Dynamically amend types to filterlist docstrings.

We want the !help invocations to give you all the information you need
in order to use the command. That also means we need to provide the
valid filterlist types, which are subject to change.

So, we fetch the valid ones from the API and then dynamically insert
them into the docstrings.

2 files changed, 38 insertions, 5 deletions

diff --git a/bot/cogs/filter_lists.py b/bot/cogs/filter_lists.py
index 8831a2143..fbd070bb9 100644
--- a/bot/cogs/filter_lists.py
+++ b/bot/cogs/filter_lists.py
@@ -17,8 +17,32 @@ log = logging.getLogger(__name__)
 class FilterLists(Cog):
     """Commands for blacklisting and whitelisting things."""
 
+    methods_with_filterlist_types = [
+        "allow_add",
+        "allow_delete",
+        "allow_get",
+        "deny_add",
+        "deny_delete",
+        "deny_get",
+    ]
+
     def __init__(self, bot: Bot) -> None:
         self.bot = bot
+        self.bot.loop.create_task(self._amend_docstrings())
+
+    async def _amend_docstrings(self) -> None:
+        """Add the valid FilterList types to the docstrings, so they'll appear in !help invocations."""
+        await self.bot.wait_until_guild_available()
+
+        # Add valid filterlist types to the docstrings
+        valid_types = await ValidFilterListType.get_valid_types(self.bot)
+        valid_types = [f"`{type_.lower()}`" for type_ in valid_types]
+
+        for method_name in self.methods_with_filterlist_types:
+            command = getattr(self, method_name)
+            command.help = (
+                f"{command.help}\n\nValid **list_type** values are {', '.join(valid_types)}."
+            )
 
     async def _add_data(
             self,
diff --git a/bot/converters.py b/bot/converters.py
index 5912e3e61..c9f525dd1 100644
--- a/bot/converters.py
+++ b/bot/converters.py
@@ -9,7 +9,7 @@ import dateutil.tz
 import discord
 from aiohttp import ClientConnectorError
 from dateutil.relativedelta import relativedelta
-from discord.ext.commands import BadArgument, Context, Converter, IDConverter, UserConverter
+from discord.ext.commands import BadArgument, Bot, Context, Converter, IDConverter, UserConverter
 
 from bot.api import ResponseCodeError
 from bot.constants import URLs
@@ -81,14 +81,23 @@ class ValidFilterListType(Converter):
     passes through the given argument otherwise.
     """
 
-    async def convert(self, ctx: Context, list_type: str) -> str:
-        """Checks whether the given string is a valid FilterList type."""
+    @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 ctx.bot.api_client.get('bot/filter-lists/get-types')
+            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.")
 
-        valid_types = [enum for enum, classname in valid_types]
+        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: