dnd-music-console/src/croaker/server.py

import logging
import os
import socket
import socketserver
import time

from croaker.gui import GUI
from croaker.path import playlist_root
from croaker.playlist import load_playlist

logger = logging.getLogger(__name__)


class RequestHandler(socketserver.StreamRequestHandler):
    """
    Instantiated by the TCPServer when a request is received. Implements the
    command and control protocol and issues commands to the GUI application.
    """

    supported_commands = {
        # command              # help text
        "PLAY": "PLAYLIST    - Switch to the specified playlist.",
        "LIST": "[PLAYLIST]  - List playlists or contents of the specified list.",
        "FFWD": "            - Skip to the next track in the playlist.",
        "HELP": "            - Display command help.",
        "KTHX": "            - Close the current connection.",
        "STOP": "            - Stop the current track and stream silence.",
        "STFU": "            - Terminate the Croaker server.",
    }

    should_listen = True

    def handle(self):
        """
        Start a command and control session. Commands are read one line at a
        time; the format is:

        Byte     Definition
        -------------------
        0-3      Command
        4        Ignored
        5+       Arguments
        """
        while self.should_listen:
            time.sleep(0.01)
            self.data = self.rfile.readline().strip().decode()
            logger.debug(f"Received: {self.data}")
            try:
                cmd = self.data[0:4].strip().upper()
                if not cmd:
                    continue
                elif cmd not in self.supported_commands:
                    self.send(f"ERR Unknown Command '{cmd}'")
            except IndexError:
                self.send(f"ERR Command not understood '{cmd}'")
                continue

            args = self.data[5:]
            if cmd == "KTHX":
                return self.send("KBAI")

            handler = getattr(self, f"handle_{cmd}", None)
            if not handler:
                self.send(f"ERR No handler for {cmd}.")
                continue

            handler(args)

    def send(self, msg):
        return self.wfile.write(msg.encode() + b"\n")

    def handle_PLAY(self, args):
        self.server.player.load(args)
        return self.send("OK")

    def handle_BACK(self, args):
        self.server.player.back_requested.set()
        return self.send("OK")

    def handle_FFWD(self, args):
        self.server.player.ffwd_requested.set()
        return self.send("OK")

    def handle_LIST(self, args):
        return self.send(self.server.list(args))

    def handle_HELP(self, args):
        return self.send("\n".join(f"{cmd} {txt}" for cmd, txt in self.supported_commands.items()))

    def handle_STOP(self, args):
        return self.server.player.stop_requested.set()

    def handle_STFU(self, args):
        self.send("Shutting down.")
        self.server.shutdown()


class Controller(socketserver.TCPServer):
    """
    A TCP Server that listens for commands and proxies the GUI audio player.
    """

    def __init__(self, player: GUI):
        self.player = player
        super().__init__((os.environ["HOST"], int(os.environ["PORT"])), RequestHandler)

    def server_bind(self):
        self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.socket.bind(self.server_address)

    def shutdown(self):
        self.player.shutdown_requested.set()
        exit()

    def list(self, playlist_name: str = None):
        if playlist_name:
            return str(load_playlist(playlist_name))
        return "\n".join([str(p.name) for p in playlist_root().iterdir()])