package db

import (
	"database/sql"
	"embed"
	"fmt"
	"strings"

	_ "github.com/go-sql-driver/mysql"
	_ "modernc.org/sqlite"

	"mind/internal/config"
)

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

func OpenAndMigrate(cfg config.Config) (*sql.DB, error) {
	dsn := cfg.DSN
	drv := strings.ToLower(cfg.Driver)
	if drv != "mysql" && drv != "sqlite" {
		drv = "sqlite"
	}
	db, err := sql.Open(drv, dsn)
	if err != nil { return nil, err }
	if err := db.Ping(); err != nil { return nil, err }
	if err := runMigrations(db, drv); err != nil { return nil, err }
	return db, nil
}

func runMigrations(db *sql.DB, driver string) error {
	files, err := migrationFS.ReadDir("migrations")
	if err != nil { return err }
	for _, f := range files {
		b, err := migrationFS.ReadFile("migrations/"+f.Name())
		if err != nil { return err }
		sqlText := string(b)
		if driver == "sqlite" {
			// very minor compatibility tweak: drop ENUM
			sqlText = strings.ReplaceAll(sqlText, "ENUM('user','assistant')", "TEXT")
		}
		if _, err := db.Exec(sqlText); err != nil {
			return fmt.Errorf("migration %s: %w", f.Name(), err)
		}
	}
	return nil
}