"""
Student Views
"""

import datetime
import json
import logging
import uuid
import warnings
from collections import defaultdict, namedtuple
from urlparse import parse_qs, urlsplit, urlunsplit

import analytics
import edx_oauth2_provider
from django.conf import settings
from django.contrib import messages
from django.contrib.auth import authenticate, login, logout
from django.contrib.auth.decorators import login_required
from django.contrib.auth.models import AnonymousUser, User
from django.contrib.auth.views import password_reset_confirm
from django.core import mail
from django.template.context_processors import csrf
from django.core.exceptions import ObjectDoesNotExist, PermissionDenied
from django.core.urlresolvers import NoReverseMatch, reverse, reverse_lazy
from django.core.validators import ValidationError, validate_email
from django.db import IntegrityError, transaction
from django.db.models.signals import post_save
from django.dispatch import Signal, receiver
from django.http import Http404, HttpResponse, HttpResponseBadRequest, HttpResponseForbidden
from django.shortcuts import redirect
from django.template.response import TemplateResponse
from django.utils.encoding import force_bytes, force_text
from django.utils.http import base36_to_int, is_safe_url, urlencode, urlsafe_base64_encode
from django.utils.translation import ugettext as _
from django.utils.translation import get_language, ungettext
from django.views.decorators.csrf import csrf_exempt, ensure_csrf_cookie
from django.views.decorators.http import require_GET, require_POST
from django.views.generic import TemplateView
from ipware.ip import get_ip
from opaque_keys import InvalidKeyError
from opaque_keys.edx.keys import CourseKey
from opaque_keys.edx.locator import CourseLocator
from provider.oauth2.models import Client
from pytz import UTC
from ratelimitbackend.exceptions import RateLimitException
from requests import HTTPError
from social_core.backends import oauth as social_oauth
from social_core.exceptions import AuthAlreadyAssociated, AuthException
from social_django import utils as social_utils

import dogstats_wrapper as dog_stats_api
import openedx.core.djangoapps.external_auth.views
import third_party_auth
from third_party_auth.saml import SAP_SUCCESSFACTORS_SAML_KEY
import track.views
from bulk_email.models import BulkEmailFlag, Optout  # pylint: disable=import-error
from certificates.api import get_certificate_url, has_html_certificates_enabled  # pylint: disable=import-error
from certificates.models import (  # pylint: disable=import-error
    CertificateStatuses,
    certificate_status_for_student
)
from course_modes.models import CourseMode
from courseware.access import has_access
from courseware.courses import get_courses, sort_by_announcement, sort_by_start_date  # pylint: disable=import-error
from django_comment_common.models import assign_role
from edxmako.shortcuts import render_to_response, render_to_string
from eventtracking import tracker
from lms.djangoapps.commerce.utils import EcommerceService  # pylint: disable=import-error
from lms.djangoapps.grades.course_grade_factory import CourseGradeFactory
from lms.djangoapps.verify_student.models import SoftwareSecurePhotoVerification  # pylint: disable=import-error
# Note that this lives in LMS, so this dependency should be refactored.
from notification_prefs.views import enable_notifications
from openedx.core.djangoapps import monitoring_utils
from openedx.core.djangoapps.catalog.utils import get_programs_with_type
from openedx.core.djangoapps.certificates.api import certificates_viewable_for_course
from openedx.core.djangoapps.credit.email_utils import get_credit_provider_display_names, make_providers_strings
from openedx.core.djangoapps.embargo import api as embargo_api
from openedx.core.djangoapps.external_auth.login_and_register import login as external_auth_login
from openedx.core.djangoapps.external_auth.login_and_register import register as external_auth_register
from openedx.core.djangoapps.external_auth.models import ExternalAuthMap
from openedx.core.djangoapps.lang_pref import LANGUAGE_KEY
from openedx.core.djangoapps.programs.models import ProgramsApiConfig
from openedx.core.djangoapps.programs.utils import ProgramProgressMeter
from openedx.core.djangoapps.site_configuration import helpers as configuration_helpers
from openedx.core.djangoapps.theming import helpers as theming_helpers
from openedx.core.djangoapps.user_api.preferences import api as preferences_api
from openedx.core.djangolib.markup import HTML
from openedx.features.course_experience import course_home_url_name
from openedx.features.enterprise_support.api import get_dashboard_consent_notification
from shoppingcart.api import order_history
from shoppingcart.models import CourseRegistrationCode, DonationConfiguration
from student.cookies import delete_logged_in_cookies, set_logged_in_cookies, set_user_info_cookie
from student.forms import AccountCreationForm, PasswordResetFormNoActive, get_registration_extension_form
from student.helpers import (
    DISABLE_UNENROLL_CERT_STATES,
    auth_pipeline_urls,
    check_verify_status_by_course,
    destroy_oauth_tokens,
    get_next_url_for_login_page
)
from student.models import (
    ALLOWEDTOENROLL_TO_ENROLLED,
    CourseAccessRole,
    CourseEnrollment,
    CourseEnrollmentAllowed,
    CourseEnrollmentAttribute,
    DashboardConfiguration,
    LinkedInAddToProfileConfiguration,
    LoginFailures,
    ManualEnrollmentAudit,
    PasswordHistory,
    PendingEmailChange,
    Registration,
    RegistrationCookieConfiguration,
    UserAttribute,
    UserProfile,
    UserSignupSource,
    UserStanding,
    anonymous_id_for_user,
    create_comments_service_user,
    unique_id_for_user
)
from student.signals import REFUND_ORDER
from student.tasks import send_activation_email
from third_party_auth import pipeline, provider
from util.bad_request_rate_limiter import BadRequestRateLimiter
from util.db import outer_atomic
from util.json_request import JsonResponse
from util.milestones_helpers import get_pre_requisite_courses_not_completed
from util.password_policy_validators import validate_password_length, validate_password_strength
from xmodule.modulestore.django import modulestore

log = logging.getLogger("edx.student")
AUDIT_LOG = logging.getLogger("audit")
ReverifyInfo = namedtuple('ReverifyInfo', 'course_id course_name course_number date status display')  # pylint: disable=invalid-name
SETTING_CHANGE_INITIATED = 'edx.user.settings.change_initiated'
# Used as the name of the user attribute for tracking affiliate registrations
REGISTRATION_AFFILIATE_ID = 'registration_affiliate_id'
REGISTRATION_UTM_PARAMETERS = {
    'utm_source': 'registration_utm_source',
    'utm_medium': 'registration_utm_medium',
    'utm_campaign': 'registration_utm_campaign',
    'utm_term': 'registration_utm_term',
    'utm_content': 'registration_utm_content',
}
REGISTRATION_UTM_CREATED_AT = 'registration_utm_created_at'
# used to announce a registration
REGISTER_USER = Signal(providing_args=["user", "registration"])

