rpc = {}

rpc.activeCalls = {}
rpc.slug = "rpc-"
rpc.ttl = 120

function rpc.callScriptedEntity(entityId, functionName, args, callback)
    local handle = rpc.getUniqueHandle()
    local call = {
        handle = handle,
        callback = callback,
        created = os.clock()
    }

    table.insert(rpc.activeCalls, call)
    world.callScriptedEntity(entityId, "rpc.recieveScriptCall", functionName, handle, args)
end

function rpc.recieveScriptCall(functionName, handle, args)
    local result = _ENV[functionName](unpack(args))
    world.setProperty(handle, result)
end

function rpc.getUniqueHandle()
    local handle = ""
    repeat
        local id = math.random(1, 9999999)
        handle = rpc.slug .. id
    until world.getProperty(handle) == nil

    return handle
end

function rpc.update()
    for i = #rpc.activeCalls, 1, -1 do
        local call = rpc.activeCalls[i]
        local remove = false

        local result = world.getProperty(call.handle)
        if result ~= nil then
            call.callback(result)
            remove = true
        end

        if os.clock() - call.created > rpc.ttl then
            table.remove()
            remove = true
        end

        if remove then
            world.setProperty(call.handle, nil)
            table.remove(rpc.activeCalls, i)
        end
    end
end