Prevent ghost-pings in pypi command (#1696)

* Update `utils.messages.wait_for_deletion`

Will now clear reactions after the timeout ends to indicate it's no longer possible to delete the message through reactions.

* Update pypi command to not ghost-ping users

Will no longer ghost-ping users when an invalid packaged is search containing a ping and reaction is pressed to delete message.

* Update local file

* Remove redundant code

No longer try to clear reactions after calling `utils.messages.wait_for_deletion()` since the util now does it.

* Remove trailing whitespace

* Remove redundant import

* Fix NameErrors

* Remove redundant import

* Reword comment

* Update `contextlib.suppress` import to be consistent

* Update docstring to reflect earlier changes

* Update docstring to be more informative

* Update to delete error message if invocation doesn't ping

* Update to delete error message if invocation doesn't ping

3 files changed, 21 insertions, 9 deletions

diff --git a/bot/exts/info/doc/_cog.py b/bot/exts/info/doc/_cog.py
index 704884fd1..fb9b2584a 100644
--- a/bot/exts/info/doc/_cog.py
+++ b/bot/exts/info/doc/_cog.py
@@ -14,7 +14,7 @@ import discord
 from discord.ext import commands
 
 from bot.bot import Bot
-from bot.constants import Emojis, MODERATION_ROLES, RedirectOutput
+from bot.constants import MODERATION_ROLES, RedirectOutput
 from bot.converters import Inventory, PackageName, ValidURL, allowed_strings
 from bot.pagination import LinePaginator
 from bot.utils.lock import SharedEvent, lock
@@ -341,13 +341,12 @@ class DocCog(commands.Cog):
             if doc_embed is None:
                 error_message = await send_denial(ctx, "No documentation found for the requested symbol.")
                 await wait_for_deletion(error_message, (ctx.author.id,), timeout=NOT_FOUND_DELETE_DELAY)
-                with suppress(discord.NotFound):
-                    await error_message.clear_reaction(Emojis.trashcan)
 
                 # Make sure that we won't cause a ghost-ping by deleting the message
                 if not (ctx.message.mentions or ctx.message.role_mentions):
                     with suppress(discord.NotFound):
                         await ctx.message.delete()
+                        await error_message.delete()
 
             else:
                 msg = await ctx.send(embed=doc_embed)
diff --git a/bot/exts/info/pypi.py b/bot/exts/info/pypi.py
index 2e42e7d6b..62498ce0b 100644
--- a/bot/exts/info/pypi.py
+++ b/bot/exts/info/pypi.py
@@ -2,13 +2,15 @@ import itertools
 import logging
 import random
 import re
+from contextlib import suppress
 
-from discord import Embed
+from discord import Embed, NotFound
 from discord.ext.commands import Cog, Context, command
 from discord.utils import escape_markdown
 
 from bot.bot import Bot
 from bot.constants import Colours, NEGATIVE_REPLIES, RedirectOutput
+from bot.utils.messages import wait_for_deletion
 
 URL = "https://pypi.org/pypi/{package}/json"
 PYPI_ICON = "https://cdn.discordapp.com/emojis/766274397257334814.png"
@@ -67,8 +69,15 @@ class PyPi(Cog):
                     log.trace(f"Error when fetching PyPi package: {response.status}.")
 
         if error:
-            await ctx.send(embed=embed, delete_after=INVALID_INPUT_DELETE_DELAY)
-            await ctx.message.delete(delay=INVALID_INPUT_DELETE_DELAY)
+            error_message = await ctx.send(embed=embed)
+            await wait_for_deletion(error_message, (ctx.author.id,), timeout=INVALID_INPUT_DELETE_DELAY)
+
+            # Make sure that we won't cause a ghost-ping by deleting the message
+            if not (ctx.message.mentions or ctx.message.role_mentions):
+                with suppress(NotFound):
+                    await ctx.message.delete()
+                    await error_message.delete()
+
         else:
             await ctx.send(embed=embed)
 
diff --git a/bot/utils/messages.py b/bot/utils/messages.py
index d4a921161..90672fba2 100644
--- a/bot/utils/messages.py
+++ b/bot/utils/messages.py
@@ -1,5 +1,4 @@
 import asyncio
-import contextlib
 import logging
 import random
 import re
@@ -69,7 +68,9 @@ async def wait_for_deletion(
     allow_mods: bool = True
 ) -> None:
     """
-    Wait for up to `timeout` seconds for a reaction by any of the specified `user_ids` to delete the message.
+    Wait for any of `user_ids` to react with one of the `deletion_emojis` within `timeout` seconds to delete `message`.
+
+    If `timeout` expires then reactions are cleared to indicate the option to delete has expired.
 
     An `attach_emojis` bool may be specified to determine whether to attach the given
     `deletion_emojis` to the message in the given `context`.
@@ -95,8 +96,11 @@ async def wait_for_deletion(
         allow_mods=allow_mods,
     )
 
-    with contextlib.suppress(asyncio.TimeoutError):
+    try:
         await bot.instance.wait_for('reaction_add', check=check, timeout=timeout)
+    except asyncio.TimeoutError:
+        await message.clear_reactions()
+    else:
         await message.delete()