From 2b39fb1b9a361150c79ba12bcd01eba7d62bb8e0 Mon Sep 17 00:00:00 2001
From: Jake Howard <git@theorangeone.net>
Date: Tue, 28 Jun 2022 22:59:17 +0100
Subject: [PATCH] Bake pygments version into style URL

It's a hack, but it does work
---
 website/contrib/code_block/tests.py | 9 +++++++++
 website/contrib/code_block/urls.py  | 6 +++++-
 website/contrib/code_block/utils.py | 4 ++++
 website/contrib/code_block/views.py | 8 ++++++++
 4 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 website/contrib/code_block/utils.py

diff --git a/website/contrib/code_block/tests.py b/website/contrib/code_block/tests.py
index 2c5edd8..d398fcd 100644
--- a/website/contrib/code_block/tests.py
+++ b/website/contrib/code_block/tests.py
@@ -2,6 +2,8 @@ from django.test import TestCase
 from django.urls import reverse
 from pygments.styles import get_all_styles
 
+from .utils import PYGMENTS_VERSION, PYGMENTS_VERSION_SLUG
+
 
 class PygmentsStylesTestCase(TestCase):
     def test_accessible(self) -> None:
@@ -12,9 +14,16 @@ class PygmentsStylesTestCase(TestCase):
                 )
                 self.assertEqual(response.status_code, 200)
                 self.assertEqual(response["Cache-Control"], "max-age=3600, public")
+                self.assertEqual(response["ETag"], f'"{PYGMENTS_VERSION}"')
 
     def test_unknown_style(self) -> None:
         response = self.client.get(
             reverse("static-pygments:styles", args=["not-a-style"])
         )
         self.assertEqual(response.status_code, 404)
+
+    def test_url_contains_version(self) -> None:
+        for style in get_all_styles():
+            with self.subTest(style=style):
+                url = reverse("static-pygments:styles", args=[style])
+                self.assertIn(PYGMENTS_VERSION_SLUG, url)
diff --git a/website/contrib/code_block/urls.py b/website/contrib/code_block/urls.py
index 8e61e93..1b9b84a 100644
--- a/website/contrib/code_block/urls.py
+++ b/website/contrib/code_block/urls.py
@@ -1,7 +1,11 @@
 from django.urls import path
 
+from .utils import PYGMENTS_VERSION_SLUG
 from .views import pygments_styles
 
 app_name = "code_block"
 
-urlpatterns = [path("<slug:name>.css", pygments_styles, name="styles")]
+urlpatterns = [
+    # HACK: Bake the pygments version into the URL, without needing a custom method
+    path(f"<slug:name>.{PYGMENTS_VERSION_SLUG}.css", pygments_styles, name="styles")
+]
diff --git a/website/contrib/code_block/utils.py b/website/contrib/code_block/utils.py
new file mode 100644
index 0000000..acfcabd
--- /dev/null
+++ b/website/contrib/code_block/utils.py
@@ -0,0 +1,4 @@
+from importlib.metadata import version
+
+PYGMENTS_VERSION = version("pygments")
+PYGMENTS_VERSION_SLUG = PYGMENTS_VERSION.replace(".", "-")
diff --git a/website/contrib/code_block/views.py b/website/contrib/code_block/views.py
index cd79ff5..03ddf4a 100644
--- a/website/contrib/code_block/views.py
+++ b/website/contrib/code_block/views.py
@@ -1,9 +1,17 @@
 from django.http import Http404, HttpRequest, HttpResponse
 from django.views.decorators.cache import cache_control
+from django.views.decorators.http import etag
 from pygments.formatters.html import HtmlFormatter
 from pygments.util import ClassNotFound
 
+from .utils import PYGMENTS_VERSION
 
+
+def pygments_etag(request: HttpRequest, name: str) -> str:
+    return PYGMENTS_VERSION
+
+
+@etag(pygments_etag)
 @cache_control(max_age=3600, public=True)
 def pygments_styles(request: HttpRequest, name: str) -> HttpResponse:
     try: