defmodule StaleMail do
	
	def start() do
		loop(%{})
	end

	def loop(state) do
		newstate = receive do
			x -> parse(state, x)
		end
	
		loop(newstate)
	end

	def parse(state, arg) do
		case arg do
			{ :new_mailbox, zname, _sender } ->
				name = String.strip(zname)
				old = Map.has_key?(state, name)
				newstate = unless old do
					Map.put(state, name, [])
				else
					state
				end	
				
				newstate
			{ :new_mail, zname, sender } ->
				name = String.strip(zname)
				# TODO: asking about new mail
				if state |> Map.has_key?(name) do
					case state |> Map.get(name, []) do
						[ head | _tail ] ->
							send sender, head
							state
						_ -> state
					end
				end

				state
			{ :got_mail, zname } ->
				name = String.strip(zname)
				# TODO: delete mail with given key
				if state |> Map.has_key?(name) do
					case state |> Map.get(name, []) do
						[ _ | tail ] ->
							state |> Map.put(name, tail)
						_ -> state
					end
				else
					state
				end
			{ :pass_message, zreceiver, zmessage, zsender } ->
				receiver = String.strip(zreceiver)
				message = String.strip(zmessage)
				sender = String.strip(zsender)

				# TODO: passes message to mailbox of receiver
				if Map.has_key?(state, receiver) do
					list = state |> Map.get(receiver, [])
					state |> Map.put(receiver, list ++ [ { :received_message, sender, message } ])
				else
					state |> Map.put(receiver, [ { :received_message, sender, message } ])
				end
		end
	end
end