#!/usr/bin/env python3
"""Small deterministic checks; this test never creates the ~1 GiB workload."""
import hashlib
from pathlib import Path
from tempfile import TemporaryDirectory
import unittest
from unittest.mock import patch

from generate_stress_pdf import IMAGE_BYTES, generate, validate_source


class StressGeneratorTest(unittest.TestCase):
    def test_real_images_are_unique_used_and_deterministic(self):
        with TemporaryDirectory(prefix="docview-generator-test-") as directory:
            paths = [Path(directory) / name for name in ("a.pdf", "b.pdf")]
            first, second = (generate(path, 5, 2) for path in paths)
            self.assertEqual(first["sha256"], second["sha256"])
            data = paths[0].read_bytes()
            self.assertEqual(hashlib.sha256(data).hexdigest(), first["sha256"])
            self.assertEqual(first["rasterPayloadBytes"], 2 * IMAGE_BYTES)
            self.assertEqual(validate_source(paths[0], first)["uniqueRasterDigests"], 2)
            self.assertEqual(data.count(b"/Subtype /Image"), 2)
            self.assertNotIn(b"/Filter", data)
            self.assertEqual(data.count(b"/Scan 4 0 R"), 3)
            self.assertEqual(data.count(b"/Scan 5 0 R"), 2)
            self.assertIn(b"DOCVIEW STRESS PAGE 00005 OF 00005 IMAGE 0000", data)

    def test_disk_limit_and_existing_files_fail_before_writing(self):
        with TemporaryDirectory(prefix="docview-generator-test-") as directory:
            path = Path(directory) / "source.pdf"
            with patch("generate_stress_pdf.shutil.disk_usage") as usage:
                usage.return_value.free = 0
                with self.assertRaises(RuntimeError):
                    generate(path, 5, 2)
                self.assertFalse(path.exists())
            path.write_bytes(b"preserve me")
            with self.assertRaises(FileExistsError):
                generate(path, 5, 2)
            self.assertEqual(path.read_bytes(), b"preserve me")


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