Unify pygments stylesheet

It's less generic and less cool, but this bakes the styles for dark and
light into a single stylesheet, and deals with switching without any JS.

static/src/js/dark-mode.js

@@ -6,9 +6,6 @@ const darkModeToggle = document.getElementById("dark-mode-toggle");
 
 const matchesDarkMode = window.matchMedia("(prefers-color-scheme: dark)");
 
-const darkModeCodeStyles = document.getElementById("pygments-dark");
-const lightModeCodeStyles = document.getElementById("pygments-light");
-
 function handleDarkMode(darkMode) {
   window.localStorage.setItem(STORAGE_KEY, darkMode.toString());
 
@@ -17,11 +14,6 @@ function handleDarkMode(darkMode) {
   } else {
     htmlTag.classList.remove(DARK_MODE_CLASS);
   }
-
-  if (darkModeCodeStyles) {
-    darkModeCodeStyles.sheet.disabled = !darkMode;
-    lightModeCodeStyles.sheet.disabled = darkMode;
-  }
 }
 
 if (window.localStorage.getItem(STORAGE_KEY) === null) {

website/common/templates/common/content_page.html

@@ -13,8 +13,7 @@
 {% block extra_css %}
   <link rel="stylesheet" type="text/css" href="{% static 'css/lite-youtube-embed.css' %}">
   <link rel="stylesheet" type="text/css" href="{% static 'contrib/shareon/shareon.min.css' %}">
-  <link rel="stylesheet" type="text/css" href="{% url 'code-block:styles' 'default' %}" id="pygments-light">
-  <link rel="stylesheet" type="text/css" href="{% url 'code-block:styles' 'monokai' %}" id="pygments-dark">
+  <link rel="stylesheet" type="text/css" href="{% url 'code-block:styles' %}">
 {% endblock %}
 
 {% block extra_js %}

website/contrib/code_block/tests.py

@@ -1,24 +1,17 @@
 from django.test import TestCase
 from django.urls import reverse
-from pygments.styles import get_all_styles
 
 from .utils import PYGMENTS_VERSION_SLUG
 
 
 class PygmentsStylesTestCase(TestCase):
-    def test_accessible(self) -> None:
-        for style in get_all_styles():
-            with self.subTest(style=style):
-                response = self.client.get(reverse("code-block:styles", args=[style]))
-                self.assertEqual(response.status_code, 200)
-                self.assertEqual(response["Cache-Control"], "max-age=3600")
+    url = reverse("code-block:styles")
 
-    def test_unknown_style(self) -> None:
-        response = self.client.get(reverse("code-block:styles", args=["not-a-style"]))
-        self.assertEqual(response.status_code, 404)
+    def test_accessible(self) -> None:
+        response = self.client.get(self.url)
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response["Cache-Control"], "max-age=3600")
+        self.assertEqual(response["Content-Type"], "text/css")
 
     def test_url_contains_version(self) -> None:
-        for style in get_all_styles():
-            with self.subTest(style=style):
-                url = reverse("code-block:styles", args=[style])
-                self.assertIn(PYGMENTS_VERSION_SLUG, url)
+        self.assertIn(PYGMENTS_VERSION_SLUG, self.url)

website/contrib/code_block/urls.py

@@ -8,7 +8,7 @@ app_name = "code-block"
 urlpatterns = [
     # HACK: Bake the pygments version into the URL, without needing a custom method
     path(
-        f"pygments-<slug:name>.{PYGMENTS_VERSION_SLUG}.css",
+        f"pygments.{PYGMENTS_VERSION_SLUG}.css",
         pygments_styles,
         name="styles",
     )

website/contrib/code_block/views.py

@@ -1,16 +1,21 @@
-from django.http import Http404, HttpRequest, HttpResponse
+from django.http import HttpRequest, HttpResponse
+from django.utils.datastructures import OrderedSet
 from django.views.decorators.cache import cache_page
 from pygments.formatters.html import HtmlFormatter
-from pygments.util import ClassNotFound
 
 
 @cache_page(3600)
-def pygments_styles(request: HttpRequest, name: str) -> HttpResponse:
-    try:
-        formatter = HtmlFormatter(style=name)
-    except ClassNotFound:
-        # Raising an exception here bypasses the cache header
-        raise Http404
-    return HttpResponse(
-        formatter.get_style_defs("." + formatter.cssclass), content_type="text/css"
+def pygments_styles(request: HttpRequest) -> HttpResponse:
+    default_styles = (
+        HtmlFormatter(style="default")
+        .get_style_defs("html:not(.dark-mode) .highlight")
+        .split("\n")
+    )
+    dark_styles = (
+        HtmlFormatter(style="monokai")
+        .get_style_defs("html.dark-mode .highlight")
+        .split("\n")
+    )
+    return HttpResponse(
+        "".join(OrderedSet(default_styles + dark_styles)), content_type="text/css"
     )