local userId = ARGV[1]
local yueId = ARGV[2]
local yueLastRdsKey = ARGV[3]
local yueSetRdsKey = ARGV[4]


local lastyueNumber = redis.call("GET",yueLastRdsKey)
if( lastyueNumber == false )
then
    return "库存信息在redis中不存在"
end

if( tonumber(lastyueNumber) <= 0)
then
    return "预约失败,当前剩下可预约人数为" .. lastyueNumber
end

local isExist = redis.call("SISMEMBER",yueSetRdsKey, userId)

if(isExist == 0)
then
    return "该用户没有预约该课程"
end

local addRes = redis.call("SREM",yueSetRdsKey, userId)

if (addRes == 0)
then
    return "redis集合移出该用户失败"
end

redis.call("INCR", yueLastRdsKey)

return "ok"