views.py

def private_chat_room_view(request, *args, **kwargs):
	room_id = request.GET.get("room_id")
	user = request.user
	if not user.is_authenticated:
		base_url = reverse('login')
		query_string = urlencode({'next': f"/chat/?room_id={room_id}"})
		url = f"{base_url}?{query_string}"
		return redirect(url)

	context = {}

	context['m_and_f'] = get_recent_chatroom_messages(user)

	context["BASE_URL"] = settings.BASE_URL
	if room_id:
		context["room_id"] = room_id
	context['debug'] = DEBUG
	context['debug_mode'] = settings.DEBUG
	return render(request, "chat/room.html", context)


def get_recent_chatroom_messages(user):
	"""
	sort in terms of most recent chats (users that you most recently had conversations with)
	"""
	# 1. Find all the rooms this user is a part of 
	rooms1 = PrivateChatRoom.objects.filter(user1=user, is_active=True)
	rooms2 = PrivateChatRoom.objects.filter(user2=user, is_active=True)

	# 2. merge the lists
	rooms = list(chain(rooms1, rooms2))

	# 3. find the newest msg in each room
	m_and_f = []
	for room in rooms:
		# Figure out which user is the "other user" (aka friend)
		if room.user1 == user:
			friend = room.user2
		else:
			friend = room.user1

		# confirm you are even friends (in case chat is left active somehow)
		friend_list = FriendList.objects.get(user=user)
		if not friend_list.is_mutual_friend(friend):
			chat = find_or_create_private_chat(user, friend)
			chat.is_active = False
			chat.save()
		else:	
			# find newest msg from that friend in the chat room
			try:
				message = RoomChatMessage.objects.filter(room=room, user=friend).latest("timestamp")
			except RoomChatMessage.DoesNotExist:
				# create a dummy message with dummy timestamp
				today = datetime(
					year=1950, 
					month=1, 
					day=1, 
					hour=1,
					minute=1,
					second=1,
					tzinfo=pytz.UTC
				)
				message = RoomChatMessage(
					user=friend,
					room=room,
					timestamp=today,
					content="",
				)
			m_and_f.append({
				'message': message,
				'friend': friend
			})

	return sorted(m_and_f, key=lambda x: x['message'].timestamp, reverse=True)