from twisted.internet.protocol import Factory 
from twisted.protocols.basic import LineReceiver 
from twisted.internet import reactor 
 
class Chat(LineReceiver): 
 
  def __init__(self, users): 
    self.users = users 
    self.name = None 
    self.state = "GETNAME" 
 
  def connectionMade(self): 
    self.sendLine("What's your name?") 
 
  def connectionLost(self, reason): 
    if self.name in self.users: 
      del self.users[self.name] 
 
  def lineReceived(self, line): 
    if self.state == "GETNAME": 
      self.handle_GETNAME(line) 
    else: 
      self.handle_CHAT(line) 
 
  def handle_GETNAME(self, name): 
    if name in self.users: 
      self.sendLine("Name taken, please choose another.") 
      return 
    self.sendLine("Welcome, %s!" % (name,)) 
    self.name = name 
    self.users[name] = self 
    self.state = "CHAT" 
 
  def handle_CHAT(self, message): 
    message = "<%s> %s" % (self.name, message) 
    for name, protocol in self.users.iteritems(): 
      if protocol != self: 
        protocol.sendLine(message) 
 
 
class ChatFactory(Factory): 
 
  def __init__(self): 
    self.users = {} # maps user names to Chat instances 
 
  def buildProtocol(self, addr): 
    return Chat(self.users) 
 
  def startFactory(self): 
    print 'start' 
 
  def stopFactory(self): 
    print 'stop' 
 
reactor.listenTCP(8123, ChatFactory()) 
reactor.run()