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from __future__ import annotations

import asyncio
import inspect
from typing import TYPE_CHECKING, cast

if TYPE_CHECKING:
    from asgiref.typing import (
        ASGI2Application,
        ASGI3Application,
        ASGIApplication,
        ASGIReceiveCallable,
        ASGISendCallable,
        Scope,
    )

# Vendored from https://github.com/django/asgiref/blob/main/asgiref/compatibility.py

if hasattr(inspect, "markcoroutinefunction"):
    iscoroutinefunction = inspect.iscoroutinefunction
else:
    iscoroutinefunction = asyncio.iscoroutinefunction  # type: ignore[assignment]


def is_double_callable(application: ASGIApplication) -> bool:
    if getattr(application, "_asgi_single_callable", False):
        return False
    if getattr(application, "_asgi_double_callable", False):
        return True
    if inspect.isclass(application):
        return True
    if callable(application) and iscoroutinefunction(application.__call__):
        return False
    return not iscoroutinefunction(application)


def double_to_single_callable(application: ASGI2Application) -> ASGI3Application:
    async def new_application(
        scope: Scope, receive: ASGIReceiveCallable, send: ASGISendCallable
    ) -> None:
        instance = application(scope)
        return await instance(receive, send)

    return new_application


def guarantee_single_callable(application: ASGIApplication) -> ASGI3Application:
    if is_double_callable(application):
        application = double_to_single_callable(cast("ASGI2Application", application))
    return cast("ASGI3Application", application)