[Permissions] Find things uniquely for models (#2258)

This is a safety measure to prevent accidentally passing a model which has the same name as another model, potentially modifying rules for the unwanted one.

redbot/cogs/permissions/converters.py

@@ -1,10 +1,133 @@
-from typing import NamedTuple, Union, Optional, cast, Type
+import itertools
+import re
+from typing import NamedTuple, Union, Optional
+
+import discord
 
 from redbot.core import commands
 from redbot.core.i18n import Translator
 
 _ = Translator("PermissionsConverters", __file__)
 
+MENTION_RE = re.compile(r"^<?(?:(?:@[!&]?)?|#)(\d{15,21})>?$")
+
+
+def _match_id(arg: str) -> Optional[int]:
+    m = MENTION_RE.match(arg)
+    if m:
+        return int(m.group(1))
+
+
+class GlobalUniqueObjectFinder(commands.Converter):
+    async def convert(
+        self, ctx: commands.Context, arg: str
+    ) -> Union[discord.Guild, discord.abc.GuildChannel, discord.abc.User, discord.Role]:
+        bot: commands.Bot = ctx.bot
+        _id = _match_id(arg)
+
+        if _id is not None:
+            guild: discord.Guild = bot.get_guild(_id)
+            if guild is not None:
+                return guild
+            channel: discord.abc.GuildChannel = bot.get_channel(_id)
+            if channel is not None:
+                return channel
+
+            user: discord.User = bot.get_user(_id)
+            if user is not None:
+                return user
+
+            for guild in bot.guilds:
+                role: discord.Role = guild.get_role(_id)
+                if role is not None:
+                    return role
+
+        objects = itertools.chain(
+            bot.get_all_channels(),
+            bot.users,
+            bot.guilds,
+            *(filter(lambda r: not r.is_default(), guild.roles) for guild in bot.guilds),
+        )
+
+        maybe_matches = []
+        for obj in objects:
+            if obj.name == arg or str(obj) == arg:
+                maybe_matches.append(obj)
+
+        if ctx.guild is not None:
+            for member in ctx.guild.members:
+                if member.nick == arg and not any(obj.id == member.id for obj in maybe_matches):
+                    maybe_matches.append(member)
+
+        if not maybe_matches:
+            raise commands.BadArgument(
+                _(
+                    '"{arg}" was not found. It must be the ID, mention, or name of a server, '
+                    "channel, user or role which the bot can see."
+                ).format(arg=arg)
+            )
+        elif len(maybe_matches) == 1:
+            return maybe_matches[0]
+        else:
+            raise commands.BadArgument(
+                _(
+                    '"{arg}" does not refer to a unique server, channel, user or role. Please use '
+                    "the ID for whatever/whoever you're trying to specify, or mention it/them."
+                ).format(arg=arg)
+            )
+
+
+class GuildUniqueObjectFinder(commands.Converter):
+    async def convert(
+        self, ctx: commands.Context, arg: str
+    ) -> Union[discord.abc.GuildChannel, discord.Member, discord.Role]:
+        guild: discord.Guild = ctx.guild
+        _id = _match_id(arg)
+
+        if _id is not None:
+            channel: discord.abc.GuildChannel = guild.get_channel(_id)
+            if channel is not None:
+                return channel
+
+            member: discord.Member = guild.get_member(_id)
+            if member is not None:
+                return member
+
+            role: discord.Role = guild.get_role(_id)
+            if role is not None and not role.is_default():
+                return role
+
+        objects = itertools.chain(
+            guild.channels, guild.members, filter(lambda r: not r.is_default(), guild.roles)
+        )
+
+        maybe_matches = []
+        for obj in objects:
+            if obj.name == arg or str(obj) == arg:
+                maybe_matches.append(obj)
+            try:
+                if obj.nick == arg:
+                    maybe_matches.append(obj)
+            except AttributeError:
+                pass
+
+        if not maybe_matches:
+            raise commands.BadArgument(
+                _(
+                    '"{arg}" was not found. It must be the ID, mention, or name of a channel, '
+                    "user or role in this server."
+                ).format(arg=arg)
+            )
+        elif len(maybe_matches) == 1:
+            return maybe_matches[0]
+        else:
+            raise commands.BadArgument(
+                _(
+                    '"{arg}" does not refer to a unique channel, user or role. Please use the ID '
+                    "for whatever/whoever you're trying to specify, or mention it/them."
+                ).format(arg=arg)
+            )
+
 
 class CogOrCommand(NamedTuple):
     type: str

redbot/cogs/permissions/permissions.py

@@ -14,7 +14,13 @@ from redbot.core.utils.chat_formatting import box
 from redbot.core.utils.menus import start_adding_reactions
 from redbot.core.utils.predicates import ReactionPredicate, MessagePredicate
 
-from .converters import CogOrCommand, RuleType, ClearableRuleType
+from .converters import (
+    CogOrCommand,
+    RuleType,
+    ClearableRuleType,
+    GuildUniqueObjectFinder,
+    GlobalUniqueObjectFinder,
+)
 
 _ = Translator("Permissions", __file__)
 
@@ -275,7 +281,7 @@ class Permissions(commands.Cog):
         ctx: commands.Context,
         allow_or_deny: RuleType,
         cog_or_command: CogOrCommand,
-        who_or_what: commands.GlobalPermissionModel,
+        who_or_what: GlobalUniqueObjectFinder,
     ):
         """Add a global rule to a command.
 
@@ -303,7 +309,7 @@ class Permissions(commands.Cog):
         ctx: commands.Context,
         allow_or_deny: RuleType,
         cog_or_command: CogOrCommand,
-        who_or_what: commands.GuildPermissionModel,
+        who_or_what: GuildUniqueObjectFinder,
     ):
         """Add a rule to a command in this server.
 
@@ -328,7 +334,7 @@ class Permissions(commands.Cog):
         self,
         ctx: commands.Context,
         cog_or_command: CogOrCommand,
-        who_or_what: commands.GlobalPermissionModel,
+        who_or_what: GlobalUniqueObjectFinder,
     ):
         """Remove a global rule from a command.
 
@@ -351,7 +357,7 @@ class Permissions(commands.Cog):
         ctx: commands.Context,
         cog_or_command: CogOrCommand,
         *,
-        who_or_what: commands.GuildPermissionModel,
+        who_or_what: GuildUniqueObjectFinder,
     ):
         """Remove a server rule from a command.