blechreiz-website/eventplanner_gcal/models.py

from apiclient.channel import new_webhook_channel, Channel
from django.db import models
from eventplanner.models import Event, EventParticipation

from apiclient.discovery import build
from apiclient.http import BatchHttpRequest

from oauth2client.file import Storage
import httplib2

from django.conf import settings
import logging
import datetime
from django.contrib.auth.models import User
import time
import uuid

logger = logging.getLogger(__name__)



class GCalMapping( models.Model ):
    gcal_id = models.CharField( max_length=64 )
    event   = models.OneToOneField( Event, primary_key=True )


class GCalPushChannel( models.Model ):
    """This table has either zero or one entry. Required to store if a channel already exists,
       when it expires, and how to stop (renew) the channel
    """

    id          = models.CharField( max_length=128, primary_key=True )
    address     = models.CharField( max_length=256 )
    token       = models.CharField( max_length=128 )
    resource_id = models.CharField( max_length=128 )
    expiration  = models.IntegerField()

    def toGChannel( self ):
        return Channel( 'web_hook', self.id, self.token, self.address, self.expiration, resource_id = self.resource_id )

    @staticmethod
    def fromGChannel( gChannel ):
        return GCalPushChannel( id         = gChannel.id,
                                address    = gChannel.address,
                                token      = gChannel.token,
                                expiration = gChannel.expiration,
                                resource_id= gChannel.resource_id )

    @staticmethod
    def createNew( callbackUrl, service, ttl = None ):
        gChannel = Channel('web_hook', str(uuid.uuid4()), 'blechreizGcal', callbackUrl, params= { 'ttl' : int(ttl) } )
        response = service.events().watch( calendarId='primary', body= gChannel.body() ).execute()
        gChannel.update( response )

        dbChannel = GCalPushChannel.fromGChannel( gChannel )
        dbChannel.save()

    @staticmethod
    def stop( service, gChannel ):
        channelService = service.channels()
        channelService.stop( body = gChannel.body() ).execute()
        GCalPushChannel.fromGChannel( gChannel ).delete()





def init( gcal_settings ):
    """Creates a API service object required by the following synchronization functions"""
    storage = Storage( gcal_settings['credentials_file'] )
    credentials = storage.get()

    if credentials is None or credentials.invalid == True:
        logger.error("Unable to initialize Google Calendar coupling. Check your settings!")
        return None

    http = httplib2.Http()
    http = credentials.authorize( http )
    return  build( serviceName='calendar', version='v3',
                   http=http, developerKey=gcal_settings['developerKey'] )



service = init( settings.GCAL_COUPLING )


def createAttendeesObj( event ):
    result = []
    for u in User.objects.all():
        if u.email.endswith( "@gmail.com") or u.email.endswith("@googlemail.com"):
            participation = EventParticipation.get_or_create( u, event )
            status = "tentative"
            if participation.status == 'Yes':  status = "accepted"
            if participation.status == 'No' :  status = "declined"

            o = {
                'id': u.email,
                'email': u.email,
                'displayName': u.username,
                'comment': participation.comment,
                'responseStatus': status,
            }
            result.append( o )

    return result


def buildGCalEvent( event, timezone="Europe/Berlin" ):
    if service is None:
        logger.error("createEvent: Google API connection not configured")
        return


    def createDateTimeObj( date, time ):
        if time is None:
            return { 'date':     unicode(date),                        'timeZone': timezone }
        else:
            return { 'dateTime': unicode(date) + 'T' + unicode(time) , 'timeZone': timezone }

    startDate = event.date
    endDate = event.end_date
    if endDate is None:  endDate = startDate

    startTime = event.meeting_time
    if startTime is None: startTime = event.time

    if startTime is None:
        endTime = None
    else:
        endTime = datetime.time( 22, 30 )

    return {
        'summary':     unicode(settings.GCAL_COUPLING['eventPrefix'] + event.title),
        'description': unicode(event.desc),
        'location':    unicode(event.location),
        'start': createDateTimeObj( startDate, startTime ),
        'end'  : createDateTimeObj( endDate,   endTime   ),
        'extendedProperties': {
            'private': {
                'blechreizEvent': 'true',
                'blechreizID': event.id,
            }
        },
        'attendees': createAttendeesObj( event ),
    }

# -------------------------------------------------------------------------------

def getAllGCalEvents( fromNow=False, pageToken=None ):

    if fromNow:
        now = datetime.datetime.now()
        minTime = now.strftime("%Y-%m-%dT%H:%M:%S-00:00")
    else:
        minTime = '2000-01-01T00:00:00-00:00'

    events = service.events().list(
        calendarId='primary',
        singleEvents=True,
        maxResults=1000,
        orderBy='startTime',
        timeMin=minTime,
        timeMax='2100-01-01T00:00:00-00:00',
        pageToken=pageToken,
        privateExtendedProperty='blechreizEvent=true',
        ).execute()
    return events['items']


def createGCalEvent( event, timezone="Europe/Berlin" ):
    googleEvent = buildGCalEvent(event,timezone)
    return service.events().insert(calendarId='primary', body=googleEvent)

def updateGCalEvent( event, timezone="Europe/Berlin"):
    googleEvent = buildGCalEvent(event,timezone)
    mapping = GCalMapping.objects.get( event=event )
    gcalId = mapping.gcal_id
    return service.events().patch(calendarId='primary', eventId= gcalId, body=googleEvent)

def deleteGCalEvent( event ):
    mapping = GCalMapping.objects.get( event=event )
    gcalId = mapping.gcal_id
    return service.events().delete(calendarId='primary', eventId=gcalId)



