"""
API views for Bulk Enrollment
"""
import itertools
import json

from edx_rest_framework_extensions.auth.jwt.authentication import JwtAuthentication
from rest_framework import status
from rest_framework.response import Response
from rest_framework.views import APIView

from bulk_enroll.serializers import BulkEnrollmentSerializer
from enrollment.views import EnrollmentUserThrottle
from instructor.views.api import students_update_enrollment
from opaque_keys import InvalidKeyError
from opaque_keys.edx.keys import CourseKey
from openedx.core.djangoapps.course_groups.cohorts import (
    get_cohort_by_name,
    add_user_to_cohort,
)
from openedx.core.djangoapps.course_groups.models import CourseUserGroup
from openedx.core.lib.api.authentication import OAuth2Authentication
from openedx.core.lib.api.permissions import IsStaff
from util.disable_rate_limit import can_disable_rate_limit


@can_disable_rate_limit
class BulkEnrollView(APIView):
    """
    **Use Case**

        Enroll multiple users in one or more courses.

    **Example Request**

        POST /api/bulk_enroll/v1/bulk_enroll/ {
            "auto_enroll": true,
            "email_students": true,
            "action": "enroll",
            "courses": "course-v1:edX+Demo+123,course-v1:edX+Demo2+456",
            "cohorts": "cohortA,cohortA",
            "identifiers": "brandon@example.com,yamilah@example.com"
        }

        **POST Parameters**

          A POST request can include the following parameters.

          * auto_enroll: When set to `true`, students will be enrolled as soon
            as they register.
          * email_students: When set to `true`, students will be sent email
            notifications upon enrollment.
          * action: Can either be set to "enroll" or "unenroll". This determines the behavior
          * cohorts: Optional. If provided, the number of items in the list should be equal to
            the number of courses. first cohort coressponds with the first course and so on.
            The learners will be added to the corresponding cohort.

    **Response Values**

        If the supplied course data is valid and the enrollments were
        successful, an HTTP 200 "OK" response is returned.

        The HTTP 200 response body contains a list of response data for each
        enrollment. (See the `instructor.views.api.students_update_enrollment`
        docstring for the specifics of the response data available for each
        enrollment)

        If a cohorts list is provided, additional 'cohort' keys will be added
        to the 'before' and 'after' states.
    """

    authentication_classes = JwtAuthentication, OAuth2Authentication
    permission_classes = (IsStaff,)
    throttle_classes = (EnrollmentUserThrottle,)

    def post(self, request):
        serializer = BulkEnrollmentSerializer(data=request.data)
        if serializer.is_valid():
            # Setting the content type to be form data makes Django Rest Framework v3.6.3 treat all passed JSON data as
            # POST parameters. This is necessary because this request is forwarded on to the student_update_enrollment
            # view, which requires all of the parameters to be passed in via POST parameters.
            metadata = request._request.META  # pylint: disable=protected-access
            metadata['CONTENT_TYPE'] = 'application/x-www-form-urlencoded'

            response_dict = {
                'auto_enroll': serializer.data.get('auto_enroll'),
                'email_students': serializer.data.get('email_students'),
                'action': serializer.data.get('action'),
                'courses': {}
            }
            for course_id, cohort_name in itertools.izip_longest(serializer.data.get('courses'),
                                                                 serializer.data.get('cohorts', [])):
                response = students_update_enrollment(self.request, course_id=course_id)
                response_content = json.loads(response.content)

                if cohort_name:
                    try:
                        course_key = CourseKey.from_string(course_id)
                        cohort = get_cohort_by_name(course_key=course_key, name=cohort_name)
                    except (CourseUserGroup.DoesNotExist, InvalidKeyError) as exc:
                        return Response(exc.message, status=status.HTTP_400_BAD_REQUEST)

                    for user_data in response_content['results']:
                        if "after" in user_data and (
                            user_data["after"].get("enrollment", False) is True or
                            user_data["after"].get("allowed", False) is True
                        ):
                            user_id = user_data['identifier']
                            try:
                                _user_obj, previous_cohort, _pre_assigned = add_user_to_cohort(cohort, user_id)
                            except ValueError:
                                # User already present in cohort
                                previous_cohort = cohort_name

                            if previous_cohort:
                                user_data['before']['cohort'] = previous_cohort
                            else:
                                user_data['before']['cohort'] = None
                            user_data['after']['cohort'] = cohort_name

                response_dict['courses'][course_id] = response_content
            return Response(data=response_dict, status=status.HTTP_200_OK)
        else:
            return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)