"""Closed-file operator backup. Shared Deployment helpers are injected by the caller."""


def backup(deployment, output):
    deployment.preflight()
    if deployment.pending.exists():
        raise RuntimeError('Resolve the pending deployment before creating a backup')
    expected = manifest(deployment.app / 'current')
    if expected != json.loads((deployment.app / 'deployed.json').read_text()):
        raise RuntimeError('Current release differs from the verified deployment manifest')
    state = deployment.command('systemctl', '--user', 'show', deployment.service, '--property=ActiveState', '--value')
    if state not in {'active', 'inactive', 'failed'}:
        raise RuntimeError('Service is transitioning; retry when its state is stable')
    was_running = state == 'active'
    if not was_running and deployment.command('systemctl', '--user', 'show', deployment.service, '--property=MainPID', '--value') != '0':
        raise RuntimeError('Stopped service still has a process')
    had_maintenance = deployment.flag.exists()
    with tempfile.TemporaryDirectory(prefix='manual-backup-', dir=deployment.app) as temporary:
        snapshot = Path(temporary)
        (snapshot / 'release').mkdir(mode=0o700)
        # Immutable release files can be copied before stopping, under the deployment lock.
        for name in ('werkjournal.jar', 'manifest.json'):
            shutil.copyfile(deployment.app / 'current' / name, snapshot / 'release' / name)
        if not had_maintenance:
            deployment.maintenance()
        if was_running:
            deployment.stop()
        try:
            shutil.copytree(deployment.app / 'data', snapshot / 'data')
            files = {}
            for path in sorted(snapshot.rglob('*')):
                if path.is_file():
                    with path.open('rb') as stream:
                        os.fsync(stream.fileno())
                    files[path.relative_to(snapshot).as_posix()] = checksum(path)
            atomic(snapshot / 'backup.json', json.dumps({
                'schemaVersion': 1, 'application': 'werkjournal', 'createdAt': int(time.time()),
                'release': expected, 'files': files}, indent=2) + '\n')
        finally:
            if was_running:
                deployment.start()
                deployment.ready(expected)
            if not had_maintenance:
                deployment.flag.unlink()
                sync_directory(deployment.site)
        # Transfer only after the former operating state has been restored.
        with tarfile.open(fileobj=output, mode='w|gz') as archive:
            for name in ['backup.json', *sorted(files)]:
                archive.add(snapshot / name, arcname=name, recursive=False)


if __name__ == '__main__':
    os.umask(0o077)
    deployment = Deployment(Path.home())
    try:
        with (deployment.app / '.deploy.lock').open('a') as lock:
            fcntl.flock(lock, fcntl.LOCK_EX | fcntl.LOCK_NB)
            backup(deployment, sys.stdout.buffer)
    except BlockingIOError:
        print('Backup refused: another deployment or maintenance operation holds the lock.', file=sys.stderr)
        raise SystemExit(1)
    except (OSError, RuntimeError, ValueError, subprocess.SubprocessError) as error:
        print('Backup failed: ' + str(error), file=sys.stderr)
        raise SystemExit(1)