from __future__ import annotations

from typing import AsyncIterator, cast

import anyio
import httpx2
from anyio.lowlevel import checkpoint

from ._httpx2 import request_exceptions, stream_consumed_exceptions

_DRAIN_TIMEOUT = 0.1


async def drain_response_async(response: httpx2.Response) -> None:
    if response.is_closed:
        return
    try:
        with anyio.move_on_after(_DRAIN_TIMEOUT):
            # Discard raw transport bytes without decoding trailing SSE or content.
            async for _ in cast(AsyncIterator[bytes], response.stream):
                # Also enforce the deadline on transports yielding buffered data.
                await checkpoint()
    except request_exceptions() + stream_consumed_exceptions():
        pass  # Cleanup must not turn completed output into a request error.
    finally:
        # Close outside our timeout scope and shield cleanup from caller
        # cancellation. Cancellation still propagates after the response closes.
        with anyio.CancelScope(shield=True):
            await response.aclose()