"""warp_to_map's img_scale param: a caller can hand it a differently-sized
image than the one `sol` was actually solved against (see
map_vision.load_full_res / ScreenshotImport.full_image), scaled to
compensate. This checks that compensation is correct, without needing a
real fixture screenshot or the (slow) line-detection/solve pipeline --
just a synthetic image and a stub solution with a predictable transform.
"""
import numpy as np
import pytest

from fenigma import map_vision


class _IdentitySolution:
    """H and lattice_to_grid() both identity: warp_to_map's transform then
    reduces to just grid_to_map, so the output is a directly px_per_km-
    scaled (and row-flipped, per warp_to_map's own comment) copy of
    whatever region of the input `warp_to_map` reads as "grid space"."""
    H = np.eye(3)

    def lattice_to_grid(self):
        return np.eye(3)


def test_img_scale_compensates_for_a_bigger_source_image():
    # A small solid-color source, plus a 2x upscaled copy of it -- same
    # content, different pixel dimensions.
    small = np.zeros((20, 20, 3), dtype=np.uint8)
    small[:, :] = (10, 20, 30)  # BGR
    big = np.zeros((40, 40, 3), dtype=np.uint8)
    big[:, :] = (10, 20, 30)

    sol = _IdentitySolution()
    out_small, ppk_small = map_vision.warp_to_map(small, sol, px_per_km=1)
    out_big, ppk_big = map_vision.warp_to_map(big, sol, px_per_km=1, img_scale=2.0)

    assert ppk_small == ppk_big == 1
    assert out_small.shape == out_big.shape  # output is always MAP_KM_W/H * px_per_km, regardless of source size
    # Same solid color warped in (opaque region only -- compare where both
    # actually painted something, alpha channel nonzero).
    painted = (out_small[:, :, 3] > 0) & (out_big[:, :, 3] > 0)
    assert painted.any()
    np.testing.assert_array_equal(out_small[painted][:, :3], out_big[painted][:, :3])


def test_default_img_scale_is_unchanged_behavior():
    """img_scale's default (1.0) must reproduce pre-existing behavior
    exactly -- every other warp_to_map call site doesn't pass it."""
    img = np.zeros((20, 20, 3), dtype=np.uint8)
    img[:, :] = (1, 2, 3)
    sol = _IdentitySolution()
    out_default, _ = map_vision.warp_to_map(img, sol, px_per_km=1)
    out_explicit, _ = map_vision.warp_to_map(img, sol, px_per_km=1, img_scale=1.0)
    np.testing.assert_array_equal(out_default, out_explicit)


def test_load_full_res_raises_like_load_on_a_bad_path(tmp_path):
    with pytest.raises(ValueError):
        map_vision.load_full_res(tmp_path / "does-not-exist.png")