"""Characterize image preparation (donor: prepare_image)."""
import base64
import io

from PIL import Image

import photo_analyzer as pa
from conftest import make_image_array


def _decode(b64: str) -> Image.Image:
    return Image.open(io.BytesIO(base64.b64decode(b64)))


def test_prepare_image_small_passthrough_jpeg(img):
    b64, mime = pa.prepare_image(img)
    assert mime == "image/jpeg"
    out = _decode(b64)
    assert out.size == (800, 600), "under MAX_LONG_EDGE → no resize"
    assert out.format == "JPEG"


def test_prepare_image_resizes_to_max_long_edge(tmp_path):
    big = tmp_path / "big.jpg"
    arr = make_image_array("fx-blocks-01")
    Image.fromarray(arr).resize((4096, 3072)).save(big, quality=90)
    b64, _ = pa.prepare_image(big)
    out = _decode(b64)
    assert max(out.size) == pa.MAX_LONG_EDGE
    assert out.size == (2048, 1536), "aspect ratio preserved"


def test_prepare_image_converts_png_alpha_to_rgb_jpeg(tmp_path):
    p = tmp_path / "alpha.png"
    Image.new("RGBA", (100, 80), (255, 0, 0, 128)).save(p)
    b64, mime = pa.prepare_image(p)
    assert mime == "image/jpeg"
    assert _decode(b64).mode == "RGB"