import pytest
from PIL import Image

from paperpod.pdf.build import images_to_pdf


def _write_png(path, color):
    Image.new("RGB", (200, 300), color).save(path)


def test_images_to_pdf_single_page(tmp_path):
    img_path = tmp_path / "page.png"
    _write_png(img_path, (255, 255, 255))
    out = tmp_path / "out.pdf"

    result = images_to_pdf([img_path], out, title="Test Doc")

    assert result == out
    assert out.exists()
    data = out.read_bytes()
    assert data.startswith(b"%PDF")


def test_images_to_pdf_multi_page(tmp_path):
    paths = []
    for i, color in enumerate([(255, 0, 0), (0, 255, 0), (0, 0, 255)]):
        p = tmp_path / f"page_{i}.png"
        _write_png(p, color)
        paths.append(p)
    out = tmp_path / "multi.pdf"

    images_to_pdf(paths, out)

    # img2pdf writes one xobject image per page; a 3-page PDF should be
    # meaningfully larger than a 1-page PDF of the same-size images.
    single = tmp_path / "single.pdf"
    images_to_pdf([paths[0]], single)
    assert out.stat().st_size > single.stat().st_size


def test_images_to_pdf_requires_at_least_one_image(tmp_path):
    with pytest.raises(ValueError):
        images_to_pdf([], tmp_path / "empty.pdf")


def test_images_to_pdf_creates_parent_dirs(tmp_path):
    img_path = tmp_path / "page.png"
    _write_png(img_path, (10, 20, 30))
    out = tmp_path / "nested" / "dir" / "out.pdf"

    images_to_pdf([img_path], out)

    assert out.exists()