package lock

import (
	"context"
	"eta/eta_api/utils"
	"fmt"
	"github.com/go-redis/redis/v8"
	"time"
)

const (
	lockName = "lock:"
)

var (
	ctx = context.Background()
)

func AcquireLock(key string, expiration int, Holder string) bool {
	script := redis.NewScript(`local key = KEYS[1]
			local clientId = ARGV[1]
			local expiration = tonumber(ARGV[2])
			if redis.call("EXISTS", key) == 0 then
				redis.call("SET", key, clientId, "EX", expiration)
				return 1
			else
				return 0
			end`)
	lockey := fmt.Sprintf("%s%s", lockName, key)
	result, err := script.Run(ctx, utils.Rc.RedisClient(), []string{lockey}, Holder, expiration).Int()
	if err != nil {
		fmt.Printf("加锁失败：err: %v", err)
		return false
	}
	if result == 1 {
		return true
	}
	return false
}

func TryLock(key string, expiration int, Holder string, timeout time.Duration) error {
	redisCtx, cancel := context.WithTimeout(context.Background(), timeout)
	defer cancel()
	for {
		select {
		case <-redisCtx.Done():
			return fmt.Errorf("等待超时")
		default:
			if AcquireLock(key, expiration, Holder) {
				// 启动异步续约
				go renewLock(key, Holder, expiration)
				return nil
			}
			// 等待重试
			time.Sleep(50 * time.Millisecond)
		}
	}
}

func renewLock(key, holder string, expiration int) {
	for {
		time.Sleep(5 * time.Second)
		script := redis.NewScript(`
            local key = KEYS[1]
			local clientId = ARGV[1]
			local expiration = tonumber(ARGV[2])
            if redis.call("get", KEYS[1]) == ARGV[1] then
                redis.call("SET", key, clientId, "EX", expiration)
				 return 1
            else
				 return 0
            end
       `)
		lockey := fmt.Sprintf("%s%s", lockName, key)
		result, err := script.Run(context.Background(), utils.Rc.RedisClient(), []string{lockey}, holder, expiration).Result()
		if err != nil {
			fmt.Println("锁续期失败:", err)
			return
		}
		if result.(int64) == 0 {
			fmt.Println("持有者变更，停止监听")
			return
		}
		fmt.Printf("锁续期成功")
	}
}

func ReleaseLock(key string, holder string) bool {
	script := redis.NewScript(`
	   if redis.call("get", KEYS[1]) == ARGV[1] then
	       return redis.call("del", KEYS[1])
	   else
	       return 0
	   end
	`)
	lockey := fmt.Sprintf("%s%s", lockName, key)
	result, err := script.Run(ctx, utils.Rc.RedisClient(), []string{lockey}, holder).Int()
	if err != nil {
		fmt.Printf("解锁失败：err: %v", err)
		return false
	}
	if result == 1 {
		return true
	}
	return false
}