"""
NTNOE SYNC is a simple script tha allows you to synchronize your NTNOE diary
with Google Calendar.

It will create a  `ntnoe` calendar among your Google calendars and write your
NTNOE calendar into. NTNOE_SYNC is availabe under the MIT license.


MIT License

Copyright (c) 2017 Hugo LEVY-FALK

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
"""

import datetime
import httplib2
import os
import requests
import logging
from logging.handlers import RotatingFileHandler

from apiclient import discovery
from oauth2client import client
from oauth2client import tools
from oauth2client.file import Storage

import icalendar

DEBUG = False
APP_DIR = os.path.dirname(os.path.abspath(__file__))
if DEBUG:
    DATA_DIR = APP_DIR
else:
    home_dir = os.path.expanduser('~')
    DATA_DIR = os.path.join(home_dir, ".ntnoe", "")
    if not os.path.exists(DATA_DIR):
        os.makedirs(DATA_DIR)

##### Logger stuff #####

logger = logging.getLogger()

if DEBUG:
    logger.setLevel(logging.DEBUG)
else:
    logger.setLevel(logging.INFO)

formatter = logging.Formatter('%(asctime)s :: %(levelname)s :: %(message)s')

file_handler = RotatingFileHandler(
    os.path.join(DATA_DIR, 'log.txt'), 'a', 1000000, 1)
if DEBUG:
    file_handler.setLevel(logging.DEBUG)
else:
    file_handler.setLevel(logging.INFO)

file_handler.setFormatter(formatter)
logger.addHandler(file_handler)

if DEBUG:
    stream_handler = logging.StreamHandler()
    stream_handler.setLevel(logging.DEBUG)
    stream_handler.setFormatter(formatter)
    logger.addHandler(stream_handler)

########################


TIMEDELTA_SYNCHRO = datetime.timedelta(days=15)  # Number of days to look for
# for synchronization

with open('ntnoe_credentials') as f:
    NTNOE_ID, NTNOE_PASS, _ = f.read().split('\n')

SCOPES = 'https://www.googleapis.com/auth/calendar'
CLIENT_SECRET_FILE = 'client_secret.json'
APPLICATION_NAME = 'Google Calendar API Python Quickstart'

class Event:
    """
    The event class allows a simple convertion between `icalendar.cal.Event`
    and a formatted `dict` for the google API.
    """

    # ColorId corresponding to course code
    EVENT_COLOR = {
        '9': '9',  # Amphi
        '11': '10',  # TL
        '10': '6',  # TD
        '13': '5',  # Autre
        '12': '3',  # Exam

    }

    def __init__(self, e):
        """ Initialize an event from a `icalendar.cal.Event`."""
        self.summary = e.decoded('SUMMARY').decode('utf-8')
        self.start = e.decoded('DTSTART')
        self.end = e.decoded('DTEND')
        self.location = e.decoded('LOCATION').decode('utf-8')
        self.colorid = self.EVENT_COLOR.get(
            e.decoded('DESCRIPTION').decode('utf-8'), '1')

    def __str__(self):
        return str(self.as_google())

    def as_google(self):
        """Returns the event as a formatted `dict` for the google API."""
        return {
            'summary': self.summary,
            'location': self.location,
            'start': {
                'dateTime': self.start.isoformat(),
                'timeZone': 'Europe/Paris',
            },
            'end': {
                'dateTime': self.end.isoformat(),
                'timeZone': 'Europe/Paris',
            },
            'colorId': self.colorid,
            'reminders': {
                'useDefault': False,
                'overrides': [],
            },

        }


def get_credentials():
    """Gets valid user credentials from storage.

    If nothing has been stored, or if the stored credentials are invalid,
    the OAuth2 flow is completed to obtain the new credentials.

    Returns:
        Credentials, the obtained credential.
    """
    credential_dir = os.path.join(DATA_DIR, 'credentials')
    if not os.path.exists(credential_dir):
        os.makedirs(credential_dir)
    credential_path = os.path.join(credential_dir, 'ntnoe.json')

    store = Storage(credential_path)
    credentials = store.get()
    if not credentials or credentials.invalid:
        flow = client.flow_from_clientsecrets(CLIENT_SECRET_FILE, SCOPES)
        flow.user_agent = APPLICATION_NAME
        logger.info('Storing credentials to ' + credential_path)
        credentials = tools.run_flow(flow, store)

    return credentials


def get_ntnoe():
    """Retrieves the calendar on NTNOE."""
    r = requests.post(
        "https://ntnoe.metz.supelec.fr/ical/index.php",
        data={"envoyer":"Utf8_All","submit":"G%E9n%E9rer"},
        auth=(NTNOE_ID, NTNOE_PASS),
    )

    url = "https://ntnoe.metz.supelec.fr/ical/EdTcustom/Eleves/edt_{}.ics"
    url = url.format(NTNOE_ID)
    r = requests.get(url, auth=(NTNOE_ID, NTNOE_PASS))
    return r.content

def main():
    """Get the events on NTNOE the puts them on Google Calendar.
    """

    # Authentication on google
    logger.info('Authenticating on Google')
    credentials = get_credentials()
    http = credentials.authorize(httplib2.Http())
    service = discovery.build('calendar', 'v3', http=http)

    # Retrieving the calendar on NTNOE
    logger.info('Requesting NTNOE for {}'.format(NTNOE_ID))
    ical = icalendar.Calendar.from_ical(get_ntnoe())

    # We need to find the id of the calendar we will edit.
    logger.info('Looking for `ntnoe` calendar.')
    calendars = service.calendarList().list().execute()
    ntnoe_calendar_id = None
    for c in calendars['items']:
        if c['summary'] == 'ntnoe':
            ntnoe_calendar_id = c['id']

    if not ntnoe_calendar_id:
        logger.info("Creating `ntnoe` calendar...")
        created = service.calendars().insert(body={
            'defaultReminders' : [],
            'selected' : True,
            'summary' : 'ntnoe',
        }).execute()
        ntnoe_calendar_id = created['id']

    now = datetime.datetime.now()
    then = now + TIMEDELTA_SYNCHRO
    time_search = datetime.datetime(now.year, now.month, now.day, 1)

    # NTNOE calendar often changes. So let's delete former synchronizations.
    logger.info('Deleting former events.')
    former_ones = service.events().list(
        calendarId=ntnoe_calendar_id,
    ).execute()

    for event in former_ones['items']:
        logger.debug('Deleting event : {}'.format(event['id']))
        service.events().delete(
            calendarId=ntnoe_calendar_id,
            eventId=event['id']
        ).execute()

    logger.info('Adding new events.')
    for e in ical.walk('VEVENT'):
        event = Event(e)
        t = (
            event.summary,
            event.start.isoformat(),
            event.end.isoformat(),
            event.location
        )
        if now >= event.end or event.start >= then:
            continue

        event = service.events().insert(
            calendarId=ntnoe_calendar_id,
            body=event.as_google()
        ).execute()
        logger.debug("Adding event : {}".format(event['id']))


if __name__ == '__main__':
    main()