#!/usr/bin/env python3

# Contest Management System - http://cms-dev.github.io/
# Copyright © 2013 Luca Wehrstedt <luca.wehrstedt@gmail.com>
# Copyright © 2013-2015 Giovanni Mascellani <mascellani@poisson.phc.unipi.it>
# Copyright © 2014 William Di Luigi <williamdiluigi@gmail.com>
# Copyright © 2016 Stefano Maggiolo <s.maggiolo@gmail.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""A script to update a dump created by CMS.

This script updates a dump (i.e. a set of exported contest data, as
created by DumpExporter) of the Contest Management System from any
of the old supported versions to the current one.

"""

# We enable monkey patching to make many libraries gevent-friendly
# (for instance, urllib3, used by requests)
import gevent.monkey
gevent.monkey.patch_all()  # noqa

import argparse
import json
import logging
import os
import shutil
import sys

from cms import utf8_decoder
from cms.db import version as model_version
from cmscommon.archive import Archive


logger = logging.getLogger(__name__)


def main():
    parser = argparse.ArgumentParser(
        description="Updater of CMS contest dumps.")
    parser.add_argument(
        "-V", "--to-version", action="store", type=int, default=-1,
        help="Update to given version number")
    parser.add_argument(
        "path", action="store", type=utf8_decoder,
        help="location of the dump or of the 'contest.json' file")

    args = parser.parse_args()
    path = args.path

    to_version = args.to_version
    if to_version == -1:
        to_version = model_version

    if not os.path.exists(path):
        logger.critical("The given path doesn't exist")
        return 1

    archive = None
    if Archive.is_supported(path):
        archive = Archive(path)
        path = archive.unpack()

        file_names = os.listdir(path)
        if len(file_names) != 1:
            logger.critical("Cannot find a root directory in the "
                            "archive.")
            archive.cleanup()
            return 1

        path = os.path.join(path, file_names[0])

    if not path.endswith("contest.json"):
        path = os.path.join(path, "contest.json")

    if not os.path.exists(path):
        logger.critical(
            "The given path doesn't contain a contest dump in a format "
            "CMS is able to understand.")
        return 1

    with open(path, 'rb') as fin:
        data = json.load(fin)

    # If no "_version" field is found we assume it's a v1.0
    # export (before the new dump format was introduced).
    dump_version = data.get("_version", 0)

    if dump_version == to_version:
        logger.info(
            "The dump you're trying to update is already stored using "
            "the target format (which is version %d).", dump_version)
        return 1

    elif dump_version > model_version:
        logger.critical(
            "The dump you're trying to update is stored using data model "
            "version %d, which is more recent than the one supported by "
            "this version of CMS (version %d). You probably need to "
            "update CMS to handle it.", dump_version, model_version)
        return 1

    elif to_version > model_version:
        logger.critical(
            "The target data model (version %d) you're trying to update "
            "to is too recent for this version of CMS (which supports up "
            "to version %d). You probably need to update CMS to handle "
            "it.", to_version, model_version)
        return 1

    elif dump_version > to_version:
        logger.critical(
            "Backward updating (from version %d to version %d) is not "
            "supported.", dump_version, to_version)
        return 1

    for version in range(dump_version, to_version):
        # Update from version to version+1
        updater = __import__(
            "cmscontrib.updaters.update_%d" % (version + 1),
            globals(), locals(), ["Updater"]).Updater(data)
        data = updater.run()
        data["_version"] = version + 1

    assert data["_version"] == to_version

    with open(path, 'wt', encoding="utf-8") as fout:
        json.dump(data, fout, indent=4, sort_keys=True)

    if archive is not None:
        # Keep the old archive, just rename it
        shutil.move(archive.path, archive.path + ".bak")
        archive.repack(os.path.abspath(archive.path))
        archive.cleanup()

    return 0


if __name__ == "__main__":
    sys.exit(main())