package mysql

import (
	"errors"
	"time"

	"gorm.io/driver/mysql"
	"gorm.io/gorm"
	"gorm.io/gorm/logger"
	"gorm.io/gorm/schema"
	"gorm.io/plugin/dbresolver"
)

var (
	_db   *gorm.DB
	_conf *Config
)

type Config struct {
	ConnString      string
	ConnMaxLifetime int64 //ConnMaxLifetime 最大连接时间，单位：小时
	MaxIdleConns    int
	MaxOpenConns    int
	InitTable       bool
}

// Init mysql初始化
func Init(config *Config) {
	if config == nil {
		config = &Config{
			MaxIdleConns: 10,
			MaxOpenConns: 100,
		}
	}
	if config.ConnString == "" {
		config.ConnString = "root:root@tcp(127.0.0.1:3306)/mysql?charset=utf8&parseTime=True&loc=Local"
	}
	if config.ConnMaxLifetime < 1 {
		config.ConnMaxLifetime = 1
	}
	if config.ConnMaxLifetime > 6 {
		config.ConnMaxLifetime = 6
	}
	if config.MaxIdleConns < 1 {
		config.MaxIdleConns = 1
	}
	if config.MaxIdleConns > 50 {
		config.MaxIdleConns = 50
	}
	if config.MaxOpenConns < 1 {
		config.MaxOpenConns = 1
	}
	if config.MaxOpenConns > 500 {
		config.MaxOpenConns = 500
	}
	_conf = config
}

// New 创建实例
func New() (*gorm.DB, error) {
	if _db != nil {
		return _db, nil
	}

	if _conf == nil {
		return nil, errors.New("组件未初始化,请执行Init!")
	}

	var err error
	_db, err = gorm.Open(mysql.Open(_conf.ConnString), &gorm.Config{
		SkipDefaultTransaction: true,
		Logger:                 logger.Default.LogMode(logger.Silent),
		NamingStrategy: schema.NamingStrategy{
			SingularTable: true,
		},
	})
	if err != nil {
		return nil, err
	}
	_db.Use(
		dbresolver.Register(dbresolver.Config{
			Sources:  []gorm.Dialector{mysql.Open(_conf.ConnString)},
			Replicas: []gorm.Dialector{mysql.Open(_conf.ConnString)},
			Policy:   dbresolver.RandomPolicy{},
		}).SetConnMaxIdleTime(time.Hour).
			SetConnMaxLifetime(time.Duration(_conf.ConnMaxLifetime) * time.Hour).
			SetMaxIdleConns(_conf.MaxIdleConns).
			SetMaxOpenConns(_conf.MaxOpenConns))
	return _db, nil
}