From a1967a7f2d8a77a3ca1e242b855254b943b7d86b Mon Sep 17 00:00:00 2001
From: Alex Vandiver <alexmv@zulip.com>
Date: Fri, 3 Feb 2023 19:53:58 +0000
Subject: [PATCH] markdown: Rewrite /static/ images to use
 staticfiles_storage.url.

---
 zerver/lib/markdown/priorities.py |  1 +
 zerver/lib/markdown/static.py     | 33 +++++++++++++++++++++++++++++++
 zerver/lib/templates.py           |  2 ++
 3 files changed, 36 insertions(+)
 create mode 100644 zerver/lib/markdown/static.py

diff --git a/zerver/lib/markdown/priorities.py b/zerver/lib/markdown/priorities.py
index 6ac58ea158..f761f09601 100644
--- a/zerver/lib/markdown/priorities.py
+++ b/zerver/lib/markdown/priorities.py
@@ -17,6 +17,7 @@ PREPROCESSOR_PRIORITES = {
     "tabbed_sections": -500,
     "nested_code_blocks": -500,
     "emoticon_translations": -505,
+    "static_images": -510,
 }
 
 BLOCK_PROCESSOR_PRIORITIES = {
diff --git a/zerver/lib/markdown/static.py b/zerver/lib/markdown/static.py
new file mode 100644
index 0000000000..f2d2a98eb2
--- /dev/null
+++ b/zerver/lib/markdown/static.py
@@ -0,0 +1,33 @@
+from typing import Any
+from xml.etree.ElementTree import Element
+
+import markdown
+from django.contrib.staticfiles.storage import staticfiles_storage
+from markdown.extensions import Extension
+
+from zerver.lib.markdown.priorities import PREPROCESSOR_PRIORITES
+
+
+class MarkdownStaticImagesGenerator(Extension):
+    def extendMarkdown(self, md: markdown.Markdown) -> None:
+        md.treeprocessors.register(
+            StaticImageProcessor(md),
+            "static_images",
+            PREPROCESSOR_PRIORITES["static_images"],
+        )
+
+
+class StaticImageProcessor(markdown.treeprocessors.Treeprocessor):
+    """
+    Rewrite img tags which refer to /static/ to use staticfiles
+    """
+
+    def run(self, root: Element) -> None:
+        for img in root.iter("img"):
+            url = img.get("src")
+            if url is not None and url.startswith("/static/"):
+                img.set("src", staticfiles_storage.url(url[len("/static/") :]))
+
+
+def makeExtension(*args: Any, **kwargs: str) -> MarkdownStaticImagesGenerator:
+    return MarkdownStaticImagesGenerator(*args, **kwargs)
diff --git a/zerver/lib/templates.py b/zerver/lib/templates.py
index 5a3e9f45de..5028770b3b 100644
--- a/zerver/lib/templates.py
+++ b/zerver/lib/templates.py
@@ -22,6 +22,7 @@ import zerver.lib.markdown.help_relative_links
 import zerver.lib.markdown.help_settings_links
 import zerver.lib.markdown.include
 import zerver.lib.markdown.nested_code_blocks
+import zerver.lib.markdown.static
 import zerver.lib.markdown.tabbed_sections
 import zerver.openapi.markdown_extension
 from zerver.lib.cache import dict_to_items_tuple, ignore_unhashable_lru_cache, items_tuple_to_dict
@@ -127,6 +128,7 @@ def render_markdown_path(
             zerver.lib.markdown.help_settings_links.makeExtension(),
             zerver.lib.markdown.help_relative_links.makeExtension(),
             zerver.lib.markdown.help_emoticon_translations_table.makeExtension(),
+            zerver.lib.markdown.static.makeExtension(),
         ]
     if "api_url" in context:
         # We need to generate the API code examples extension each