order south migration

order_migrations.py

from argparse import ArgumentParser
from contextlib import contextmanager
from subprocess import Popen, PIPE
import sys
import os
import re


def git(*args):
    resp = Popen(['git'] + list(args), stdout=PIPE, stderr=PIPE)
    return resp.stdout.readline()[:-1]


@contextmanager
def branch(dest, current):
    try:
        yield git('checkout', dest)
    finally:
        git('checkout', current)


def get_opts():
    parser = ArgumentParser()
    parser.add_argument(
        '--to-branch', type=unicode, default='master')
    parser.add_argument(
        '--path', type=unicode, required=True)
    return parser.parse_args(sys.argv[1:])


def get_migrations(path):
    return [x for x in os.listdir(path)
            if not x.endswith('.pyc')
            and not x == '__init__.py']


def to_pairs(migrations):
    pairs = [
        (int(re.match(r'^(\d+).*', m).group(1)), m)
        for m in migrations]
    return sorted(pairs, key=lambda m: m[0])


def last_number(migrations):
    return to_pairs(migrations)[-1][0]


def replace_number(migration, number):
    rest = re.match(r'^\d+(.*)', migration).group(1)
    return '{0:04d}{rest}'.format(number, rest=rest)


def get_replacements(number, new_migrations):
    return [
        (name, replace_number(name, n))
        for n, (_, name) in enumerate(to_pairs(new_migrations),
                                      start=number)]


def is_replacements_confirmed(replacements):
    print 'Are you sure want to rename migrations:'
    for orig, new in replacements:
        print '{} -> {}'.format(orig, new)
    return raw_input('Y/N: ') in ('y', 'Y')


def perform_replacements(replacements, path):
    for orig, new in replacements:
        new_path = os.path.join(path, new)
        os.rename(os.path.join(path, orig),
                  new_path)
        git('add', new_path)


def main():
    opts = get_opts()

    current_branch = git('rev-parse', '--abbrev-ref', 'HEAD')
    current_migrations = get_migrations(opts.path)

    with branch(opts.to_branch, current_branch):
        dest_migrations = get_migrations(opts.path)

    new_migrations = set(current_migrations).difference(dest_migrations)

    number = last_number(dest_migrations) + 1

    replacements = get_replacements(number, new_migrations)

    if is_replacements_confirmed(replacements):
        perform_replacements(replacements, opts.path)
        print 'All migrations renamed!'
    else:
        print 'Abort.'


if __name__ == '__main__':
    main()