simple_chatserver.erl

-module(simple_chatserver).
-export([start/0]).
-define(PORT, 33333).

% External API function for starting chat server
start() ->
    % Start a process for coordinating communication between clients
    CoordinatorPid = spawn(fun() -> coordinator(dict:new()) end),

    % Listen to a TCP socket and start a process that accepts incoming
    % connections. The Parameters should be explained at some point.
    Parameters = [binary, {reuseaddr, true}, {active, false}, {buffer, 1024}],
    case gen_tcp:listen(?PORT, Parameters) of
        {ok, ListenSocket} ->
            spawn(fun() -> acceptor(ListenSocket, CoordinatorPid) end),
            ok;
        Otherwise ->
            io:format("Cannot listen to socket: ~p~n", [Otherwise]),
            error
    end.

acceptor(ListenSocket, CoordinatorPid) ->
    case gen_tcp:accept(ListenSocket) of
        {ok, Socket} ->
            WorkerRef = make_ref(),
            WorkerPid = spawn(fun() -> worker_init(Socket, CoordinatorPid, WorkerRef) end),
            CoordinatorPid ! {worker, WorkerRef, WorkerPid},
            acceptor(ListenSocket, CoordinatorPid)
    end.

coordinator(WorkerDict) ->
    receive
        {worker, WorkerRef, WorkerPid} ->
            coordinator(dict:store(WorkerRef, WorkerPid, WorkerDict))
    end.

worker_init(Socket, CoordinatorPid, WorkerRef) ->
    inet:setopts(Socket, [{active, once}, {packet, line}]),
    worker(CoordinatorPid, WorkerRef).

worker(CoordinatorPid, WorkerRef) ->
    receive
        {tcp, _Socket, Data} ->
            io:format("Got message: ~p~n", [Data]),
            gen_tcp:send(_Socket, <<"Hello!\r\n">>),
            worker(CoordinatorPid, WorkerRef)
    end.