"""进程内后台任务登记与关停语义测试。"""

import asyncio
import concurrent.futures
import inspect
import threading
import weakref
from collections.abc import Coroutine
from typing import Any

import pytest

from app.runtime.tasks import TaskRegistry


class _CloseCountingCoroutine(Coroutine[Any, Any, None]):
    """记录 pending submission 的协程关闭所有权。"""

    def __init__(self) -> None:
        self.close_count = 0

    def __await__(self):
        return self

    def send(self, _value):
        raise StopIteration

    def throw(self, typ, val=None, tb=None):
        if val is None:
            raise typ
        raise val.with_traceback(tb)

    def close(self) -> None:
        self.close_count += 1


def test_task_registry_removes_completed_task() -> None:
    """正常完成的任务应自动退出登记表，避免长期持有请求对象。"""

    async def scenario() -> None:
        registry = TaskRegistry()
        release = asyncio.Event()

        async def worker() -> None:
            """等待测试释放信号。"""
            await release.wait()

        task = registry.create(worker(), owner="test.completed")
        assert [record.owner for record in registry.records] == ["test.completed"]

        release.set()
        await task
        await asyncio.sleep(0)

        assert registry.records == ()

    asyncio.run(scenario())


def test_task_registry_cancels_tasks_and_rejects_late_registration() -> None:
    """关停应取消存量任务，并拒绝在资源释放阶段继续产生新任务。"""

    async def scenario() -> None:
        registry = TaskRegistry()
        started = asyncio.Event()
        cancelled = asyncio.Event()

        async def worker() -> None:
            """记录任务收到取消信号。"""
            started.set()
            try:
                await asyncio.Event().wait()
            except asyncio.CancelledError:
                cancelled.set()
                raise

        task = registry.create(worker(), owner="test.shutdown")
        await started.wait()
        assert await registry.shutdown(timeout_seconds=1.0) is True

        assert task.cancelled()
        assert cancelled.is_set()
        assert registry.records == ()

        async def late_worker() -> None:
            """模拟关停开始后到达的晚任务。"""

        with pytest.raises(RuntimeError, match="正在关闭"):
            registry.create(late_worker(), owner="test.late")

    asyncio.run(scenario())


def test_task_registry_runs_sync_function_and_tracks_until_completion() -> None:
    """同步任务应在线程池执行，并在真实完成前保留 owner 记录。"""

    async def scenario() -> None:
        registry = TaskRegistry()
        release = asyncio.Event()

        def worker(value: int) -> int:
            """返回传入值，验证参数和结果没有被登记器改写。"""
            return value

        task = registry.create_sync(worker, 7, owner="test.sync")
        assert [record.owner for record in registry.records] == ["test.sync"]
        assert await task == 7
        await asyncio.sleep(0)
        assert registry.records == ()

        release.set()

    asyncio.run(scenario())


def test_task_registry_owns_threadsafe_submission_until_shutdown() -> None:
    """宿主线程提交的协程应先登记 owner，并由 Registry 关停取消和等待。"""

    async def scenario() -> None:
        registry = TaskRegistry()
        loop = asyncio.get_running_loop()
        started = asyncio.Event()
        cleaned = asyncio.Event()

        async def worker() -> None:
            """保持运行直到 Registry 发出取消，并记录清理已完成。"""
            started.set()
            try:
                await asyncio.Event().wait()
            finally:
                cleaned.set()

        completion = await asyncio.to_thread(
            registry.submit_threadsafe,
            worker(),
            loop=loop,
            owner="test.threadsafe",
        )
        await asyncio.wait_for(started.wait(), timeout=1)
        assert [record.owner for record in registry.records] == [
            "test.threadsafe"
        ]

        assert await registry.shutdown(timeout_seconds=1.0) is True
        assert cleaned.is_set()
        assert completion.cancelled()
        assert registry.records == ()

    asyncio.run(scenario())


def test_task_registry_rejects_threadsafe_submission_after_shutdown() -> None:
    """关停先赢得竞态时应关闭协程并同步拒绝提交。"""

    async def scenario() -> None:
        registry = TaskRegistry()
        loop = asyncio.get_running_loop()

        async def late_worker() -> None:
            """模拟关停完成后从宿主线程到达的晚任务。"""

        assert await registry.shutdown(timeout_seconds=1.0) is True
        coroutine = late_worker()
        with pytest.raises(RuntimeError, match="正在关闭"):
            await asyncio.to_thread(
                registry.submit_threadsafe,
                coroutine,
                loop=loop,
                owner="test.threadsafe-late",
            )

