Make FetchedUser a subclass of UserConverter

6 files changed, 52 insertions, 50 deletions

diff --git a/bot/cogs/alias.py b/bot/cogs/alias.py
index 03c49c2f4..e709be85d 100644
--- a/bot/cogs/alias.py
+++ b/bot/cogs/alias.py
@@ -1,8 +1,7 @@
 import inspect
 import logging
-from typing import Union
 
-from discord import Colour, Embed, Member, User
+from discord import Colour, Embed
 from discord.ext.commands import Cog, Command, Context, clean_content, command, group
 
 from bot.bot import Bot
@@ -60,18 +59,12 @@ class Alias (Cog):
         await self.invoke(ctx, "site tools")
 
     @command(name="watch", hidden=True)
-    async def bigbrother_watch_alias(
-            self,
-            ctx: Context,
-            user: Union[Member, User, FetchedUser],
-            *,
-            reason: str
-    ) -> None:
+    async def bigbrother_watch_alias(self, ctx: Context, user: FetchedUser, *, reason: str) -> None:
         """Alias for invoking <prefix>bigbrother watch [user] [reason]."""
         await self.invoke(ctx, "bigbrother watch", user, reason=reason)
 
     @command(name="unwatch", hidden=True)
-    async def bigbrother_unwatch_alias(self, ctx: Context, user: Union[User, FetchedUser], *, reason: str) -> None:
+    async def bigbrother_unwatch_alias(self, ctx: Context, user: FetchedUser, *, reason: str) -> None:
         """Alias for invoking <prefix>bigbrother unwatch [user] [reason]."""
         await self.invoke(ctx, "bigbrother unwatch", user, reason=reason)
 
@@ -137,12 +130,12 @@ class Alias (Cog):
         await self.invoke(ctx, "docs get", symbol)
 
     @command(name="nominate", hidden=True)
-    async def nomination_add_alias(self, ctx: Context, user: Union[Member, User, FetchedUser], *, reason: str) -> None:
+    async def nomination_add_alias(self, ctx: Context, user: FetchedUser, *, reason: str) -> None:
         """Alias for invoking <prefix>talentpool add [user] [reason]."""
         await self.invoke(ctx, "talentpool add", user, reason=reason)
 
     @command(name="unnominate", hidden=True)
-    async def nomination_end_alias(self, ctx: Context, user: Union[User, FetchedUser], *, reason: str) -> None:
+    async def nomination_end_alias(self, ctx: Context, user: FetchedUser, *, reason: str) -> None:
         """Alias for invoking <prefix>nomination end [user] [reason]."""
         await self.invoke(ctx, "nomination end", user, reason=reason)
 
diff --git a/bot/cogs/moderation/infractions.py b/bot/cogs/moderation/infractions.py
index 5b6a63dbb..264d8bcf5 100644
--- a/bot/cogs/moderation/infractions.py
+++ b/bot/cogs/moderation/infractions.py
@@ -14,12 +14,10 @@ from bot.decorators import respect_role_hierarchy
 from bot.utils.checks import with_role_check
 from . import utils
 from .scheduler import InfractionScheduler
-from .utils import MemberObject, UserTypes
+from .utils import MemberObject
 
 log = logging.getLogger(__name__)
 
-MemberConverter = t.Union[UserTypes, FetchedUser]
-
 
 class Infractions(InfractionScheduler, commands.Cog):
     """Apply and pardon infractions on users for moderation purposes."""
@@ -68,7 +66,7 @@ class Infractions(InfractionScheduler, commands.Cog):
         await self.apply_kick(ctx, user, reason, active=False)
 
     @command()
-    async def ban(self, ctx: Context, user: MemberConverter, *, reason: str = None) -> None:
+    async def ban(self, ctx: Context, user: FetchedUser, *, reason: str = None) -> None:
         """Permanently ban a user for the given reason."""
         await self.apply_ban(ctx, user, reason)
 
@@ -95,7 +93,7 @@ class Infractions(InfractionScheduler, commands.Cog):
         await self.apply_mute(ctx, user, reason, expires_at=duration)
 
     @command()
-    async def tempban(self, ctx: Context, user: MemberConverter, duration: utils.Expiry, *, reason: str = None) -> None:
+    async def tempban(self, ctx: Context, user: FetchedUser, duration: utils.Expiry, *, reason: str = None) -> None:
         """
         Temporarily ban a user for the given reason and duration.
 
