fix: add custom lyrics restore conflict choices

app/src/main/java/dev/amenhancer/module/lyrics/CustomLyricsManager.kt

@@ -107,13 +107,18 @@ internal class CustomLyricsManager(
     }
 
     /**
-     * Streams a bounded ZIP backup from [input] into a merge-restore: backup
-     * entries overwrite same-ID current entries, current-only IDs are kept,
-     * every restored entry gets a fresh remote fileId. TTML bodies are
-     * validated and written one at a time, never all at once. Consumes and
-     * closes [input].
+     * Streams a bounded ZIP backup from [input] into a merge-restore. Under
+     * [CustomLyricsRestorePolicy.OVERWRITE] backup entries overwrite same-ID
+     * current entries; under [CustomLyricsRestorePolicy.KEEP_EXISTING]
+     * same-ID conflicts keep the current entry. Current-only IDs are kept and
+     * backup-only IDs are appended under either policy; every restored entry
+     * gets a fresh remote fileId. TTML bodies are validated and written one
+     * at a time, never all at once. Consumes and closes [input].
      */
-    fun restore(input: InputStream): CustomLyricsRestoreResult = synchronized(mutationLock) {
+    fun restore(
+        input: InputStream,
+        policy: CustomLyricsRestorePolicy = CustomLyricsRestorePolicy.OVERWRITE,
+    ): CustomLyricsRestoreResult = synchronized(mutationLock) {
         if (!isWritable()) return CustomLyricsRestoreResult.Failed("libxposed remote file 服务不可用")
         val state = configStore.indexState(snapshot)
         return CustomLyricsRestoreTransaction(
@@ -123,7 +128,7 @@ internal class CustomLyricsManager(
             deleteRemoteFile = { fileId ->
                 if (ModuleApplication.isCurrentSnapshot(snapshot)) snapshot.deleteRemoteFile(fileId)
             },
-        ).merge(state.manifest) { onFile -> CustomLyricsBackupCodec.decode(input, onFile) }
+        ).merge(state.manifest, policy) { onFile -> CustomLyricsBackupCodec.decode(input, onFile) }
     }
 
     private fun readRemoteFile(fileId: String): ByteArray? {

app/src/main/java/dev/amenhancer/module/lyrics/CustomLyricsRestoreTransaction.kt

@@ -10,14 +10,30 @@ internal sealed interface CustomLyricsRestoreResult {
 }
 
 /**
- * Merge-restore semantics: backup entries overwrite current entries with the
- * same Apple Music ID, current-only IDs are kept. The backup's files arrive
- * one at a time through the caller-supplied stream; every one is written to a
- * fresh remote fileId as it arrives, the merged manifest is published once
- * after the whole backup scans, then old files of overwritten IDs are
- * deleted. Any scan, write, or publish failure rolls back only the new files
- * and leaves the old manifest and old files untouched. An empty backup is a
- * successful no-op.
+ * Conflict strategy applied per Apple Music ID when a restore meets both a
+ * current entry and a backup entry with the same ID.
+ */
+internal enum class CustomLyricsRestorePolicy {
+    /** Same-ID conflicts take the backup entry; the overwritten current file is retired. */
+    OVERWRITE,
+
+    /** Same-ID conflicts keep the current entry; the written backup file is dropped after publish. */
+    KEEP_EXISTING,
+}
+
+/**
+ * Merge-restore semantics: under [CustomLyricsRestorePolicy.OVERWRITE] backup
+ * entries overwrite current entries with the same Apple Music ID; under
+ * [CustomLyricsRestorePolicy.KEEP_EXISTING] same-ID conflicts keep the
+ * current entry. Current-only IDs are kept and backup-only IDs are appended
+ * under either policy. The backup's files arrive one at a time through the
+ * caller-supplied stream; every one is written to a fresh remote fileId as it
+ * arrives, the merged manifest is published once after the whole backup
+ * scans, then files that no longer reference any entry are deleted: old files
+ * of overwritten IDs under OVERWRITE, written-but-dropped backup files under
+ * KEEP_EXISTING. Any scan, write, or publish failure rolls back only the new
+ * files and leaves the old manifest and old files untouched. An empty backup
+ * is a successful no-op.
  */
 internal class CustomLyricsRestoreTransaction(
     private val fileIdFactory: () -> String,
@@ -27,6 +43,7 @@ internal class CustomLyricsRestoreTransaction(
 ) {
     fun merge(
         oldManifest: CustomLyricsManifest,
+        policy: CustomLyricsRestorePolicy = CustomLyricsRestorePolicy.OVERWRITE,
         streamBackup: (onFile: (fileId: String, bytes: ByteArray) -> Unit) -> CustomLyricsBackupDecodeResult,
     ): CustomLyricsRestoreResult {
         val allocatedFileIds = oldManifest.entries.mapTo(mutableSetOf(), CustomLyricsEntry::fileId)
@@ -65,34 +82,46 @@ internal class CustomLyricsRestoreTransaction(
             }
             is CustomLyricsBackupDecodeResult.Decoded -> {
                 val backup = scan.backup
-                if (backup.manifest.entries.isEmpty()) {
-                    return CustomLyricsRestoreResult.Restored(oldManifest)
-                }
                 val error = writeError
                 if (error != null) {
                     written.forEach { runCatching { deleteRemoteFile(it) } }
                     return CustomLyricsRestoreResult.Failed(error)
                 }
+                if (backup.manifest.entries.isEmpty()) {
+                    written.forEach { runCatching { deleteRemoteFile(it) } }
+                    return CustomLyricsRestoreResult.Restored(oldManifest)
+                }
                 val rebuilt = mutableListOf<CustomLyricsEntry>()
+                val incomingById = linkedMapOf<Long, CustomLyricsEntry>()
                 for (incoming in backup.manifest.entries) {
                     val fileId = newFileIds[incoming.fileId]
                     if (fileId == null) {
                         written.forEach { runCatching { deleteRemoteFile(it) } }
                         return CustomLyricsRestoreResult.Failed("备份内容缺失")
                     }
-                    rebuilt += incoming.copy(fileId = fileId)
+                    val entry = incoming.copy(fileId = fileId)
+                    if (incomingById.putIfAbsent(entry.appleMusicId, entry) != null) {
+                        written.forEach { runCatching { deleteRemoteFile(it) } }
+                        return CustomLyricsRestoreResult.Failed("备份条目重复")
+                    }
+                    rebuilt += entry
                 }
-                val incomingById = rebuilt.associateBy(CustomLyricsEntry::appleMusicId)
                 val currentIds = oldManifest.entries.mapTo(mutableSetOf(), CustomLyricsEntry::appleMusicId)
                 val mergedEntries = mutableListOf<CustomLyricsEntry>()
                 val retiredFileIds = mutableListOf<String>()
+                val droppedFileIds = mutableListOf<String>()
                 oldManifest.entries.forEach { current ->
                     val replacement = incomingById[current.appleMusicId]
-                    if (replacement != null) {
-                        mergedEntries += replacement
-                        retiredFileIds += current.fileId
-                    } else {
-                        mergedEntries += current
+                    when {
+                        replacement == null -> mergedEntries += current
+                        policy == CustomLyricsRestorePolicy.OVERWRITE -> {
+                            mergedEntries += replacement
+                            retiredFileIds += current.fileId
+                        }
+                        else -> {
+                            mergedEntries += current
+                            droppedFileIds += replacement.fileId
+                        }
                     }
                 }
                 rebuilt.forEach { entry ->
@@ -103,7 +132,7 @@ internal class CustomLyricsRestoreTransaction(
                     written.forEach { runCatching { deleteRemoteFile(it) } }
                     return CustomLyricsRestoreResult.Failed("无法发布歌词映射")
                 }
-                retiredFileIds.forEach { runCatching { deleteRemoteFile(it) } }
+                (retiredFileIds + droppedFileIds).forEach { runCatching { deleteRemoteFile(it) } }
                 CustomLyricsRestoreResult.Restored(merged)
             }
         }

