"""platform/images — pure decode + resolution bar + WebP renditions (SD-0002 §6.2)."""
import io

from PIL import Image

from app.platform import images


def _png(width: int, height: int, color=(120, 80, 200)) -> bytes:
    buf = io.BytesIO()
    Image.new("RGB", (width, height), color).save(buf, format="PNG")
    return buf.getvalue()


def _jpeg(width: int, height: int) -> bytes:
    buf = io.BytesIO()
    Image.new("RGB", (width, height), (10, 200, 90)).save(buf, format="JPEG")
    return buf.getvalue()


def test_good_image_produces_three_webp_renditions():
    result = images.process(_png(1200, 900))
    assert isinstance(result, images.Processed)
    assert result.source_format == "PNG"
    assert set(result.renditions) == {"thumb", "card", "detail"}
    for name, blob in result.renditions.items():
        with Image.open(io.BytesIO(blob)) as im:
            assert im.format == "WEBP"
    with Image.open(io.BytesIO(result.renditions["thumb"])) as im:
        assert max(im.size) <= images.RENDITIONS["thumb"]
    with Image.open(io.BytesIO(result.renditions["detail"])) as im:
        assert max(im.size) <= images.RENDITIONS["detail"]


def test_downscale_only_never_upscales_small_source():
    result = images.process(_png(520, 520))
    with Image.open(io.BytesIO(result.renditions["detail"])) as im:
        assert im.size == (520, 520)


def test_below_resolution_bar_rejected_low_res():
    result = images.process(_png(300, 1200))  # shorter side 300 < 500
    assert isinstance(result, images.Rejected)
    assert result.reason == "rejected_low_res"


def test_not_an_image_rejected_not_image():
    result = images.process(b"this is not an image")
    assert isinstance(result, images.Rejected)
    assert result.reason == "rejected_not_image"


def test_jpeg_source_format_preserved_in_result():
    result = images.process(_jpeg(800, 800))
    assert result.source_format == "JPEG"


def test_decompression_bomb_rejected_not_image(monkeypatch):
    # A small file whose pixel count exceeds Pillow's bomb threshold must be a
    # typed rejection, never an escaping exception.
    from PIL import Image as PILImage
    monkeypatch.setattr(PILImage, "MAX_IMAGE_PIXELS", 100)  # 10x10 exceeds it
    result = images.process(_png(800, 800))
    assert isinstance(result, images.Rejected)
    assert result.reason == "rejected_not_image"