manager

-- Manager
local storage = {}

function addStorage(sender, resource)
  print(("Attempting to add %s from %d"):format(resource, sender))

  if not storage[resource] then
    storage[resource] = {}
  end

  table.insert(storage[resource], sender)

  print(("Storage table is now: %s"):format(textutils.serialize(storage)))

  local message = {command = "ack"}
  rednet.send(sender, textutils.serialize(message))
end

function handleCommunications()
  local sender, message = rednet.receive()

  -- message { command = "storage", resource = "gravel|cobblestone|andesite|etc"}
  -- message { command = "request", resource = "gravel|cobblestone|andesite|etc", amount = 64}
  local actualMessage = textutils.unserialize(message)

  if actualMessage.command == "storage" then
    addStorage(sender, actualMessage.resource)
  elseif actualMessage.command == "request" then
    handleRequest(sender, actualMessage.resource, actualMessage.amount)
  elseif actualMessage.command == "bye" then
    handleGoodbye(sender)
  elseif actualMessage.command == "helo" then
    handleHello(sender)
  end
end

function handleGoodbye(sender)
  print(("Attempting goodbye for %d"):format(sender))
  for resource, list in pairs(storage) do
    for index, which in ipairs(list) do
      if which == sender then
        print(("Removing sender %d from %s"):format(sender, resource))
        table.remove(storage[resource], index)
      end
    end
  end

  local message = {command="ack"}
  rednet.send(sender, textutils.serialize(message))
end

function handleHello(sender)
  print(("Received hello from %d"):format(sender))

  local message = {command = "hello"}
  rednet.send(sender, textutils.serialize(message))
end

function handleRequest(sender, resource, amount)
  print(("Request received for %d %s from %d"):format(amount, resource, sender))

  if not storage[resource] then return end
  local resourceCount = table.maxn(storage[resource])
  if resourceCount > 0 then
    local perHost = math.ceil(amount / resourceCount)

    for _, host in ipairs(storage[resource]) do
      local message = {command = "request", amount = perHost}
      rednet.send(host, textutils.serialize(message))
    end
  end

  local message = {command = "ack"}
  rednet.send(sender, textutils.serialize(message))
end

function main()
  peripheral.find("modem", rednet.open)

  while true do
    handleCommunications()
  end
end

main()