# Disable this warning because it doesn't make sense to completely refactor tests to appease Pylint
# pylint: disable=logging-format-interpolation


def csrf_token(context):
    """A csrf token that can be included in a form."""
    token = context.get('csrf_token', '')
    if token == 'NOTPROVIDED':
        return ''
    return (u'<div style="display:none"><input type="hidden"'
            ' name="csrfmiddlewaretoken" value="%s" /></div>' % (token))


# NOTE: This view is not linked to directly--it is called from
# branding/views.py:index(), which is cached for anonymous users.
# This means that it should always return the same thing for anon
# users. (in particular, no switching based on query params allowed)
def index(request, extra_context=None, user=AnonymousUser()):
    """
    Render the edX main page.

    extra_context is used to allow immediate display of certain modal windows, eg signup,
    as used by external_auth.
    """
    if extra_context is None:
        extra_context = {}

    programs_list = []
    courses = get_courses(user)

    if configuration_helpers.get_value(
            "ENABLE_COURSE_SORTING_BY_START_DATE",
            settings.FEATURES["ENABLE_COURSE_SORTING_BY_START_DATE"],
    ):
        courses = sort_by_start_date(courses)
    else:
        courses = sort_by_announcement(courses)

    context = {'courses': courses}

    context['homepage_overlay_html'] = configuration_helpers.get_value('homepage_overlay_html')

    # This appears to be an unused context parameter, at least for the master templates...
    context['show_partners'] = configuration_helpers.get_value('show_partners', True)

    # TO DISPLAY A YOUTUBE WELCOME VIDEO
    # 1) Change False to True
    context['show_homepage_promo_video'] = configuration_helpers.get_value('show_homepage_promo_video', False)

    # Maximum number of courses to display on the homepage.
    context['homepage_course_max'] = configuration_helpers.get_value(
        'HOMEPAGE_COURSE_MAX', settings.HOMEPAGE_COURSE_MAX
    )

    # 2) Add your video's YouTube ID (11 chars, eg "123456789xX"), or specify via site configuration
    # Note: This value should be moved into a configuration setting and plumbed-through to the
    # context via the site configuration workflow, versus living here
    youtube_video_id = configuration_helpers.get_value('homepage_promo_video_youtube_id', "your-youtube-id")
    context['homepage_promo_video_youtube_id'] = youtube_video_id

    # allow for theme override of the courses list
    context['courses_list'] = theming_helpers.get_template_path('courses_list.html')

    # Insert additional context for use in the template
    context.update(extra_context)

    # Add marketable programs to the context.
    context['programs_list'] = get_programs_with_type(request.site, include_hidden=False)

    return render_to_response('index.html', context)


def process_survey_link(survey_link, user):
    """
    If {UNIQUE_ID} appears in the link, replace it with a unique id for the user.
    Currently, this is sha1(user.username).  Otherwise, return survey_link.
    """
    return survey_link.format(UNIQUE_ID=unique_id_for_user(user))


def cert_info(user, course_overview, course_mode):
    """
    Get the certificate info needed to render the dashboard section for the given
    student and course.

    Arguments:
        user (User): A user.
        course_overview (CourseOverview): A course.
        course_mode (str): The enrollment mode (honor, verified, audit, etc.)

    Returns:
        dict: A dictionary with keys:
            'status': one of 'generating', 'downloadable', 'notpassing', 'processing', 'restricted', 'unavailable', or
                'certificate_earned_but_not_available'
            'download_url': url, only present if show_download_url is True
            'show_survey_button': bool
            'survey_url': url, only if show_survey_button is True
            'grade': if status is not 'processing'
            'can_unenroll': if status allows for unenrollment
    """
    return _cert_info(
        user,
        course_overview,
        certificate_status_for_student(user, course_overview.id),
        course_mode
    )


def reverification_info(statuses):
    """
    Returns reverification-related information for *all* of user's enrollments whose
    reverification status is in statuses.

    Args:
        statuses (list): a list of reverification statuses we want information for
            example: ["must_reverify", "denied"]

    Returns:
        dictionary of lists: dictionary with one key per status, e.g.
            dict["must_reverify"] = []
            dict["must_reverify"] = [some information]
    """
    reverifications = defaultdict(list)

    # Sort the data by the reverification_end_date
    for status in statuses:
        if reverifications[status]:
            reverifications[status].sort(key=lambda x: x.date)
    return reverifications


def get_course_enrollments(user, org_whitelist, org_blacklist):
    """
    Given a user, return a filtered set of his or her course enrollments.

    Arguments:
        user (User): the user in question.
        org_whitelist (list[str]): If not None, ONLY courses of these orgs will be returned.
        org_blacklist (list[str]): Courses of these orgs will be excluded.

    Returns:
        generator[CourseEnrollment]: a sequence of enrollments to be displayed
        on the user's dashboard.
    """
    for enrollment in CourseEnrollment.enrollments_for_user_with_overviews_preload(user):

        # If the course is missing or broken, log an error and skip it.
        course_overview = enrollment.course_overview
        if not course_overview:
            log.error(
                "User %s enrolled in broken or non-existent course %s",
                user.username,
                enrollment.course_id
            )
            continue

        # Filter out anything that is not in the whitelist.
        if org_whitelist and course_overview.location.org not in org_whitelist:
            continue

        # Conversely, filter out any enrollments in the blacklist.
        elif org_blacklist and course_overview.location.org in org_blacklist:
            continue

        # Else, include the enrollment.
        else:
            yield enrollment


def get_org_black_and_whitelist_for_site(user):
    """
    Returns the org blacklist and whitelist for the current site.

