feat: markdown about renderHEADmain

1 files changed, 72 insertions, 0 deletions

diff --git a/about-filter.py b/about-filter.py
new file mode 100644
index 0000000..5e97bbe
--- /dev/null
+++ b/about-filter.py
@@ -0,0 +1,72 @@
+#!/usr/bin/env python3
+
+"""Render cgit repository READMEs as safe HTML."""
+
+import html
+import os
+import subprocess
+import sys
+
+
+MARKDOWN_EXTENSIONS = (".md", ".markdown")
+CMARK_COMMAND = (
+    "/usr/bin/cmark-gfm",
+    "--validate-utf8",
+    "--extension",
+    "table",
+    "--extension",
+    "autolink",
+    "--extension",
+    "strikethrough",
+    "--extension",
+    "tasklist",
+)
+
+STYLE = """<style>
+.markdown-body { line-height: 1.6; overflow-wrap: anywhere; }
+.markdown-body img { max-width: 100%; }
+.markdown-body pre { overflow-x: auto; padding: 1em; background: rgb(255 255 255 / 6%); }
+.markdown-body code { padding: .15em .3em; background: rgb(255 255 255 / 8%); }
+.markdown-body pre code { padding: 0; background: none; }
+.markdown-body blockquote { margin-left: 0; padding-left: 1em; color: #aaa; border-left: .25em solid #555; }
+.markdown-body table { display: block; max-width: 100%; overflow-x: auto; border-collapse: collapse; }
+.markdown-body th, .markdown-body td { padding: .4em .8em; border: 1px solid #555; }
+.markdown-body input[type="checkbox"] { margin-right: .4em; }
+</style>
+"""
+
+
+def render_markdown(source: bytes) -> bytes:
+    """Render Markdown with cmark-gfm's safe defaults."""
+    result = subprocess.run(
+        CMARK_COMMAND,
+        input=source,
+        stdout=subprocess.PIPE,
+        check=True,
+    )
+    return result.stdout
+
+
+def render_plain_text(source: bytes) -> bytes:
+    """Return arbitrary input as escaped, readable text."""
+    text = source.decode("utf-8", errors="replace")
+    return f"<pre>{html.escape(text)}</pre>\n".encode()
+
+
+def main() -> None:
+    filename = sys.argv[1] if len(sys.argv) > 1 else ""
+    source = sys.stdin.buffer.read()
+
+    if os.path.splitext(filename)[1].lower() in MARKDOWN_EXTENSIONS:
+        rendered = render_markdown(source)
+    else:
+        rendered = render_plain_text(source)
+
+    sys.stdout.buffer.write(STYLE.encode())
+    sys.stdout.buffer.write(b'<div class="markdown-body">\n')
+    sys.stdout.buffer.write(rendered)
+    sys.stdout.buffer.write(b"</div>\n")
+
+
+if __name__ == "__main__":
+    main()