"""自适应线程池测试。

覆盖决策函数（增/减/保持/边界）、map 顺序返回、worker 异常隔离，
以及"10s 窗口内平均响应 < 0.3s 加线程 / > 1.0s 减线程"的弹性行为
（通过注入假时钟做确定性验证）。
"""

import time

from nodes.adaptive_pool import AdaptiveThreadPool, decide


class FakeClock:
    """可手动拨动的假时钟，用于确定性验证弹性窗口逻辑。"""

    def __init__(self, now: float = 0.0) -> None:
        self.now = now

    def __call__(self) -> float:
        return self.now

    def advance(self, seconds: float) -> None:
        self.now += seconds


def test_decide_increase_when_fast() -> None:
    """平均响应低于 fast_threshold 且未达上限：线程数 +1。"""
    assert decide(1, 0.1, 1, 16, 0.3, 1.0) == 2


def test_decide_decrease_when_slow() -> None:
    """平均响应高于 slow_threshold 且高于下限：线程数 -1。"""
    assert decide(3, 2.0, 1, 16, 0.3, 1.0) == 2


def test_decide_keep_when_mid() -> None:
    """平均响应介于两阈值之间：保持不变。"""
    assert decide(2, 0.5, 1, 16, 0.3, 1.0) == 2


def test_decide_bounds() -> None:
    """已达上限不再增、已达下限不再减。"""
    assert decide(16, 0.1, 1, 16, 0.3, 1.0) == 16
    assert decide(1, 2.0, 1, 16, 0.3, 1.0) == 1


def test_pool_map_ordered_results() -> None:
    """map 按输入顺序返回结果，worker 简单映射。"""
    pool = AdaptiveThreadPool(worker=lambda item: item * 2)
    assert pool.map([1, 2, 3, 4]) == [2, 4, 6, 8]


def test_pool_on_progress_callback() -> None:
    """进度回调：每次完成触发一次，携带已完成数/总数/速度。"""
    progress: list[tuple[int, int, float]] = []
    pool = AdaptiveThreadPool(
        worker=lambda item: item,
        on_progress=lambda done, total, rate: progress.append((done, total, rate)),
    )
    pool.map([10, 20, 30])
    assert [item[0] for item in progress] == [1, 2, 3]  # 已完成数递增。
    assert all(item[1] == 3 for item in progress)  # 总数固定。
    assert all(item[2] > 0 for item in progress)  # 速度为正值。

def test_pool_map_empty() -> None:
    """空输入：不启动任务，直接返回空列表。"""
    pool = AdaptiveThreadPool(worker=lambda item: item)
    assert pool.map([]) == []


def test_pool_worker_exception_isolated() -> None:
    """worker 抛异常时以异常对象作为结果，不拖垮整体。"""
    def boom(item):
        raise RuntimeError("boom")

    pool = AdaptiveThreadPool(worker=boom)
    results = pool.map([1, 2])
    assert len(results) == 2
    assert all(isinstance(result, RuntimeError) for result in results)


def test_pool_grows_when_fast() -> None:
    """10s 窗口内平均响应 < 0.3s：线程数从 1 增至 2（弹性扩容）。"""
    clock = FakeClock()
    pool = AdaptiveThreadPool(
        worker=lambda item: item,
        min_workers=1, max_workers=16,
        window_seconds=10.0, fast_threshold=0.3,
        clock=clock,
    )
    # 拨快时钟越过窗口：首个任务完成即触发评估 → 平均响应≈0 < 0.3 → +1 线程。
    clock.advance(11)
    pool.map(list(range(4)))
    assert pool.max_concurrency == 2


def test_pool_shrink_when_slow() -> None:
    """窗口平均响应 > 1.0s：线程数从 2 减至 1（弹性退避）。"""
    clock = FakeClock()
    pool = AdaptiveThreadPool(
        worker=lambda item: item,
        min_workers=1, max_workers=16,
        window_seconds=10.0, fast_threshold=0.3, slow_threshold=1.0,
        clock=clock,
    )
    pool._resize(2)  # 先扩到 2 个线程。
    clock.advance(11)
    pool._tick(2.0)  # 窗口内平均 2.0 > 1.0 → 缩回 1。
    deadline = time.monotonic() + 2
    while len(pool._threads) > 1 and time.monotonic() < deadline:
        time.sleep(0.01)
    assert len(pool._threads) == 1
    pool._stop.set()


def test_resize_shrink_idempotent() -> None:
    """回归：重复缩容到同一目标不会重复放哨兵（曾因并发缩容毒死全部线程而死锁）。"""
    pool = AdaptiveThreadPool(worker=lambda item: item, min_workers=1, max_workers=8)
    pool._resize(3)
    assert pool._target_workers == 3
    pool._resize(2)
    pool._resize(2)  # 目标已是 2：幂等，不再放哨兵。
    assert pool._target_workers == 2
    # 只有 1 个线程被哨兵退出，最终存活 2 个。
    deadline = time.monotonic() + 2
    while len(pool._threads) > 2 and time.monotonic() < deadline:
        time.sleep(0.01)
    assert len(pool._threads) == 2
    pool._stop.set()


def test_pool_survives_mixed_grow_shrink() -> None:
    """回归：扩容+缩容混合场景 map 必须完成且保序（修复前会死锁挂起）。"""
    clock = FakeClock()
    state = {"count": 0}

    def worker(item):
        state["count"] += 1
        clock.advance(0.06 if state["count"] <= 20 else 0.6)
        return item

    pool = AdaptiveThreadPool(
        worker=worker, min_workers=1, max_workers=4,
        window_seconds=0.5, fast_threshold=0.2, slow_threshold=0.4,
        clock=clock,
    )
    out = pool.map(list(range(60)))
    assert out == list(range(60))