package db

import (
	"fmt"
	"time"

	"gorm.io/driver/mysql"
	"gorm.io/gorm"
	"gorm.io/gorm/logger"
)

// Options defines optsions for mysql database.
type Options struct {
	Host                  string
	Username              string
	Password              string
	Database              string
	UseUnixSocket         bool
	MaxIdleConnections    int
	MaxOpenConnections    int
	MaxConnectionLifeTime time.Duration
	LogLevel              int
	Logger                logger.Interface
	Tls                   bool
}

// New create a new gorm db instance with the given options.
func New(opts *Options) (*gorm.DB, error) {
	p := "tcp"
	if opts.UseUnixSocket {
		p = "unix"
	}

	dsn := fmt.Sprintf(`%s:%s@%s(%s)/%s?charset=utf8&parseTime=%t&loc=%s&tls=%t`,
		opts.Username,
		opts.Password,
		p,
		opts.Host,
		opts.Database,
		true,
		"UTC",
		opts.Tls,
	)

	db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{
		Logger: opts.Logger,
	})
	if err != nil {
		return nil, err
	}

	sqlDB, err := db.DB()
	if err != nil {
		return nil, err
	}

	// SetMaxOpenConns sets the maximum number of open connections to the database.
	sqlDB.SetMaxOpenConns(opts.MaxOpenConnections)

	// SetConnMaxLifetime sets the maximum amount of time a connection may be reused.
	sqlDB.SetConnMaxLifetime(opts.MaxConnectionLifeTime)

	// SetMaxIdleConns sets the maximum number of connections in the idle connection pool.
	sqlDB.SetMaxIdleConns(opts.MaxIdleConnections)

	// SetConnMaxIdleTime sets the maximum amount of time a connection may be idle.
	// This prevents "unexpected EOF" / "driver: bad connection" errors
	// when the MySQL server closes idle connections (default wait_timeout=28800s).
	sqlDB.SetConnMaxIdleTime(5 * time.Minute)

	return db, nil
}