"""montage_pngs 单元测试。"""

import tempfile
from pathlib import Path

from PIL import Image


def _make_test_png(path, w=200, h=100, color="red"):
    """创建测试用 PNG。"""
    img = Image.new("RGB", (w, h), color)
    img.save(path)
    return str(path)


def test_montage_basic():
    """4 张图拼成 2x2 网格。"""
    from ts_anomaly_td.visualize import montage_pngs

    with tempfile.TemporaryDirectory() as tmpdir:
        paths = []
        for i, color in enumerate(["red", "green", "blue", "yellow"]):
            p = Path(tmpdir) / f"img_{i}.png"
            _make_test_png(p, color=color)
            paths.append(str(p))

        out = Path(tmpdir) / "montage.png"
        result = montage_pngs(paths, str(out), cols=2, title="Test")
        assert Path(result).exists()
        assert Path(result).stat().st_size > 1000


def test_montage_uneven():
    """3 张图拼成 2 列（第二行只 1 张）。"""
    from ts_anomaly_td.visualize import montage_pngs

    with tempfile.TemporaryDirectory() as tmpdir:
        paths = []
        for i in range(3):
            p = Path(tmpdir) / f"img_{i}.png"
            _make_test_png(p)
            paths.append(str(p))

        out = Path(tmpdir) / "montage_uneven.png"
        result = montage_pngs(paths, str(out), cols=2)
        assert Path(result).exists()


def test_montage_empty():
    """空列表应抛 ValueError。"""
    from ts_anomaly_td.visualize import montage_pngs

    try:
        montage_pngs([], "/dev/null")
        assert False, "应抛 ValueError"
    except ValueError:
        pass