def parse_stupid_date(c):
    """
    kdbが返してくる間抜けな授業時間をパースしてdatetimeを返す

    例:

        月1
        木3,4
        水3,4金5,6
        月・火・水3-6

        sqlite3 ~/.course_list.db 'select periods from courses'|sort|uniq
    """
    start_time = {
        1: { "hour": 8, "minute": 40 },
        2: { "hour": 10, "minute": 10 },
        3: { "hour": 12, "minute": 15 },
        4: { "hour": 13, "minute": 45 },
        5: { "hour": 15, "minute": 15 },
        6: { "hour": 16, "minute": 45 },
    }

    end_time = {
        1: { "hour": 9, "minute": 55 },
        2: { "hour": 11, "minute": 25 },
        3: { "hour": 13, "minute": 30 },
        4: { "hour": 15, "minute": 0 },
        5: { "hour": 16, "minute": 30 },
        6: { "hour": 18, "minute": 0 },
    }

    periods = c['periods']
    dates = []
    while len(periods) > 0:
        m = re.search('((?:.・)*(?:.))([0-9])([,-])([0-9])', periods)
        assert(m is not None)

        groups = list(reversed(list(m.groups())))
        weekdays = groups.pop().split('・')
        period_start = int(groups.pop())

        if len(groups) == 0:
            sep = ','
            period_end = period_start
        else:
            sep = groups.pop()
            period_end = int(groups.pop())

        assert(sep in ['-', ','])
        assert(1 <= period_start <= 6)
        assert(1 <= period_end <= 6)

        if sep == ',':
            assert(period_end - period_start == 1)

        for weekday in weekdays:
            dt = get_start_date(c['modules'], weekday)
            dt_start = dt.replace(**start_time[period_start])
            dt_end = dt.replace(**end_time[period_end])
            dates.append((dt_start, dt_end))

        periods = periods[m.span()[1]:]

    return dates