    Returns:
        (org_whitelist, org_blacklist): A tuple of lists of orgs that serve as
            either a blacklist or a whitelist of orgs for the current site. The
            whitelist takes precedence, and the blacklist is used if the
            whitelist is None.
    """
    # Default blacklist is empty.
    org_blacklist = None
    # Whitelist the orgs configured for the current site.  Each site outside
    # of edx.org has a list of orgs associated with its configuration.
    org_whitelist = configuration_helpers.get_current_site_orgs()

    if not org_whitelist:
        # If there is no whitelist, the blacklist will include all orgs that
        # have been configured for any other sites. This applies to edx.org,
        # where it is easier to blacklist all other orgs.
        org_blacklist = configuration_helpers.get_all_orgs()

    return (org_whitelist, org_blacklist)


def _cert_info(user, course_overview, cert_status, course_mode):  # pylint: disable=unused-argument
    """
    Implements the logic for cert_info -- split out for testing.

    Arguments:
        user (User): A user.
        course_overview (CourseOverview): A course.
        course_mode (str): The enrollment mode (honor, verified, audit, etc.)
    """
    # simplify the status for the template using this lookup table
    template_state = {
        CertificateStatuses.generating: 'generating',
        CertificateStatuses.downloadable: 'downloadable',
        CertificateStatuses.notpassing: 'notpassing',
        CertificateStatuses.restricted: 'restricted',
        CertificateStatuses.auditing: 'auditing',
        CertificateStatuses.audit_passing: 'auditing',
        CertificateStatuses.audit_notpassing: 'auditing',
        CertificateStatuses.unverified: 'unverified',
    }

    certificate_earned_but_not_available_status = 'certificate_earned_but_not_available'
    default_status = 'processing'

    default_info = {
        'status': default_status,
        'show_survey_button': False,
        'can_unenroll': True,
    }

    if cert_status is None:
        return default_info

    status = template_state.get(cert_status['status'], default_status)
    is_hidden_status = status in ('unavailable', 'processing', 'generating', 'notpassing', 'auditing')

    if (
        not certificates_viewable_for_course(course_overview) and
        (status in CertificateStatuses.PASSED_STATUSES) and
        course_overview.certificate_available_date
    ):
        status = certificate_earned_but_not_available_status

    if (
        course_overview.certificates_display_behavior == 'early_no_info' and
        is_hidden_status
    ):
        return default_info

    status_dict = {
        'status': status,
        'mode': cert_status.get('mode', None),
        'linked_in_url': None,
        'can_unenroll': status not in DISABLE_UNENROLL_CERT_STATES,
    }

    if not status == default_status and course_overview.end_of_course_survey_url is not None:
        status_dict.update({
            'show_survey_button': True,
            'survey_url': process_survey_link(course_overview.end_of_course_survey_url, user)})
    else:
        status_dict['show_survey_button'] = False

    if status == 'downloadable':
        # showing the certificate web view button if certificate is downloadable state and feature flags are enabled.
        if has_html_certificates_enabled(course_overview):
            if course_overview.has_any_active_web_certificate:
                status_dict.update({
                    'show_cert_web_view': True,
                    'cert_web_view_url': get_certificate_url(course_id=course_overview.id, uuid=cert_status['uuid'])
                })
            else:
                # don't show download certificate button if we don't have an active certificate for course
                status_dict['status'] = 'unavailable'
        elif 'download_url' not in cert_status:
            log.warning(
                u"User %s has a downloadable cert for %s, but no download url",
                user.username,
                course_overview.id
            )
            return default_info
        else:
            status_dict['download_url'] = cert_status['download_url']

            # If enabled, show the LinkedIn "add to profile" button
            # Clicking this button sends the user to LinkedIn where they
            # can add the certificate information to their profile.
            linkedin_config = LinkedInAddToProfileConfiguration.current()

            # posting certificates to LinkedIn is not currently
            # supported in White Labels
            if linkedin_config.enabled and not theming_helpers.is_request_in_themed_site():
                status_dict['linked_in_url'] = linkedin_config.add_to_profile_url(
                    course_overview.id,
                    course_overview.display_name,
                    cert_status.get('mode'),
                    cert_status['download_url']
                )

    if status in {'generating', 'downloadable', 'notpassing', 'restricted', 'auditing', 'unverified'}:
        cert_grade_percent = -1
        persisted_grade_percent = -1
        persisted_grade = CourseGradeFactory().read(user, course=course_overview, create_if_needed=False)
        if persisted_grade is not None:
            persisted_grade_percent = persisted_grade.percent

        if 'grade' in cert_status:
            cert_grade_percent = float(cert_status['grade'])

        if cert_grade_percent == -1 and persisted_grade_percent == -1:
            # Note: as of 11/20/2012, we know there are students in this state-- cs169.1x,
            # who need to be regraded (we weren't tracking 'notpassing' at first).
            # We can add a log.warning here once we think it shouldn't happen.
            return default_info

        status_dict['grade'] = unicode(max(cert_grade_percent, persisted_grade_percent))

    return status_dict


@ensure_csrf_cookie
def signin_user(request):
    """Deprecated. To be replaced by :class:`student_account.views.login_and_registration_form`."""
    external_auth_response = external_auth_login(request)
    if external_auth_response is not None:
        return external_auth_response
    # Determine the URL to redirect to following login:
    redirect_to = get_next_url_for_login_page(request)
    if request.user.is_authenticated():
        return redirect(redirect_to)

    third_party_auth_error = None
    for msg in messages.get_messages(request):
        if msg.extra_tags.split()[0] == "social-auth":
            # msg may or may not be translated. Try translating [again] in case we are able to:
            third_party_auth_error = _(unicode(msg))  # pylint: disable=translation-of-non-string
            break

    context = {
        'login_redirect_url': redirect_to,  # This gets added to the query string of the "Sign In" button in the header
        # Bool injected into JS to submit form if we're inside a running third-
        # party auth pipeline; distinct from the actual instance of the running
        # pipeline, if any.
        'pipeline_running': 'true' if pipeline.running(request) else 'false',
        'pipeline_url': auth_pipeline_urls(pipeline.AUTH_ENTRY_LOGIN, redirect_url=redirect_to),
        'platform_name': configuration_helpers.get_value(
            'platform_name',
            settings.PLATFORM_NAME
        ),
        'third_party_auth_error': third_party_auth_error
    }

    return render_to_response('login.html', context)


