feat: support custom task recurrence

backend/mvp.py

@@ -73,9 +73,22 @@ def parse_rrule(value: str) -> dict[str, str]:
             raise HTTPException(422, "无效的 RRULE")
         key, val = part.split("=", 1)
         parts[key] = val
+    allowed = {"FREQ", "INTERVAL", "BYDAY", "BYMONTHDAY", "BYMONTH", "COUNT", "UNTIL"}
+    if set(parts) - allowed:
+        raise HTTPException(422, "重复规则包含不支持的字段")
     if parts.get("FREQ") not in {"DAILY", "WEEKLY", "MONTHLY", "YEARLY"}:
         raise HTTPException(422, "仅支持 DAILY、WEEKLY、MONTHLY、YEARLY")
+    if "BYDAY" in parts:
+        weekdays = parts["BYDAY"].split(",")
+        if not weekdays or any(day not in _WEEKDAYS for day in weekdays):
+            raise HTTPException(422, "无效的重复星期")
     try:
+        month_days = [int(day) for day in parts.get("BYMONTHDAY", "").split(",") if day]
+        months = [int(month) for month in parts.get("BYMONTH", "").split(",") if month]
+        if any(day < 1 or day > 31 for day in month_days) or any(month < 1 or month > 12 for month in months):
+            raise ValueError
+        if "UNTIL" in parts:
+            datetime.fromisoformat(parts["UNTIL"])
         if "INTERVAL" in parts and int(parts["INTERVAL"]) < 1:
             raise ValueError
         if "COUNT" in parts and int(parts["COUNT"]) < 1: