client.py

from socket import socket, AF_INET, SOCK_STREAM, SOL_SOCKET, SO_REUSEADDR
from threading import Thread
from datetime import datetime
from select import select
from sys import exit
import errno


class ChatClient():
    def __init__(self):
        self.HEADER_LENGTH = 10
        self.server_addr = ('localhost', 1234)
        self.client_socket = socket(AF_INET, SOCK_STREAM)
        self.client_socket.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
        self.client_socket.connect((self.server_addr[0], self.server_addr[1]))
        self.client_socket.setblocking(False)

        self.my_username = input("Username: ")

    def run(self):
        username = self.my_username.encode('utf-8')
        username_header = f"{len(username):<{self.HEADER_LENGTH}}".encode('utf-8')
        self.client_socket.send(username_header+ username)
        while True:
            Thread(target=self.send_message).start()
            try:
                while True:
                    self.username_header = self.client_socket.recv(self.HEADER_LENGTH)
                    Thread(target=self.receive_message).start()
                    if not len(self.username_header):
                        print('Connection closed by the server')
                        exit()


            except IOError as e:
                if e.errno != errno.EAGAIN and e.errno != errno.EWOULDBLOCK:
                    print(f"Reading error: {str(e)}")
                    exit()
            except Exception as e:
                print(f"Reading error: {str(e)}")
                exit()
                continue
    def send_message(self):
        message = input(f'{self.my_username}> ')
        if message:
            message = message.encode('utf-8')
            self.message_header = f"{len(message):<{self.HEADER_LENGTH}}".encode('utf-8')
            self.client_socket.send(self.message_header + message)
    def receive_message(self):
        username_lenght = int(self.username_header.decode('utf-8').strip())
        username = self.client_socket.recv(username_lenght).decode('utf-8')
        message_header = self.client_socket.recv(self.HEADER_LENGTH)
        message_lenght = int(message_header.decode('utf-8').strip())
        message = self.client_socket.recv(message_lenght).decode('utf-8')
        print(f"{username}> {message}")

c = ChatClient().run()