Add user nick name moderation, and change user nickname to random name

.gitignore

@@ -12,7 +12,10 @@ build/
 env/
 lib64
 .mypy_cache/
+.ruff_cache/
 .pytest_cache
 tmp
 .coverage
+.python-version
 .venv
+.vscode

bot/extensions/name_moderation_cog.py

@@ -0,0 +1,82 @@
+import logging
+
+from discord import Member
+from discord.errors import Forbidden
+from discord.ext.commands import Cog
+
+from bot import app
+from bot.grace import Grace
+from bot.helpers.log_helper import notice
+from bot.services.random_name_service import make_random_name
+
+logger = logging.getLogger(__name__)
+
+
+class NameModerationCog(
+    Cog, name="Names", description="Checks and changes user's nickname."
+):
+    """
+    A cog that checks when a member joins if they have a bad word in their name,
+    and changes their name in case they do.
+
+    Configure in the .env file like this:
+        BLACKLISTED_NAMES = bad_word1, bad_word2, bad_word3,...
+    """
+
+    def __init__(self, bot: Grace):
+        self.bot: Grace = bot
+        self.bad_words = set(app.config.get("name_moderation", "blacklist", []))
+
+    @property
+    def moderation_channel(self):
+        return self.bot.get_channel_by_name("moderation_logs")
+
+    @Cog.listener()
+    async def on_member_join(self, member: Member) -> None:
+        """Chnage a user's nickname if it contains a bad word.
+
+        :param member: The member to check their username or display name.
+        :type member: discord.Member
+        """
+
+        name = member.display_name
+
+        if not self.contains_bad_word(name):
+            return
+
+        try:
+            good_name = make_random_name()
+            await member.edit(nick=good_name)
+
+            log = notice("NAME", f"Username of {name} was changed.")
+            log.add_field(
+                "Reason: ",
+                f"User {name} joined with an inappropriate name, thus it was changed to {good_name}.",
+            )
+
+            if self.moderation_channel:
+                await log.send(self.moderation_channel)
+
+            await member.send(
+                f"Your name has an inappropriate word in it, thus it was changed from {name} to {good_name}."
+            )
+
+        except Forbidden:
+            logger.info("User left before we could send them a message.")
+
+    def contains_bad_word(self, name: str) -> bool:
+        """Checks if a name has a bad word in it.
+
+        :param name: The name to check.
+        :type name: str
+
+        :return: True if the name has a bad word, otherwise false.
+        :rtype: bool
+        """
+        lowered = name.lower()
+
+        return any(bad_word in lowered for bad_word in self.bad_words)
+
+
+async def setup(bot: Grace):
+    await bot.add_cog(NameModerationCog(bot))