@ensure_csrf_cookie
def register_user(request, extra_context=None):
    """Deprecated. To be replaced by :class:`student_account.views.login_and_registration_form`."""
    # Determine the URL to redirect to following login:
    redirect_to = get_next_url_for_login_page(request)
    if request.user.is_authenticated():
        return redirect(redirect_to)

    external_auth_response = external_auth_register(request)
    if external_auth_response is not None:
        return external_auth_response

    context = {
        'login_redirect_url': redirect_to,  # This gets added to the query string of the "Sign In" button in the header
        'email': '',
        'name': '',
        'running_pipeline': None,
        'pipeline_urls': auth_pipeline_urls(pipeline.AUTH_ENTRY_REGISTER, redirect_url=redirect_to),
        'platform_name': configuration_helpers.get_value(
            'platform_name',
            settings.PLATFORM_NAME
        ),
        'selected_provider': '',
        'username': '',
    }

    if extra_context is not None:
        context.update(extra_context)

    if context.get("extauth_domain", '').startswith(
            openedx.core.djangoapps.external_auth.views.SHIBBOLETH_DOMAIN_PREFIX
    ):
        return render_to_response('register-shib.html', context)

    # If third-party auth is enabled, prepopulate the form with data from the
    # selected provider.
    if third_party_auth.is_enabled() and pipeline.running(request):
        running_pipeline = pipeline.get(request)
        current_provider = provider.Registry.get_from_pipeline(running_pipeline)
        if current_provider is not None:
            overrides = current_provider.get_register_form_data(running_pipeline.get('kwargs'))
            overrides['running_pipeline'] = running_pipeline
            overrides['selected_provider'] = current_provider.name
            context.update(overrides)

    return render_to_response('register.html', context)


def complete_course_mode_info(course_id, enrollment, modes=None):
    """
    We would like to compute some more information from the given course modes
    and the user's current enrollment

    Returns the given information:
        - whether to show the course upsell information
        - numbers of days until they can't upsell anymore
    """
    if modes is None:
        modes = CourseMode.modes_for_course_dict(course_id)

    mode_info = {'show_upsell': False, 'days_for_upsell': None}
    # we want to know if the user is already enrolled as verified or credit and
    # if verified is an option.
    if CourseMode.VERIFIED in modes and enrollment.mode in CourseMode.UPSELL_TO_VERIFIED_MODES:
        mode_info['show_upsell'] = True
        mode_info['verified_sku'] = modes['verified'].sku
        mode_info['verified_bulk_sku'] = modes['verified'].bulk_sku
        # if there is an expiration date, find out how long from now it is
        if modes['verified'].expiration_datetime:
            today = datetime.datetime.now(UTC).date()
            mode_info['days_for_upsell'] = (modes['verified'].expiration_datetime.date() - today).days

    return mode_info


def is_course_blocked(request, redeemed_registration_codes, course_key):
    """Checking either registration is blocked or not ."""
    blocked = False
    for redeemed_registration in redeemed_registration_codes:
        # registration codes may be generated via Bulk Purchase Scenario
        # we have to check only for the invoice generated registration codes
        # that their invoice is valid or not
        if redeemed_registration.invoice_item:
            if not redeemed_registration.invoice_item.invoice.is_valid:
                blocked = True
                # disabling email notifications for unpaid registration courses
                Optout.objects.get_or_create(user=request.user, course_id=course_key)
                log.info(
                    u"User %s (%s) opted out of receiving emails from course %s",
                    request.user.username,
                    request.user.email,
                    course_key,
                )
                track.views.server_track(
                    request,
                    "change-email1-settings",
                    {"receive_emails": "no", "course": course_key.to_deprecated_string()},
                    page='dashboard',
                )
                break

    return blocked


def generate_activation_email_context(user, registration):
    """
    Constructs a dictionary for use in activation email contexts

    Arguments:
        user (User): Currently logged-in user
        registration (Registration): Registration object for the currently logged-in user
    """
    return {
        'name': user.profile.name,
        'key': registration.activation_key,
        'lms_url': configuration_helpers.get_value('LMS_ROOT_URL', settings.LMS_ROOT_URL),
        'platform_name': configuration_helpers.get_value('PLATFORM_NAME', settings.PLATFORM_NAME),
        'support_url': configuration_helpers.get_value('SUPPORT_SITE_LINK', settings.SUPPORT_SITE_LINK),
        'support_email': configuration_helpers.get_value('CONTACT_EMAIL', settings.CONTACT_EMAIL),
    }


def compose_and_send_activation_email(user, profile, user_registration=None):
    """
    Construct all the required params and send the activation email
    through celery task

    Arguments:
        user: current logged-in user
        profile: profile object of the current logged-in user
        user_registration: registration of the current logged-in user
    """
    dest_addr = user.email
    if user_registration is None:
        user_registration = Registration.objects.get(user=user)
    context = generate_activation_email_context(user, user_registration)
    subject = render_to_string('emails/activation_email_subject.txt', context)
    # Email subject *must not* contain newlines
    subject = ''.join(subject.splitlines())
    message_for_activation = render_to_string('emails/activation_email.txt', context)
    from_address = configuration_helpers.get_value('email_from_address', settings.DEFAULT_FROM_EMAIL)
    from_address = configuration_helpers.get_value('ACTIVATION_EMAIL_FROM_ADDRESS', from_address)
    if settings.FEATURES.get('REROUTE_ACTIVATION_EMAIL'):
        dest_addr = settings.FEATURES['REROUTE_ACTIVATION_EMAIL']
        message_for_activation = ("Activation for %s (%s): %s\n" % (user, user.email, profile.name) +
                                  '-' * 80 + '\n\n' + message_for_activation)
    send_activation_email.delay(subject, message_for_activation, from_address, dest_addr)


@login_required
@ensure_csrf_cookie
def dashboard(request):
    """
    Provides the LMS dashboard view

    TODO: This is lms specific and does not belong in common code.

