import hashlib
import io
import json
from pathlib import Path
import tarfile
import tempfile
import unittest

from materialize_agent_context import materialize


class MaterializeTests(unittest.TestCase):
    def fixture(self, root, member='Dockerfile', payload=b'FROM scratch\n'):
        root = Path(root)
        archive = root / 'context.tar.gz'
        with tarfile.open(archive, 'w:gz') as tar:
            info = tarfile.TarInfo(member)
            info.size = len(payload)
            info.mode = 0o644
            tar.addfile(info, io.BytesIO(payload))
        data = archive.read_bytes()
        record = {'archive': {'path': archive.name, 'sha256': hashlib.sha256(data).hexdigest(), 'bytes': len(data)},
                  'files': [{'path': member, 'sha256': hashlib.sha256(payload).hexdigest(), 'bytes': len(payload), 'mode': 0o644}]}
        (root / 'context-manifest.json').write_text(json.dumps(record))
        return root / 'context-manifest.json'

    def test_exact_context_is_restored(self):
        with tempfile.TemporaryDirectory() as temp:
            record = self.fixture(temp)
            out = Path(temp) / 'out'
            materialize(record, out)
            self.assertEqual((out / 'Dockerfile').read_bytes(), b'FROM scratch\n')

    def test_tampered_archive_is_rejected_before_extraction(self):
        with tempfile.TemporaryDirectory() as temp:
            record = self.fixture(temp)
            with (Path(temp) / 'context.tar.gz').open('ab') as stream:
                stream.write(b'changed')
            with self.assertRaises(ValueError):
                materialize(record, Path(temp) / 'out')
            self.assertFalse((Path(temp) / 'out').exists())

    def test_traversal_member_is_rejected(self):
        with tempfile.TemporaryDirectory() as temp:
            record = self.fixture(temp, '../escape')
            with self.assertRaises(ValueError):
                materialize(record, Path(temp) / 'out')
            self.assertFalse((Path(temp) / 'escape').exists())

    def test_existing_output_is_preserved(self):
        with tempfile.TemporaryDirectory() as temp:
            record = self.fixture(temp)
            out = Path(temp) / 'out'
            out.mkdir()
            (out / 'keep').write_text('preserve')
            with self.assertRaises(FileExistsError):
                materialize(record, out)
            self.assertEqual((out / 'keep').read_text(), 'preserve')

    def test_unlisted_member_is_rejected(self):
        with tempfile.TemporaryDirectory() as temp:
            record = self.fixture(temp)
            data = json.loads(record.read_text())
            data['files'] = []
            record.write_text(json.dumps(data))
            with self.assertRaises(ValueError):
                materialize(record, Path(temp) / 'out')


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