// Copyright 2019 getensh.com. All rights reserved.
// Use of this source code is governed by getensh.com.

package transtasker

import (
	"fmt"
	"log"

	"gorm.io/gorm"
)

// Tasker 任务接口
type Tasker interface {
	Exec(db *gorm.DB) error
	Rollback(db *gorm.DB) error
}

// Exec 执行任务
func Exec(gormdb *gorm.DB, tasks ...Tasker) error {
	// 如果gormdb句柄为nil，直接返回错误
	if gormdb == nil {
		log.Println("error: gormdb is nil")
		return fmt.Errorf("gormdb is nil")
	}

	var err error

	db := gormdb.Begin()

	commited := false
	oktasks := make([]Tasker, 0)

	defer func() {
		// 捕获异常，并执行回滚操作
		if v := recover(); v != nil || !commited {
			for _, task := range oktasks {
				task.Rollback(db)
			}

			// db 统一回滚
			db.Rollback()

			// 向上层抛出异常
			if v != nil {
				panic(v)
			}
		}
	}()

	defer func() {
		if err != nil {
			for _, task := range oktasks {
				task.Rollback(db)
			}

			// db 统一回滚
			db.Rollback()
		}
	}()

	// 顺序执行任务
	for _, task := range tasks {
		if task != nil {
			if err = task.Exec(db); err != nil {
				return err
			}
		}

		oktasks = append(oktasks, task)
	}

	// 事务提交
	db.Commit()
	commited = true

	return nil
}