import importlib.util
import tempfile
import unittest
from pathlib import Path


MODULE_PATH = Path(__file__).parents[2] / "autoinstall/offline/python-environment-checkpoint.py"
SPEC = importlib.util.spec_from_file_location("python_environment_checkpoint", MODULE_PATH)
MODULE = importlib.util.module_from_spec(SPEC)
assert SPEC.loader
SPEC.loader.exec_module(MODULE)


class PythonEnvironmentCheckpointTests(unittest.TestCase):
    def test_create_verify_modify_and_restore(self):
        with tempfile.TemporaryDirectory() as directory:
            root = Path(directory)
            target = root / "venv"
            target.mkdir()
            (target / "package.py").write_text("old\n")
            (target / "link").symlink_to("package.py")
            checkpoint = root / "checkpoint"
            created = MODULE.create(target, checkpoint, "op-1")
            self.assertEqual(MODULE.verify(checkpoint, target)["inventory_sha256"],
                             created["inventory_sha256"])
            (target / "package.py").write_text("new\n")
            MODULE.restore(checkpoint, target)
            self.assertEqual((target / "package.py").read_text(), "old\n")
            self.assertEqual((target / "link").readlink(), Path("package.py"))

    def test_payload_tamper_fails(self):
        with tempfile.TemporaryDirectory() as directory:
            root = Path(directory)
            target = root / "venv"
            target.mkdir()
            (target / "package.py").write_text("old\n")
            checkpoint = root / "checkpoint"
            MODULE.create(target, checkpoint, "op-1")
            (checkpoint / "payload/package.py").write_text("tampered\n")
            with self.assertRaisesRegex(MODULE.CheckpointError, "PAYLOAD_INVALID"):
                MODULE.verify(checkpoint, target)

    def test_absent_target_restore_quarantines_new_tree(self):
        with tempfile.TemporaryDirectory() as directory:
            root = Path(directory)
            target = root / "venv"
            checkpoint = root / "checkpoint"
            MODULE.create(target, checkpoint, "op-1")
            target.mkdir()
            (target / "new").write_text("new")
            MODULE.restore(checkpoint, target)
            self.assertFalse(target.exists())
            self.assertTrue((root / ".venv.rollback-discard/new").exists())

    def test_recover_after_quarantine_and_after_activation(self):
        with tempfile.TemporaryDirectory() as directory:
            root = Path(directory)
            target = root / "venv"
            target.mkdir()
            (target / "package.py").write_text("old\n")
            checkpoint = root / "checkpoint"
            MODULE.create(target, checkpoint, "op-1")
            (target / "package.py").write_text("new\n")
            quarantine = root / ".venv.rollback-discard"
            target.rename(quarantine)
            MODULE.recover_restore(checkpoint, target)
            self.assertEqual((target / "package.py").read_text(), "old\n")
            # A retry after activation is idempotent and preserves the failed tree.
            MODULE.recover_restore(checkpoint, target)
            self.assertEqual((quarantine / "package.py").read_text(), "new\n")


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