Tweak code highlight

app/source.py

@@ -3,12 +3,12 @@ import typing
 
 from loguru import logger
 from mistletoe import Document  # type: ignore
+from mistletoe.block_token import CodeFence  # type: ignore
 from mistletoe.html_renderer import HTMLRenderer  # type: ignore
 from mistletoe.span_token import SpanToken  # type: ignore
-from pygments import highlight  # type: ignore
 from pygments.formatters import HtmlFormatter  # type: ignore
 from pygments.lexers import get_lexer_by_name as get_lexer  # type: ignore
-from pygments.lexers import guess_lexer  # type: ignore
+from pygments.util import ClassNotFound  # type: ignore
 from sqlalchemy import select
 
 from app import webfinger
@@ -104,10 +104,16 @@ class CustomRenderer(HTMLRenderer):
         )
         return link
 
-    def render_block_code(self, token: typing.Any) -> str:
+    def render_block_code(self, token: CodeFence) -> str:
+        lexer_attr = ""
+        try:
+            lexer = get_lexer(token.language)
+            lexer_attr = f' data-microblogpub-lexer="{lexer.aliases[0]}"'
+        except ClassNotFound:
+            pass
+
         code = token.children[0].content
-        lexer = get_lexer(token.language) if token.language else guess_lexer(code)
-        return highlight(code, lexer, _FORMATTER)
+        return f"<pre><code{lexer_attr}>\n{code}\n</code></pre>"
 
 
 async def _prefetch_mentioned_actors(

app/utils/highlight.py

@@ -32,15 +32,11 @@ def highlight(html: str) -> str:
 
         # If this comes from a microblog.pub instance we may have the language
         # in the class name
-        if "class" in code.attrs and code.attrs["class"][0].startswith("language-"):
+        if "data-microblogpub-lexer" in code.attrs:
             try:
-                lexer = get_lexer_by_name(
-                    code.attrs["class"][0].removeprefix("language-")
-                )
+                lexer = get_lexer_by_name(code.attrs["data-microblogpub-lexer"])
             except Exception:
                 lexer = guess_lexer(code_content)
-        else:
-            lexer = guess_lexer(code_content)
 
             # Replace the code with Pygment output
             # XXX: the HTML escaping causes issue with Python type annotations
@@ -50,5 +46,8 @@ def highlight(html: str) -> str:
                     phighlight(code_content, lexer, _FORMATTER), "html5lib"
                 ).body.next
             )
+        else:
+            code.name = "div"
+            code["class"] = code.get("class", []) + ["highlight"]
 
     return soup.body.encode_contents().decode()