regenerate something when the sentences changed

android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/CourseCatalogController.kt

@@ -2,6 +2,7 @@ package cn.learningpad.oraltrainer.sample
 
 import cn.learningpad.oraltrainer.sdk.OralTrainerController
 import cn.learningpad.oraltrainer.sdk.OralTrainerSdk
+import cn.learningpad.oraltrainer.sdk.SentenceBoundary
 import cn.learningpad.oraltrainer.sdk.SentenceBoundaryApiCallback
 import cn.learningpad.oraltrainer.sdk.SentenceBoundaryApiResult
 import cn.learningpad.oraltrainer.sdk.TrainingVideoSummary
@@ -26,6 +27,7 @@ internal class CourseCatalogController(
         fun onSentencePlaceholder(meta: String, text: String)
         fun refreshPlayerUi()
         fun openTrainingModule()
+        fun syncSentenceExplanations(videoHash: String, sentences: List<SentenceBoundary>)
     }
 
     fun loadCatalog() {
@@ -101,6 +103,7 @@ internal class CourseCatalogController(
             override fun onSuccess(result: SentenceBoundaryApiResult) {
                 if (!screenState.isCurrentCatalogRequest(generation)) return
                 screenState.courseBoundaries[result.videoHash] = result
+                host.syncSentenceExplanations(result.videoHash, result.sentences)
                 updateCatalogVideo(video.videoHash, result)
                 if (screenState.activeItemId == result.videoHash) {
                     controller.updateSentences(result.videoHash, result.sentences)
@@ -174,6 +177,9 @@ internal class CourseCatalogController(
         host.onCatalogChanged()
 
         val cachedBoundary = screenState.courseBoundaries[video.videoHash]
+        if (cachedBoundary != null) {
+            host.syncSentenceExplanations(cachedBoundary.videoHash, cachedBoundary.sentences)
+        }
         controller.loadItem(video.toTrainingMediaItem(cachedBoundary?.sentences.orEmpty()))
         screenState.currentSentenceCount = cachedBoundary?.sentences?.size ?: video.sentenceCount
         if (cachedBoundary == null) {
@@ -198,6 +204,7 @@ internal class CourseCatalogController(
                     return
                 }
                 screenState.courseBoundaries[result.videoHash] = result
+                host.syncSentenceExplanations(result.videoHash, result.sentences)
                 updateCatalogVideo(video.videoHash, result)
                 screenState.currentSentenceCount = result.sentences.size
                 controller.updateSentences(video.videoHash, result.sentences)

android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/MainActivity.kt

@@ -480,10 +480,12 @@ class MainActivity : Activity() {
             val sentence = controller.currentSentence() ?: return
             if (sentence.text.isNullOrBlank()) return
             controller.pause()
+            val item = controller.currentTrainingItem()
             explanationOverlay.show(
                 sentence,
-                controller.currentTrainingItem()?.title.orEmpty(),
-                controller.currentTrainingItem()?.id.orEmpty(),
+                item?.title.orEmpty(),
+                item?.id.orEmpty(),
+                item?.sentences.orEmpty(),
             )
         }
 
@@ -561,6 +563,13 @@ class MainActivity : Activity() {
             screenFactory.renderCatalog()
             refreshCurrentUi()
         }
+
+        override fun syncSentenceExplanations(
+            videoHash: String,
+            sentences: List<SentenceBoundary>,
+        ) {
+            SentenceExplanationStore(this@MainActivity).sync(videoHash, sentences)
+        }
     }
 
     private fun testHost() = object : TestSessionController.Host {

android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/SentenceExplanationOverlay.kt

@@ -23,7 +23,15 @@ internal class SentenceExplanationOverlay(
     private var currentRequest: CancellableExplanationRequest? = null
     private var requestGeneration = 0
 
-    fun show(sentence: SentenceBoundary, courseTitle: String, mediaId: String) {
+    fun show(
+        sentence: SentenceBoundary,
+        courseTitle: String,
+        mediaId: String,
+        sentences: List<SentenceBoundary> = emptyList(),
+    ) {
+        if (sentences.isNotEmpty()) {
+            store.sync(mediaId, sentences)
+        }
         close()
         val generation = ++requestGeneration
         val root = FrameLayout(activity).apply {

android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/SentenceExplanationStore.kt

@@ -1,6 +1,7 @@
 package cn.learningpad.oraltrainer.sample
 
 import android.content.Context
+import cn.learningpad.oraltrainer.sdk.SentenceBoundary
 import java.io.File
 import java.util.Locale
 
@@ -23,12 +24,34 @@ internal class SentenceExplanationStore(context: Context) {
         return file.isFile && file.length() > 0L
     }
 
+    fun sync(mediaId: String, sentences: List<SentenceBoundary>) {
+        if (sentences.isEmpty()) return
+        val directoryName = sanitize(mediaId) ?: return
+        val dir = File(rootDir, directoryName)
+        val revision = revisionFor(sentences)
+        val marker = File(dir, REVISION_FILE)
+        val previous = marker.takeIf { it.isFile }?.readText()?.trim().orEmpty()
+        if (previous == revision) return
+        if (dir.exists()) {
+            dir.deleteRecursively()
+        }
+        dir.mkdirs()
+        marker.writeText(revision)
+    }
+
     private fun fileFor(mediaId: String, sentenceIndex: Int): File? {
         val directoryName = sanitize(mediaId) ?: return null
         return File(File(rootDir, directoryName), "$sentenceIndex.txt")
     }
 
     companion object {
+        private const val REVISION_FILE = "revision.txt"
+
+        fun revisionFor(sentences: List<SentenceBoundary>): String =
+            sentences.joinToString("\n") { sentence ->
+                "${sentence.index}\t${sentence.text.orEmpty().trim()}"
+            }
+
         fun sanitize(mediaId: String): String? {
             val filtered = mediaId.trim().lowercase(Locale.US)
                 .replace(Regex("[^a-z0-9._-]"), "_")