From 6815bca50816678f6069516ef564ecb4a4d01d83 Mon Sep 17 00:00:00 2001
From: Sebastiaan Zeeff <33516116+SebastiaanZ@users.noreply.github.com>
Date: Wed, 18 Sep 2019 08:55:56 +0200
Subject: Escape markdown in codeblock suggestion embed

https://github.com/python-discord/bot/issues/434

If the content we prepare for the codeblock suggestion embed defined
in the `bot` cog contains markdown characters (e.g., `__`, `**`), this
will cause Discord to apply markdown, since both the codeblock syntax
example as well as the codeblock result example will contain the
characters, making it a matched formatting pair.

This will hide those characters, which often have a function in the
code, and break the example of a formatted codeblock.

To deal with that, I've added a regex substitution that substitutes
markdown characters by an escaped version of that markdown character.

Example:
`'__hello__'` will become `'\_\_hello\_\_'`

I've added this substitution to both paths in the `on_message` event
listener, since we can't substitute at an earlier place due to it
generating `SyntaxErrors` with the `ast.parse` check.

This closes #434
---
 bot/cogs/bot.py | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/bot/cogs/bot.py b/bot/cogs/bot.py
index e88b1d9b5..577865a65 100644
--- a/bot/cogs/bot.py
+++ b/bot/cogs/bot.py
@@ -6,15 +6,14 @@ import time
 from discord import Embed, Message, RawMessageUpdateEvent
 from discord.ext.commands import Bot, Cog, Context, command, group
 
-from bot.constants import (
-    Channels, Guild, MODERATION_ROLES,
-    Roles, URLs,
-)
+from bot.constants import Channels, DEBUG_MODE, Guild, MODERATION_ROLES, Roles, URLs
 from bot.decorators import with_role
 from bot.utils.messages import wait_for_deletion
 
 log = logging.getLogger(__name__)
 
+RE_MARKDOWN = re.compile(r'([*_~`|>])')
+
 
 class Bot(Cog):
     """
@@ -255,7 +254,7 @@ class Bot(Cog):
 
         if parse_codeblock:
             on_cooldown = (time.time() - self.channel_cooldowns.get(msg.channel.id, 0)) < 300
-            if not on_cooldown:
+            if not on_cooldown or DEBUG_MODE:
                 try:
                     if self.has_bad_ticks(msg):
                         ticks = msg.content[:3]
@@ -280,13 +279,14 @@ class Bot(Cog):
                                 current_length += len(line)
                                 lines_walked += 1
                             content = content[:current_length] + "#..."
-
+                        content_escaped_markdown = RE_MARKDOWN.sub(r'\\\1', content)
                         howto = (
                             "It looks like you are trying to paste code into this channel.\n\n"
                             "You seem to be using the wrong symbols to indicate where the codeblock should start. "
                             f"The correct symbols would be \\`\\`\\`, not `{ticks}`.\n\n"
                             "**Here is an example of how it should look:**\n"
-                            f"\\`\\`\\`python\n{content}\n\\`\\`\\`\n\n**This will result in the following:**\n"
+                            f"\\`\\`\\`python\n{content_escaped_markdown}\n\\`\\`\\`\n\n"
+                            "**This will result in the following:**\n"
                             f"```python\n{content}\n```"
                         )
 
@@ -322,13 +322,15 @@ class Bot(Cog):
                                     lines_walked += 1
                                 content = content[:current_length] + "#..."
 
+                            content_escaped_markdown = RE_MARKDOWN.sub(r'\\\1', content)
                             howto += (
                                 "It looks like you're trying to paste code into this channel.\n\n"
                                 "Discord has support for Markdown, which allows you to post code with full "
                                 "syntax highlighting. Please use these whenever you paste code, as this "
                                 "helps improve the legibility and makes it easier for us to help you.\n\n"
                                 f"**To do this, use the following method:**\n"
-                                f"\\`\\`\\`python\n{content}\n\\`\\`\\`\n\n**This will result in the following:**\n"
+                                f"\\`\\`\\`python\n{content_escaped_markdown}\n\\`\\`\\`\n\n"
+                                "**This will result in the following:**\n"
                                 f"```python\n{content}\n```"
                             )
 
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