"""Regression tests for Gateway lifespan shutdown.

These tests guard the invariant that lifespan shutdown is *bounded*: a
misbehaving channel whose ``stop()`` blocks forever must not keep the
uvicorn worker alive. A hung worker is the precondition for the
signal-reentrancy deadlock described in
``app.gateway.app._SHUTDOWN_HOOK_TIMEOUT_SECONDS``.
"""

from __future__ import annotations

import asyncio
import logging
from contextlib import asynccontextmanager
from types import SimpleNamespace
from unittest.mock import AsyncMock, MagicMock, patch

from fastapi import FastAPI


@asynccontextmanager
async def _noop_langgraph_runtime(_app, _startup_config):
    yield


async def _run_lifespan_with_hanging_stop() -> float:
    """Drive the lifespan context with stop_channel_service hanging forever.

    Returns the elapsed wall-clock seconds.
    """
    from app.gateway.app import _SHUTDOWN_HOOK_TIMEOUT_SECONDS, lifespan

    async def hang_forever() -> None:
        await asyncio.sleep(3600)

    app = FastAPI()
    startup_config = MagicMock()
    startup_config.log_level = "INFO"
    # Keep this test focused on the channel-hang timing: skip the memory drain.
    startup_config.memory.enabled = False
    startup_config.memory.shutdown_flush_timeout_seconds = 5.0
    fake_service = MagicMock()
    fake_service.get_status = MagicMock(return_value={})

    async def fake_start(_startup_config):
        return fake_service

    close_oidc_service = AsyncMock()

    with (
        patch("app.gateway.app.get_app_config", return_value=startup_config),
        patch("app.gateway.app.get_gateway_config", return_value=MagicMock(host="x", port=0)),
        patch("app.gateway.app.langgraph_runtime", _noop_langgraph_runtime),
        patch("app.gateway.app.auth.close_oidc_service", close_oidc_service),
        patch("app.channels.service.start_channel_service", side_effect=fake_start),
        patch("app.channels.service.stop_channel_service", side_effect=hang_forever),
        patch("deerflow.agents.memory.get_memory_manager", return_value=MagicMock()),
    ):
        loop = asyncio.get_event_loop()
        start = loop.time()
        async with lifespan(app):
            pass
        elapsed = loop.time() - start

    close_oidc_service.assert_awaited_once()
    assert _SHUTDOWN_HOOK_TIMEOUT_SECONDS < 30.0, "Timeout constant must stay modest"
    return elapsed


def test_shutdown_is_bounded_when_channel_stop_hangs():
    """Lifespan exit must complete near the configured timeout, not hang."""
    from app.gateway.app import _SHUTDOWN_HOOK_TIMEOUT_SECONDS

    elapsed = asyncio.run(_run_lifespan_with_hanging_stop())

    # Generous upper bound: timeout + 2s slack for scheduling overhead.
    assert elapsed < _SHUTDOWN_HOOK_TIMEOUT_SECONDS + 2.0, f"Lifespan shutdown took {elapsed:.2f}s; expected <= {_SHUTDOWN_HOOK_TIMEOUT_SECONDS + 2.0:.1f}s"
    # Lower bound: the wait_for should actually have waited.
    assert elapsed >= _SHUTDOWN_HOOK_TIMEOUT_SECONDS - 0.5, f"Lifespan exited too quickly ({elapsed:.2f}s); wait_for may not have been invoked."


async def _run_lifespan_with_upload_staging_cleanup():
    from app.gateway.app import lifespan

    app = FastAPI()
    startup_config = SimpleNamespace(log_level="INFO", memory=SimpleNamespace(token_counting="char", enabled=False, shutdown_flush_timeout_seconds=30.0))
    fake_service = MagicMock()
    fake_service.get_status = MagicMock(return_value={})
    cleanup_upload_staging_files = MagicMock(return_value=2)
    close_oidc_service = AsyncMock()
    stop_channel_service = AsyncMock()

