from datetime import date, timedelta,datetime
import calendar
import sys


def read_date_from_argument(value, default_value):
    if value is not None:
        if type(value) is list:
            value = value[0]
        return datetime.strptime(value, "%Y-%m-%d").date()
    return default_value


def get_time(args, def_start=date.today(), def_end=date.today()):

    if (args.start is not None or args.end is not None) and (args.date is not None or args.week is True or args.month is True):
        print "Either specify period options or reference options"
        sys.exit(1)

    if args.start is not None or args.end is not None:
        return read_date_from_argument(args.start, def_start),read_date_from_argument(args.end, def_end)

    if args.date is not None or args.week is True or args.month is True:
        base_date = read_date_from_argument(args.date, def_start)
        if args.week is True:
            return get_week_dates(base_date)
        if args.month is True:
            return get_month_dates(base_date)
        return base_date, base_date

    return def_start, def_end


def get_month_dates(base_date):
    last_day_of_the_month = calendar.monthrange(base_date.year, base_date.month)[1]
    start_date = datetime.strptime(str(base_date.year) + "-" + str(base_date.month) + "-1", "%Y-%m-%d").date()
    end_date = datetime.strptime(str(base_date.year) + "-" + str(base_date.month) + "-" + str(last_day_of_the_month), "%Y-%m-%d").date()
    if start_date > date.today():
        start_date = date.today()
    if end_date > date.today():
        end_date = date.today()
    return start_date, end_date


def get_week_dates(base_date):
    monday = base_date - timedelta(days=base_date.isoweekday() - 1)
    week_dates = [monday + timedelta(days=i) for i in range(7)]
    start_date = week_dates[0]
    end_date = week_dates[6]
    if start_date > date.today():
        start_date = date.today()
    if end_date > date.today():
        end_date = date.today()
    return start_date, end_date


def add_time_options(parser):
    group1 = parser.add_argument_group('period', 'Period Selection')
    group1.add_argument('--start', nargs=1, help='Start Date')
    group1.add_argument('--end', nargs=1, help='End Date')
    group2 = parser.add_argument_group('reference', 'Reference date selection')
    group2.add_argument('--date', nargs=1, help='Reference date/today')
    group2.add_argument('--month', action='store_true', help='Display the month of the reference')
    group2.add_argument('--week', action='store_true', help='Display the week of the reference')