[Core] Add Red.message_eligible_as_command (#4077)

* [Core] Add `Red.message_eligible_as_command`

  - This is a small utility function which makes it easy for cog
  creators to treat non-command messages as commands correctly.

  - This also modifies `Red.ignored_channel_or_guild`'s signature to
  explicitly add support for passing a message object (the only needed
  attributes are entirely shared with context)

* Update redbot/core/bot.py

Co-authored-by: jack1142 <6032823+jack1142@users.noreply.github.com>

* address review

* Rename

* remove webhhok check, the issue wasn't possible under normal operation

* Ah yes, ctx.bot in a method of the bot...

Co-authored-by: jack1142 <6032823+jack1142@users.noreply.github.com>

redbot/core/bot.py

@@ -3,7 +3,6 @@ import inspect
 import logging
 import os
 import platform
-import re
 import shutil
 import sys
 import contextlib
@@ -19,7 +18,6 @@ from typing import (
     Dict,
     NoReturn,
     Set,
-    Coroutine,
     TypeVar,
     Callable,
     Awaitable,
@@ -30,7 +28,6 @@ from types import MappingProxyType
 import discord
 from discord.ext import commands as dpy_commands
 from discord.ext.commands import when_mentioned_or
-from discord.ext.commands.bot import BotBase
 
 from . import Config, i18n, commands, errors, drivers, modlog, bank
 from .cog_manager import CogManager, CogManagerUI
@@ -406,14 +403,60 @@ class RedBase(
 
         return True
 
-    async def ignored_channel_or_guild(self, ctx: commands.Context) -> bool:
+    async def message_eligible_as_command(self, message: discord.Message) -> bool:
+        """
+        Runs through the things which apply globally about commands
+        to determine if a message may be responded to as a command.
+
+        This can't interact with permissions as permissions is hyper-local
+        with respect to command objects, create command objects for this
+        if that's needed.
+
+        This also does not check for prefix or command conflicts,
+        as it is primarily designed for non-prefix based response handling
+        via on_message_without_command
+
+        Parameters
+        ----------
+        message
+            The message object to check
+
+        Returns
+        -------
+        bool
+            Whether or not the message is eligible to be treated as a command.
+        """
+
+        channel = message.channel
+        guild = message.guild
+
+        if message.author.bot:
+            return False
+
+        if guild:
+            assert isinstance(channel, discord.abc.GuildChannel)  # nosec
+            if not channel.permissions_for(guild.me).send_messages:
+                return False
+            if not (await self.ignored_channel_or_guild(message)):
+                return False
+
+        if not (await self.allowed_by_whitelist_blacklist(message.author)):
+            return False
+
+        return True
+
+    async def ignored_channel_or_guild(
+        self, ctx: Union[commands.Context, discord.Message]
+    ) -> bool:
         """
         This checks if the bot is meant to be ignoring commands in a channel or guild,
         as considered by Red's whitelist and blacklist.
 
         Parameters
         ----------
-        ctx : Context of where the command is being run.
+        ctx :
+            Context object of the command which needs to be checked prior to invoking
+            or a Message object which might be intended for use as a command.
 
         Returns
         -------
@@ -424,8 +467,8 @@ class RedBase(
         surpass_ignore = (
             isinstance(ctx.channel, discord.abc.PrivateChannel)
             or perms.manage_guild
-            or await ctx.bot.is_owner(ctx.author)
+            or await self.is_owner(ctx.author)
-            or await ctx.bot.is_admin(ctx.author)
+            or await self.is_admin(ctx.author)
         )
         if surpass_ignore:
             return True

redbot/core/global_checks.py

@@ -4,25 +4,5 @@ from . import commands
 
 def init_global_checks(bot):
     @bot.check_once
-    def minimum_bot_perms(ctx) -> bool:
+    async def check_message_is_eligible_as_command(ctx: commands.Context) -> bool:
-        """
+        return await ctx.bot.message_eligible_as_command(ctx.message)
-        Too many 403, 401, and 429 Errors can cause bots to get global'd
-
-        It's reasonable to assume the below as a minimum amount of perms for
-        commands.
-        """
-        return ctx.channel.permissions_for(ctx.me).send_messages
-
-    @bot.check_once
-    async def whiteblacklist_checks(ctx) -> bool:
-        return await ctx.bot.allowed_by_whitelist_blacklist(ctx.author)
-
-    @bot.check_once
-    async def ignore_checks(ctx) -> bool:
-        """Check the channel or server is not ignored"""
-        return await ctx.bot.ignored_channel_or_guild(ctx)
-
-    @bot.check_once
-    def bots(ctx) -> bool:
-        """Check the user is not another bot."""
-        return not ctx.author.bot