#!/usr/bin/python

import socketserver

import json

from typing import List

clients = []

ROWS, COLS = 24, 79

def replace_substring_at_index(s: str, new_substring: str, index: int) -> str:

return s[:index] + new_substring + s[index + len(new_substring):]

def initial_canvas() -> List[str]:

canvas: List[str] = [f" __MINITALK{'_'*(COLS-12)} "]

canvas.append(f"/{' '*(COLS-2)}\\")

for _ in range(ROWS-3):

canvas.append(f"|{' '*(COLS-2)}|")

canvas.append(f"\\{'_'*(COLS-2)}/")

return canvas

class TextEditorServer(socketserver.BaseRequestHandler):

canvas: List[str] = initial_canvas()

def handle(self):

print(f"Client {self.client_address} connected.")

# Add client to the list

clients.append(self.request)

# First connection: send the whole canvas

first_message = {

"type": "sync",

"canvas": TextEditorServer.canvas

}

self.request.sendall(json.dumps(first_message).encode())

try:

while True:

# Wait for any client to send us data

data = self.request.recv(1024).decode()

if not data:

print(f"Client {self.client_address} disconnected.")

break

print(f"Received data:", data)

# We expect from a client:

# { "type": "update", "text": "...", "row": ..., "col": ..., "client_id": "...", "username": "..." }

# Sometimes multiple messages are sent together

# which means we receive invalid json: {...}{...}

split_data = data.replace("}{", "}|{").split('|')

for d in split_data:

update = json.loads(d)

if update["text"] == "\u000b":

print("received C-k so clearing the canvas")

TextEditorServer.canvas = initial_canvas()

update = {

"type": "sync",

"canvas": TextEditorServer.canvas

}

data = json.dumps(update)

else:

TextEditorServer.canvas[update["row"]] = \

replace_substring_at_index(

TextEditorServer.canvas[update["row"]],

update["text"],

update["col"]

)

# Broadcast received data to other clients

print(f"broadcasting {update['type']}")

data = json.dumps(update)

for client in clients:

if update["type"] == "sync" or client != self.request:

client.sendall(data.encode())

print(f"Sent data to client")

finally:

clients.remove(self.request)

print(f"Client {self.client_address} removed from active clients.")

if __name__ == "__main__":

HOST, PORT = "0.0.0.0", 9999

print(f"Starting server on {HOST}:{PORT}.")

server = socketserver.ThreadingTCPServer((HOST, PORT), TextEditorServer)

server.serve_forever()