Refactor db code. Add migration support

internal/repository/migration.go

@@ -0,0 +1,137 @@
+package repository
+
+import (
+	"database/sql"
+	"embed"
+	"fmt"
+	"log/slog"
+
+	"github.com/golang-migrate/migrate/v4"
+	"github.com/golang-migrate/migrate/v4/database/sqlite3"
+	"github.com/golang-migrate/migrate/v4/source/iofs"
+)
+
+const Version uint = 1
+
+//go:embed migrations/*
+var migrationFiles embed.FS
+
+func checkDBVersion(db *sql.DB) error {
+	var m *migrate.Migrate
+
+	driver, err := sqlite3.WithInstance(db, &sqlite3.Config{})
+	if err != nil {
+		return err
+	}
+	d, err := iofs.New(migrationFiles, "migrations")
+	if err != nil {
+		return err
+	}
+
+	m, err = migrate.NewWithInstance("iofs", d, "sqlite3", driver)
+	if err != nil {
+		return err
+	}
+
+	v, dirty, err := m.Version()
+	if err != nil {
+		if err == migrate.ErrNilVersion {
+			slog.Warn("Legacy database without version or missing database file!")
+		} else {
+			return err
+		}
+	}
+
+	if v < Version {
+		return fmt.Errorf("unsupported database version %d, need %d.\nPlease backup your database file and run cc-backend -migrate-db", v, Version)
+	} else if v > Version {
+		return fmt.Errorf("unsupported database version %d, need %d.\nPlease refer to documentation how to downgrade db with external migrate tool", v, Version)
+	}
+
+	if dirty {
+		return fmt.Errorf("last migration to version %d has failed, please fix the db manually and force version with -force-db flag", Version)
+	}
+
+	return nil
+}
+
+func getMigrateInstance(dsnURI string) (m *migrate.Migrate, err error) {
+	d, err := iofs.New(migrationFiles, "migrations")
+	if err != nil {
+		slog.Error("failed to get instance", "Error", err)
+	}
+
+	m, err = migrate.NewWithSourceInstance("iofs", d, dsnURI)
+	if err != nil {
+		return m, err
+	}
+
+	return m, nil
+}
+
+func MigrateDB(db string) error {
+	m, err := getMigrateInstance(db)
+	if err != nil {
+		return err
+	}
+
+	v, dirty, err := m.Version()
+	if err != nil {
+		if err == migrate.ErrNilVersion {
+			slog.Warn("Legacy database without version or missing database file!")
+		} else {
+			return err
+		}
+	}
+
+	if v < Version {
+		slog.Info("unsupported database version %d, need %d.\nPlease backup your database file and run cc-backend -migrate-db", v, Version)
+	}
+
+	if dirty {
+		return fmt.Errorf("last migration to version %d has failed, please fix the db manually and force version with -force-db flag", Version)
+	}
+
+	if err := m.Up(); err != nil {
+		if err == migrate.ErrNoChange {
+			slog.Info("DB already up to date!")
+		} else {
+			return err
+		}
+	}
+
+	m.Close()
+	return nil
+}
+
+func RevertDB(db string) error {
+	m, err := getMigrateInstance(db)
+	if err != nil {
+		return err
+	}
+
+	if err := m.Migrate(Version - 1); err != nil {
+		if err == migrate.ErrNoChange {
+			slog.Info("DB already up to date!")
+		} else {
+			return err
+		}
+	}
+
+	m.Close()
+	return nil
+}
+
+func ForceDB(db string) error {
+	m, err := getMigrateInstance(db)
+	if err != nil {
+		return err
+	}
+
+	if err := m.Force(int(Version)); err != nil {
+		return err
+	}
+
+	m.Close()
+	return nil
+}