Fix accept header parsing

app/main.py

@@ -1,3 +1,4 @@
+import logging
 from contextlib import asynccontextmanager
 from typing import Annotated, Union
 
@@ -40,10 +41,16 @@ async def lifespan(app: FastAPI):
 
 app.profile_loader = None
 
+logger = logging.getLogger('uvicorn.error')
+
 
 @app.get('/', response_model=model.LandingPage)
 def capabilities(req: Request, accept: Annotated[str | None, Header()] = None) -> model.LandingPage | HTMLResponse:
-    req_media_type = util.match_accept_header(accept, [MEDIA_TEXT_HTML, MEDIA_APPLICATION_JSON])
+    try:
+        req_media_type = util.match_accept_header(accept, [MEDIA_TEXT_HTML, MEDIA_APPLICATION_JSON])
+    except Exception as e:
+        req_media_type = MEDIA_TEXT_HTML
+        logger.error(f'Error parsing Accept header "{accept}"', e)
 
     if req_media_type is None:
         raise HTTPException(

app/util.py

@@ -1,5 +1,6 @@
 import re
 from pathlib import Path
+from typing import Any
 
 
 def is_xml(s: str) -> bool:
@@ -18,13 +19,32 @@ def match_media_type(a: list[str], b: list[str]):
     return (a[0] == '*' or b[0] == '*' or a[0] == b[0]) and (a[1] == '*' or b[1] == '*' or a[1] == b[1])
 
 
+def parse_accept_entries(header: str) -> dict[str, Any]:
+    entries = {}
+    for e in header.split(','):
+        parts = e.strip().split(';')
+        if not parts:
+            continue
+        entry = {
+            'q': 1.0
+        }
+        for part in parts[1:]:
+            kv = part.split('=', 1)
+            if kv[0] == 'q':
+                kv[1] = float(kv[1])
+            entry[kv[0]] = kv[1]
+        entries[parts[0]] = entry
+    return entries
+
+
 def match_accept_header(header: str, options: list[str], def_value=None) -> str:
     if not header:
         return def_value
 
     options = [o.strip().lower().split('/') for o in options]
-    for entry in sorted((e.strip().lower().split(';') for e in header.split(',')
-                         if e.strip()), key=lambda e: float(e[1][2:]) if len(e) > 1 else 1.0):
+    entries = parse_accept_entries(header)
+    for entry in sorted(entries.items(), key=lambda e: -e[1]['q']):
+        print(entry)
         parts = entry[0].split('/')
         for option in options:
             if match_media_type(option, parts):