@@ -117,7 +115,7 @@ class Infractions(InfractionScheduler, commands.Cog):
     # region: Permanent shadow infractions
 
     @command(hidden=True)
-    async def note(self, ctx: Context, user: MemberConverter, *, reason: str = None) -> None:
+    async def note(self, ctx: Context, user: FetchedUser, *, reason: str = None) -> None:
         """Create a private note for a user with the given reason without notifying the user."""
         infraction = await utils.post_infraction(ctx, user, "note", reason, hidden=True, active=False)
         if infraction is None:
@@ -131,7 +129,7 @@ class Infractions(InfractionScheduler, commands.Cog):
         await self.apply_kick(ctx, user, reason, hidden=True, active=False)
 
     @command(hidden=True, aliases=['shadowban', 'sban'])
-    async def shadow_ban(self, ctx: Context, user: MemberConverter, *, reason: str = None) -> None:
+    async def shadow_ban(self, ctx: Context, user: FetchedUser, *, reason: str = None) -> None:
         """Permanently ban a user for the given reason without notifying the user."""
         await self.apply_ban(ctx, user, reason, hidden=True)
 
@@ -161,7 +159,7 @@ class Infractions(InfractionScheduler, commands.Cog):
     async def shadow_tempban(
         self,
         ctx: Context,
-        user: MemberConverter,
+        user: FetchedUser,
         duration: utils.Expiry,
         *,
         reason: str = None
@@ -187,12 +185,12 @@ class Infractions(InfractionScheduler, commands.Cog):
     # region: Remove infractions (un- commands)
 
     @command()
-    async def unmute(self, ctx: Context, user: MemberConverter) -> None:
+    async def unmute(self, ctx: Context, user: FetchedUser) -> None:
         """Prematurely end the active mute infraction for the user."""
         await self.pardon_infraction(ctx, "mute", user)
 
     @command()
-    async def unban(self, ctx: Context, user: MemberConverter) -> None:
+    async def unban(self, ctx: Context, user: FetchedUser) -> None:
         """Prematurely end the active ban infraction for the user."""
         await self.pardon_infraction(ctx, "ban", user)
 
diff --git a/bot/cogs/moderation/management.py b/bot/cogs/moderation/management.py
index fff86e9ea..2ec69960e 100644
--- a/bot/cogs/moderation/management.py
+++ b/bot/cogs/moderation/management.py
@@ -20,8 +20,6 @@ from .modlog import ModLog
 
 log = logging.getLogger(__name__)
 
-UserConverter = t.Union[discord.User, proxy_user]
-
 
 class ModManagement(commands.Cog):
     """Management of infractions."""
@@ -182,7 +180,7 @@ class ModManagement(commands.Cog):
             await ctx.invoke(self.search_reason, query)
 
     @infraction_search_group.command(name="user", aliases=("member", "id"))
-    async def search_user(self, ctx: Context, user: UserConverter) -> None:
+    async def search_user(self, ctx: Context, user: t.Union[discord.User, proxy_user]) -> None:
         """Search for infractions by member."""
         infraction_list = await self.bot.api_client.get(
             'bot/infractions',
diff --git a/bot/cogs/watchchannels/bigbrother.py b/bot/cogs/watchchannels/bigbrother.py
index 7a30d5033..b2cb99368 100644
--- a/bot/cogs/watchchannels/bigbrother.py
+++ b/bot/cogs/watchchannels/bigbrother.py
@@ -1,8 +1,6 @@
 import logging
 from collections import ChainMap
-from typing import Union
 
-from discord import User
 from discord.ext.commands import Cog, Context, group
 
 from bot.bot import Bot
@@ -47,7 +45,7 @@ class BigBrother(WatchChannel, Cog, name="Big Brother"):
 
     @bigbrother_group.command(name='watch', aliases=('w',))
     @with_role(*MODERATION_ROLES)
-    async def watch_command(self, ctx: Context, user: Union[User, FetchedUser], *, reason: str) -> None:
+    async def watch_command(self, ctx: Context, user: FetchedUser, *, reason: str) -> None:
         """
         Relay messages sent by the given `user` to the `#big-brother` channel.
 
@@ -94,7 +92,7 @@ class BigBrother(WatchChannel, Cog, name="Big Brother"):
 
     @bigbrother_group.command(name='unwatch', aliases=('uw',))
     @with_role(*MODERATION_ROLES)
-    async def unwatch_command(self, ctx: Context, user: Union[User, FetchedUser], *, reason: str) -> None:
+    async def unwatch_command(self, ctx: Context, user: FetchedUser, *, reason: str) -> None:
         """Stop relaying messages by the given `user`."""
         active_watches = await self.bot.api_client.get(
             self.api_endpoint,
diff --git a/bot/cogs/watchchannels/talentpool.py b/bot/cogs/watchchannels/talentpool.py
index 62be3bc3b..776f0ea87 100644
--- a/bot/cogs/watchchannels/talentpool.py
+++ b/bot/cogs/watchchannels/talentpool.py
@@ -1,9 +1,8 @@
 import logging
 import textwrap
 from collections import ChainMap
-from typing import Union
 
-from discord import Color, Embed, Member, User
+from discord import Color, Embed, Member
 from discord.ext.commands import Cog, Context, group
 
 from bot.api import ResponseCodeError
@@ -50,7 +49,7 @@ class TalentPool(WatchChannel, Cog, name="Talentpool"):
 
     @nomination_group.command(name='watch', aliases=('w', 'add', 'a'))
     @with_role(*STAFF_ROLES)
-    async def watch_command(self, ctx: Context, user: Union[Member, User, FetchedUser], *, reason: str) -> None:
+    async def watch_command(self, ctx: Context, user: FetchedUser, *, reason: str) -> None:
         """
         Relay messages sent by the given `user` to the `#talent-pool` channel.
 
