from datetime import datetime

from django.contrib.auth.models import User

from pytask.taskapp.models import Notification

def create_notification(to,subject,message):

    """

    creates a notification based on the passed arguments.

        to - a list of users to which the notification is to be sent

        subject - subject of the notification message to be sent

        message - message body of the notification

    """

    notification = Notification(sent_date = datetime.now())

    notification.save()

    notification.sent_to = to

    notification.sub = subject

    notification.message = message

    notification.save()

def mark_notification_read(notification_id):

    """

    makes a notification identified by the notification_id read.

    arguments:

        notification_id - a number denoting the id of the Notification object

    """

    try:

        notification = Notification.objects.get(id = notification_id)

    except Notification.DoesNotExist:

        return False

    notification.is_read = True

    notification.save()

    return True

def delete_notification(notification_id):

    """

    deletes a notification identified by the notification_id.

    arguments:

        notification_id - a number denoting the id of the Notification object

    """

    try:

        notification = Notification.objects.get(id = notification_id)

    except Notification.DoesNotExist:

        return False

    notification.is_deleted = True

    notification.save()

    return True

def get_notification(nid, user):

    """ if notification exists, and belongs to the current user, return it.

    else return None.

    """

    try:

        notify_obj = Notification.objects.get(id=nid)

    except Notification.DoesNotExist:

        return None

    try:

        notify_obj.sent_to.get(id=user.id)

    except User.DoesNotExist:

        return None

    if not notify_obj.is_deleted:

        return notify_obj