from django.db.models.signals import post_save, m2m_changed
from django.dispatch import receiver
from django.conf import settings
from django.core.urlresolvers import reverse
from django.contrib.sites.shortcuts import get_current_site
from django.contrib.auth.models import User

from .models import ConversationWithParticipant, ConversationAboutTalk, Message
from .utils import notify_by_email
from proposals.models import Talk, Topic
from proposals.signals import new_talk
from accounts.models import Participation


@receiver(post_save, sender=Participation, dispatch_uid="Create ConversationWithParticipant")
def create_conversation_with_participant(sender, instance, created, **kwargs):
    if not created:
        return
    conversation = ConversationWithParticipant(participation=instance)
    conversation.save()


@receiver(post_save, sender=Talk, dispatch_uid="Create ConversationAboutTalk")
def create_conversation_about_talk(sender, instance, created, **kwargs):
    if not created:
        return
    conversation = ConversationAboutTalk(talk=instance)
    conversation.save()


@receiver(new_talk, dispatch_uid="Notify new talk")
def notify_new_talk(sender, instance, **kwargs):
    # Subscribe reviewer for these topics to the conversation
    topics = instance.topics.all()
    reviewers = User.objects.filter(participation__review_topics=topics).all()
    instance.conversation.subscribers.add(*reviewers)
    # Notification of this new talk
    message = Message(conversation=instance.conversation, author=instance.proposer,
            content='The talk has been proposed.')
    message.save()


@receiver(post_save, sender=Message, dispatch_uid="Notify new message")
def notify_new_message(sender, instance, created, **kwargs):
    if not created:
        # Possibly send a modification notification?
        return
    instance.conversation.new_message(instance)