Add code block

requirements.txt

@@ -2,3 +2,4 @@ Django==4.0.5
 wagtail==3.0
 django-environ==0.8.1
 whitenoise[brotli]==6.2.0
+pygments==2.12.0

static/src/scss/_bulma_overrides.scss

@@ -1,3 +1,4 @@
 @use "bulma/sass/utilities/initial-variables" as *;
 
 $container-max-width: $widescreen;
+$pre-background: unset;

templates/base.html

@@ -16,6 +16,7 @@
 
     <link rel="stylesheet" type="text/css" href="{% static 'css/base.css' %}">
     <link rel="stylesheet" type="text/css" href="{% static 'contrib/fontawesome/css/all.min.css' %}">
+    <link rel="stylesheet" type="text/css" href="{% url 'static-pygments:styles' 'default' %}">
 
     {% block extra_css %}{% endblock %}
   </head>

website/common/streamfield.py

@@ -7,6 +7,8 @@ from wagtail import blocks
 from wagtail.embeds.blocks import EmbedBlock
 from wagtail.images.blocks import ImageChooserBlock
 
+from website.contrib.code_block.blocks import CodeBlock
+
 IGNORE_PLAINTEXT_BLOCKS = (blocks.RawHTMLBlock, EmbedBlock)
 
 RICH_TEXT_FEATURES = [
@@ -68,6 +70,7 @@ def get_blocks() -> list[tuple[str, blocks.BaseBlock]]:
         ("lorem", LoremBlock()),
         ("html", blocks.RawHTMLBlock()),
         ("image", ImageCaptionBlock()),
+        ("code", CodeBlock()),
     ]
 
 

website/contrib/code_block/README.md

@@ -0,0 +1,3 @@
+# `code_block`
+
+Heavily based on [`wagtail-pygments`](https://github.com/truongvan/wagtail-pygments), with several changes to the block, as well as a view for exposing the CSS styles.

website/contrib/code_block/blocks.py

@@ -0,0 +1,33 @@
+from typing import Iterator
+
+from django.utils.safestring import mark_safe
+from pygments import highlight
+from pygments.formatters.html import HtmlFormatter
+from pygments.lexers import get_all_lexers, get_lexer_by_name
+from wagtail.blocks import ChoiceBlock, StructBlock, StructValue, TextBlock
+
+
+def get_language_choices() -> Iterator[tuple[str, str]]:
+    for name, _, _, _ in sorted(get_all_lexers()):
+        yield (name, name)
+
+
+class CodeStructValue(StructValue):
+    def code(self) -> str:
+        lexer = get_lexer_by_name(self.get("language"))
+        formatter = HtmlFormatter(
+            linenos=None,
+        )
+        return mark_safe(highlight(self.get("source"), lexer, formatter))
+
+
+class CodeBlock(StructBlock):
+    language = ChoiceBlock(
+        choices=get_language_choices(),
+    )
+    source = TextBlock()
+
+    class Meta:
+        icon = "code"
+        value_class = CodeStructValue
+        template = "contrib/blocks/code.html"

website/contrib/code_block/templates/contrib/blocks/code.html

@@ -0,0 +1 @@
+{{ value.code }}

website/contrib/code_block/tests.py

@@ -0,0 +1,20 @@
+from django.test import TestCase
+from django.urls import reverse
+from pygments.styles import get_all_styles
+
+
+class PygmentsStylesTestCase(TestCase):
+    def test_accessible(self) -> None:
+        for style in get_all_styles():
+            with self.subTest(style=style):
+                response = self.client.get(
+                    reverse("static-pygments:styles", args=[style])
+                )
+                self.assertEqual(response.status_code, 200)
+                self.assertEqual(response["Cache-Control"], "max-age=3600, public")
+
+    def test_unknown_style(self) -> None:
+        response = self.client.get(
+            reverse("static-pygments:styles", args=["not-a-style"])
+        )
+        self.assertEqual(response.status_code, 404)

website/contrib/code_block/urls.py

@@ -0,0 +1,7 @@
+from django.urls import path
+
+from .views import pygments_styles
+
+app_name = "code_block"
+
+urlpatterns = [path("<slug:name>.css", pygments_styles, name="styles")]

website/contrib/code_block/views.py

@@ -0,0 +1,16 @@
+from django.http import Http404, HttpRequest, HttpResponse
+from django.views.decorators.cache import cache_control
+from pygments.formatters.html import HtmlFormatter
+from pygments.util import ClassNotFound
+
+
+@cache_control(max_age=3600, public=True)
+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"
+    )

website/settings.py

@@ -23,6 +23,7 @@ INSTALLED_APPS = [
     "website.home",
     "website.search",
     "website.blog",
+    "website.contrib.code_block",
     "wagtail.contrib.forms",
     "wagtail.contrib.redirects",
     "wagtail.contrib.modeladmin",

website/urls.py

@@ -13,6 +13,10 @@ urlpatterns = [
     path("admin/", include(wagtailadmin_urls)),
     path("documents/", include(wagtaildocs_urls)),
     path("search/", search_views.search, name="search"),
+    path(
+        "static-pygments/",
+        include("website.contrib.code_block.urls", namespace="static-pygments"),
+    ),
     re_path(
         r"^images/([^/]*)/(\d*)/([^/]*)/[^/]*$",
         ServeView.as_view(action="redirect"),