import datetime
import dateutil
from apistar.typesystem import TypeSystemError


class Datetime(datetime.datetime):
    native_type = datetime.datetime

    def __new__(cls, *args, **kwargs) -> datetime:
        if args and isinstance(args[0], cls.native_type):
            return args[0]
        if args and isinstance(args[0], str):
            try:
                return dateutil.parser.parse(args[0])
            except ValueError:
                raise TypeSystemError(cls=cls, code='type') from None
        return cls.native_type(*args, **kwargs)