(moderation): tickets command and note ticket.

Add new `tickets` command for viewing moderation tickets.
Add `Note` ticket implementation, with command.
Add `offer_delete` context utility.
Add `guild_moderator` command ward.

bot/utils/ctx_addons.py

@@ -1,8 +1,10 @@
+import asyncio
 import discord
 from cmdClient import Context
 
 from data import tables
 from core import Lion
+from . import lib
 from settings import GuildSettings, UserSettings
 
 
@@ -43,6 +45,85 @@ async def error_reply(ctx, error_str, **kwargs):
             return message
 
 
+@Context.util
+async def offer_delete(ctx: Context, *to_delete, timeout=300):
+    """
+    Offers to delete the provided messages via a reaction on the last message.
+    Removes the reaction if the offer times out.
+
+    If any exceptions occur, handles them silently and returns.
+
+    Parameters
+    ----------
+    to_delete: List[Message]
+        The messages to delete.
+
+    timeout: int
+        Time in seconds after which to remove the delete offer reaction.
+    """
+    # Get the delete emoji from the config
+    emoji = lib.cross
+
+    # Return if there are no messages to delete
+    if not to_delete:
+        return
+
+    # The message to add the reaction to
+    react_msg = to_delete[-1]
+
+    # Build the reaction check function
+    if ctx.guild:
+        modrole = ctx.guild_settings.mod_role.value if ctx.guild else None
+
+        def check(reaction, user):
+            if not (reaction.message.id == react_msg.id and reaction.emoji == emoji):
+                return False
+            if user == ctx.guild.me:
+                return False
+            return ((user == ctx.author)
+                    or (user.permissions_in(ctx.ch).manage_messages)
+                    or (modrole and modrole in user.roles))
+    else:
+        def check(reaction, user):
+            return user == ctx.author and reaction.message.id == react_msg.id and reaction.emoji == emoji
+
+    try:
+        # Add the reaction to the message
+        await react_msg.add_reaction(emoji)
+
+        # Wait for the user to press the reaction
+        reaction, user = await ctx.client.wait_for("reaction_add", check=check, timeout=timeout)
+
+        # Since the check was satisfied, the reaction is correct. Delete the messages, ignoring any exceptions
+        deleted = False
+        # First try to bulk delete if we have the permissions
+        if ctx.guild and ctx.ch.permissions_for(ctx.guild.me).manage_messages:
+            try:
+                await ctx.ch.delete_messages(to_delete)
+                deleted = True
+            except Exception:
+                deleted = False
+
+        # If we couldn't bulk delete, delete them one by one
+        if not deleted:
+            try:
+                asyncio.gather(*[message.delete() for message in to_delete], return_exceptions=True)
+            except Exception:
+                pass
+    except (asyncio.TimeoutError, asyncio.CancelledError):
+        # Timed out waiting for the reaction, attempt to remove the delete reaction
+        try:
+            await react_msg.remove_reaction(emoji, ctx.client.user)
+        except Exception:
+            pass
+    except discord.Forbidden:
+        pass
+    except discord.NotFound:
+        pass
+    except discord.HTTPException:
+        pass
+
+
 def context_property(func):
     setattr(Context, func.__name__, property(func))
     return func