init

backend/internal/db/db.go

@@ -0,0 +1,80 @@
+package db
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	_ "github.com/jackc/pgx/v5/stdlib"
+	_ "modernc.org/sqlite"
+)
+
+func New(ctx context.Context, driver, dsn string) (*sql.DB, error) {
+	driverName, err := normalizeDriver(driver)
+	if err != nil {
+		return nil, err
+	}
+	if driverName == "sqlite" {
+		if err := ensureSQLiteDirectory(dsn); err != nil {
+			return nil, fmt.Errorf("prepare sqlite path: %w", err)
+		}
+	}
+
+	database, err := sql.Open(driverName, dsn)
+	if err != nil {
+		return nil, fmt.Errorf("open %s database: %w", driverName, err)
+	}
+
+	if driverName == "sqlite" {
+		// In-memory databases are connection-local, so keep SQLite single-connection
+		// and enable foreign keys for every operation through this handle.
+		database.SetMaxOpenConns(1)
+		database.SetMaxIdleConns(1)
+		if _, err := database.ExecContext(ctx, "PRAGMA foreign_keys = ON"); err != nil {
+			database.Close()
+			return nil, fmt.Errorf("configure sqlite: %w", err)
+		}
+	} else {
+		database.SetMaxOpenConns(10)
+		database.SetMaxIdleConns(1)
+	}
+
+	if err := database.PingContext(ctx); err != nil {
+		database.Close()
+		return nil, fmt.Errorf("ping %s database: %w", driverName, err)
+	}
+
+	return database, nil
+}
+
+func normalizeDriver(driver string) (string, error) {
+	switch strings.ToLower(strings.TrimSpace(driver)) {
+	case "postgres", "postgresql", "pgx":
+		return "pgx", nil
+	case "sqlite", "sqlite3":
+		return "sqlite", nil
+	default:
+		return "", fmt.Errorf("unsupported database driver %q (use postgres or sqlite)", driver)
+	}
+}
+
+func ensureSQLiteDirectory(dsn string) error {
+	if dsn == ":memory:" || strings.HasPrefix(dsn, "file::memory:") {
+		return nil
+	}
+
+	path := strings.SplitN(dsn, "?", 2)[0]
+	path = strings.TrimPrefix(path, "file:")
+	if path == "" || path == ":memory:" {
+		return nil
+	}
+
+	directory := filepath.Dir(path)
+	if directory == "." || directory == "" {
+		return nil
+	}
+	return os.MkdirAll(directory, 0o755)
+}