1 files changed, 102 insertions, 1 deletions

diff --git a/bot/converters.py b/bot/converters.py
index 4a0633951..c9f525dd1 100644
--- a/bot/converters.py
+++ b/bot/converters.py
@@ -9,8 +9,11 @@ import dateutil.tz
 import discord
 from aiohttp import ClientConnectorError
 from dateutil.relativedelta import relativedelta
-from discord.ext.commands import BadArgument, Context, Converter, UserConverter
+from discord.ext.commands import BadArgument, Bot, Context, Converter, IDConverter, UserConverter
 
+from bot.api import ResponseCodeError
+from bot.constants import URLs
+from bot.utils.regex import INVITE_RE
 
 log = logging.getLogger(__name__)
 
@@ -34,6 +37,78 @@ def allowed_strings(*values, preserve_case: bool = False) -> t.Callable[[str], s
     return converter
 
 
+class ValidDiscordServerInvite(Converter):
+    """
+    A converter that validates whether a given string is a valid Discord server invite.
+
+    Raises 'BadArgument' if:
+    - The string is not a valid Discord server invite.
+    - The string is valid, but is an invite for a group DM.
+    - The string is valid, but is expired.
+
+    Returns a (partial) guild object if:
+    - The string is a valid vanity
+    - The string is a full invite URI
+    - The string contains the invite code (the stuff after discord.gg/)
+
+    See the Discord API docs for documentation on the guild object:
+    https://discord.com/developers/docs/resources/guild#guild-object
+    """
+
+    async def convert(self, ctx: Context, server_invite: str) -> dict:
+        """Check whether the string is a valid Discord server invite."""
+        invite_code = INVITE_RE.search(server_invite)
+        if invite_code:
+            response = await ctx.bot.http_session.get(
+                f"{URLs.discord_invite_api}/{invite_code[1]}"
+            )
+            if response.status != 404:
+                invite_data = await response.json()
+                return invite_data.get("guild")
+
+        id_converter = IDConverter()
+        if id_converter._get_id_match(server_invite):
+            raise BadArgument("Guild IDs are not supported, only invites.")
+
+        raise BadArgument("This does not appear to be a valid Discord server invite.")
+
+
+class ValidFilterListType(Converter):
+    """
+    A converter that checks whether the given string is a valid FilterList type.
+
+    Raises `BadArgument` if the argument is not a valid FilterList type, and simply
+    passes through the given argument otherwise.
+    """
+
+    @staticmethod
+    async def get_valid_types(bot: Bot) -> list:
+        """
+        Try to get a list of valid filter list types.
+
+        Raise a BadArgument if the API can't respond.
+        """
+        try:
+            valid_types = await bot.api_client.get('bot/filter-lists/get-types')
+        except ResponseCodeError:
+            raise BadArgument("Cannot validate list_type: Unable to fetch valid types from API.")
+
+        return [enum for enum, classname in valid_types]
+
+    async def convert(self, ctx: Context, list_type: str) -> str:
+        """Checks whether the given string is a valid FilterList type."""
+        valid_types = await self.get_valid_types(ctx.bot)
+        list_type = list_type.upper()
+
+        if list_type not in valid_types:
+            valid_types_list = '\n'.join([f"• {type_.lower()}" for type_ in valid_types])
+            raise BadArgument(
+                f"You have provided an invalid list type!\n\n"
+                f"Please provide one of the following: \n{valid_types_list}"
+            )
+        return list_type
+
+
 class ValidPythonIdentifier(Converter):
     """
     A converter that checks whether the given string is a valid Python identifier.
@@ -237,6 +312,32 @@ class Duration(DurationDelta):
             raise BadArgument(f"`{duration}` results in a datetime outside the supported range.")
 
 
+class OffTopicName(Converter):
+    """A converter that ensures an added off-topic name is valid."""
+
+    async def convert(self, ctx: Context, argument: str) -> str:
+        """Attempt to replace any invalid characters with their approximate Unicode equivalent."""
+        allowed_characters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ!?'`-"
+
+        # Chain multiple words to a single one
+        argument = "-".join(argument.split())
+
+        if not (2 <= len(argument) <= 96):
+            raise BadArgument("Channel name must be between 2 and 96 chars long")
+
+        elif not all(c.isalnum() or c in allowed_characters for c in argument):
+            raise BadArgument(
+                "Channel name must only consist of "
+                "alphanumeric characters, minus signs or apostrophes."
+            )
+
+        # Replace invalid characters with unicode alternatives.
+        table = str.maketrans(
+            allowed_characters, '𝖠𝖡𝖢𝖣𝖤𝖥𝖦𝖧𝖨𝖩𝖪𝖫𝖬𝖭𝖮𝖯𝖰𝖱𝖲𝖳𝖴𝖵𝖶𝖷𝖸𝖹ǃ？’’-'
+        )
+        return argument.translate(table)
+
+
 class ISODateTime(Converter):
     """Converts an ISO-8601 datetime string into a datetime.datetime."""