@@ -88,9 +94,24 @@ struct RootView: View {
                 Task { await loadCourses() }
             }
         }
+        .onChange(of: showChineseSubtitles) { enabled in
+            if enabled {
+                ensureChineseTranslations()
+            } else {
+                chineseTranslationTask?.cancel()
+                chineseTranslationLoading = false
+            }
+        }
+        .onChange(of: controller.currentItem?.id) { _ in
+            ensureChineseTranslations()
+        }
+        .onChange(of: controller.currentItem?.sentences.count) { _ in
+            ensureChineseTranslations()
+        }
         .onChange(of: activeModule) { module in
             if module == .train {
                 controller.setContinuousPlayback(continuousPlayback)
+                ensureChineseTranslations()
             } else if module == .test {
                 // 与安卓测试页一致：按当前句窗口播放，避免滑进下一句。
                 controller.setContinuousPlayback(false)
@@ -115,7 +136,9 @@ struct RootView: View {
         .fullScreenCover(isPresented: $showFullscreenPlayer) {
             FullscreenPlayerView(
                 controller: controller,
-                showsLessonTitle: activeModule != .train
+                showsLessonTitle: activeModule != .train,
+                showChineseSubtitles: showChineseSubtitles,
+                chineseSubtitlePlaceholder: chineseSubtitlePlaceholder
             ) {
                 exitFullscreen()
             }
@@ -593,4 +616,59 @@ struct RootView: View {
         AppDelegate.lockOrientation(restored)
         showFullscreenPlayer = false
     }
+
+    private var chineseSubtitlePlaceholder: String {
+        if chineseTranslationLoading {
+            return "正在翻译中文字幕…"
+        }
+        if !chineseTranslationError.isEmpty {
+            return chineseTranslationError
+        }
+        return "暂无中文字幕"
+    }
+
+    private func ensureChineseTranslations() {
+        guard showChineseSubtitles, activeModule == .train else {
+            return
+        }
+        guard let item = controller.currentItem else {
+            return
+        }
+        let needsTranslation = item.sentences.contains {
+            !($0.text ?? "").trimmingCharacters(in: .whitespacesAndNewlines).isEmpty &&
+                ($0.zhText ?? "").trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
+        }
+        guard needsTranslation else {
+            chineseTranslationLoading = false
+            chineseTranslationError = ""
+            return
+        }
+        chineseTranslationTask?.cancel()
+        chineseTranslationLoading = true
+        chineseTranslationError = ""
+        let mediaId = item.id
+        chineseTranslationTask = Task {
+            do {
+                let map = try await SentenceBoundaryAPI.translateSubtitles(videoHash: mediaId)
+                guard !Task.isCancelled else { return }
+                await MainActor.run {
+                    guard controller.currentItem?.id == mediaId else { return }
+                    let updated = (controller.currentItem?.sentences ?? []).map { sentence in
+                        sentence.withZhText(map[sentence.index] ?? sentence.zhText)
+                    }
+                    controller.updateBoundaries(updated)
+                    chineseTranslationLoading = false
+                    chineseTranslationError = ""
+                    controller.showTransientMessage("已加载中文字幕")
+                }
+            } catch {
+                guard !Task.isCancelled else { return }
+                await MainActor.run {
+                    chineseTranslationLoading = false
+                    chineseTranslationError = "中文字幕翻译失败"
+                    controller.showTransientMessage("中文字幕翻译失败：\(error.localizedDescription)")
+                }
+            }
+        }
+    }
 }