main.py

from fastapi import FastAPI, WebSocket
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import HTMLResponse
import subprocess
import asyncio
import os

from threading import Thread
from queue import Queue, Empty

os.environ['LD_LIBRARY_PATH'] = '/engines/maia:' + os.environ.get('LD_LIBRARY_PATH', '')

def enqueue_output(out, queue):
    for line in iter(out.readline, b''):
        queue.put(line)
    out.close()

class EngineChess:
    def __init__(self, path_engine):
        self.path_engine = path_engine
        self._stockfish = subprocess.Popen(
            path_engine,
            universal_newlines=True,
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
            stderr=subprocess.STDOUT,
        )
        self.queueOutput = Queue()
        self.thread = Thread(target=enqueue_output, args=(self._stockfish.stdout, self.queueOutput))
        self.thread.daemon = True # thread dies with the program
        self.thread.start()
        
        self._has_quit_command_been_sent = False
        self._debug_view = True

    def _put(self, command):
        if not self._stockfish.stdin:
            raise BrokenPipeError()
        if self._stockfish.poll() is None and not self._has_quit_command_been_sent:
            self._stockfish.stdin.write(f"{command}\n")
            self._stockfish.stdin.flush()
            if command == "quit":
                self._has_quit_command_been_sent = True
    
    def _read_line(self) -> str:
        if not self._stockfish.stdout:
            raise BrokenPipeError()
        if self._stockfish.poll() is not None:
            raise StockfishException("The Stockfish process has crashed")
            
        try:
            line = self.queueOutput.get_nowait() # or q.get(timeout=.1)
        except Empty:
            return ""
        
        if self._debug_view:
            print(f"Engine {self.path_engine[0]}:", line.strip())
        return line.strip()
    
    def _is_ready(self) -> None:
        self._put("isready")
        while self._read_line() != "readyok":
            pass
    
    def put(self, cmd):
        return self._put(cmd)
        
    def read_line(self) -> str:
        return self._read_line()

app = FastAPI()

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

@app.websocket("/stockfish-{version}")
async def websocket_endpoint(websocket: WebSocket, version: str):
    await websocket.accept()
    
    stockfish = EngineChess([f"engines/stockfish/stockfish-{version}-uci"])

    async def read_from_socket(websocket: WebSocket):
        async for data in websocket.iter_text():
            print(f"Stockfish Client: {data}")
            stockfish.put(data)
                    
    asyncio.create_task(read_from_socket(websocket))

    while True:
        while True:
            res = stockfish.read_line()
            if res:
                await websocket.send_text(f"{res}")
            else:
                break
        await asyncio.sleep(0.1)

@app.websocket("/maia-{elo}")
async def websocket_endpoint(websocket: WebSocket, elo: str):
    await websocket.accept()
    
    stockfish = EngineChess(["./engines/maia/lc0", "--backend=trivial", f"--weights=./engines/maia-{elo}.pb.gz"])

    async def read_from_socket(websocket: WebSocket):
        async for data in websocket.iter_text():
            print(f"Maia Client: {data}")
            stockfish.put(data)
                    
    asyncio.create_task(read_from_socket(websocket))

    while True:
        while True:
            res = stockfish.read_line()
            if res:
                await websocket.send_text(f"{res}")
            else:
                break
        await asyncio.sleep(0.1)





########################
async def get_prompt():
    # Get current working directory
    cwd = os.getcwd()
    # Shorten path if it is too long
    if len(cwd) > 30:
        cwd = os.path.basename(cwd)
        cwd = f".../{cwd}"
    return f"{cwd}$ "

async def exec_command(command):
    try:
        # Execute command using subprocess
        process = await asyncio.create_subprocess_shell(
            command,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            shell=True,
            executable='/bin/bash'
        )

        # Wait for command to complete
        stdout, stderr = await process.communicate()

        # Prepare output to send back
        output = stdout.decode() + stderr.decode()

    except Exception as e:
        output = str(e)

    return output

async def send_prompt(websocket):
    # Send initial prompt to client
    prompt = await get_prompt()
    await websocket.send_text(prompt)

@app.websocket("/shell")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    await send_prompt(websocket)

    try:
        while True:
            # Receive command from client
            command = await websocket.receive_text()

            if command == "exit":
                await websocket.send_text("Goodbye!")
                break

            # Execute command
            output = await exec_command(command)

            # Send output to client
            await websocket.send_text(output)

            # Send updated prompt to client
            await send_prompt(websocket)

    except websockets.exceptions.ConnectionClosedError:
        pass