bot: cogs: add Debug cog and load extensions when bot is ready

As the name implies, the Debug cog is solely there to debug stuff. In
the future the commands in that cog should only respond to whoever has
the provided `BOT_OWNER_ID` (me).

Additionally, extensions for discord.py are now loaded dynamically in
`main.py`.

Signed-off-by: Max R. Carrara <max@aequito.sh>

src/bot/cogs/debug.py

@@ -0,0 +1,43 @@
+import asyncio
+import logging
+
+import discord
+from discord.ext import commands
+
+from bot.types import RichEmbed
+
+_log = logging.getLogger(__name__)
+
+
+class Debug(commands.Cog):
+    def __init__(self, bot: commands.Bot) -> None:
+        self.bot = bot
+
+    @commands.command()
+    async def ping(self, ctx: commands.Context):
+        _log.debug("pong!")
+
+        embed: RichEmbed = {
+            "type": "rich",
+            "description": "Pong."
+        }
+
+        await ctx.send(embed=discord.Embed.from_dict(embed))
+
+
+async def setup(bot: commands.Bot):
+    _log.debug("Adding Debug cog")
+    await bot.add_cog(Debug(bot))
+
+    cog = bot.get_cog(Debug.__name__)
+
+    if cog is None:
+        return
+
+    _log.debug("Loaded Debug cog with the following commands:")
+    _log.debug([c.name for c in cog.get_commands()])
+
+
+async def teardown(bot: commands.Bot):
+    _log.debug("Removing Debug cog")
+    await bot.remove_cog(Debug.__name__)

src/bot/main.py

@@ -12,6 +12,9 @@ from bot.env import Environment
 
 
 _log = logging.getLogger(__name__)
+_default_extensions: dict[str, str] = {
+    "Debug": "bot.cogs.debug",
+}
 
 
 def setup_logging():
@@ -127,6 +130,17 @@ def register_event_handlers(bot: commands.Bot):
     async def on_ready():
         _log.info("Ready: Connected to Discord")
 
+        _log.info("Loading extensions")
+        for ext_name, ext_path in _default_extensions.items():
+            try:
+                _log.info(f'Loading extension "{ext_name}" ({ext_path})')
+                await bot.load_extension(ext_path)
+                _log.info(f'Loaded extension "{ext_name}" ({ext_path})')
+            except Exception as e:
+                _log.error(
+                    f'Failed to load extension "{ext_name}" ({ext_path})', exc_info=e
+                )
+
     @bot.event
     async def on_resumed():
         _log.info("Resumed: Session with Discord resumed")