fix: support yearly recurrence in calendar

backend/mvp.py

@@ -64,8 +64,8 @@ def parse_rrule(value: str) -> dict[str, str]:
             raise HTTPException(422, "无效的 RRULE")
         key, val = part.split("=", 1)
         parts[key] = val
-    if parts.get("FREQ") not in {"DAILY", "WEEKLY", "MONTHLY"}:
-        raise HTTPException(422, "仅支持 DAILY、WEEKLY、MONTHLY")
+    if parts.get("FREQ") not in {"DAILY", "WEEKLY", "MONTHLY", "YEARLY"}:
+        raise HTTPException(422, "仅支持 DAILY、WEEKLY、MONTHLY、YEARLY")
     try:
         if "INTERVAL" in parts and int(parts["INTERVAL"]) < 1:
             raise ValueError
@@ -103,10 +103,15 @@ def occurrences(rule: str, starts: datetime, start: datetime, end: datetime, cut
         elif parts["FREQ"] == "WEEKLY":
             days = {_WEEKDAYS[x] for x in parts.get("BYDAY", list(_WEEKDAYS)[starts.weekday()]).split(",")}
             include = cursor.weekday() in days and ((cursor.date() - starts.date()).days // 7) % interval == 0
-        else:
+        elif parts["FREQ"] == "MONTHLY":
             month_delta = (cursor.year - starts.year) * 12 + cursor.month - starts.month
             month_days = {int(x) for x in parts.get("BYMONTHDAY", str(starts.day)).split(",")}
             include = month_delta % interval == 0 and cursor.day in month_days
+        else:
+            years = cursor.year - starts.year
+            months = {int(x) for x in parts.get("BYMONTH", str(starts.month)).split(",")}
+            month_days = {int(x) for x in parts.get("BYMONTHDAY", str(starts.day)).split(",")}
+            include = years % interval == 0 and cursor.month in months and cursor.day in month_days
         if include and cursor >= starts:
             emitted += 1
             if start <= cursor <= end: