Bot now responds to commands and channels can be added to list of watched channels

.gitignore

@@ -3,3 +3,4 @@
 __pycache__/
 
 .token
+channels.json

VocalMaisBot.py

@@ -3,6 +3,9 @@ import argparse
 import logging
 import sys
 from pathlib import Path
+import json
+from typing import TextIO, Any, List, Dict
+import textwrap
 
 import discord
 import discord.utils
@@ -12,9 +15,16 @@ logger = logging.getLogger("VocalMaisBot")
 
 class VocalMaisBot(discord.Client):
 
-	def __init__(self, token: str):
-		super().__init__()
-		self.run(token)
+	def __init__(self, watched_channels_file: TextIO):
+		super().__init__(
+			intents = discord.Intents(voice_states = True, guild_messages = True, guilds = True)
+		)
+		self.watched_channels_file = watched_channels_file
+		try:
+			self.watched_channels = json.load(watched_channels_file)
+		except json.JSONDecodeError as e:
+			logger.critical(f"Impossible to parse watched channels file, JSON error: {e}")
+			sys.exit(1)
 
 	async def on_ready(self):
 		logger.info("Connected and ready!")
@@ -26,11 +36,92 @@ class VocalMaisBot(discord.Client):
 		)
 		logger.info(f"You can invite the bot to your server using the following link: {oauth_url}")
 
+	async def on_message(self, message: discord.Message):
+		if self.user not in message.mentions:  # We only ever react to messages that mention us
+			return
+		if message.author.bot or message.is_system():  # We ignore messages from automated sources
+			return
+
+		contents = message.content.split()
+		if _check_list_element(contents, 1, "help"):
+			return await self.print_help(message.channel)
+		elif _check_list_element(contents, 1, "ping"):
+			return await message.channel.send(":ping_pong:")
+		elif _check_list_element(contents, 1, "register"):
+			return await self.register_channel(message)
+		else:
+			return self.sorry_do_not_understand(message)
+
+	async def print_help(self, channel: discord.TextChannel):
+		me = self.user.display_name
+		message = f"""
+			**·** `@{me}register channel_id` : make me watch the voice channel with id `channel_id`
+			**·** `@{me} help` : print this help
+			**·** `@{me} ping` : pong
+		"""
+		await channel.send(embed = discord.Embed(title = "Available commands", description = textwrap.dedent(message)))
+
+	async def register_channel(self, message: discord.Message):
+		message_elements = message.content.split()
+		if len(message_elements) < 3:
+			return await self.sorry_do_not_understand(message)
+		channel_id = message_elements[2]
+		try:
+			channel_id = int(channel_id)
+		except ValueError:
+			return await message.channel.send(f":x: {channel_id} can not be converted to number")
+
+		# Retrieving the channel
+		channel = self.get_channel(channel_id)
+		if channel is None:
+			return await message.channel.send(f"I could not find a channel with id {channel_id} :cry:")
+
+		# Adding the channel to the list of watched channels
+		guild_id = str(message.guild.id)
+		if guild_id not in self.watched_channels:
+			self.watched_channels[guild_id] = {
+				"_name": message.guild.name,
+				"watched_channels": [],
+			}
+		watched_channel_for_this_guild = self.watched_channels[guild_id]["watched_channels"]
+
+		if channel_id in watched_channel_for_this_guild:
+			return await message.channel.send(":thumbsup: I was already watching this channel")
+		else:
+			watched_channel_for_this_guild.append(channel_id)
+			self.loop.call_soon(self.write_watched_channels_file)
+			return await message.channel.send(f":white_check_mark: I am now watching {channel.name}")
+
+	async def sorry_do_not_understand(self, message: discord.Message):
+		await message.channel.send(f"Sorry I did not understand this message. Try `@{self.user.display_name} help` for help")
+
+	def write_watched_channels_file(self):
+		logger.debug("Writing watched channels information to file")
+		self.watched_channels_file.seek(0)
+		self.watched_channels_file.truncate()
+		json.dump(self.watched_channels, self.watched_channels_file, indent = 2)
+		self.watched_channels_file.flush()
+		logger.debug("Written watched channels information to file")
+
+
+def _check_list_element(l: List, index: int, expected_value: Any) -> bool:
+	try:
+		return l[index] == expected_value
+	except IndexError:
+		return False
+
+
+def _check_dict_element(d: Dict, key: Any, expected_value: Any) -> bool:
+	try:
+		return d[key] == expected_value
+	except KeyError:
+		return False
+
 
 if __name__ == '__main__':
 	argparser = argparse.ArgumentParser(description = "Discord bot to automatically create temporary voice channels for users when they connect to a special channel", formatter_class = argparse.ArgumentDefaultsHelpFormatter)
 	argparser.add_argument("-t", "--token-file", default = ".token", help = "File where the discord bot token is stored")
-	# argparser.add_argument("-c", "--config-file", default = "config.json", help = "Bot config file")
+	argparser.add_argument("-w", "--watched-channels-file", default = "channels.json", help = "Used to store the list of channels that the bot watches")
 	argparser.add_argument("-v", "--verbose", action = "store_true", help = "Print debug messages")
 
 	ARGS = argparser.parse_args()
@@ -40,6 +131,8 @@ if __name__ == '__main__':
 		format = "%(asctime)s %(name)s [%(levelname)s] %(message)s'"
 	)
 
+	logger.info(f"Using discord.py version {discord.__version__}")
+
 	token_file_path = Path(ARGS.token_file).absolute()
 	if not token_file_path.is_file():
 		logger.error(f"Token file {token_file_path} does not exist")
@@ -47,4 +140,13 @@ if __name__ == '__main__':
 	with token_file_path.open("r") as token_file:
 		token = token_file.readline().strip()
 
-	VocalMaisBot(token)
+	watched_channels_file_path = Path(ARGS.watched_channels_file).absolute()
+	if not watched_channels_file_path.exists():
+		logger.info(f"Watched channels file {watched_channels_file_path} does not exist, creating it...")
+		with watched_channels_file_path.open("w") as watched_channels_file:
+			json.dump({}, watched_channels_file)
+
+	with watched_channels_file_path.open("r+") as watched_channels_file:
+		bot = VocalMaisBot(watched_channels_file)
+		bot.run(token)
+		watched_channels_file.flush()