from typing import Protocol

from synctoy.data_model import NonNullRecord, ObjectId, RNull, Record


class Selector(Protocol):
    def includes_object_id(self, object_id: ObjectId):
        raise NotImplementedError


class SAll(object):
    def includes_object_id(self, object_id: ObjectId):
        return True

class SList(object):
    def __init__(self, object_ids: list[ObjectId]):
        self._object_ids = object_ids

    def includes_object_id(self, object_id: ObjectId):
        return object_id in self._object_ids

class Snapshot(object):
    def __init__(self, selector: Selector, data: dict[ObjectId, NonNullRecord]):
        self._selector = selector
        self._data = data

    def __getitem__(self, object_id: ObjectId):
        if not self._selector.includes_object_id(object_id):
            raise KeyError(f"{object_id} was not selected and cannot be viewed")

        return self._data.get(object_id) or RNull(id=object_id)

    def __setitem__(self, object_id: ObjectId, value: Record):
        if not self._selector.includes_object_id(object_id):
            raise KeyError(f"{object_id} was not selected and cannot be staged")

        if isinstance(value, RNull):
            self._data.pop(object_id, None)
        else:
            self._data[object_id] = value

    def populated_records(self) -> dict[ObjectId, NonNullRecord]:
        return dict(self._data)