package storage

import (
	"database/sql"
	"embed"
	"fmt"
	"log"
	"os"

	_ "github.com/go-sql-driver/mysql"
	"github.com/golang-migrate/migrate/v4"
	"github.com/golang-migrate/migrate/v4/database/mysql"
	iofs "github.com/golang-migrate/migrate/v4/source/iofs"
)

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

var DB *sql.DB

// InitDB connects to MySQL, runs migrations, and returns the DB handle.
func InitDB() *sql.DB {
	cfg := getDSNFromEnv()

	db, err := sql.Open("mysql", cfg)
	if err != nil {
		log.Fatalf("❌ Failed to connect to MySQL: %v", err)
	}

	if err := db.Ping(); err != nil {
		log.Fatalf("❌ MySQL not reachable: %v", err)
	}

	if err := runMigrations(db); err != nil {
		log.Fatalf("❌ Migration failed: %v", err)
	}

	DB = db
	return db
}

// runMigrations applies any pending .sql files in migrations/
func runMigrations(db *sql.DB) error {
	driver, err := mysql.WithInstance(db, &mysql.Config{})
	if err != nil {
		return err
	}

	src, err := iofs.New(migrationFiles, "migrations")
	if err != nil {
		return err
	}

	m, err := migrate.NewWithInstance("iofs", src, "mysql", driver)
	if err != nil {
		return err
	}

	err = m.Up()
	if err == migrate.ErrNoChange {
		log.Println("✅ Database schema up to date.")
		return nil
	}
	return err
}

func getDSNFromEnv() string {
	user := os.Getenv("DB_USER")
	pass := os.Getenv("DB_PASS")
	host := os.Getenv("DB_HOST") // e.g. localhost or 127.0.0.1
	port := os.Getenv("DB_PORT") // e.g. 3306
	name := os.Getenv("DB_NAME") // e.g. synlotto
	params := "parseTime=true&multiStatements=true"

	dsn := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s?%s",
		user, pass, host, port, name, params)
	return dsn
}