"""Real-Git checks for pinned initialization and safe legacy migration; no network."""
import importlib.util
import os
from pathlib import Path
import subprocess
import tempfile
import unittest
from unittest.mock import patch

spec = importlib.util.spec_from_file_location('airdef_tool', Path(__file__).with_name('airdef.py'))
tool = importlib.util.module_from_spec(spec)
spec.loader.exec_module(tool)


def git(where, *args):
    return subprocess.check_output(['git', '-C', str(where), *args], stderr=subprocess.STDOUT, text=True).strip()


class CheckoutTests(unittest.TestCase):
    def setUp(self):
        self.tmp = tempfile.TemporaryDirectory()
        self.addCleanup(self.tmp.cleanup)
        self.base = Path(self.tmp.name)
        self.engine = self.base / 'engine'
        self.engine.mkdir()
        git(self.engine, 'init', '-q')
        git(self.engine, 'config', 'user.name', 'Fixture')
        git(self.engine, 'config', 'user.email', 'fixture@example.invalid')
        (self.engine / 'marker').write_text('old')
        git(self.engine, 'add', 'marker')
        git(self.engine, 'commit', '-qm', 'old')
        self.old = git(self.engine, 'rev-parse', 'HEAD')
        (self.engine / 'marker').write_text('new')
        git(self.engine, 'commit', '-qam', 'new')
        self.new = git(self.engine, 'rev-parse', 'HEAD')
        self.parent = self.base / 'airdef'
        self.parent.mkdir()
        git(self.parent, 'init', '-q')
        (self.parent / '.gitmodules').write_text('[submodule "horizon"]\n path = horizon\n url = ' + str(self.engine) + '\n')
        git(self.parent, 'add', '.gitmodules')
        self.pin(self.old)
        self.addCleanup(patch.stopall)
        patch.object(tool, 'ROOT', self.parent).start()
        patch.object(tool, 'FORK', self.parent / 'horizon').start()
        patch.dict(os.environ, {'GIT_ALLOW_PROTOCOL': 'file'}).start()

    def pin(self, sha):
        git(self.parent, 'update-index', '--add', '--cacheinfo', '160000,' + sha + ',horizon')

    def test_initialization_uses_pin_instead_of_newer_tip(self):
        tool.fork()
        self.assertEqual(git(tool.FORK, 'rev-parse', 'HEAD'), self.old)
        self.assertEqual((tool.FORK / 'marker').read_text(), 'old')
        tool.fork()  # idempotent

    def test_dirty_checkout_is_preserved_when_pin_changes(self):
        tool.fork()
        (tool.FORK / 'marker').write_text('user changes')
        self.pin(self.new)
        with self.assertRaises(SystemExit):
            tool.fork()
        self.assertEqual((tool.FORK / 'marker').read_text(), 'user changes')
        self.assertEqual(git(tool.FORK, 'rev-parse', 'HEAD'), self.old)

    def test_old_standalone_clone_is_absorbed_without_losing_branches(self):
        git(self.parent, 'clone', str(self.engine), 'horizon')
        git(tool.FORK, 'checkout', '-qb', 'my-work', self.old)
        self.pin(self.new)
        tool.fork()
        self.assertTrue((tool.FORK / '.git').is_file())
        self.assertEqual(git(tool.FORK, 'rev-parse', 'HEAD'), self.new)
        self.assertEqual(git(tool.FORK, 'rev-parse', 'my-work'), self.old)


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