#!/usr/bin/python3

# Copyright (C) 2015  Stefano Zacchiroli <zack@upsilon.cc>
# License: GNU General Public License version 3, or any later version
# See top-level LICENSE file for more information

import argparse
import configparser
import logging
import os
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

from ghlister import lister, models


DEFAULT_CONF = {
    'cache_dir': './cache',
    'log_dir': './log',
}


# where to store raw json answers, for further processing/re-injection
CACHE_DIR = 'cache'


def db_connect(db_url):
    engine = create_engine(db_url)
    Session = sessionmaker(bind=engine)

    return (engine, Session)


def int_interval(s):
    """parse an "N-M" string as an interval.

    Return an (N,M) int (or None) pair

    """
    def not_an_interval():
        raise argparse.ArgumentTypeError('not an interval: ' + s)

    def parse_int(s):
        if s:
            return int(s)
        else:
            return None

    if '-' not in s:
        not_an_interval()
    parts = s.split('-')
    if len(parts) > 2:
        not_an_interval()
    return tuple([parse_int(p) for p in parts])


def parse_args():
    cli = argparse.ArgumentParser(
        description='list GitHub repositories and load them into a DB')
    cli.add_argument('--db-url', '-d', metavar='SQLALCHEMY_URL',
                     help='SQLAlchemy DB URL (override conffile); see '
        + '<http://docs.sqlalchemy.org/en/latest/core/engines.html#database-urls>')  # NOQA
    cli.add_argument('--verbose', '-v', action='store_true',
                     help='be verbose')

    subcli = cli.add_subparsers(dest='action')
    subcli.add_parser('createdb', help='initialize DB')
    subcli.add_parser('dropdb', help='destroy DB')

    list_cli = subcli.add_parser('list', help='list repositories')
    list_cli.add_argument('interval',
                          type=int_interval,
                          help='interval of repository IDs to list, '
                          + 'in N-M format; either N or M can be omitted.')

    args = cli.parse_args()

    return args


def read_conf(args):
    config = configparser.ConfigParser(defaults=DEFAULT_CONF)
    config.read(os.path.expanduser('~/.config/ghlister.ini'))

    conf = config._sections['main']

    # overrides
    if args.db_url:
        conf['db_url'] = args.db_url

    return conf


if __name__ == '__main__':
    logging.basicConfig(level=logging.INFO)  # XXX

    args = parse_args()
    conf = read_conf(args)

    db_engine, mk_session = db_connect(conf['db_url'])

    if args.action == 'createdb':
        models.SQLBase.metadata.create_all(db_engine)
    elif args.action == 'dropdb':
        models.SQLBase.metadata.drop_all(db_engine)
    elif args.action == 'list':
        lister.fetch(conf,
                     mk_session,
                     min_id=args.interval[0],
                     max_id=args.interval[1])