An IRC bot that is as simple as possible, but not simpler

irc_bot.py

import socket

# change these
HOST = 'irc.undernet.org'
PORT = 6667
NICK = 'rex'
CHAN = '#dashin'


# this is the function I will use when I want to send a message to the IRC server
def send_line(irc: socket.socket, line: str):
    print(f'=> {line}')
    # add \r\n to the end of the line and convert it from string to bytes, then send
    irc.send(f'{line}\r\n'.encode())


# this is the function I will use when I want to process a message I received from the IRC server
def handle_line(irc: socket.socket, line: bytes):
    # convert line from bytes to string, and remove leading and trailing whitespace
    line = line.decode().strip()
    print(f'<= {line}')
    # split the line on whitespace into a list of tokens
    tokens = line.split()
    if tokens[0] == 'PING':
        # when the server sends PING, I automatically reply with PONG
        send_line(irc, f'PONG {tokens[1]}')
    elif tokens[1] in ('376', '422'):
        # 376 means the server has finished sending the message of the day
        # 422 means there is no message of the day to send
        # in any case, now I can join my channel
        send_line(irc, f'JOIN {CHAN}')


# this is where I start my work
def main():
    irc = socket.socket()
    irc.connect((HOST, PORT))
    print(f'** connected to {HOST}')
    # identify myself to the IRC server
    send_line(irc, f'NICK {NICK}')
    send_line(irc, f'USER {NICK} {HOST} x :{NICK}')

    # set up a buffer that I can use to receive messages from the server
    buffer = b''
    while True:
        # receive what the server has sent me
        buffer = buffer + irc.recv(4096)
        # split it into lines
        lines = buffer.split(b'\n')
        # the last line might be incomplete, put it back in the buffer
        buffer = lines.pop()
        # handle each of the lines that the server sent me
        for line in lines:
            handle_line(irc, line)


if __name__ == '__main__':
    main()