Update antimalware.py to be more consistent with other information messages & improve code a slight bit

bot/cogs/antimalware.py

@@ -1,9 +1,9 @@
 import logging
 
-from discord import Message, NotFound
+from discord import Embed, Message, NotFound
 from discord.ext.commands import Bot, Cog
 
-from bot.constants import AntiMalware as AntiMalwareConfig, Channels
+from bot.constants import AntiMalware as AntiMalwareConfig, Channels, URLs
 
 log = logging.getLogger(__name__)
 
@@ -17,31 +17,29 @@ def __init__(self, bot: Bot):
     @Cog.listener()
     async def on_message(self, message: Message) -> None:
         """Identify messages with prohibited attachments."""
-        rejected_attachments = False
-        detected_pyfile = False
+        if not message.attachments:
+            return
+
+        embed = Embed()
         for attachment in message.attachments:
-            if attachment.filename.lower().endswith('.py'):
-                detected_pyfile = True
-                break  # Other detections irrelevant because we prioritize the .py message.
-            if not attachment.filename.lower().endswith(tuple(AntiMalwareConfig.whitelist)):
-                rejected_attachments = True
-
-        if detected_pyfile or rejected_attachments:
-            # Send a message to the user indicating the problem (with special treatment for .py)
-            author = message.author
-            if detected_pyfile:
-                msg = (
-                    f"{author.mention}, it looks like you tried to attach a Python file - please "
-                    f"use a code-pasting service such as https://paste.pythondiscord.com/ instead."
+            filename = attachment.filename.lower()
+            if filename.endswith('.py'):
+                embed.description = (
+                    f"It looks like you tried to attach a Python file - please "
+                    f"use a code-pasting service such as {URLs.paste_service}"
                 )
-            else:
+                break  # Other detections irrelevant because we prioritize the .py message.
+            if not filename.endswith(tuple(AntiMalwareConfig.whitelist)):
+                whitelisted_types = ', '.join(AntiMalwareConfig.whitelist)
                 meta_channel = self.bot.get_channel(Channels.meta)
-                msg = (
-                    f"{author.mention}, it looks like you tried to attach a file type we don't "
-                    f"allow. Feel free to ask in {meta_channel.mention} if you think this is a mistake."
+                embed.description = (
+                    f"It looks like you tried to attach a file type that we "
+                    f"do not allow. We currently allow the following file "
+                    f"types: **{whitelisted_types}**. \n\n Feel free to ask "
+                    f"in {meta_channel.mention} if you think this is a mistake."
                 )
-
-            await message.channel.send(msg)
+        if embed.description:
+            await message.channel.send(f"Hey {message.author.mention}!", embed=embed)
 
             # Delete the offending message:
             try: