package worker

import (
	"context"
	"errors"
	"goRedisDLM/engine"
	"goRedisDLM/redisLock"
	"log"
	"math/rand"
	"strconv"
	"time"

	"github.com/go-redis/redis/v8"
	"github.com/google/uuid"
)

type Inventory struct {
	Client *redis.Client
}

func (i *Inventory) Work(request engine.Request, response *engine.Response) error {
	value := uuid.New()

	//log.Printf("uuid: %s, lock key: %s\n", value.String(), request.Dlock)

	ctx := context.Background()

	lock := redisLock.CreateRedisLock(i.Client, ctx, request.Dlock, value.String(), 100)
	lock.Lock()

	time.Sleep(time.Duration(rand.Int31n(100)) * time.Millisecond)

	get := i.Client.Get(ctx, "inventory")
	log.Printf("%s\n", get)

	inventory, err := strconv.Atoi(get.Val())
	if err != nil {
		goto Error
	}
	inventory = inventory - 1
	if inventory >= 0 {
		//这里应该使用lua脚本，再检测一下当前是否获取到锁，获取到之后再进行扣减。类似双检加锁的思想，因为此时可能会续期失败。
		//i.Client.Set(ctx, "inventory", fmt.Sprintf("%d", inventory), redis.KeepTTL)
		script := `if redis.call('hexists',KEYS[1],ARGV[1]) == 1 then return redis.call('set',KEYS[2],ARGV[2])
					else return 0 end`

		val := i.Client.Eval(ctx, script, []string{request.Dlock, "inventory"}, value.String(), inventory).Val()
		if res, ok := val.(string); ok && res == "OK" {

		} else {
			//任务执行失败需要通知调用者，让调用者自己决策是否需要重新调度还是放弃，这样worker和主线程实现了解偶
			log.Println("error set inventory")
			err = errors.New("inventory err")
			goto Error
		}
	} else {
		log.Printf("error DLock error :%d\n", inventory)
		err = errors.New("inventory err")
		goto Error
	}
	lock.Unlock()

	response.Id = request.Id

	return nil

Error:
	lock.Unlock()
	return err
}