# -------------------------------------------------------------------------------

def deleteAllGCalEvents():
    if service is None:
        logger.error("deleteAllGCalEvents: Google API connection not configured")
        return

    gcalIds = [ ev['id'] for ev in getAllGCalEvents() ]
    l = len(gcalIds)
    if l == 0:
        return l

    batch = BatchHttpRequest()
    for id in gcalIds:
        batch.add( service.events().delete(calendarId='primary', eventId=id) )
    batch.execute()

    return l




def syncGCalEvents():
    if service is None:
        logger.error("syncGCalEvents: Google API connection not configured")
        return

    allEvents = getAllGCalEvents()

    eventsAtGoogle_djangoID = set()
    eventsAtGoogle_googleID = set()
    for gcalEv in allEvents:
        eventsAtGoogle_djangoID.add( int(gcalEv['extendedProperties']['private']['blechreizID'] ) )
        eventsAtGoogle_googleID.add( gcalEv['id'] )

    localEvents_djangoID = set( Event.      objects.all().values_list('pk'     , flat=True) )
    localEvents_googleID = set( GCalMapping.objects.all().values_list('gcal_id', flat=True) )

    eventsToCreate_djangoID = localEvents_djangoID - eventsAtGoogle_djangoID
    eventsToDelete_googleID = eventsAtGoogle_googleID - localEvents_googleID


    def onGcalEventCreated( request_id, response, exception ):
        """Callback function for created events"""
        if exception is not None:
            print ( "response " + str( response ) )
            raise exception

        googleId = response['id']
        djangoId = response['extendedProperties']['private']['blechreizID']
        mapping = GCalMapping( gcal_id = googleId, event = Event.objects.get( pk=djangoId ) )
        mapping.save()


    batch = BatchHttpRequest()

    batchIsEmpty = True
    for eventDjangoID in eventsToCreate_djangoID:
        batch.add( createGCalEvent( Event.objects.get( pk=eventDjangoID ) ), callback=onGcalEventCreated )
        batchIsEmpty=False

    for eventGoogleID in eventsToDelete_googleID:
        batch.add( service.events().delete(calendarId='primary', eventId=eventGoogleID) )
        batchIsEmpty=False

    if not batchIsEmpty:
        batch.execute()

    return len (eventsToCreate_djangoID), len(eventsToDelete_googleID )


def syncParticipationFromGoogleToLocal():
    allEvents = getAllGCalEvents(fromNow=True)
    for e in allEvents:
        localId    = e['extendedProperties']['private']['blechreizID']
        localEvent = Event.objects.get( pk=localId )
        for a in e['attendees']:
            user = User.objects.get( email= a['email'] )
            part = EventParticipation.get_or_create( user, localEvent )
            if 'comment' in a:
                part.comment = a['comment']

            if a['responseStatus'] == 'needsAction' or a['responseStatus']=='tentative':
                part.status = '?'
            elif a['responseStatus'] == 'accepted':
                part.status = 'Yes'
            elif a['responseStatus'] == 'declined':
                part.status = 'No'
            else:
                logger.error("Unknown response status when mapping gcal event: " + a['responseStatus'] )

            part.save()


def checkGCalSubscription():
    global service
    callbackUrl = settings.GCAL_COUPLING['push_url']

    timeToLive        = 14*24*3600 # how long the channel should be active
    renewBeforeExpiry =  2*24*3600 # duration before expiry when channel is renewed
    #timeToLive = 60*5
    #renewBeforeExpiry = 60*3

    # Test if a channel already exists for this callbackURL
    try:
        dbChannel = GCalPushChannel.objects.get( address=callbackUrl )
        gChannel = dbChannel.toGChannel()

        # if expiration time between 0 and two days: stop and create new channel
        curTime = int( time.time() * 1000)
        if gChannel.expiration > curTime:
            # not yet expired
            if curTime + renewBeforeExpiry*1000 > gChannel.expiration:
                #will expire in less than "renewBeforeExpiry"
                print ( "Renewing Google Calendar Subscription: " + callbackUrl )
                GCalPushChannel.stop( service, gChannel )
                GCalPushChannel.createNew( callbackUrl, service, timeToLive )
            else:
                print ("Channel active until %d " % ( gChannel.expiration, ) )
        else:
            print( "Google calendar subscription had expired - getting new subscription" )
            syncParticipationFromGoogleToLocal()
            GCalPushChannel.createNew( callbackUrl, service, timeToLive )

    except GCalPushChannel.DoesNotExist:
        # create new channel and save it in database
        print ( "No CGalCallback Channel exists yet for: " + callbackUrl )
        syncParticipationFromGoogleToLocal()
        GCalPushChannel.createNew( callbackUrl, service,  timeToLive )


def stopAllGCalSubscriptions():
    for dbChannel in GCalPushChannel.objects.all():
        print("Stopping %s expiry at %d " % ( dbChannel.id, dbChannel.expiration ) )
        GCalPushChannel.stop( service, dbChannel.toGChannel() )