    Arguments:
        request: The request object.

    Returns:
        The dashboard response.

    """
    user = request.user
    if not UserProfile.objects.filter(user=user).exists():
        return redirect(reverse('account_settings'))

    platform_name = configuration_helpers.get_value("platform_name", settings.PLATFORM_NAME)
    enable_verified_certificates = configuration_helpers.get_value(
        'ENABLE_VERIFIED_CERTIFICATES',
        settings.FEATURES.get('ENABLE_VERIFIED_CERTIFICATES')
    )
    display_course_modes_on_dashboard = configuration_helpers.get_value(
        'DISPLAY_COURSE_MODES_ON_DASHBOARD',
        settings.FEATURES.get('DISPLAY_COURSE_MODES_ON_DASHBOARD', True)
    )
    activation_email_support_link = configuration_helpers.get_value(
        'ACTIVATION_EMAIL_SUPPORT_LINK', settings.ACTIVATION_EMAIL_SUPPORT_LINK
    ) or settings.SUPPORT_SITE_LINK

    # get the org whitelist or the org blacklist for the current site
    site_org_whitelist, site_org_blacklist = get_org_black_and_whitelist_for_site(user)
    course_enrollments = list(get_course_enrollments(user, site_org_whitelist, site_org_blacklist))

    # Record how many courses there are so that we can get a better
    # understanding of usage patterns on prod.
    monitoring_utils.accumulate('num_courses', len(course_enrollments))

    # sort the enrollment pairs by the enrollment date
    course_enrollments.sort(key=lambda x: x.created, reverse=True)

    # Retrieve the course modes for each course
    enrolled_course_ids = [enrollment.course_id for enrollment in course_enrollments]
    __, unexpired_course_modes = CourseMode.all_and_unexpired_modes_for_courses(enrolled_course_ids)
    course_modes_by_course = {
        course_id: {
            mode.slug: mode
            for mode in modes
        }
        for course_id, modes in unexpired_course_modes.iteritems()
    }

    # Check to see if the student has recently enrolled in a course.
    # If so, display a notification message confirming the enrollment.
    enrollment_message = _create_recent_enrollment_message(
        course_enrollments, course_modes_by_course
    )

    course_optouts = Optout.objects.filter(user=user).values_list('course_id', flat=True)

    sidebar_account_activation_message = ''
    banner_account_activation_message = ''
    display_account_activation_message_on_sidebar = configuration_helpers.get_value(
        'DISPLAY_ACCOUNT_ACTIVATION_MESSAGE_ON_SIDEBAR',
        settings.FEATURES.get('DISPLAY_ACCOUNT_ACTIVATION_MESSAGE_ON_SIDEBAR', False)
    )

    # Display activation message in sidebar if DISPLAY_ACCOUNT_ACTIVATION_MESSAGE_ON_SIDEBAR
    # flag is active. Otherwise display existing message at the top.
    if display_account_activation_message_on_sidebar and not user.is_active:
        sidebar_account_activation_message = render_to_string(
            'registration/account_activation_sidebar_notice.html',
            {
                'email': user.email,
                'platform_name': platform_name,
                'activation_email_support_link': activation_email_support_link
            }
        )
    elif not user.is_active:
        banner_account_activation_message = render_to_string(
            'registration/activate_account_notice.html',
            {'email': user.email}
        )

    enterprise_message = get_dashboard_consent_notification(request, user, course_enrollments)

    # Disable lookup of Enterprise consent_required_course due to ENT-727
    # Will re-enable after fixing WL-1315
    consent_required_courses = set()
    enterprise_customer_name = None

    # Account activation message
    account_activation_messages = [
        message for message in messages.get_messages(request) if 'account-activation' in message.tags
    ]

    # Global staff can see what courses encountered an error on their dashboard
    staff_access = False
    errored_courses = {}
    if has_access(user, 'staff', 'global'):
        # Show any courses that encountered an error on load
        staff_access = True
        errored_courses = modulestore().get_errored_courses()

    show_courseware_links_for = frozenset(
        enrollment.course_id for enrollment in course_enrollments
        if has_access(request.user, 'load', enrollment.course_overview)
    )

    # Find programs associated with course runs being displayed. This information
    # is passed in the template context to allow rendering of program-related
    # information on the dashboard.
    meter = ProgramProgressMeter(request.site, user, enrollments=course_enrollments)
    inverted_programs = meter.invert_programs()

    # Construct a dictionary of course mode information
    # used to render the course list.  We re-use the course modes dict
    # we loaded earlier to avoid hitting the database.
    course_mode_info = {
        enrollment.course_id: complete_course_mode_info(
            enrollment.course_id, enrollment,
            modes=course_modes_by_course[enrollment.course_id]
        )
        for enrollment in course_enrollments
    }

    # Determine the per-course verification status
    # This is a dictionary in which the keys are course locators
    # and the values are one of:
    #
    # VERIFY_STATUS_NEED_TO_VERIFY
    # VERIFY_STATUS_SUBMITTED
    # VERIFY_STATUS_APPROVED
    # VERIFY_STATUS_MISSED_DEADLINE
    #
    # Each of which correspond to a particular message to display
    # next to the course on the dashboard.
    #
    # If a course is not included in this dictionary,
    # there is no verification messaging to display.
    verify_status_by_course = check_verify_status_by_course(user, course_enrollments)
    cert_statuses = {
        enrollment.course_id: cert_info(request.user, enrollment.course_overview, enrollment.mode)
        for enrollment in course_enrollments
    }

    # only show email settings for Mongo course and when bulk email is turned on
    show_email_settings_for = frozenset(
        enrollment.course_id for enrollment in course_enrollments if (
            BulkEmailFlag.feature_enabled(enrollment.course_id)
        )
    )

    # Verification Attempts
    # Used to generate the "you must reverify for course x" banner
    verification_status, verification_error_codes = SoftwareSecurePhotoVerification.user_status(user)
    verification_errors = get_verification_error_reasons_for_display(verification_error_codes)

