import hashlib
import io
import json
import os
from pathlib import Path
import tarfile
import tempfile
import unittest
from materialize_agent_context import materialize


def fixture(root, target='/testbed/npm/pacote', declared=True, wrong_blob=False):
    expected = '/testbed/npm/pacote'
    blob = hashlib.sha1(b'blob ' + str(len(expected)).encode() + b'\0' + expected.encode()).hexdigest()
    link = {'path': 'node_modules/pacote', 'original_target': expected, 'expected_blob': '0' * 40 if wrong_blob else blob, 'target_repository': 'provider'}
    instance = {'repositories': [{'key': 'cli', 'path': '/testbed/npm/cli', 'workspace_links': [link] if declared else []},
                                  {'key': 'provider', 'path': expected, 'workspace_links': []}]}
    payload = {'instance.json': json.dumps(instance).encode(), 'testbed/npm/pacote/package.json': b'{}'}
    archive = root / 'context.tar.gz'; entries = []
    with tarfile.open(archive, 'w:gz') as tf:
        for name, data in payload.items():
            info = tarfile.TarInfo(name); info.size = len(data); info.mode = 0o644
            tf.addfile(info, io.BytesIO(data))
            entries.append({'path': name, 'bytes': len(data), 'sha256': hashlib.sha256(data).hexdigest(), 'mode': 0o644})
        name = 'testbed/npm/cli/node_modules/pacote'
        info = tarfile.TarInfo(name); info.type = tarfile.SYMTYPE; info.linkname = target; info.mode = 0o777; tf.addfile(info)
        entries.append({'path': name, 'kind': 'symlink', 'target': target, 'bytes': len(target), 'sha256': hashlib.sha256(target.encode()).hexdigest(), 'mode': 0o777})
    raw = archive.read_bytes()
    manifest = root / 'context-manifest.json'
    manifest.write_text(json.dumps({'schema_version': 3, 'archive': {'path': archive.name, 'bytes': len(raw), 'sha256': hashlib.sha256(raw).hexdigest()}, 'files': entries}))
    return manifest


class ContainerLinkTests(unittest.TestCase):
    def test_declared_paired_link_preserves_exact_git_blob(self):
        with tempfile.TemporaryDirectory() as tmp:
            root = Path(tmp); manifest = fixture(root)
            materialize(manifest, root / 'out')
            self.assertEqual(os.readlink(root / 'out/testbed/npm/cli/node_modules/pacote'), '/testbed/npm/pacote')
            self.assertEqual((root / 'out/testbed/npm/pacote/package.json').read_bytes(), b'{}')

    def test_undeclared_absolute_link_is_rejected(self):
        with tempfile.TemporaryDirectory() as tmp:
            root = Path(tmp)
            with self.assertRaises(ValueError): materialize(fixture(root, declared=False), root / 'out')

    def test_declaration_cannot_authorize_an_unrelated_absolute_path(self):
        with tempfile.TemporaryDirectory() as tmp:
            root = Path(tmp)
            with self.assertRaises(ValueError): materialize(fixture(root, target='/etc'), root / 'out')

    def test_wrong_git_blob_is_rejected(self):
        with tempfile.TemporaryDirectory() as tmp:
            root = Path(tmp)
            with self.assertRaises(ValueError): materialize(fixture(root, wrong_blob=True), root / 'out')


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