split database migration helpers

internal/database/schema_media_search.go

@@ -0,0 +1,91 @@
+package database
+
+import "gorm.io/gorm"
+
+// mediaSearchIndexSchemaVersion identifies the physical FTS index layout.
+// v2 aligns FTS rowids with media rowids and keeps the index current with
+// triggers.
+const mediaSearchIndexSchemaVersion = 2
+
+func ensureMediaSearchIndex(db *gorm.DB) error {
+	if err := ensureMediaSearchMetaTable(db); err != nil {
+		return nil
+	}
+	version := currentMediaSearchIndexVersion(db)
+	if version != mediaSearchIndexSchemaVersion {
+		resetMediaSearchIndex(db)
+	}
+	if !createMediaSearchFTSTable(db) {
+		return nil
+	}
+	if err := createMediaSearchTriggers(db); err != nil {
+		return err
+	}
+	if version != mediaSearchIndexSchemaVersion {
+		return markMediaSearchIndexVersion(db)
+	}
+	return nil
+}
+
+func ensureMediaSearchMetaTable(db *gorm.DB) error {
+	return db.Exec(`CREATE TABLE IF NOT EXISTS media_search_meta (id INTEGER PRIMARY KEY CHECK (id = 1), version INTEGER NOT NULL)`).Error
+}
+
+func currentMediaSearchIndexVersion(db *gorm.DB) int {
+	var version int
+	_ = db.Raw(`SELECT version FROM media_search_meta WHERE id = 1`).Scan(&version).Error
+	return version
+}
+
+func resetMediaSearchIndex(db *gorm.DB) {
+	for _, stmt := range []string{
+		`DROP TRIGGER IF EXISTS media_search_fts_ai`,
+		`DROP TRIGGER IF EXISTS media_search_fts_au`,
+		`DROP TRIGGER IF EXISTS media_search_fts_ad`,
+		`DROP TABLE IF EXISTS media_search_fts`,
+	} {
+		_ = db.Exec(stmt).Error
+	}
+}
+
+func createMediaSearchFTSTable(db *gorm.DB) bool {
+	if err := db.Exec(`CREATE VIRTUAL TABLE IF NOT EXISTS media_search_fts USING fts5(media_id UNINDEXED, title, original_name, path, genres, tokenize='trigram')`).Error; err == nil {
+		return true
+	}
+	if err := db.Exec(`CREATE VIRTUAL TABLE IF NOT EXISTS media_search_fts USING fts5(media_id UNINDEXED, title, original_name, path, genres, tokenize='unicode61')`).Error; err == nil {
+		return true
+	}
+	// FTS is an acceleration path. Some embedded SQLite builds may omit FTS5;
+	// keep startup working and let repository queries fall back to LIKE search.
+	return false
+}
+
+func createMediaSearchTriggers(db *gorm.DB) error {
+	for _, stmt := range mediaSearchTriggerStatements {
+		if err := db.Exec(stmt).Error; err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+var mediaSearchTriggerStatements = []string{
+	`CREATE TRIGGER IF NOT EXISTS media_search_fts_ai AFTER INSERT ON media WHEN new.deleted_at IS NULL BEGIN
+		DELETE FROM media_search_fts WHERE rowid = new.rowid;
+		INSERT INTO media_search_fts(rowid, media_id, title, original_name, path, genres)
+		VALUES (new.rowid, new.id, COALESCE(new.title, ''), COALESCE(new.original_name, ''), COALESCE(new.path, ''), COALESCE(new.genres, ''));
+	END`,
+	`CREATE TRIGGER IF NOT EXISTS media_search_fts_au AFTER UPDATE OF title, original_name, path, genres, deleted_at ON media BEGIN
+		DELETE FROM media_search_fts WHERE rowid = old.rowid;
+		INSERT INTO media_search_fts(rowid, media_id, title, original_name, path, genres)
+		SELECT new.rowid, new.id, COALESCE(new.title, ''), COALESCE(new.original_name, ''), COALESCE(new.path, ''), COALESCE(new.genres, '')
+		WHERE new.deleted_at IS NULL;
+	END`,
+	`CREATE TRIGGER IF NOT EXISTS media_search_fts_ad AFTER DELETE ON media BEGIN
+		DELETE FROM media_search_fts WHERE rowid = old.rowid;
+	END`,
+}
+
+func markMediaSearchIndexVersion(db *gorm.DB) error {
+	return db.Exec(`INSERT INTO media_search_meta(id, version) VALUES (1, ?) ON CONFLICT(id) DO UPDATE SET version = excluded.version`, mediaSearchIndexSchemaVersion).Error
+}