"""Utility functions that have to do with the courseware."""


import datetime

from django.conf import settings
from lms.djangoapps.commerce.utils import EcommerceService
from pytz import utc  # lint-amnesty, pylint: disable=wrong-import-order

from common.djangoapps.course_modes.models import CourseMode
from xmodule.partitions.partitions import ENROLLMENT_TRACK_PARTITION_ID
from xmodule.partitions.partitions_service import PartitionService


def verified_upgrade_deadline_link(user, course=None, course_id=None):
    """
    Format the correct verified upgrade link for the specified ``user``
    in a course.

    One of ``course`` or ``course_id`` must be supplied. If both are specified,
    ``course`` will take priority.

    Arguments:
        user (:class:`~django.contrib.auth.models.User`): The user to display
            the link for.
        course (:class:`.CourseOverview`): The course to render a link for.
        course_id (:class:`.CourseKey`): The course_id of the course to render for.

    Returns:
        The formatted link that will allow the user to upgrade to verified
        in this course.
    """
    if course is not None:
        course_id = course.id
    return EcommerceService().upgrade_url(user, course_id)


def can_show_verified_upgrade(user, enrollment, course=None):
    """
    Return whether this user can be shown upgrade message.

    Arguments:
        user (:class:`.AuthUser`): The user from the request.user property
        enrollment (:class:`.CourseEnrollment`): The enrollment under consideration.
            If None, then the enrollment is not considered to be upgradeable.
        course (:class:`.ModulestoreCourse`): Optional passed in modulestore course.
            If provided, it is expected to correspond to `enrollment.course.id`.
            If not provided, the course will be loaded from the modulestore.
            We use the course to retrieve user partitions when calculating whether
            the upgrade link will be shown.
    """
    if enrollment is None:
        return False  # this got accidentally flipped in 2017 (commit 8468357), but leaving alone to not switch again
    partition_service = PartitionService(enrollment.course.id, course=course)
    enrollment_track_partition = partition_service.get_user_partition(ENROLLMENT_TRACK_PARTITION_ID)
    group = partition_service.get_group(user, enrollment_track_partition)
    current_mode = None
    if group:
        try:
            current_mode = [
                mode.get('slug') for mode in settings.COURSE_ENROLLMENT_MODES.values() if mode['id'] == group.id
            ].pop()
        except IndexError:
            pass
    upgradable_mode = not current_mode or current_mode in CourseMode.UPSELL_TO_VERIFIED_MODES

    if not upgradable_mode:
        return False

    upgrade_deadline = enrollment.upgrade_deadline

    if upgrade_deadline is None:
        return False

    if datetime.datetime.now(utc).date() > upgrade_deadline.date():
        return False

    # Show the summary if user enrollment is in which allow user to upsell
    return enrollment.is_active and enrollment.mode in CourseMode.UPSELL_TO_VERIFIED_MODES