    # Gets data for midcourse reverifications, if any are necessary or have failed
    statuses = ["approved", "denied", "pending", "must_reverify"]
    reverifications = reverification_info(statuses)

    block_courses = frozenset(
        enrollment.course_id for enrollment in course_enrollments
        if is_course_blocked(
            request,
            CourseRegistrationCode.objects.filter(
                course_id=enrollment.course_id,
                registrationcoderedemption__redeemed_by=request.user
            ),
            enrollment.course_id
        )
    )

    enrolled_courses_either_paid = frozenset(
        enrollment.course_id for enrollment in course_enrollments
        if enrollment.is_paid_course()
    )

    # If there are *any* denied reverifications that have not been toggled off,
    # we'll display the banner
    denied_banner = any(item.display for item in reverifications["denied"])

    # Populate the Order History for the side-bar.
    order_history_list = order_history(user, course_org_filter=site_org_whitelist, org_filter_out_set=site_org_blacklist)

    # get list of courses having pre-requisites yet to be completed
    courses_having_prerequisites = frozenset(
        enrollment.course_id for enrollment in course_enrollments
        if enrollment.course_overview.pre_requisite_courses
    )
    courses_requirements_not_met = get_pre_requisite_courses_not_completed(user, courses_having_prerequisites)

    if 'notlive' in request.GET:
        redirect_message = _("The course you are looking for does not start until {date}.").format(
            date=request.GET['notlive']
        )
    elif 'course_closed' in request.GET:
        redirect_message = _("The course you are looking for is closed for enrollment as of {date}.").format(
            date=request.GET['course_closed']
        )
    else:
        redirect_message = ''

    valid_verification_statuses = ['approved', 'must_reverify', 'pending', 'expired']
    display_sidebar_on_dashboard = len(order_history_list) or verification_status in valid_verification_statuses

    context = {
        'enterprise_message': enterprise_message,
        'consent_required_courses': consent_required_courses,
        'enterprise_customer_name': enterprise_customer_name,
        'enrollment_message': enrollment_message,
        'redirect_message': redirect_message,
        'account_activation_messages': account_activation_messages,
        'course_enrollments': course_enrollments,
        'course_optouts': course_optouts,
        'banner_account_activation_message': banner_account_activation_message,
        'sidebar_account_activation_message': sidebar_account_activation_message,
        'staff_access': staff_access,
        'errored_courses': errored_courses,
        'show_courseware_links_for': show_courseware_links_for,
        'all_course_modes': course_mode_info,
        'cert_statuses': cert_statuses,
        'credit_statuses': _credit_statuses(user, course_enrollments),
        'show_email_settings_for': show_email_settings_for,
        'reverifications': reverifications,
        'verification_status': verification_status,
        'verification_status_by_course': verify_status_by_course,
        'verification_errors': verification_errors,
        'block_courses': block_courses,
        'denied_banner': denied_banner,
        'billing_email': settings.PAYMENT_SUPPORT_EMAIL,
        'user': user,
        'logout_url': reverse('logout'),
        'platform_name': platform_name,
        'enrolled_courses_either_paid': enrolled_courses_either_paid,
        'provider_states': [],
        'order_history_list': order_history_list,
        'courses_requirements_not_met': courses_requirements_not_met,
        'nav_hidden': True,
        'inverted_programs': inverted_programs,
        'show_program_listing': ProgramsApiConfig.is_enabled(),
        'show_dashboard_tabs': True,
        'disable_courseware_js': True,
        'display_course_modes_on_dashboard': enable_verified_certificates and display_course_modes_on_dashboard,
        'display_sidebar_on_dashboard': display_sidebar_on_dashboard,
    }

    ecommerce_service = EcommerceService()
    if ecommerce_service.is_enabled(request.user):
        context.update({
            'use_ecommerce_payment_flow': True,
            'ecommerce_payment_page': ecommerce_service.payment_page_url(),
        })

    response = render_to_response('dashboard.html', context)
    set_user_info_cookie(response, request)
    return response


@login_required
def course_run_refund_status(request, course_id):
    """
    Get Refundable status for a course.

    Arguments:
        request: The request object.
        course_id (str): The unique identifier for the course.

    Returns:
        Json response.

    """

    try:
        course_key = CourseKey.from_string(course_id)
        course_enrollment = CourseEnrollment.get_enrollment(request.user, course_key)

    except InvalidKeyError:
        logging.exception("The course key used to get refund status caused InvalidKeyError during look up.")

        return JsonResponse({'course_refundable_status': ''}, status=406)

    refundable_status = course_enrollment.refundable()
    logging.info("Course refund status for course {0} is {1}".format(course_id, refundable_status))

    return JsonResponse({'course_refundable_status': refundable_status}, status=200)


def get_verification_error_reasons_for_display(verification_error_codes):
    verification_errors = []
    verification_error_map = {
        'photos_mismatched': _('Photos are mismatched'),
        'id_image_missing_name': _('Name missing from ID photo'),
        'id_image_missing': _('ID photo not provided'),
        'id_invalid': _('ID is invalid'),
        'user_image_not_clear': _('Learner photo is blurry'),
        'name_mismatch': _('Name on ID does not match name on account'),
        'user_image_missing': _('Learner photo not provided'),
        'id_image_not_clear': _('ID photo is blurry'),
    }

    for error in verification_error_codes:
        error_text = verification_error_map.get(error)
        if error_text:
            verification_errors.append(error_text)

    return verification_errors


def _create_recent_enrollment_message(course_enrollments, course_modes):  # pylint: disable=invalid-name
    """
    Builds a recent course enrollment message.

    Constructs a new message template based on any recent course enrollments
    for the student.

    Args:
        course_enrollments (list[CourseEnrollment]): a list of course enrollments.
        course_modes (dict): Mapping of course ID's to course mode dictionaries.

    Returns:
        A string representing the HTML message output from the message template.
        None if there are no recently enrolled courses.

