From 6ee4ef26e1558287924e163e1c0fddaa59ad5c43 Mon Sep 17 00:00:00 2001
From: Mattia Basaglia <glax@dragon.best>
Date: Tue, 31 Oct 2023 20:27:24 +0100
Subject: [PATCH] Syntax highlighting support for markdown parse_mode

---
 telethon/extensions/markdown.py | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/telethon/extensions/markdown.py b/telethon/extensions/markdown.py
index 78f28385..dc8b2f80 100644
--- a/telethon/extensions/markdown.py
+++ b/telethon/extensions/markdown.py
@@ -99,7 +99,17 @@ def parse(message, delimiters=None, url_re=None):
                 # Append the found entity
                 ent = delimiters[delim]
                 if ent == MessageEntityPre:
-                    result.append(ent(i, end - i - len(delim), ''))  # has 'lang'
+                    # Parse ```language
+                    lang = ''
+                    try:
+                        newline = message.index('\n', i, end)
+                        if newline > i:
+                            lang = message[i:newline]
+                            message = message[:i] + message[newline+1:]
+                            end -= len(lang) + 1
+                    except ValueError:
+                        pass
+                    result.append(ent(i, end - i - len(delim), lang))
                 else:
                     result.append(ent(i, end - i - len(delim)))