app/src/main/java/dev/amenhancer/module/ui/SettingsActivity.kt

@@ -48,6 +48,7 @@ import dev.amenhancer.module.lyrics.CustomLyricsMutationResult
 import dev.amenhancer.module.lyrics.CustomLyricsOnlineImportResult
 import dev.amenhancer.module.lyrics.CustomLyricsOnlineImporter
 import dev.amenhancer.module.lyrics.CustomLyricsRestoreResult
+import dev.amenhancer.module.lyrics.CustomLyricsRestorePolicy
 import dev.amenhancer.module.lyrics.CustomLyricsSaveResult
 import dev.amenhancer.module.model.CustomLyricsEntry
 import dev.amenhancer.module.model.CustomLyricsManifest
@@ -761,22 +762,27 @@ class SettingsActivity : Activity() {
 
     private fun confirmRestoreCustomLyrics(uri: android.net.Uri) {
         AlertDialog.Builder(this)
-            .setTitle("合并恢复歌词备份")
-            .setMessage(
-                "同 Apple Music ID 的歌词将使用备份版本；" +
-                    "当前独有歌词会保留；总开关不会改变。是否继续？",
-            )
+            .setTitle("恢复歌词备份")
+            .setMessage("覆盖：冲突歌词使用备份版本；不覆盖：冲突歌词保留当前版本。")
             .setNegativeButton("取消", null)
-            .setPositiveButton("恢复") { _, _ -> restoreCustomLyrics(uri) }
+            .setNeutralButton("不覆盖") { _, _ ->
+                restoreCustomLyrics(uri, CustomLyricsRestorePolicy.KEEP_EXISTING)
+            }
+            .setPositiveButton("覆盖") { _, _ ->
+                restoreCustomLyrics(uri, CustomLyricsRestorePolicy.OVERWRITE)
+            }
             .show()
     }
 
-    private fun restoreCustomLyrics(uri: android.net.Uri) {
+    private fun restoreCustomLyrics(
+        uri: android.net.Uri,
+        policy: CustomLyricsRestorePolicy,
+    ) {
         val snapshot = ModuleApplication.serviceSnapshot
         backgroundExecutor.execute {
             val result = runCatching {
                 contentResolver.openInputStream(uri)?.use { input ->
-                    CustomLyricsManager(snapshot, store).restore(input)
+                    CustomLyricsManager(snapshot, store).restore(input, policy)
                 } ?: CustomLyricsRestoreResult.Failed("无法读取备份文件")
             }.getOrElse { CustomLyricsRestoreResult.Failed("读取备份失败") }
             runOnUiThread {