DISCO Chat Client

#!/usr/bin/python2

# sockets are the interface to network
# connections for programmers
import socket

# the regular expressions are needed
# to parse the protocol; see FGDP or
# https://docs.python.org/2/howto/regex.html
import re

# https://docs.python.org/2/library/threading.html#threading.Timer
from threading import Timer

# some global variables for configuration
username = "123456"
password = "name@provider.com"
chathost = "131.246.19.102"
chatport = 1337

# setup connection to the chat server
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setblocking(True)
s.connect((chathost, chatport))

last = None
def resend():
    global s, last
    s.send(last+"\r\n")

def send(msg):
    global s, last
    s.send(msg+"\r\n")
    last = msg

# line by line
for m in s.makefile():

    msg = re.match("^([0-9]+)(#(.+))?\r$", m)

    if msg is None:
        print "Warning: server sent message with unknown format:\n\t'%s'" % m
        continue # skip this message

    cmd, _, args = msg.groups()

    # server message
    if cmd == "0":
        print "Server: %s" % args

    # servers requests username
    elif cmd == "1":
        print "Server: %s" % args
        send("1#%s" % username)
        print "Client: My name is '%s'" % username

    # server requests password
    elif cmd == "2":
        print "Server: %s" % args
        send("2#%s" % password)
        print "Client: Password is '%s'" % password

    # logged in successfully
    elif cmd == "3":
        print "Server: %s" % args
        send("6") # request list of online users
        print "Client: Who's online?"

    # another user logged in
    elif cmd == "4":
        print "Server: User '%s' joined the chat." % args

    # another user logged out
    elif cmd == "5":
        print "Server: User '%s' left the chat." % args

    # list of online users
    elif cmd == "6":
        usrs = args.split("#")
        print "Server: Online users are "+", ".join(usrs)
        send("9")
        print "Client: Which exercises did I pass so far?"

    # message from another user
    elif cmd == "7":
        user, text = re.match("^(.+?)#(.+)$", args).groups()
        print "%s: %s" % (user, text)

    # list of all finished assignments
    elif cmd == "9":
        if (args == None):
            print "Server: You've not completed any task yet? Come ooooonn...."
            continue
        exs = args.split("#")
        print "Server: You've completed exercises "+", ".join(exs)
        send("12") # start the game

    # received challenge response
    elif cmd == "11":
        print "Server: %s" % args

    # count up
    elif cmd == "12":
        print "Server: The counter is at %s." % args
        send("12#"+args)

    # unknown message type
    else:
        print "Warning: Received unimplemented message of type %s." % cmd

print "Exiting..."