"""flow_control 前馈误差滑窗的离线自测（不连接硬件）。"""

from collections import deque

import pytest

from flow_control import FlowControlLoop


def _pid_threshold_loop():
    """只构造测试 FAR/NEAR 阈值计算所需的状态。"""
    loop = FlowControlLoop.__new__(FlowControlLoop)
    loop.pid_near_error_min_slm = 1.0
    loop.pid_near_error_max_slm = 3.0
    loop.pid_near_error_target_ratio = 0.05
    loop.pid_far_error_min_slm = 4.0
    loop.pid_far_error_max_slm = 12.0
    loop.pid_far_error_target_ratio = 0.20
    return loop


@pytest.mark.parametrize(
    ("target", "expected_near", "expected_far"),
    [
        (10.0, 1.0, 4.0),       # 比例值低于下限
        (30.0, 1.5, 6.0),       # 比例值位于上下限之间
        (60.0, 3.0, 12.0),      # 比例值恰好达到上限
        (300.0, 3.0, 12.0),     # 比例值超过上限
    ],
)
def test_pid_error_thresholds_are_clamped(target, expected_near, expected_far):
    loop = _pid_threshold_loop()

    near, far = loop._pid_error_thresholds(target)

    assert near == pytest.approx(expected_near)
    assert far == pytest.approx(expected_far)


def _feedforward_window_loop():
    """只构造测试滑窗所需的最小 FlowControlLoop 状态。"""
    loop = FlowControlLoop.__new__(FlowControlLoop)
    loop.target_flow_slm = 100.0
    loop.feedforward_update_window_s = 3.0
    loop._feedforward_error_window = deque()
    loop._feedforward_window_ready = False
    return loop


def test_feedforward_window_stays_ready_despite_sampling_jitter():
    loop = _feedforward_window_loop()

    # 首个完整 3 s 窗口内误差恒为 2 SLM。
    sample_times = [0.0, 0.099]
    sample_times.extend(0.201 + 0.1 * index for index in range(28))
    sample_times.append(3.0)
    means = [
        loop._feedforward_window_mean_abs_error(timestamp, 98.0)
        for timestamp in sample_times
    ]

    assert all(value is None for value in means[:-1])
    assert means[-1] == pytest.approx(2.0)
    assert loop._feedforward_window_ready

    # 下一周期淘汰旧样本后，队列首尾跨度仅 2.899 s。窗口仍应保持
    # ready，并返回最近 3 s 的误差均值，不能因约 0.1 s 抖动返回 None。
    mean = loop._feedforward_window_mean_abs_error(3.1, 98.0)

    span = (
        loop._feedforward_error_window[-1][0]
        - loop._feedforward_error_window[0][0]
    )
    assert span == pytest.approx(2.899)
    assert mean == pytest.approx(2.0)
    assert loop._feedforward_window_ready


def test_ready_window_keeps_tracking_recent_error_and_can_reset():
    loop = _feedforward_window_loop()
    loop._feedforward_window_mean_abs_error(0.0, 98.0)
    assert loop._feedforward_window_mean_abs_error(3.0, 98.0) == pytest.approx(2.0)

    # 就绪状态不会冻结均值本身；最近 3 s 都变成 10 SLM 误差后，
    # 返回的新均值会超过默认 5 SLM 阈值，从而触发上层前馈更新。
    for index in range(1, 32):
        mean = loop._feedforward_window_mean_abs_error(
            3.0 + index * 0.1,
            90.0,
        )
    assert mean == pytest.approx(10.0)

    loop._reset_feedforward_error_window()
    assert not loop._feedforward_window_ready
    assert not loop._feedforward_error_window
    assert loop._feedforward_window_mean_abs_error(10.0, 90.0) is None