# pylint: disable=unused-import
"""
Python APIs exposed by the bulk_email app to other in-process apps.
"""
import logging

from django.conf import settings
from django.urls import reverse

from lms.djangoapps.bulk_email.models import CourseEmail
from lms.djangoapps.bulk_email.models_api import (
    is_bulk_email_disabled_for_course,
    is_bulk_email_feature_enabled,
    is_user_opted_out_for_course
)
from lms.djangoapps.discussion.notification_prefs.views import UsernameCipher
from openedx.core.djangoapps.site_configuration import helpers as configuration_helpers

log = logging.getLogger(__name__)


def get_emails_enabled(user, course_id):
    """
    Get whether or not emails are enabled in the context of a course.

    Arguments:
        user: the user object for which we want to check whether emails are enabled
        course_id (string): the course id of the course

    Returns:
        (bool): True if emails are enabled for the course associated with course_id for the user;
        False otherwise
    """
    if is_bulk_email_feature_enabled(course_id=course_id) and not is_bulk_email_disabled_for_course(course_id):
        return not is_user_opted_out_for_course(user=user, course_id=course_id)
    return None


def get_unsubscribed_link(username, course_id):
    """
    :param username: username
    :param course_id:
    :return: AES encrypted token based on the user email
    """
    lms_root_url = configuration_helpers.get_value('LMS_ROOT_URL', settings.LMS_ROOT_URL)
    token = UsernameCipher.encrypt(username)
    optout_url = reverse('bulk_email_opt_out', kwargs={'token': token, 'course_id': course_id})
    url = f'{lms_root_url}{optout_url}'
    return url


def create_course_email(course_id, sender, targets, subject, html_message, text_message=None, template_name=None,
                        from_addr=None):
    """
    Python API for creating a new CourseEmail instance.

    Args:
        course_id (CourseKey): The CourseKey of the course.
        sender (String): Email author.
        targets (Target): Recipient groups the message should be sent to (e.g. SEND_TO_MYSELF)
        subject (String)): Email subject.
        html_message (String): Email body. Includes HTML markup.
        text_message (String, optional): Plaintext version of email body. Defaults to None.
        template_name (String, optional): Name of custom email template to use. Defaults to None.
        from_addr (String, optional): Custom sending address, if desired. Defaults to None.

    Returns:
        CourseEmail: Returns the created CourseEmail instance.
    """
    try:
        course_email = CourseEmail.create(
            course_id,
            sender,
            targets,
            subject,
            html_message,
            text_message=text_message,
            template_name=template_name,
            from_addr=from_addr
        )

        return course_email
    except ValueError as err:
        log.exception(f"Cannot create course email for {course_id} requested by user {sender} for targets {targets}")
        raise ValueError from err


def get_course_email(email_id):
    """
    Utility function for retrieving a CourseEmail instance from a given CourseEmail id.

    Args:
        email_id (int): The ID of the CourseEmail instance you want to retrieve.

    Returns:
        CourseEmail: The CourseEmail instance, if it exists.
    """
    try:
        return CourseEmail.objects.get(id=email_id)
    except CourseEmail.DoesNotExist:
        log.exception(f"CourseEmail instance with id '{email_id}' could not be found")

    return None