from pathlib import Path

from PIL import Image

from scripts.derive_yolo_nonoverlap_evaluation_view import (
    image_has_low_visual_variance,
    select_nonoverlap_tiles,
)


def tile(name: str, index: int, split: str = "val") -> dict[str, object]:
    return {
        "image_path": f"/data/sample_{index:04d}_{name}.png",
        "tile_index": index,
        "sample_slug": "sample",
        "split": split,
        "kept": True,
    }


def test_select_nonoverlap_tiles_keeps_complete_512_grid() -> None:
    tiles = [
        tile("r0_c0", 0),
        tile("r0_c256", 1),
        tile("r0_c512", 2),
        tile("r256_c0", 3),
        tile("r256_c256", 4),
        tile("r256_c512", 5),
        tile("r512_c0", 6),
        tile("r512_c256", 7),
        tile("r512_c512", 8),
        tile("r0_c0", 9, split="train"),
    ]

    selected = select_nonoverlap_tiles(tiles, 512)

    assert [item["tile_index"] for item in selected] == [0, 2, 6, 8]


def test_image_has_low_visual_variance_rejects_blank_no_data(tmp_path: Path) -> None:
    blank = tmp_path / "blank.png"
    real = tmp_path / "real.png"
    Image.new("L", (8, 8), color=255).save(blank)
    image = Image.new("L", (8, 8), color=100)
    image.putpixel((0, 0), 120)
    image.save(real)

    assert image_has_low_visual_variance(blank, 3) is True
    assert image_has_low_visual_variance(real, 3) is False