"""视差取点器测试（规格 §6.1/§11.4：同侧边缘、框宽差隔离、越窗回退、边界含等号）。"""

import pytest

from stereo_ranger import Detection, DisparitySource, StereoConfig, sample_point, select_disparity

CFG = StereoConfig()


def _box(x1: float, x2: float, *, y1: float = 500.0, y2: float = 540.0) -> Detection:
    return Detection(x1, y1, x2, y2)


def _disparity(left: Detection, right: Detection):
    return select_disparity(sample_point(left), sample_point(right), CFG)


def test_left_edge_used_as_primary_sampling():
    d = _disparity(_box(1000.0, 1060.0), _box(990.4, 1050.4))
    assert d.source is DisparitySource.LEFT_EDGE
    assert d.d_px == pytest.approx(9.6)
    assert d.in_domain and d.positive and not d.fallback_used


def test_box_width_difference_does_not_enter_edge_disparity():
    # §11.4：构造两目不等宽框，断言同侧边缘视差相同（框宽差不进入视差）
    left = _box(1000.0, 1100.0)          # 宽 100
    right_narrow = _box(994.0, 1024.0)   # 宽 30，左边缘差同 6 px
    right_wide = _box(994.0, 1094.0)     # 宽 100
    d_narrow = _disparity(left, right_narrow)
    d_wide = _disparity(left, right_wide)
    assert d_narrow.d_px == pytest.approx(6.0)
    assert d_wide.d_px == pytest.approx(6.0)


def test_center_disparity_would_be_polluted_by_width_difference():
    # 对照：中心视差 41 px = 边缘视差 6 px + 框宽差的一半 35 px，证明主取点选择边缘的理由
    left = _box(1000.0, 1100.0)          # 宽 100, center 1050
    right_narrow = _box(994.0, 1024.0)   # 宽 30,  center 1009
    assert (left.cx - right_narrow.cx) == pytest.approx(41.0)


def test_center_fallback_when_edge_out_of_window():
    # 边缘视差 60 px 越窗（> 57.6），中心视差 40 px 在域内 → 回退中心并标记
    left = _box(1000.0, 1060.0)   # center 1030
    right = _box(940.0, 1040.0)   # center 990
    d = _disparity(left, right)
    assert d.fallback_used is True
    assert d.source is DisparitySource.CENTER_FALLBACK
    assert d.d_px == pytest.approx(40.0)
    assert d.in_domain and d.positive


def test_both_out_of_window_keeps_edge_value_for_diagnostics():
    left = _box(1000.0, 1200.0)   # center 1100
    right = _box(900.0, 1000.0)   # center 950
    d = _disparity(left, right)
    assert d.d_px == pytest.approx(100.0)  # 边缘值保留（诊断 + 违例告警）
    assert not d.in_domain and not d.fallback_used and d.positive


def test_domain_boundaries_are_inclusive():
    assert _disparity(_box(1000.0, 1060.0), _box(997.0, 1057.0)).in_domain  # D = 3.0 = 下限
    # 上限用二进制可精确表示的 57.5 构造：十进制字面量 57.6 无法精确表示，
    # 框坐标相减会落到 57.6 常量之上，边界断言被浮点舍入干扰
    exact_cfg = StereoConfig(disparity_max_px=57.5)
    left, right = _box(1000.0, 1060.0), _box(942.5, 1002.5)
    assert select_disparity(sample_point(left), sample_point(right), exact_cfg).in_domain  # D = 57.5 = 上限


def test_negative_disparity_flagged_as_violation():
    d = _disparity(_box(1000.0, 1060.0), _box(1010.0, 1070.0))
    assert d.d_px == pytest.approx(-10.0)
    assert not d.positive and not d.in_domain


def test_non_finite_box_marked_unusable():
    assert sample_point(Detection(float("nan"), 0.0, 10.0, 10.0)).finite is False
    assert sample_point(Detection(0.0, 0.0, 10.0, 10.0)).finite is True