# -*- coding: utf-8 -*-
# (c) Nelen & Schuurmans
from abc import abstractmethod, abstractproperty
from typing import Generic, List, Optional, TypeVar

from .exceptions import BadRequest, DoesNotExist
from .gateway import Filter
from .manage import Manage
from .pagination import PageOptions
from .root_entity import RootEntity
from .value_object import ValueObject

E = TypeVar("E", bound=RootEntity)  # External
T = TypeVar("T", bound=ValueObject)  # Internal


# don't subclass Gateway; Gateway makes Json objects
class InternalGateway(Generic[E, T]):
    @abstractproperty
    def manage(self) -> Manage[E]:
        raise NotImplementedError()

    @abstractmethod
    def _map(self, obj: E) -> T:
        raise NotImplementedError()

    async def get(self, id: int) -> Optional[T]:
        try:
            result = await self.manage.retrieve(id)
        except DoesNotExist:
            return None
        else:
            return self._map(result)

    async def filter(
        self, filters: List[Filter], params: Optional[PageOptions] = None
    ) -> List[T]:
        page = await self.manage.filter(filters, params)
        return [self._map(x) for x in page.items]

    async def add(self, item: T) -> T:
        try:
            created = await self.manage.create(item.dict())
        except BadRequest as e:
            raise ValueError(e)
        return self._map(created)

    async def remove(self, id) -> bool:
        return await self.manage.destroy(id)

    async def count(self, filters: List[Filter]) -> int:
        return await self.manage.count(filters)

    async def exists(self, filters: List[Filter]) -> bool:
        return await self.manage.exists(filters)