    async def fake_start(_startup_config):
        return fake_service

    with (
        patch("app.gateway.app.get_app_config", return_value=startup_config),
        patch("app.gateway.app.get_gateway_config", return_value=MagicMock(host="x", port=0)),
        patch("app.gateway.app.langgraph_runtime", _noop_langgraph_runtime),
        patch("app.gateway.app.cleanup_stale_upload_staging_files", cleanup_upload_staging_files),
        patch("app.gateway.app.auth.close_oidc_service", close_oidc_service),
        patch("app.channels.service.start_channel_service", side_effect=fake_start),
        patch("app.channels.service.stop_channel_service", stop_channel_service),
    ):
        async with lifespan(app):
            pass

    return cleanup_upload_staging_files, close_oidc_service, stop_channel_service


def test_lifespan_sweeps_upload_staging_files_on_startup():
    cleanup_upload_staging_files, close_oidc_service, stop_channel_service = asyncio.run(_run_lifespan_with_upload_staging_cleanup())

    cleanup_upload_staging_files.assert_called_once_with()
    close_oidc_service.assert_awaited_once()
    stop_channel_service.assert_awaited_once()


async def _run_lifespan_with_memory_flush(*, enabled: bool, flush_return: bool) -> MagicMock:
    """Drive lifespan with a spied memory manager.shutdown_flush.

    Returns the manager mock so the caller can assert the shutdown flush was
    reached (and with what timeout). The host calls ``shutdown_flush``
    unconditionally when memory is enabled -- there is no host-level
    ``pending_count/is_processing`` gate, because the backend short-circuits on
    an idle buffer and keeping the in-flight race inside the backend means the
    host cannot "forget" it (review #6 on the original PR).
    """
    from app.gateway.app import lifespan

    app = FastAPI()
    startup_config = SimpleNamespace(
        log_level="INFO",
        memory=SimpleNamespace(
            token_counting="char",
            enabled=enabled,
            shutdown_flush_timeout_seconds=5.0,
        ),
    )
    fake_service = MagicMock()
    fake_service.get_status = MagicMock(return_value={})
    close_oidc_service = AsyncMock()
    stop_channel_service = AsyncMock()

    async def fake_start(_startup_config):
        return fake_service

    manager = MagicMock()
    manager.shutdown_flush.return_value = flush_return

    with (
        patch("app.gateway.app.get_app_config", return_value=startup_config),
        patch("app.gateway.app.get_gateway_config", return_value=MagicMock(host="x", port=0)),
        patch("app.gateway.app.langgraph_runtime", _noop_langgraph_runtime),
        patch("app.gateway.app.auth.close_oidc_service", close_oidc_service),
        patch("app.channels.service.start_channel_service", side_effect=fake_start),
        patch("app.channels.service.stop_channel_service", stop_channel_service),
        patch("deerflow.agents.memory.get_memory_manager", return_value=manager),
    ):
        async with lifespan(app):
            pass

    return manager


def test_lifespan_drains_memory_on_shutdown_with_configured_timeout(caplog) -> None:
    """When memory is enabled, shutdown calls manager.shutdown_flush with the
    configured timeout (asserts the timeout is forwarded, review #3) and logs
    'completed' at INFO when the drain finishes."""
    caplog.set_level(logging.INFO, logger="app.gateway.app")
    manager = asyncio.run(_run_lifespan_with_memory_flush(enabled=True, flush_return=True))
    manager.shutdown_flush.assert_called_once_with(5.0)
    assert any(r.levelno == logging.INFO and "flush completed" in r.message for r in caplog.records)


def test_lifespan_warns_when_memory_flush_does_not_finish(caplog) -> None:
    """A False return (timeout/failure) is the path operators actually see when
    K8s SIGKILLs the drain; the host must log a WARNING (not 'completed'), so
    the loss risk is visible (review #3 False-branch coverage; review #2/#4
    failed-flush semantics)."""
    caplog.set_level(logging.WARNING, logger="app.gateway.app")
    manager = asyncio.run(_run_lifespan_with_memory_flush(enabled=True, flush_return=False))
    manager.shutdown_flush.assert_called_once_with(5.0)
    assert any(r.levelno == logging.WARNING and "did not finish" in r.message for r in caplog.records)
    assert not any("flush completed" in r.message for r in caplog.records)


def test_lifespan_skips_memory_flush_when_disabled() -> None:
    """memory.enabled=False skips the drain entirely."""
    manager = asyncio.run(_run_lifespan_with_memory_flush(enabled=False, flush_return=True))
    manager.shutdown_flush.assert_not_called()