"""Lawn-mask → editable polygon vectorization (W4b). No network/model."""

from __future__ import annotations

import numpy as np

from lawn_estimator.pipeline import _mask_to_polygon_px


def test_traces_rectangle_outline():
    m = np.zeros((100, 100), bool)
    m[20:80, 30:70] = True
    poly = _mask_to_polygon_px(m, simplify_px=2.0)
    assert len(poly) >= 4  # a closed ring
    xs, ys = [p[0] for p in poly], [p[1] for p in poly]
    assert min(xs) < 35 and max(xs) > 65   # spans the rectangle in x
    assert min(ys) < 25 and max(ys) > 75   # spans it in y


def test_empty_mask_gives_no_polygon():
    assert _mask_to_polygon_px(np.zeros((50, 50), bool)) == []


def test_picks_largest_region_and_caps_vertices():
    m = np.zeros((160, 160), bool)
    m[10:20, 10:20] = True            # small blob
    yy, xx = np.mgrid[0:160, 0:160]
    m |= (xx - 100) ** 2 + (yy - 100) ** 2 < 45 ** 2   # big disc → the "lawn"
    poly = _mask_to_polygon_px(m, simplify_px=1.0, max_points=30)
    assert 4 <= len(poly) <= 31       # simplified under the cap
    xs = [p[0] for p in poly]
    assert min(xs) > 40               # it traced the big disc, not the corner blob