@@ -115,7 +114,7 @@ class TalentPool(WatchChannel, Cog, name="Talentpool"):
 
     @nomination_group.command(name='history', aliases=('info', 'search'))
     @with_role(*MODERATION_ROLES)
-    async def history_command(self, ctx: Context, user: Union[User, FetchedUser]) -> None:
+    async def history_command(self, ctx: Context, user: FetchedUser) -> None:
         """Shows the specified user's nomination history."""
         result = await self.bot.api_client.get(
             self.api_endpoint,
@@ -144,7 +143,7 @@ class TalentPool(WatchChannel, Cog, name="Talentpool"):
 
     @nomination_group.command(name='unwatch', aliases=('end', ))
     @with_role(*MODERATION_ROLES)
-    async def unwatch_command(self, ctx: Context, user: Union[User, FetchedUser], *, reason: str) -> None:
+    async def unwatch_command(self, ctx: Context, user: FetchedUser, *, reason: str) -> None:
         """
         Ends the active nomination of the specified user with the given reason.
 
diff --git a/bot/converters.py b/bot/converters.py
index a2e445d74..4fb800a01 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
+from discord.ext.commands import BadArgument, Context, Converter, UserConverter
 
 
 log = logging.getLogger(__name__)
@@ -303,30 +303,46 @@ def proxy_user(user_id: str) -> discord.Object:
     return user
 
 
-class FetchedUser(Converter):
+class FetchedUser(UserConverter):
     """
-    Fetches from the Discord API and returns a `discord.User` or `discord.Object` object, given an ID.
+    Converts to a `discord.User` or, if it fails, a `discord.Object`.
 
-    If the fetching is successful, a `discord.User` object is returned. If it fails and
-    the error doesn't imply the user doesn't exist, then a `discord.Object` is returned
-    via the `user_proxy` function.
+    Unlike the default `UserConverter`, which only does lookups via the global user cache, this
+    converter attempts to fetch the user via an API call to Discord when the using the cache is
+    unsuccessful.
+
+    If the fetch also fails and the error doesn't imply the user doesn't exist, then a
+    `discord.Object` is returned via the `user_proxy` converter.
+
+    The lookup strategy is as follows (in order):
+
+    1. Lookup by ID.
+    2. Lookup by mention.
+    3. Lookup by name#discrim
+    4. Lookup by name
+    5. Lookup via API
+    6. Create a proxy user with discord.Object
     """
 
-    @staticmethod
-    async def convert(ctx: Context, user_id: str) -> t.Union[discord.User, discord.Object]:
-        """Convert `user_id` to a `discord.User` object, after fetching from the Discord API."""
+    async def convert(self, ctx: Context, arg: str) -> t.Union[discord.User, discord.Object]:
+        """Convert the `arg` to a `discord.User` or `discord.Object`."""
+        try:
+            return await super().convert(ctx, arg)
+        except BadArgument:
+            pass
+
         try:
-            user_id = int(user_id)
+            user_id = int(arg)
             log.trace(f"Fetching user {user_id}...")
             return await ctx.bot.fetch_user(user_id)
         except ValueError:
-            log.debug(f"Failed to fetch user {user_id}: could not convert to int.")
-            raise BadArgument(f"The provided argument can't be turned into integer: `{user_id}`")
+            log.debug(f"Failed to fetch user {arg}: could not convert to int.")
+            raise BadArgument(f"The provided argument can't be turned into integer: `{arg}`")
         except discord.HTTPException as e:
-            # If the Discord error isn't `Unknown user`, save it in the log and return a proxy instead
+            # If the Discord error isn't `Unknown user`, return a proxy instead
             if e.code != 10013:
                 log.warning(f"Failed to fetch user, returning a proxy instead: status {e.status}")
-                return proxy_user(user_id)
+                return proxy_user(arg)
 
-            log.debug(f"Failed to fetch user {user_id}: user does not exist.")
-            raise BadArgument(f"User `{user_id}` does not exist")
+            log.debug(f"Failed to fetch user {arg}: user does not exist.")
+            raise BadArgument(f"User `{arg}` does not exist")