优化兼容性

internal/service/backup.go

@@ -1,9 +1,13 @@
 // Package service — database hot backup and restore.
 //
-// BackupService uses SQLite's "VACUUM INTO" (available since 3.27.0) to
-// produce a consistent copy of the database without blocking writers.
-// Backup files are stored under {data_dir}/backups/ with a timestamp
-// suffix. The admin UI can list / download / delete / restore them.
+// Backup files are stored under {data_dir}/backups/ with a timestamp suffix.
+// The admin UI can list / download / delete / restore them.
+//
+// 两种方言的备份形态不同：
+//   - SQLite：用 "VACUUM INTO"（3.27.0 起可用）产出一个一致的库文件，
+//     扩展名 .db；恢复即「替换库文件 + 重启」。
+//   - PostgreSQL：没有单文件语义，用逻辑备份（见 backup_postgres.go），
+//     扩展名 .json.gz；恢复是在单个事务内重建全部表。
 package service
 
 import (
@@ -65,18 +69,34 @@ func (b *BackupService) backupFilePath(filename string) (string, error) {
 	return path, nil
 }
 
-// Create produces a new hot backup via "VACUUM INTO".
+// isPostgres reports whether the service is backed by PostgreSQL.
+//
+// PostgreSQL 不支持 SQLite 的 "VACUUM INTO"，按文件替换恢复也会写错目标，
+// 因此备份/恢复必须按方言分支，不能共用一条路径。
+func (b *BackupService) isPostgres() bool {
+	return b.db != nil && b.db.Dialector != nil && b.db.Dialector.Name() == "postgres"
+}
+
+// Create produces a new hot backup. SQLite uses "VACUUM INTO"; PostgreSQL uses
+// a logical dump.
 func (b *BackupService) Create(ctx context.Context) (*BackupInfo, error) {
 	dir := b.backupDir()
 	if err := os.MkdirAll(dir, 0o750); err != nil {
 		return nil, err
 	}
 	ts := time.Now().Format("20060102_150405")
-	dst := filepath.Join(dir, fmt.Sprintf("mebox_%s.db", ts))
 
-	// VACUUM INTO creates a clean, non-WAL copy atomically.
-	if err := b.db.WithContext(ctx).Exec("VACUUM INTO ?", dst).Error; err != nil {
-		return nil, fmt.Errorf("VACUUM INTO failed: %w", err)
+	var (
+		dst string
+		err error
+	)
+	if b.isPostgres() {
+		dst, err = b.createPostgresBackup(ctx, ts)
+	} else {
+		dst, err = b.createSQLiteBackup(ctx, ts)
+	}
+	if err != nil {
+		return nil, err
 	}
 	stat, err := os.Stat(dst)
 	if err != nil {
@@ -91,6 +111,15 @@ func (b *BackupService) Create(ctx context.Context) (*BackupInfo, error) {
 	}, nil
 }
 
+func (b *BackupService) createSQLiteBackup(ctx context.Context, stamp string) (string, error) {
+	dst := filepath.Join(b.backupDir(), fmt.Sprintf("mebox_%s.db", stamp))
+	// VACUUM INTO creates a clean, non-WAL copy atomically.
+	if err := b.db.WithContext(ctx).Exec("VACUUM INTO ?", dst).Error; err != nil {
+		return "", fmt.Errorf("VACUUM INTO failed: %w", err)
+	}
+	return dst, nil
+}
+
 // List returns every backup file in the backup directory, newest first.
 func (b *BackupService) List() ([]BackupInfo, error) {
 	dir := b.backupDir()
@@ -103,7 +132,7 @@ func (b *BackupService) List() ([]BackupInfo, error) {
 	}
 	out := make([]BackupInfo, 0, len(entries))
 	for _, e := range entries {
-		if e.IsDir() || !strings.HasSuffix(e.Name(), ".db") {
+		if e.IsDir() || !isBackupFilename(e.Name()) {
 			continue
 		}
 		info, err := e.Info()
@@ -132,9 +161,10 @@ func (b *BackupService) Delete(filename string) error {
 	return os.Remove(path)
 }
 
-// Restore copies a backup over the live database using VACUUM INTO in
-// reverse. WARNING: this is destructive — the live DB will be replaced.
-// Callers should shut down the server after this call.
+// Restore replaces the live database with the given backup.
+// WARNING: this is destructive. SQLite restores by swapping the database file
+// (the caller should shut down the server afterwards); PostgreSQL restores by
+// rebuilding every table inside a single transaction.
 func (b *BackupService) Restore(ctx context.Context, filename string) error {
 	src, err := b.backupFilePath(filename)
 	if err != nil {
@@ -143,6 +173,19 @@ func (b *BackupService) Restore(ctx context.Context, filename string) error {
 	if _, err := os.Stat(src); err != nil {
 		return fmt.Errorf("backup not found: %s", filename)
 	}
+	if b.isPostgres() {
+		if !strings.HasSuffix(filename, postgresBackupSuffix) {
+			return errors.New("该备份是 SQLite 文件备份，当前运行在 PostgreSQL 上，无法恢复")
+		}
+		return b.restorePostgresBackup(ctx, src)
+	}
+	if !strings.HasSuffix(filename, ".db") {
+		return errors.New("该备份是 PostgreSQL 逻辑备份，当前运行在 SQLite 上，无法恢复")
+	}
+	return b.restoreSQLiteBackup(filename, src)
+}
+
+func (b *BackupService) restoreSQLiteBackup(filename, src string) error {
 	dbPath, err := filepath.Abs(b.cfg.Database.DBPath)
 	if err != nil || dbPath == "" {
 		return errors.New("invalid database path")
@@ -171,7 +214,13 @@ func (b *BackupService) Restore(ctx context.Context, filename string) error {
 	return nil
 }
 
-// isValidBackupFilename rejects path traversal attempts and non-.db files.
+// isBackupFilename reports whether name looks like a backup produced by either
+// dialect (SQLite ".db" or PostgreSQL ".json.gz").
+func isBackupFilename(name string) bool {
+	return strings.HasSuffix(name, ".db") || strings.HasSuffix(name, postgresBackupSuffix)
+}
+
+// isValidBackupFilename rejects path traversal attempts and non-backup files.
 func isValidBackupFilename(name string) bool {
 	if name == "" {
 		return false
@@ -179,8 +228,5 @@ func isValidBackupFilename(name string) bool {
 	if strings.ContainsAny(name, "/\\") || strings.Contains(name, "..") {
 		return false
 	}
-	if !strings.HasSuffix(name, ".db") {
-		return false
-	}
-	return true
+	return isBackupFilename(name)
 }