        assert inspect.getcoroutinestate(coroutine) == inspect.CORO_CLOSED
        assert registry.records == ()

    asyncio.run(scenario())


def test_task_registry_shutdown_closes_submission_before_loop_dispatch() -> None:
    """回调尚未执行时关停也必须关闭协程并结束 completion。"""
    registry = TaskRegistry()
    loop = asyncio.new_event_loop()

    async def worker() -> None:
        """不应被迟到的 loop callback 启动。"""

    coroutine = worker()
    completion = registry.submit_threadsafe(
        coroutine,
        loop=loop,
        owner="test.threadsafe-pending",
    )

    assert asyncio.run(registry.shutdown(timeout_seconds=0.01)) is True
    assert completion.cancelled()
    assert inspect.getcoroutinestate(coroutine) == inspect.CORO_CLOSED

    loop.run_until_complete(asyncio.sleep(0))
    assert registry.records == ()
    loop.close()


def test_task_registry_caller_cancels_before_loop_dispatch() -> None:
    """调用方在 callback 前取消时应关闭协程，迟到 callback 不得创建 Task。"""
    registry = TaskRegistry()
    loop = asyncio.new_event_loop()

    async def worker() -> None:
        """不应在 completion 取消后启动。"""

    coroutine = worker()
    completion = registry.submit_threadsafe(
        coroutine,
        loop=loop,
        owner="test.threadsafe-cancel-before-dispatch",
    )

    assert completion.cancel()
    assert inspect.getcoroutinestate(coroutine) == inspect.CORO_CLOSED
    loop.run_until_complete(asyncio.sleep(0))

    assert registry.records == ()
    loop.close()


def test_task_registry_closes_submission_when_loop_rejects_callback() -> None:
    """目标 loop 已关闭时同步失败，并且不遗留未等待协程。"""
    registry = TaskRegistry()
    loop = asyncio.new_event_loop()
    loop.close()

    async def worker() -> None:
        """模拟无法进入目标 loop 的提交。"""

    coroutine = worker()
    with pytest.raises(RuntimeError, match="closed"):
        registry.submit_threadsafe(
            coroutine,
            loop=loop,
            owner="test.threadsafe-closed-loop",
        )

    assert inspect.getcoroutinestate(coroutine) == inspect.CORO_CLOSED


def test_task_registry_shutdown_owns_close_before_loop_rejection() -> None:
    """shutdown 已取走 pending 后，迟到的投递失败不得再次关闭同一协程。"""
    registry = TaskRegistry()
    dispatch_entered = threading.Event()
    release_dispatch = threading.Event()
    coroutine = _CloseCountingCoroutine()

    class BlockingClosedLoop:
        """让 shutdown 稳定发生在投递抛错之前。"""

        @staticmethod
        def call_soon_threadsafe(_callback) -> None:
            dispatch_entered.set()
            release_dispatch.wait()
            raise RuntimeError("loop closed")

    with concurrent.futures.ThreadPoolExecutor(max_workers=1) as executor:
        submission = executor.submit(
            registry.submit_threadsafe,
            coroutine,
            loop=BlockingClosedLoop(),
            owner="test.threadsafe-shutdown-before-rejection",
        )
        assert dispatch_entered.wait(1.0)
        assert asyncio.run(registry.shutdown(timeout_seconds=0.01)) is True
        release_dispatch.set()
        with pytest.raises(RuntimeError, match="loop closed"):
            submission.result(timeout=1.0)

    assert coroutine.close_count == 1


def test_task_registry_shutdown_rejects_late_successful_dispatch() -> None:
    """shutdown 取走 pending 后，迟到的成功投递也不得发布真实 Task。"""
    registry = TaskRegistry()
    dispatch_entered = threading.Event()
    release_dispatch = threading.Event()
    callbacks = []
    coroutine = _CloseCountingCoroutine()

    class BlockingLoop:
        """让 shutdown 稳定发生在 loop 接受 callback 之前。"""

