from __future__ import annotations

import json
import subprocess
import sys
from pathlib import Path

from PIL import Image


SCRIPT = Path(__file__).parents[2] / "scripts" / "build_grayscale_yolo_dataset.py"


def test_grayscale_builder_preserves_labels_and_split(tmp_path: Path) -> None:
    source = tmp_path / "source"
    (source / "images" / "train").mkdir(parents=True)
    (source / "labels" / "train").mkdir(parents=True)
    image = source / "images" / "train" / "tile.png"
    label = source / "labels" / "train" / "tile.txt"
    Image.new("RGB", (8, 8), (255, 0, 0)).save(image)
    label.write_text("0 0.5 0.5 0.5 0.5\n", encoding="utf-8")
    summary = source / "yolo_tile_dataset_summary.json"
    summary.write_text(
        json.dumps(
            {
                "tiles": [
                    {
                        "split": "train",
                        "image_path": str(image),
                        "label_path": str(label),
                    }
                ]
            }
        ),
        encoding="utf-8",
    )
    output = tmp_path / "gray"
    subprocess.run(
        [sys.executable, str(SCRIPT), "--summary", str(summary), "--output-dir", str(output)],
        check=True,
    )
    converted = Image.open(output / "images" / "train" / "tile.png")
    r, g, b = converted.getpixel((0, 0))
    assert r == g == b
    assert (output / "labels" / "train" / "tile.txt").read_text() == label.read_text()
    evidence = json.loads((output / "grayscale-dataset-evidence.json").read_text())
    assert evidence["converted_tile_count"] == 1