star.py

'''server implementation'''

from twisted.internet import protocol,reactor


class StarProtocol(protocol.Protocol):

    def __init__(self,factory):
        self.factory = factory   #factory that stores all the clients connected to the server 
        self.name = None         #name of the client that will connect to the server 

    def connectionMade(self):
        '''establishing a connection to the server'''

        print('New client connected: ',self.transport.getPeer())
        self.factory.clients.append(self)

    def connectionLost(self, reason):
        
        print("Client disconnected")
        self.factory.remove(self)

    def dataReceived(self, data):
        message = data.decode().strip()

        if not self.name:
            self.name = message 
            print(self.name,' has connected to the server.')   #if the client has not connected to the server before 

        else:
            if message.startswith('@'):                        #already existing client sends a message 
                '''one client will send message to another client '''
                recipient, private_message = message[1:].split(":", 1)
                self.sendthroughServer(recipient, private_message)

            else:
                '''if destination is not specified, the message is simply sent to the server.'''
                self.transport.write(message)

    def sendthroughServer(self,recipient,message):
        self.transport.write(message)     #the message first goes to the server
        self.transport.write('message sending.....')
        self.sendPrivateMessage(recipient,message)    #the message is then sent to the destination through the server 


    def sendPrivateMessage(self,recipient,message):
        for client in self.factory.clients:
            if client.name == recipient:
                client.transport.write(f"(Private) {self.name}: {message}\n".encode())
                break
        else:
            self.transport.write(f"Error: User {recipient} not found.\n".encode())


class StarFactory(protocol.Factory):

    def __init__(self):
        self.clients = []
    def buildProtocol(self, addr):
        return StarProtocol(self)
    

if __name__ == "__main__":
    reactor.listenTCP(8080, StarFactory())
    print("Server started. Listening on port 8080...")
    print("Enter client name to register. Enter @ before the starting of a message to send message to another client.")
    reactor.run()