[V3 Mod] Use a composite class for mod (#2501)

* [V3 Mod] Use a composite class for mod

This turns mod.py into acomposite class

I've split things in this up based on purpose, including `movetocore`

`movetocore` is a set of things which likely belong in the core bot and
not relying on mod being loaded.

This is part of #2500

Per discussion in discord, this should be the first thing in #2500
merged

* Move this back,
mod was importable,
and this was intended as non-breaking

* Prevent fix from being lost if merged before this.

see Cog-Creators/Red-DiscordBot#2510

* Move case creation to before sending

see #2515

* fix failed merge done in web

redbot/cogs/mod/movetocore.py

@@ -0,0 +1,125 @@
+import asyncio
+import contextlib
+
+import discord
+from redbot.core import commands, checks, i18n
+from redbot.core.utils.chat_formatting import box
+from .abc import MixinMeta
+from .log import log
+
+_ = i18n.Translator("Mod", __file__)
+
+
+# TODO: Empty this to core red.
+class MoveToCore(MixinMeta):
+    """
+    Mixin for things which should really not be in mod, but have not been moved out yet.
+    """
+
+    async def on_command_completion(self, ctx: commands.Context):
+        await self._delete_delay(ctx)
+
+    # noinspection PyUnusedLocal
+    async def on_command_error(self, ctx: commands.Context, error):
+        await self._delete_delay(ctx)
+
+    async def _delete_delay(self, ctx: commands.Context):
+        """Currently used for:
+            * delete delay"""
+        guild = ctx.guild
+        if guild is None:
+            return
+        message = ctx.message
+        delay = await self.settings.guild(guild).delete_delay()
+
+        if delay == -1:
+            return
+
+        async def _delete_helper(m):
+            with contextlib.suppress(discord.HTTPException):
+                await m.delete()
+                log.debug("Deleted command msg {}".format(m.id))
+
+        await asyncio.sleep(delay)
+        await _delete_helper(message)
+
+    # When the below are moved to core, the global check in .modcore needs to be moved as well.
+    @commands.group()
+    @commands.guild_only()
+    @checks.admin_or_permissions(manage_channels=True)
+    async def ignore(self, ctx: commands.Context):
+        """Add servers or channels to the ignore list."""
+        if ctx.invoked_subcommand is None:
+            await ctx.send(await self.count_ignored())
+
+    @ignore.command(name="channel")
+    async def ignore_channel(self, ctx: commands.Context, channel: discord.TextChannel = None):
+        """Ignore commands in the channel.
+
+        Defaults to the current channel.
+        """
+        if not channel:
+            channel = ctx.channel
+        if not await self.settings.channel(channel).ignored():
+            await self.settings.channel(channel).ignored.set(True)
+            await ctx.send(_("Channel added to ignore list."))
+        else:
+            await ctx.send(_("Channel already in ignore list."))
+
+    @ignore.command(name="server", aliases=["guild"])
+    @checks.admin_or_permissions(manage_guild=True)
+    async def ignore_guild(self, ctx: commands.Context):
+        """Ignore commands in this server."""
+        guild = ctx.guild
+        if not await self.settings.guild(guild).ignored():
+            await self.settings.guild(guild).ignored.set(True)
+            await ctx.send(_("This server has been added to the ignore list."))
+        else:
+            await ctx.send(_("This server is already being ignored."))
+
+    @commands.group()
+    @commands.guild_only()
+    @checks.admin_or_permissions(manage_channels=True)
+    async def unignore(self, ctx: commands.Context):
+        """Remove servers or channels from the ignore list."""
+        if ctx.invoked_subcommand is None:
+            await ctx.send(await self.count_ignored())
+
+    @unignore.command(name="channel")
+    async def unignore_channel(self, ctx: commands.Context, channel: discord.TextChannel = None):
+        """Remove a channel from ignore the list.
+
+        Defaults to the current channel.
+        """
+        if not channel:
+            channel = ctx.channel
+
+        if await self.settings.channel(channel).ignored():
+            await self.settings.channel(channel).ignored.set(False)
+            await ctx.send(_("Channel removed from ignore list."))
+        else:
+            await ctx.send(_("That channel is not in the ignore list."))
+
+    @unignore.command(name="server", aliases=["guild"])
+    @checks.admin_or_permissions(manage_guild=True)
+    async def unignore_guild(self, ctx: commands.Context):
+        """Remove this server from the ignore list."""
+        guild = ctx.message.guild
+        if await self.settings.guild(guild).ignored():
+            await self.settings.guild(guild).ignored.set(False)
+            await ctx.send(_("This server has been removed from the ignore list."))
+        else:
+            await ctx.send(_("This server is not in the ignore list."))
+
+    async def count_ignored(self):
+        ch_count = 0
+        svr_count = 0
+        for guild in self.bot.guilds:
+            if not await self.settings.guild(guild).ignored():
+                for channel in guild.text_channels:
+                    if await self.settings.channel(channel).ignored():
+                        ch_count += 1
+            else:
+                svr_count += 1
+        msg = _("Currently ignoring:\n{} channels\n{} guilds\n").format(ch_count, svr_count)
+        return box(msg)