split sqlite migration helpers

internal/database/sqlite_migration_source.go

@@ -0,0 +1,77 @@
+package database
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/glebarez/sqlite"
+	"go.uber.org/zap"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+
+	"github.com/ShukeBta/MediaStationGo/internal/config"
+)
+
+func openSQLiteMigrationSource(cfg *config.Config, sqlitePath string) (*gorm.DB, error) {
+	srcCfg := *cfg
+	srcCfg.Database.Type = "sqlite"
+	srcCfg.Database.DBPath = sqlitePath
+	return gorm.Open(sqlite.Open(buildSQLiteDSN(&srcCfg)), &gorm.Config{
+		Logger: logger.Default.LogMode(logger.Silent),
+	})
+}
+
+func sqliteMigrationSourcePath(cfg *config.Config, log *zap.Logger) (string, error) {
+	configured := strings.TrimSpace(cfg.Database.DBPath)
+	if configured != "" {
+		exists, err := regularFileExists(configured)
+		if err != nil {
+			return "", fmt.Errorf("stat sqlite migration source: %w", err)
+		}
+		if exists {
+			return configured, nil
+		}
+	}
+
+	fallback := filepath.Join(strings.TrimSpace(cfg.App.DataDir), "mediastation.db")
+	if fallback == "" || sameCleanPath(configured, fallback) {
+		return "", nil
+	}
+	exists, err := regularFileExists(fallback)
+	if err != nil {
+		return "", fmt.Errorf("stat default sqlite migration source: %w", err)
+	}
+	if !exists {
+		return "", nil
+	}
+	if log != nil && configured != "" {
+		log.Warn("configured sqlite migration source not found; using data-dir default",
+			zap.String("configured", configured),
+			zap.String("fallback", fallback))
+	}
+	return fallback, nil
+}
+
+func regularFileExists(path string) (bool, error) {
+	if strings.TrimSpace(path) == "" {
+		return false, nil
+	}
+	info, err := os.Stat(path)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return false, nil
+		}
+		return false, err
+	}
+	return !info.IsDir(), nil
+}
+
+func sameCleanPath(a, b string) bool {
+	if a == "" || b == "" {
+		return false
+	}
+	return filepath.Clean(a) == filepath.Clean(b)
+}