package dbutil

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

	"github.com/go-sql-driver/mysql"
)

func OpenMySQLAndCreateDatabaseIfMissing(dsn string) (*sql.DB, error) {
	db, err := sql.Open("mysql", dsn)
	if err != nil {
		return nil, err
	}
	if err := db.Ping(); err == nil {
		return db, nil
	} else {
		_ = db.Close()
		var mysqlErr *mysql.MySQLError
		if !errors.As(err, &mysqlErr) || mysqlErr.Number != 1049 {
			return nil, err
		}
	}

	cfg, err := mysql.ParseDSN(dsn)
	if err != nil {
		return nil, err
	}
	if cfg.DBName == "" {
		return nil, errors.New("DSN does not include a database name")
	}
	databaseName := cfg.DBName
	cfg.DBName = ""

	adminDB, err := sql.Open("mysql", cfg.FormatDSN())
	if err != nil {
		return nil, err
	}
	defer adminDB.Close()
	if err := adminDB.Ping(); err != nil {
		return nil, err
	}
	if _, err := adminDB.Exec("CREATE DATABASE IF NOT EXISTS " + QuoteMySQLIdentifier(databaseName) + " CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci"); err != nil {
		return nil, err
	}
	fmt.Printf("created database %q\n", databaseName)

	db, err = sql.Open("mysql", dsn)
	if err != nil {
		return nil, err
	}
	if err := db.Ping(); err != nil {
		_ = db.Close()
		return nil, err
	}
	return db, nil
}

func QuoteMySQLIdentifier(name string) string {
	return "`" + strings.ReplaceAll(name, "`", "``") + "`"
}

func IsDuplicateColumnError(err error) bool {
	var mysqlErr *mysql.MySQLError
	return errors.As(err, &mysqlErr) && mysqlErr.Number == 1060
}