feat(hot_reload.py): add hot reloading functionality for bot extensions

This commit introduces a new feature that allows for hot reloading of bot extensions. This is achieved by continuously checking for changes in extension files and reloading them if any modifications are detected. This feature improves the development workflow by eliminating the need to manually restart the bot whenever an extension is updated.

tux/handlers/hot_reload.py

@@ -0,0 +1,75 @@
+import os
+from pathlib import Path
+
+from discord.ext import commands, tasks
+from loguru import logger
+
+from tux.bot import Tux
+
+
+def path_from_extension(extension: str) -> Path:
+    """Convert an extension notation to a file path."""
+    base_dir = Path(__file__).parent.parent
+    relative_path = extension.replace(".", os.sep) + ".py"
+    return (base_dir / relative_path).resolve()
+
+
+class HotReload(commands.Cog):
+    def __init__(self, bot: Tux) -> None:
+        self.bot = bot
+        self.last_modified_time: dict[str, float] = {}
+        self.hot_reload_loop.start()
+
+    async def cog_unload(self) -> None:
+        self.hot_reload_loop.stop()
+
+    @tasks.loop(seconds=3)
+    async def hot_reload_loop(self) -> None:
+        """Loop to check for changes in extension files and reload them if modified."""
+        for extension in list(self.bot.extensions.keys()):
+            if extension == "jishaku":
+                continue
+
+            path: Path = path_from_extension(extension)
+
+            try:
+                modification_time: float = path.stat().st_mtime
+            except FileNotFoundError:
+                logger.error(f"File not found for extension {extension} at {path}")
+                continue
+
+            if self.last_modified_time.get(extension) == modification_time:
+                continue
+
+            # Reload the extension if it has been modified
+            self.last_modified_time[extension] = modification_time
+
+            try:
+                await self.bot.reload_extension(extension)
+            except commands.ExtensionNotLoaded:
+                pass
+            except commands.ExtensionError as e:
+                logger.error(f"Failed to reload extension {extension}: {e}")
+            else:
+                logger.info(f"Reloaded {extension}")
+
+    @hot_reload_loop.before_loop
+    async def cache_last_modified_time(self) -> None:
+        """Cache the last modified time of all extensions before the loop starts."""
+        for extension in self.bot.extensions:
+            if extension == "jishaku":
+                continue
+
+            path: Path = path_from_extension(extension)
+
+            try:
+                modification_time: float = path.stat().st_mtime
+            except FileNotFoundError:
+                logger.error(f"File not found for extension {extension} at {path}")
+                continue
+
+            self.last_modified_time[extension] = modification_time
+
+
+async def setup(bot: Tux) -> None:
+    await bot.add_cog(HotReload(bot))