import abc
import dataclasses
import datetime
from collections.abc import Iterable, Mapping
from decimal import Decimal
from typing import TypeVar

import enforce_typing
from fin_defs import Asset


@enforce_typing.enforce_types
@dataclasses.dataclass(frozen=True)
class Depo(abc.ABC):
    """A depository tracking some amount of assets.

    Depo can either be DepoSingle, which is the base layer of the depository
    structure, or nested in DepoGroup, which allows for a complex hierarcy of
    depositories.

    The depository structure exposed by each backend depends upon the logical
    structure of the relevant service and the API of this service.
    """

    name: str
    updated_time: datetime.datetime

    @abc.abstractmethod
    def assets(self) -> Iterable[Asset]:
        """Returns the different assets managed by this depo."""

    @abc.abstractmethod
    def get_amount_of_asset(self, asset: Asset) -> Decimal:
        """Returns the amount of owned assets for all nested depos.

        Must return 0 if depo does not contain the given asset.
        """


@enforce_typing.enforce_types
@dataclasses.dataclass(frozen=True)
class DepoSingle(Depo):
    """Base level of depository."""

    _assets: Mapping[Asset, Decimal]

    def __post_init__(self):
        assert None not in self._assets

    def assets(self) -> Iterable[Asset]:
        return self._assets

    def get_amount_of_asset(self, asset: Asset) -> Decimal:
        return self._assets.get(asset, Decimal(0))


@enforce_typing.enforce_types
@dataclasses.dataclass(frozen=True)
class DepoGroup(Depo):
    """Nested depository."""

    nested: list[Depo]

    def __post_init__(self):
        assert None not in self.nested

    def assets(self) -> Iterable[Asset]:
        assets: set[Asset] = set()
        for nested_depo in self.nested:
            assets.update(nested_depo.assets())
        return assets

    def get_amount_of_asset(self, asset: Asset) -> Decimal:
        summed: Decimal = Decimal(0)
        for nested_depo in self.nested:
            summed += nested_depo.get_amount_of_asset(asset)
            del nested_depo
        return summed


T = TypeVar('T')


class DepoFetcher(abc.ABC):
    """Base `Depo` fetcher interface.

    Used to get depository information for specific websites/backends.
    """

    @abc.abstractmethod
    def get_depo(self) -> Depo:
        """Fetches the `Depo`s available for the fetcher, possibly as
        a `DepoGroup`.
        """

    def assert_param(self, param_name: str, param_type: type[T], param_value: T) -> T:
        if not isinstance(param_value, param_type):
            msg = f'{self} expected {param_name} parameter of type {param_type}, but got: {param_value}'
            raise TypeError(msg)
        return param_value


@enforce_typing.enforce_types
@dataclasses.dataclass(frozen=True)
class TradeOrderDetails:
    """Information about an executed trade.

    Includes both well-structured data about the order, and unstructured data
    from the backend. The unstructured data might be needed for tax purposes.

    Fields:
    - `input_asset`: Asset that have been sold
    - `input_amount`: Amount of asset that has been sold
    - `output_asset`: Asset that have been bought
    - `output_amount`: Amount of asset that have been bought.
    - `fee_asset`: Asset used to pay fee.
    - `fee_amount`: Amount of asset that have been used to pay fee.
    - `executed_time`: Point in time when order was executed.
    - `order_id`: Unique identifier of order. Determined by backend.
    - `raw_order_details`: For storing arbitrary unstructured data from backend.
    """

    input_asset: Asset
    input_amount: Decimal
    output_asset: Asset
    output_amount: Decimal
    fee_asset: Asset
    fee_amount: Decimal
    executed_time: datetime.datetime

    order_id: object
    raw_order_details: object