import importlib.util
import json
from pathlib import Path
import subprocess
import tempfile
import unittest
from unittest.mock import patch

spec=importlib.util.spec_from_file_location('backup',Path(__file__).parents[1]/'scripts/backup.py')
b=importlib.util.module_from_spec(spec); spec.loader.exec_module(b)


class BackupTests(unittest.TestCase):
    def test_restores_original_file_and_removes_new_file(self):
        with tempfile.TemporaryDirectory() as d:
            base=Path(d); original=base/'old.conf'; new=base/'new.conf'
            original.write_text('original')
            def ctl(*args): return subprocess.CompletedProcess(args, 1, stdout='')
            with patch.object(b,'PATHS',[str(original),str(new)]), patch.object(b,'ctl',side_effect=ctl):
                b.snapshot(base/'backup')
                original.write_text('changed'); new.write_text('new')
                b.restore(base/'backup')
            self.assertEqual(original.read_text(),'original')
            self.assertFalse(new.exists())

    def test_preserves_symlinks(self):
        with tempfile.TemporaryDirectory() as d:
            base=Path(d); link=base/'service'; original=base/'target'
            original.write_text('original'); link.symlink_to(original)
            def ctl(*args): return subprocess.CompletedProcess(args, 1, stdout='')
            with patch.object(b,'PATHS',[str(link)]), patch.object(b,'ctl',side_effect=ctl):
                b.snapshot(base/'backup')
                link.unlink(); link.write_text('replaced')
                b.restore(base/'backup')
            self.assertTrue(link.is_symlink())
            self.assertEqual(link.read_text(),'original')

    def test_rejects_snapshot_with_unexpected_file(self):
        with tempfile.TemporaryDirectory() as d:
            base=Path(d)
            (base/'manifest.json').write_text(json.dumps({'files':{'/unexpected':True},'units':{}}))
            with patch.object(b,'ctl') as ctl, self.assertRaises(ValueError): b.restore(base)
            ctl.assert_not_called()


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