    """
    recently_enrolled_courses = _get_recently_enrolled_courses(course_enrollments)

    if recently_enrolled_courses:
        enrollments_count = len(recently_enrolled_courses)
        course_name_separator = ', '
        # If length of enrolled course 2, join names with 'and'
        if enrollments_count == 2:
            course_name_separator = _(' and ')

        course_names = course_name_separator.join(
            [enrollment.course_overview.display_name for enrollment in recently_enrolled_courses]
        )

        allow_donations = any(
            _allow_donation(course_modes, enrollment.course_overview.id, enrollment)
            for enrollment in recently_enrolled_courses
        )

        platform_name = configuration_helpers.get_value('platform_name', settings.PLATFORM_NAME)

        return render_to_string(
            'enrollment/course_enrollment_message.html',
            {
                'course_names': course_names,
                'enrollments_count': enrollments_count,
                'allow_donations': allow_donations,
                'platform_name': platform_name,
                'course_id': recently_enrolled_courses[0].course_overview.id if enrollments_count == 1 else None
            }
        )


def _get_recently_enrolled_courses(course_enrollments):
    """
    Given a list of enrollments, filter out all but recent enrollments.

    Args:
        course_enrollments (list[CourseEnrollment]): A list of course enrollments.

    Returns:
        list[CourseEnrollment]: A list of recent course enrollments.
    """
    seconds = DashboardConfiguration.current().recent_enrollment_time_delta
    time_delta = (datetime.datetime.now(UTC) - datetime.timedelta(seconds=seconds))
    return [
        enrollment for enrollment in course_enrollments
        # If the enrollment has no created date, we are explicitly excluding the course
        # from the list of recent enrollments.
        if enrollment.is_active and enrollment.created > time_delta
    ]


def _allow_donation(course_modes, course_id, enrollment):
    """Determines if the dashboard will request donations for the given course.

    Check if donations are configured for the platform, and if the current course is accepting donations.

    Args:
        course_modes (dict): Mapping of course ID's to course mode dictionaries.
        course_id (str): The unique identifier for the course.
        enrollment(CourseEnrollment): The enrollment object in which the user is enrolled

    Returns:
        True if the course is allowing donations.

    """
    if course_id not in course_modes:
        flat_unexpired_modes = {
            unicode(course_id): [mode for mode in modes]
            for course_id, modes in course_modes.iteritems()
        }
        flat_all_modes = {
            unicode(course_id): [mode.slug for mode in modes]
            for course_id, modes in CourseMode.all_modes_for_courses([course_id]).iteritems()
        }
        log.error(
            u'Can not find `%s` in course modes.`%s`. All modes: `%s`',
            course_id,
            flat_unexpired_modes,
            flat_all_modes
        )
    donations_enabled = configuration_helpers.get_value(
        'ENABLE_DONATIONS',
        DonationConfiguration.current().enabled
    )
    return (
        donations_enabled and
        enrollment.mode in course_modes[course_id] and
        course_modes[course_id][enrollment.mode].min_price == 0
    )


def _update_email_opt_in(request, org):
    """Helper function used to hit the profile API if email opt-in is enabled."""

    email_opt_in = request.POST.get('email_opt_in')
    if email_opt_in is not None:
        email_opt_in_boolean = email_opt_in == 'true'
        preferences_api.update_email_opt_in(request.user, org, email_opt_in_boolean)


def _credit_statuses(user, course_enrollments):
    """
    Retrieve the status for credit courses.

    A credit course is a course for which a user can purchased
    college credit.  The current flow is:

    1. User becomes eligible for credit (submits verifications, passes the course, etc.)
    2. User purchases credit from a particular credit provider.
    3. User requests credit from the provider, usually creating an account on the provider's site.
    4. The credit provider notifies us whether the user's request for credit has been accepted or rejected.

    The dashboard is responsible for communicating the user's state in this flow.

    Arguments:
        user (User): The currently logged-in user.
        course_enrollments (list[CourseEnrollment]): List of enrollments for the
            user.

    Returns: dict

    The returned dictionary has keys that are `CourseKey`s and values that
    are dictionaries with:

        * eligible (bool): True if the user is eligible for credit in this course.
        * deadline (datetime): The deadline for purchasing and requesting credit for this course.
        * purchased (bool): Whether the user has purchased credit for this course.
        * provider_name (string): The display name of the credit provider.
        * provider_status_url (string): A URL the user can visit to check on their credit request status.
        * request_status (string): Either "pending", "approved", or "rejected"
        * error (bool): If true, an unexpected error occurred when retrieving the credit status,
            so the user should contact the support team.

    Example:
    >>> _credit_statuses(user, course_enrollments)
    {
        CourseKey.from_string("edX/DemoX/Demo_Course"): {
            "course_key": "edX/DemoX/Demo_Course",
            "eligible": True,
            "deadline": 2015-11-23 00:00:00 UTC,
            "purchased": True,
            "provider_name": "Hogwarts",
            "provider_status_url": "http://example.com/status",
            "request_status": "pending",
            "error": False
        }
    }

    """
    from openedx.core.djangoapps.credit import api as credit_api

    # Feature flag off
    if not settings.FEATURES.get("ENABLE_CREDIT_ELIGIBILITY"):
        return {}

    request_status_by_course = {
        request["course_key"]: request["status"]
        for request in credit_api.get_credit_requests_for_user(user.username)
    }

    credit_enrollments = {
        enrollment.course_id: enrollment
        for enrollment in course_enrollments
        if enrollment.mode == "credit"
    }

    # When a user purchases credit in a course, the user's enrollment
    # mode is set to "credit" and an enrollment attribute is set
    # with the ID of the credit provider.  We retrieve *all* such attributes
    # here to minimize the number of database queries.
    purchased_credit_providers = {
        attribute.enrollment.course_id: attribute.value
        for attribute in CourseEnrollmentAttribute.objects.filter(
            namespace="credit",
            name="provider_id",
            enrollment__in=credit_enrollments.values()
        ).select_related("enrollment")
    }

    provider_info_by_id = {
        provider["id"]: provider
        for provider in credit_api.get_credit_providers()
    }

    statuses = {}
    for eligibility in credit_api.get_eligibilities_for_user(user.username):
        course_key = CourseKey.from_string(unicode(eligibility["course_key"]))
        providers_names = get_credit_provider_display_names(course_key)
        status = {
            "course_key": unicode(course_key),
            "eligible": True,
            "deadline": eligibility["deadline"],
            "purchased": course_key in credit_enrollments,
            "provider_name": make_providers_strings(providers_names),
            "provider_status_url": None,
            "provider_id": None,
            "request_status": request_status_by_course.get(course_key),
            "error": False,
        }

