from abc import ABC, abstractmethod
from dataclasses import dataclass
from typing import List, Optional


@dataclass(frozen=True)
class PropertyReference:
    """A property's landlord reference and resolved UPRN, as held in the
    ``property`` table. ``uprn`` is nullable — a property whose UPRN has not been
    resolved yet cannot receive condition rows."""

    landlord_property_id: Optional[str]
    uprn: Optional[int]


class PropertyReferenceReader(ABC):
    @abstractmethod
    def references_for_portfolio(self, portfolio_id: int) -> List[PropertyReference]:
        ...