swty_downloader.py

#!/usr/local/bin/python

import argparse
import datetime
import os
import re
import urllib

class NotMatchingDateFormatException(Exception):
    pass

#TODO: Following two blocks can be simplified by using calendar module
class Weekday:
  MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY = range(7)
  WORKDAYS = [MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY]
  WEEKENDS = [SATURDAY, SUNDAY]
  WEEKDAYS = WORKDAYS + WEEKENDS


_MAP_WEEKDAY_TO_STR = {
      Weekday.MONDAY: 'Monday',
      Weekday.TUESDAY: 'Tuesday',
      Weekday.WEDNESDAY: 'Wednesday',
      Weekday.THURSDAY: 'Thursday',
      Weekday.FRIDAY: 'Friday',
      Weekday.SATURDAY: 'Saturday',
      Weekday.SUNDAY: 'Sunday',
    }

class Downloader(object):
    def __init__(self, start_date, end_date, chosen_days):
        self._start_date = start_date
        self._end_date = end_date
        self._chosen_days = chosen_days

    def start(self):
        for day in self._chosen_days:
            self._download_certain_weekday_programs(day)

    def _date_range(self):
        cur_date = self._start_date
        while cur_date <= self._end_date:
            yield cur_date
            cur_date += datetime.timedelta(days=1)

    def _download_certain_weekday_programs(self, day):
        weekday_name = _MAP_WEEKDAY_TO_STR[day]
        print('==>downloading {} programs'.format(weekday_name))
        for date in (date for date in self._date_range() if date.weekday() == day):
            self._download_program_of_date(date, weekday_name)

    def _download_program_of_date(self, date, subfolder):
        url = self._construct_url(date)
        filename = '{}_{}_{}.mp3'.format(date.year, date.month, date.day)
        if not os.path.exists(subfolder):
            os.mkdir(subfolder)
        self._download_file(url, os.path.join(subfolder, filename))

    def _construct_url(self, date):
        return 'http://swtychina.com/gb/audiodoc/{year}/{year}{month:02d}/{year}{month:02d}{day:02d}.mp3'.format(
                year=date.year,
                month=date.month,
                day=date.day,
                )

    def _download_file(self, url, filepath):
        print('-->downloading {}'.format(filepath))
        urllib.urlretrieve(url, filepath)

def _parse_string_to_date(date_str):
    re_parttern = '\d{4}-\d{1,2}-\d{1,2}'
    if not re.match(re_parttern, date_str):
        raise NotMatchingDateFormatException(
                'The format of date {} does not match the re patten {}'.format(date_str, re_parttern))
    date_list = date_str.split('-')
    date_list = map(int, date_list)
    return datetime.date(*date_list)

def _extract_chosen_workdays_from_args(args):
    chosen_workdays = []
    if args.mon:
        chosen_workdays.append(Weekday.MONDAY)
    if args.tue:
        chosen_workdays.append(Weekday.TUESDAY) 
    if args.wed:
        chosen_workdays.append(Weekday.WEDNESDAY)
    if args.thu:
        chosen_workdays.append(Weekday.THURSDAY)
    if args.fri:
        chosen_workdays.append(Weekday.FRIDAY) 

    if len(chosen_workdays) == 0:
      # if none of the workdays is chosen then return all workdays
      return Weekday.WORKDAYS
    else:
      return chosen_workdays

def _print_download_title(start_date, end_date, chosen_workdays):
    print('Downloading swty *{}* programs from {} to {}...'.format(
        ' '.join(map(lambda wd:_MAP_WEEKDAY_TO_STR[wd] ,chosen_workdays)),
        start_date,
        end_date
        )
    )

def main():
    parser = argparse.ArgumentParser('swty downloader')
    parser.add_argument('start_date', type=str, help='start date of downloading')
    parser.add_argument('end_date', type=str, help='end date of downloading')
    parser.add_argument('--mon', action='store_true', help='download Monday program')
    parser.add_argument('--tue', action='store_true', help='download Tuesday program')
    parser.add_argument('--wed', action='store_true', help='download Wednesday program')
    parser.add_argument('--thu', action='store_true', help='download Thursday program')
    parser.add_argument('--fri', action='store_true', help='download Friday program')
    args = parser.parse_args()

    start_date = _parse_string_to_date(args.start_date)
    end_date = _parse_string_to_date(args.end_date)
    assert start_date <= end_date, 'The start date must be before or equal to the end date'
    chosen_workdays = _extract_chosen_workdays_from_args(args)
    _print_download_title(start_date, end_date, chosen_workdays)

    downloader = Downloader(start_date, end_date, chosen_workdays)
    downloader.start()

if __name__ == '__main__':
    main()