"""方案 B 定位逻辑的真值测试（合成 mask，纯 numpy，无需 torch）。"""
import numpy as np

from face_analysis.hair_segmenter import locate_hairline_by_segmentation


def test_locate_on_synthetic_mask():
    """已知头发上沿 row=10、中轴线发际线 row=80，应被精确定位。"""
    H, W = 200, 100
    cx = W // 2
    mask = np.zeros((H, W), dtype=bool)
    mask[10:51, :] = True               # 顶部头发块，最高点 row=10
    mask[10:81, cx - 1:cx + 2] = True   # 中轴线碎发延伸到 row=80
    res = locate_hairline_by_segmentation(mask, cx, H)
    assert res is not None
    hairline_y, hair_top_y = res
    assert hairline_y == 80
    assert hair_top_y == 10
    assert hair_top_y < hairline_y


def test_locate_none_on_empty():
    assert locate_hairline_by_segmentation(None, 50, 200) is None
    assert locate_hairline_by_segmentation(np.zeros((200, 100), bool), 50, 200) is None


def test_locate_handles_out_of_range_x():
    """brow_center_x 越界应被夹回，不抛异常。"""
    H, W = 100, 60
    mask = np.zeros((H, W), dtype=bool)
    mask[5:30, :] = True
    assert locate_hairline_by_segmentation(mask, 9999, H) is not None
    assert locate_hairline_by_segmentation(mask, -50, H) is not None