import tempfile
import unittest
from pathlib import Path

from PIL import Image

from split_nsfw_test_image import split_image


class SplitImageTests(unittest.TestCase):
    def setUp(self):
        self.temporary = tempfile.TemporaryDirectory()
        self.addCleanup(self.temporary.cleanup)
        self.root = Path(self.temporary.name)
        self.source = self.root / "source.png"
        self.image = Image.new("RGBA", (4, 3))
        self.image.putdata([(i * 21, 255 - i * 21, i * 7, i * 23) for i in range(12)])
        self.image.save(self.source)

    def test_random_shares_losslessly_reconstruct_pixels_and_alpha(self):
        first, second = split_image(self.source, self.root / "one")
        self.assertEqual((first.name, second.name), ("image_1a.png", "image_1b.png"))
        with Image.open(first) as a, Image.open(second) as b:
            self.assertEqual(a.mode, "RGBA")
            self.assertEqual(a.size, self.image.size)
            self.assertEqual(b.size, self.image.size)
            reconstructed = bytes(x ^ y for x, y in zip(a.tobytes(), b.tobytes()))
            self.assertEqual(reconstructed, self.image.tobytes())
        other_first, _ = split_image(self.source, self.root / "two")
        self.assertNotEqual(first.read_bytes(), other_first.read_bytes())

    def test_refuses_to_overwrite_and_supports_numbered_pairs(self):
        directory = self.root / "fixtures"
        first, second = split_image(self.source, directory)
        original = (first.read_bytes(), second.read_bytes())
        with self.assertRaises(FileExistsError):
            split_image(self.source, directory)
        self.assertEqual((first.read_bytes(), second.read_bytes()), original)
        next_pair = split_image(self.source, directory, index=2)
        self.assertEqual(tuple(path.name for path in next_pair), ("image_2a.png", "image_2b.png"))

    def test_rejects_nonpositive_indices_and_nonimages_without_writing_parts(self):
        directory = self.root / "fixtures"
        for index in (0, -1):
            with self.assertRaises(ValueError):
                split_image(self.source, directory, index)
        invalid = self.root / "invalid.txt"
        invalid.write_text("not an image")
        with self.assertRaises(OSError):
            split_image(invalid, directory)
        self.assertFalse(directory.exists())


if __name__ == "__main__":
    unittest.main()