_self_injecting.py

# -*- coding: utf-8 -*-
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from __future__ import annotations

__all__: list[str] = ["AsyncSelfInjecting", "SelfInjecting"]

import typing
from collections import abc as collections

from . import abc as alluka

_CallbackSigT = typing.TypeVar("_CallbackSigT", bound=alluka.CallbackSig[typing.Any])
_SyncCallbackT = typing.TypeVar("_SyncCallbackT", bound=collections.Callable[..., typing.Any])
_T = typing.TypeVar("_T")
_CoroT = collections.Coroutine[typing.Any, typing.Any, _T]


class AsyncSelfInjecting(alluka.AsyncSelfInjecting[_CallbackSigT]):
    """Class used to link a sync function to a client to make it self-injecting.

    Examples
    --------
    ```py
    async def callback(database: Database = alluka.inject(type=Database)) -> None:
        await database.do_something()
    ...

    client = alluka.Client()
    injecting_callback = alluka.AsyncSelfInjecting(callback, client)
    await injecting_callback()
    ```

    Alternatively [alluka.abc.Client.as_async_self_injecting][] may be used:

    ```py
    client = alluka.Client()

    @client.as_async_self_injecting
    async def callback(database: Database = alluka.inject(type=Database)) -> None:
        ...
    ```
    """

    __slots__ = ("_callback", "_client", "_get_client")

    def __init__(
        self, client: typing.Union[alluka.Client, collections.Callable[[], alluka.Client]], callback: _CallbackSigT, /
    ) -> None:
        """Initialise a self injecting callback.

        Parameters
        ----------
        client
            Either the injection client instance to use to resolve dependencies
            or a callback used to get the client instance.
        callback : alluka.abc.CallbackSig
            The callback to make self-injecting.

            This may be sync or async.

        Raises
        ------
        ValueError
            If `callback` has any injected arguments which can only be passed
            positionally.
        """
        self._callback = callback

        if isinstance(client, alluka.Client):
            self._client: typing.Optional[alluka.Client] = client
            self._get_client: typing.Optional[collections.Callable[[], alluka.Client]] = None

        else:
            self._client = None
            self._get_client = client

    @typing.overload
    async def __call__(
        self: AsyncSelfInjecting[collections.Callable[..., _CoroT[_T]]], *args: typing.Any, **kwargs: typing.Any
    ) -> _T:
        ...

    @typing.overload
    async def __call__(
        self: AsyncSelfInjecting[collections.Callable[..., _T]], *args: typing.Any, **kwargs: typing.Any
    ) -> _T:
        ...

    async def __call__(
        self: typing.Union[
            AsyncSelfInjecting[collections.Callable[..., _T]], AsyncSelfInjecting[collections.Callable[..., _CoroT[_T]]]
        ],
        *args: typing.Any,
        **kwargs: typing.Any,
    ) -> _T:
        # <<inherited docstring from alluka.abc.AsyncSelfInjecting>>.
        client = self._client
        if not client:
            assert self._get_client
            client = self._get_client()

        return await client.call_with_async_di(self._callback, *args, **kwargs)

    @property
    def callback(self) -> _CallbackSigT:
        # <<inherited docstring from alluka.abc.AsyncSelfInjecting>>.
        return self._callback


class SelfInjecting(alluka.SelfInjecting[_SyncCallbackT]):
    """Class used to link a sync function to a client to make it self-injecting.

    !!! note
        This executes the callback synchronously and therefore will error if
        any of the callback's dependencies are async.

    Examples
    --------
    ```py
    async def callback(database: Database = alluka.inject(type=Database)) -> None:
        await database.do_something()
    ...

    client = alluka.Client()
    injecting_callback = alluka.SelfInjecting(callback, client)
    await injecting_callback()
    ```

    Alternatively [alluka.abc.Client.as_self_injecting][] may be used:

    ```py
    client = alluka.Client()

    @client.as_self_injecting
    async def callback(database: Database = alluka.inject(type=Database)) -> None:
        ...
    ```
    """

    __slots__ = ("_callback", "_client", "_get_client")

    def __init__(
        self, client: typing.Union[alluka.Client, collections.Callable[[], alluka.Client]], callback: _SyncCallbackT, /
    ) -> None:
        """Initialise a sync self injecting callback.

        Parameters
        ----------
        client
            Either the injection client instance to use to resolve dependencies
            or a callback used to get the client instance.
        callback : collections.abc.Callable
            The callback to make self-injecting.

        Raises
        ------
        ValueError
            If `callback` has any injected arguments which can only be passed
            positionally.
        """
        self._callback = callback

        if isinstance(client, alluka.Client):
            self._client: typing.Optional[alluka.Client] = client
            self._get_client: typing.Optional[collections.Callable[[], alluka.Client]] = None

        else:
            self._client = None
            self._get_client = client

    def __call__(self: SelfInjecting[collections.Callable[..., _T]], *args: typing.Any, **kwargs: typing.Any) -> _T:
        # <<inherited docstring from alluka.abc.SelfInjecting>>.
        client = self._client
        if not client:
            assert self._get_client
            client = self._get_client()

        return client.call_with_di(self._callback, *args, **kwargs)

    @property
    def callback(self) -> _SyncCallbackT:
        # <<inherited docstring from alluka.abc.SelfInjecting>>.
        return self._callback