#!/usr/bin/env python3

import argparse
import os
import sys
import dateutil.parser
import subprocess

PROG = os.path.basename(sys.argv[0])

SCRIPT_PATH = os.path.realpath(__file__)
ROOT_DIR = os.path.dirname(SCRIPT_PATH)

LAMMPS_REPO_DIR = os.path.join(ROOT_DIR, "../lammps")

def main():
    parser = argparse.ArgumentParser(
        description='checks out a version for the lammps submodule',
    )
    parser.add_argument('STYLE',
        choices=['stable', 'patch'],
        help='stable release or not?')
    parser.add_argument('DATE',
        type=dateutil.parser.parse,
        help='release date of desired version. It will be parsed by'
        ' dateutil.parser.parse which accepts a variety of formats.')
    args = parser.parse_args()

    tag = lammps_git_tag_from_datetime(args.STYLE, args.DATE)
    cmd_checkout_for_submodule(tag)

def lammps_git_tag_from_datetime(style, dt):
    # can't use strftime because the month abbreviations must not be
    # dependent on the locale
    month = [None,
        'Jan', 'Feb', 'Mar', 'Apr',
        'May', 'Jun', 'Jul', 'Aug',
        'Sep', 'Oct', 'Nov', 'Dec',
    ][dt.month]

    # ladies and gentleman, I present to you the worst possible date
    # format for anything that is to be lexically sorted.
    return '{}_{}{}{}'.format(style, dt.day, month, dt.year)

def cmd_checkout_for_submodule(commit_or_tag):
    subprocess.check_call(
        ['git', 'fetch', "--tags"],
        cwd=os.path.join(LAMMPS_REPO_DIR),
    )
    return subprocess.check_call(
        ['git', 'checkout', commit_or_tag],
        cwd=os.path.join(LAMMPS_REPO_DIR),
    )

# ------------------------------------------------------

def warn(*args, **kw):
    print(f'{PROG}:', *args, file=sys.stderr, **kw)

def die(*args, code=1):
    warn('Fatal:', *args)
    sys.exit(code)

# ------------------------------------------------------

if __name__ == '__main__':
    main()