import tempfile
import time
import unittest
from pathlib import Path

from backend.utils import cache as cache_utils


class CacheUtilsTests(unittest.TestCase):
    def setUp(self) -> None:
        self._tmp_dir = tempfile.TemporaryDirectory()
        self._old_cache_dir = cache_utils.CACHE_DIR
        cache_utils.CACHE_DIR = Path(self._tmp_dir.name) / "cache"

        self._work_dir = Path(self._tmp_dir.name) / "work"
        self._work_dir.mkdir(parents=True, exist_ok=True)
        self._src_file = self._work_dir / "sample.txt"
        self._src_file.write_text("hello", encoding="utf-8")

    def tearDown(self) -> None:
        cache_utils.CACHE_DIR = self._old_cache_dir
        self._tmp_dir.cleanup()

    def test_get_file_hash_returns_none_for_missing_file(self) -> None:
        missing = self._work_dir / "missing.txt"
        self.assertIsNone(cache_utils.get_file_hash(missing))

    def test_save_and_load_round_trip(self) -> None:
        payload = {"value": 123, "ok": True}
        saved = cache_utils.save_to_cache(self._src_file, payload, model="m1", operation="transcribe")
        self.assertTrue(saved)

        loaded = cache_utils.load_from_cache(self._src_file, model="m1", operation="transcribe")
        self.assertEqual(payload, loaded)

    def test_load_from_cache_respects_max_age(self) -> None:
        payload = {"value": 999}
        self.assertTrue(cache_utils.save_to_cache(self._src_file, payload, operation="transcribe"))

        time.sleep(0.02)
        expired = cache_utils.load_from_cache(self._src_file, operation="transcribe", max_age=0.001)
        self.assertIsNone(expired)

    def test_clear_cache_deletes_files(self) -> None:
        self.assertTrue(cache_utils.save_to_cache(self._src_file, {"a": 1}, operation="transcribe"))
        self.assertTrue(cache_utils.save_to_cache(self._src_file, {"a": 2}, operation="summarize"))

        deleted_count = cache_utils.clear_cache()
        self.assertGreaterEqual(deleted_count, 1)

        size_bytes, file_count = cache_utils.get_cache_size()
        self.assertEqual(size_bytes, 0)
        self.assertEqual(file_count, 0)


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