package database

import (
	"time"

	"go.uber.org/zap"
	"gorm.io/driver/mysql"
	"gorm.io/gorm"
)

type MySQLOptions struct {
	MaxOpenConns       int
	MaxIdleConns       int
	ConnMaxLifetime    time.Duration
	ConnMaxIdleTime    time.Duration
	SlowQueryThreshold time.Duration
}

func DefaultMySQLOptions() MySQLOptions {
	return MySQLOptions{
		MaxOpenConns:       50,
		MaxIdleConns:       10,
		ConnMaxLifetime:    30 * time.Minute,
		ConnMaxIdleTime:    5 * time.Minute,
		SlowQueryThreshold: 500 * time.Millisecond,
	}
}

func OpenMySQL(dsn string, logLevel string, appLogger *zap.Logger) (*gorm.DB, error) {
	return OpenMySQLWithOptions(dsn, logLevel, appLogger, DefaultMySQLOptions())
}

func OpenMySQLWithOptions(dsn string, logLevel string, appLogger *zap.Logger, options MySQLOptions) (*gorm.DB, error) {
	defaults := DefaultMySQLOptions()
	if options.MaxOpenConns < 1 {
		options.MaxOpenConns = defaults.MaxOpenConns
	}
	if options.MaxIdleConns < 0 {
		options.MaxIdleConns = defaults.MaxIdleConns
	}
	if options.ConnMaxLifetime <= 0 {
		options.ConnMaxLifetime = defaults.ConnMaxLifetime
	}
	if options.ConnMaxIdleTime < 0 {
		options.ConnMaxIdleTime = defaults.ConnMaxIdleTime
	}
	if options.SlowQueryThreshold <= 0 {
		options.SlowQueryThreshold = defaults.SlowQueryThreshold
	}
	if options.MaxIdleConns > options.MaxOpenConns {
		options.MaxIdleConns = options.MaxOpenConns
	}
	db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{
		Logger: newGormLoggerWithThreshold(logLevel, appLogger, options.SlowQueryThreshold),
	})
	if err != nil {
		return nil, err
	}

	sqlDB, err := db.DB()
	if err != nil {
		return nil, err
	}
	// 限制连接池，避免单个实例耗尽 MySQL max_connections。
	sqlDB.SetMaxOpenConns(options.MaxOpenConns)
	sqlDB.SetMaxIdleConns(options.MaxIdleConns)
	sqlDB.SetConnMaxLifetime(options.ConnMaxLifetime)
	sqlDB.SetConnMaxIdleTime(options.ConnMaxIdleTime)

	return db, nil
}