from django.db.models.signals import post_save,pre_delete
from django.dispatch import receiver
from eventplanner.models import Event, EventParticipation
from django.contrib.auth.models import User
import eventplanner_gcal.models
import logging

logger = logging.getLogger( __name__ )


class SignalLock:
    def __init__(self):
        self.locked=False

    def __enter__(self):
        if self.locked:
            return False

        self.locked=True
        return True

    def __exit__(self, type, value, traceback):
        self.locked=False

    def isLocked(self):
        return self.locked

signalLock = SignalLock()


def onGoogleCallback():
    if not signalLock.isLocked():
        with signalLock:
	    logger.info( "Sync back from google" )
            eventplanner_gcal.models.syncParticipationFromGoogleToLocal()


@receiver( post_save, sender=User )
def user_changed( **kwargs ):
    logger.info("User info changed")
    if not signalLock.isLocked():
        with signalLock:
            logger.info("Synchronizing with google - user information changed")
            eventplanner_gcal.models.deleteAllGCalEvents()
            eventplanner_gcal.models.syncGCalEvents()


@receiver( post_save,sender= Event)
def event_post_save_handler( **kwargs):
    if not signalLock.isLocked():
        with signalLock:
            event = kwargs['instance']
            created = kwargs['created']
            if created:
                logger.info("Creating Gcal event")
                eventplanner_gcal.models.createGCalEvent( event ).execute()
            else:
                logger.info( "Updating Gcal event")
                eventplanner_gcal.models.updateGCalEvent( event ).execute()



@receiver( pre_delete,sender= Event)
def event_pre_delete_handler( **kwargs):
    if not signalLock.isLocked():
        with signalLock:
            event = kwargs['instance']
            logger.info ("Deleting GCAL event")
            eventplanner_gcal.models.deleteGCalEvent( event ).execute()


@receiver( post_save, sender=EventParticipation )
def participation_post_save_handler( **kwargs):
    if not signalLock.isLocked():
        with signalLock:
            participation = kwargs['instance']
            logger.info("Participation post save -> update gcal")
            eventplanner_gcal.models.updateGCalEvent( participation.event ).execute()




# -------------- For management commands ------------------------


def stopAllGCalSubscriptions():
    if not signalLock.isLocked():
        with signalLock:
            eventplanner_gcal.models.stopAllGCalSubscriptions()

def checkGCalSubscription():
    if not signalLock.isLocked():
        with signalLock:
            eventplanner_gcal.models.checkGCalSubscription()


def deleteAllGCalEvents():
    if not signalLock.isLocked():
        with signalLock:
            eventplanner_gcal.models.deleteAllGCalEvents()

def syncGCalEvents():
    if not signalLock.isLocked():
        with signalLock:
            eventplanner_gcal.models.syncGCalEvents()