added sorting and artist dates

api/datasource.py

@@ -109,3 +109,38 @@ def iter_artist_names(event: Event):
         for artist in group:
             if artist.artist_name:
                 yield artist.artist_name
+
+
+def sort_events(events: List[Event], sort: Optional[str]) -> List[Event]:
+    """Sort events per the ``?sort=`` query param.
+
+    "asc"/"desc" order chronologically by ``event_date``; events with an
+    unparseable date always sort last, regardless of direction. "az"/"za"
+    order alphabetically (case-insensitive) by ``event_name``. Any other
+    value (including None) leaves the events in their existing order.
+    """
+    if sort in ("asc", "desc"):
+        with_parsed = [(e, parse_event_date(e.event_date)) for e in events]
+        dated = sorted(
+            (item for item in with_parsed if item[1] is not None),
+            key=lambda item: item[1],
+            reverse=(sort == "desc"),
+        )
+        undated = [e for e, parsed in with_parsed if parsed is None]
+        return [e for e, _ in dated] + undated
+    if sort in ("az", "za"):
+        return sorted(events, key=lambda e: e.event_name.lower(), reverse=(sort == "za"))
+    return events
+
+
+def sort_date_strings(dates) -> List[str]:
+    """Sort raw ``dd.mm.yy`` date strings chronologically, de-duplicated.
+
+    Unparseable strings sort last (alphabetically among themselves).
+    """
+    unique = set(dates)
+    dated = sorted(
+        (d for d in unique if parse_event_date(d) is not None), key=parse_event_date
+    )
+    undated = sorted(d for d in unique if parse_event_date(d) is None)
+    return dated + undated