--[[
  Adds a repeatable job

    Input:
      KEYS[1] 'repeat' key

      ARGV[1] next milliseconds
      ARGV[2] custom key
      ARGV[3] legacy custom key TODO: remove this logic in next breaking change
      
      Output:
        repeatableKey  - OK
]]
local rcall = redis.call
local repeatKey = KEYS[1]
local nextMillis = ARGV[1]
local customKey = ARGV[2]
local legacyCustomKey = ARGV[3]

if rcall("ZSCORE", repeatKey, customKey) then
    rcall("ZADD", repeatKey, nextMillis, customKey)
    return customKey
elseif rcall("ZSCORE", repeatKey, legacyCustomKey) ~= false then
    rcall("ZADD", repeatKey, nextMillis, legacyCustomKey)
    return legacyCustomKey
end

return ''