package redisLock

import (
	"context"
	"log"
	"time"

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

type redisCommInfo struct {
	key   string
	value string
	ttl   int
}

type RedisLock struct {
	client          *redis.Client
	ctx             context.Context
	lockKeepAliveCh chan struct{}
	kvt             redisCommInfo
}

func CreateRedisLock(c *redis.Client, ctx context.Context, k, v string, ttl int) *RedisLock {
	return &RedisLock{c, ctx, make(chan struct{}, 1), redisCommInfo{k, v, ttl}}
}

func (r *RedisLock) Lock() {
	//for r.client.SetNX(r.ctx, r.kvt.key, r.kvt.value, time.Duration(r.kvt.ttl)*time.Second).Val() == false {
	//	time.Sleep(time.Millisecond * 20)
	//}

	script := `if redis.call('exists',KEYS[1]) == 0 or redis.call('hexists',KEYS[1],ARGV[1]) == 1 then
				    redis.call('hincrby',KEYS[1],ARGV[1],1)
					redis.call('expire',KEYS[1],ARGV[2])
					return 1
				else
					return 0
				end`

	for r.client.Eval(r.ctx, script, []string{r.kvt.key}, r.kvt.value, r.kvt.ttl).Val().(int64) == 0 {
		time.Sleep(time.Millisecond * 20)
	}

	select {
	case r.lockKeepAliveCh <- struct{}{}:
		go r.autoReNewExpire()
	default:

	}

	log.Printf("lock ok: %s,%s,%d\n", r.kvt.key, r.kvt.value, r.kvt.ttl)
}

func (r *RedisLock) Unlock() {
	//if r.client.Get(r.ctx, r.kvt.key).Val() == r.kvt.value {
	//	r.client.Del(r.ctx, r.kvt.key)
	//}

	//script := "if (redis.call('get',KEYS[1]) == ARGV[1]) then return redis.call('del',KEYS[1]) else return 0 end"
	//r.client.Eval(r.ctx, script, []string{r.kvt.key}, r.kvt.value)

	script := `if redis.call('hexists',KEYS[1],ARGV[1]) == 0 then return nil
			 elseif redis.call('hincrby',KEYS[1],ARGV[1],-1) == 0 then return redis.call('del',KEYS[1])
			 else return 0 end`
	r.client.Eval(r.ctx, script, []string{r.kvt.key}, r.kvt.value)

	log.Printf("unlock ok: %s,%s,%d\n", r.kvt.key, r.kvt.value, r.kvt.ttl)
}

func (r *RedisLock) autoReNewExpire() {
	defer func() {
		<-r.lockKeepAliveCh
	}()

	tc := time.NewTicker(time.Duration(r.kvt.ttl) * time.Second / 3)
	defer tc.Stop()

	for {
		select {
		case <-tc.C:
			script := `if redis.call('hexists',KEYS[1],ARGV[1]) == 1 then return redis.call('expire',KEYS[1],ARGV[2])
					else return 0 end`
			if r.client.Eval(r.ctx, script, []string{r.kvt.key}, r.kvt.value).Val().(int64) == 0 {
				return
			}
		}
	}
}