package db

import (
	"embed"
	"errors"
	"fmt"

	"github.com/golang-migrate/migrate/v4"
	_ "github.com/golang-migrate/migrate/v4/database/postgres"
	"github.com/golang-migrate/migrate/v4/source/iofs"
)

//go:embed migrations/*.sql
var migrationsFS embed.FS

// RunMigrations runs all pending database migrations.
// It uses embedded SQL files and is safe to call on every startup.
// Returns nil if migrations succeed or if there are no changes to apply.
func RunMigrations(databaseURL string) error {
	source, err := iofs.New(migrationsFS, "migrations")
	if err != nil {
		return fmt.Errorf("failed to create migration source: %w", err)
	}

	m, err := migrate.NewWithSourceInstance("iofs", source, databaseURL)
	if err != nil {
		return fmt.Errorf("failed to create migrate instance: %w", err)
	}
	defer m.Close()

	if err := m.Up(); err != nil && !errors.Is(err, migrate.ErrNoChange) {
		return fmt.Errorf("failed to run migrations: %w", err)
	}

	return nil
}