        @staticmethod
        def call_soon_threadsafe(callback) -> None:
            dispatch_entered.set()
            release_dispatch.wait()
            callbacks.append(callback)

    with concurrent.futures.ThreadPoolExecutor(max_workers=1) as executor:
        submission = executor.submit(
            registry.submit_threadsafe,
            coroutine,
            loop=BlockingLoop(),
            owner="test.threadsafe-shutdown-before-dispatch",
        )
        assert dispatch_entered.wait(1.0)
        assert asyncio.run(registry.shutdown(timeout_seconds=0.01)) is True
        release_dispatch.set()
        completion = submission.result(timeout=1.0)

    assert completion.cancelled()
    callbacks[0]()
    assert coroutine.close_count == 1
    assert registry.records == ()


def test_task_registry_completion_does_not_retain_itself_after_cancellation() -> None:
    """终态回调不得让已取消 completion 依赖循环 GC 才能释放。"""
    registry = TaskRegistry()
    loop = asyncio.new_event_loop()
    completion = registry.submit_threadsafe(
        _CloseCountingCoroutine(),
        loop=loop,
        owner="test.threadsafe-completion-release",
    )
    completion_ref = weakref.ref(completion)

    assert completion.cancel()
    loop.run_until_complete(asyncio.sleep(0))
    del completion

    assert completion_ref() is None
    loop.close()


def test_task_registry_pending_non_cancellable_work_does_not_start_on_shutdown() -> None:
    """尚未发布成 Task 的 non-cancellable 工作仍应在关停时直接关闭。"""
    registry = TaskRegistry()
    loop = asyncio.new_event_loop()

    async def worker() -> None:
        """未开始的同步兼容工作不应拖延关停。"""

    coroutine = worker()
    completion = registry.submit_threadsafe(
        coroutine,
        loop=loop,
        owner="test.threadsafe-pending-non-cancellable",
        cancel_on_shutdown=False,
    )

    assert asyncio.run(registry.shutdown(timeout_seconds=0.01)) is True
    assert completion.cancelled()
    assert inspect.getcoroutinestate(coroutine) == inspect.CORO_CLOSED

    loop.run_until_complete(asyncio.sleep(0))
    assert registry.records == ()
    loop.close()


def test_task_registry_keeps_timed_out_sync_owner_until_real_completion() -> None:
    """同步线程超过关停预算后仍应保留 owner，不能把包装任务取消成伪完成。"""

    async def scenario() -> None:
        registry = TaskRegistry()
        started = threading.Event()
        release = threading.Event()
        reports: list[dict[str, object]] = []
        loop = asyncio.get_running_loop()
        previous_handler = loop.get_exception_handler()
        loop.set_exception_handler(lambda _, context: reports.append(context))

        def worker() -> None:
            """模拟无法由 asyncio 取消、需要外部资源自行结束的同步工作。"""
            started.set()
            release.wait()

        try:
            task = registry.create_sync(worker, owner="test.sync-timeout")
            assert await asyncio.to_thread(started.wait, 1.0)

            assert await registry.shutdown(timeout_seconds=0.001) is False

            assert not task.done()
            assert [record.owner for record in registry.records] == [
                "test.sync-timeout"
            ]
            assert reports[-1]["owners"] == ("test.sync-timeout",)

            release.set()
            await task
            await asyncio.sleep(0)
            assert registry.records == ()
        finally:
            release.set()
            loop.set_exception_handler(previous_handler)

    asyncio.run(scenario())


def test_task_registry_keeps_stubborn_cancelled_task_visible() -> None:
    """协程清理超过预算时只收一次取消，并在最终退出后自动清理。"""

    async def scenario() -> None:
        registry = TaskRegistry()
        started = asyncio.Event()
        cleanup_started = asyncio.Event()
        release = asyncio.Event()
        cancellation_count = 0
        reports: list[dict[str, object]] = []
        loop = asyncio.get_running_loop()
        previous_handler = loop.get_exception_handler()
        loop.set_exception_handler(lambda _, context: reports.append(context))

        async def worker() -> None:
            """模拟收到取消后仍必须完成的异步清理。"""
            nonlocal cancellation_count
            started.set()
            try:
                await asyncio.Event().wait()
            except asyncio.CancelledError:
                cancellation_count += 1
                cleanup_started.set()
                await release.wait()

        task = registry.create(worker(), owner="test.stubborn")
        await started.wait()
        try:
            assert await registry.shutdown(timeout_seconds=0.001) is False

            assert cleanup_started.is_set()
            assert not task.done()
            assert cancellation_count == 1
            assert [record.owner for record in registry.records] == [
                "test.stubborn"
            ]
            assert reports[-1]["owners"] == ("test.stubborn",)

            assert await registry.shutdown(timeout_seconds=0.001) is False
            assert not task.done()
            assert cancellation_count == 1
            assert len(reports) == 1

            release.set()
            await task
            await asyncio.sleep(0)
            assert registry.records == ()
        finally:
            release.set()
            loop.set_exception_handler(previous_handler)

    asyncio.run(scenario())