#!/usr/bin/env python3
import configparser, logging, requests, traceback
from icalendar.cal import Calendar

log_option = {
    'format': '[%(asctime)s] [%(levelname)s] %(message)s',
    'level': getattr(logging, 'INFO')
}
logging.basicConfig(**log_option)
logging.getLogger("requests").setLevel(logging.WARNING)

CALDAVURL = '%sremote.php/dav/calendars/%s/%s'


def do_import(username, password, calendar, server, ics_url, ics_username, ics_password):
    logging.info('  Working with calendar %s...' % calendar)
    base_url = CALDAVURL % (server, username, calendar)

    target_fetch_url = '%s?export' % base_url
    r = requests.get(target_fetch_url, auth=(username, password))
    r.raise_for_status()
    try:
        target_cal = Calendar.from_ical(r.text)
    except ValueError as e:
        logging.error('    Warning: Could not parse iCal (%s)' % target_fetch_url)
        logging.error(e)
        return

    existing_uids = [bytes.decode(e['UID'].to_ical()).replace('\'', '').replace('/', 'slash') for e in target_cal.walk('VEVENT')]

    sourceRequest = requests.get(ics_url, auth=(ics_username, ics_password))
    sourceRequest.encoding = 'utf-8'
    sourceContent = sourceRequest.text
    c = Calendar.from_ical(sourceContent)

    distant_uids = [bytes.decode(e['UID'].to_ical()).replace('\'', '').replace('/', 'slash') for e in c.walk('VEVENT')]

    imported_uids = []
    for e in c.walk('VEVENT'):
        uid = bytes.decode(e['UID'].to_ical()).replace('\'', '').replace('/', 'slash')
        name = bytes.decode(e['SUMMARY'].to_ical())
        if uid not in existing_uids:
            cal = Calendar()
            cal.add_component(e)
            r = requests.put('%s/%s.ics' % (base_url, uid),
                             data=cal.to_ical(),
                             auth=(username, password),
                             headers={'content-type': 'text/calendar; charset=UTF-8'}
                             )
            if r.status_code == 500 and r'Sabre\VObject\Recur\NoInstancesException' in r.text:
                logging.warning('   No valid instances: %s (%s)' % (uid, name))
            elif r.status_code == 201 or r.status_code == 204:
                logging.info('   Imported: %s (%s)' % (uid, name))
                imported_uids.append(uid)
            else:
                r.raise_for_status()

    for euid in existing_uids:
        if not euid in distant_uids:
            r = requests.delete('%s/%s.ics' % (base_url, euid), auth=(username, password))
        if r.status_code == 204:
            logging.info('Deleted %s' % euid)
        elif r.status_code == 404:
            pass
        else:
            r.raise_for_status()
    logging.info('  Done.')


if __name__ == '__main__':
    logging.info('Initializing script...')
    Config = configparser.RawConfigParser()
    Config.read('nextcloud_ics_sync.ini')
    logging.info('Done.')
    logging.info('Importing calendars...')
    for key in Config.sections():
        logging.info(' Working on section %s' % key)
        try:
            do_import(
                Config.get(key, 'username'), Config.get(key, 'password'), Config.get(key, 'calendar'), Config.get(key, 'server'),
                Config.get(key, 'ics_url'), Config.get(key, 'ics_username'), Config.get(key, 'ics_password')
            )
        except Exception as e:
            logging.error(traceback.print_exc())
        logging.info(' Done.')
    logging.info('Done.')