# -*- coding: utf-8 -*-
"""
Contains code related to computing content gating course duration limits
and course access based on these limits.
"""
from datetime import timedelta

from django.apps import apps
from django.utils import timezone
from django.utils.translation import ugettext as _


from lms.djangoapps.courseware.access_response import AccessError
from lms.djangoapps.courseware.access_utils import ACCESS_GRANTED


class AuditExpiredError(AccessError):
    """
    Access denied because the user's audit timespan has expired
    """
    def __init__(self, user, course, end_date):
        error_code = "audit_expired"
        developer_message = "User {} had access to {} until {}".format(user, course, end_date)
        # TODO: Translate the end_date
        user_message = _("Course access expired on ") + end_date.strftime("%B %d, %Y")
        super(AuditExpiredError, self).__init__(error_code, developer_message, user_message)


def check_course_expired(user, course):
    """
    Check if the course expired for the user.
    """
    # TODO: Only limit audit users
    # TODO: Limit access to instructor paced courses based on end-date, rather than content availability date
    CourseEnrollment = apps.get_model('student.CourseEnrollment')
    enrollment = CourseEnrollment.get_enrollment(user, course.id)
    if enrollment is None:
        return ACCESS_GRANTED

    try:
        start_date = enrollment.schedule.start
    except CourseEnrollment.schedule.RelatedObjectDoesNotExist:
        start_date = max(enrollment.created, course.start)

    end_date = start_date + timedelta(days=28)

    if timezone.now() > end_date:
        return AuditExpiredError(user, course, end_date)

    return ACCESS_GRANTED