        # If the user has purchased credit, then include information about the credit
        # provider from which the user purchased credit.
        # We retrieve the provider's ID from the an "enrollment attribute" set on the user's
        # enrollment when the user's order for credit is fulfilled by the E-Commerce service.
        if status["purchased"]:
            provider_id = purchased_credit_providers.get(course_key)
            if provider_id is None:
                status["error"] = True
                log.error(
                    u"Could not find credit provider associated with credit enrollment "
                    u"for user %s in course %s.  The user will not be able to see his or her "
                    u"credit request status on the student dashboard.  This attribute should "
                    u"have been set when the user purchased credit in the course.",
                    user.id, course_key
                )
            else:
                provider_info = provider_info_by_id.get(provider_id, {})
                status["provider_name"] = provider_info.get("display_name")
                status["provider_status_url"] = provider_info.get("status_url")
                status["provider_id"] = provider_id

        statuses[course_key] = status

    return statuses


@transaction.non_atomic_requests
@require_POST
@outer_atomic(read_committed=True)
def change_enrollment(request, check_access=True):
    """
    Modify the enrollment status for the logged-in user.

    TODO: This is lms specific and does not belong in common code.

    The request parameter must be a POST request (other methods return 405)
    that specifies course_id and enrollment_action parameters. If course_id or
    enrollment_action is not specified, if course_id is not valid, if
    enrollment_action is something other than "enroll" or "unenroll", if
    enrollment_action is "enroll" and enrollment is closed for the course, or
    if enrollment_action is "unenroll" and the user is not enrolled in the
    course, a 400 error will be returned. If the user is not logged in, 403
    will be returned; it is important that only this case return 403 so the
    front end can redirect the user to a registration or login page when this
    happens. This function should only be called from an AJAX request, so
    the error messages in the responses should never actually be user-visible.

    Args:
        request (`Request`): The Django request object

    Keyword Args:
        check_access (boolean): If True, we check that an accessible course actually
            exists for the given course_key before we enroll the student.
            The default is set to False to avoid breaking legacy code or
            code with non-standard flows (ex. beta tester invitations), but
            for any standard enrollment flow you probably want this to be True.

    Returns:
        Response

    """
    # Get the user
    user = request.user

    # Ensure the user is authenticated
    if not user.is_authenticated():
        return HttpResponseForbidden()

    # Ensure we received a course_id
    action = request.POST.get("enrollment_action")
    if 'course_id' not in request.POST:
        return HttpResponseBadRequest(_("Course id not specified"))

    try:
        course_id = CourseKey.from_string(request.POST.get("course_id"))
    except InvalidKeyError:
        log.warning(
            u"User %s tried to %s with invalid course id: %s",
            user.username,
            action,
            request.POST.get("course_id"),
        )
        return HttpResponseBadRequest(_("Invalid course id"))

    # Allow us to monitor performance of this transaction on a per-course basis since we often roll-out features
    # on a per-course basis.
    monitoring_utils.set_custom_metric('course_id', unicode(course_id))

    if action == "enroll":
        # Make sure the course exists
        # We don't do this check on unenroll, or a bad course id can't be unenrolled from
        if not modulestore().has_course(course_id):
            log.warning(
                u"User %s tried to enroll in non-existent course %s",
                user.username,
                course_id
            )
            return HttpResponseBadRequest(_("Course id is invalid"))

        # Record the user's email opt-in preference
        if settings.FEATURES.get('ENABLE_MKTG_EMAIL_OPT_IN'):
            _update_email_opt_in(request, course_id.org)

        available_modes = CourseMode.modes_for_course_dict(course_id)

        # Check whether the user is blocked from enrolling in this course
        # This can occur if the user's IP is on a global blacklist
        # or if the user is enrolling in a country in which the course
        # is not available.
        redirect_url = embargo_api.redirect_if_blocked(
            course_id, user=user, ip_address=get_ip(request),
            url=request.path
        )
        if redirect_url:
            return HttpResponse(redirect_url)

        # Check that auto enrollment is allowed for this course
        # (= the course is NOT behind a paywall)
        if CourseMode.can_auto_enroll(course_id):
            # Enroll the user using the default mode (audit)
            # We're assuming that users of the course enrollment table
            # will NOT try to look up the course enrollment model
            # by its slug.  If they do, it's possible (based on the state of the database)
            # for no such model to exist, even though we've set the enrollment type
            # to "audit".
            try:
                enroll_mode = CourseMode.auto_enroll_mode(course_id, available_modes)
                if enroll_mode:
                    CourseEnrollment.enroll(user, course_id, check_access=check_access, mode=enroll_mode)
            except Exception:  # pylint: disable=broad-except
                return HttpResponseBadRequest(_("Could not enroll"))

        # If we have more than one course mode or professional ed is enabled,
        # then send the user to the choose your track page.
        # (In the case of no-id-professional/professional ed, this will redirect to a page that
        # funnels users directly into the verification / payment flow)
        if CourseMode.has_verified_mode(available_modes) or CourseMode.has_professional_mode(available_modes):
            return HttpResponse(
                reverse("course_modes_choose", kwargs={'course_id': unicode(course_id)})
            )

        # Otherwise, there is only one mode available (the default)
        return HttpResponse()
    elif action == "unenroll":
        enrollment = CourseEnrollment.get_enrollment(user, course_id)
        if not enrollment:
            return HttpResponseBadRequest(_("You are not enrolled in this course"))

        certificate_info = cert_info(user, enrollment.course_overview, enrollment.mode)
        if certificate_info.get('status') in DISABLE_UNENROLL_CERT_STATES:
            return HttpResponseBadRequest(_("Your certificate prevents you from unenrolling from this course"))

        CourseEnrollment.unenroll(user, course_id)
        REFUND_ORDER.send(sender=None, course_enrollment=enrollment)
        return HttpResponse()
    else:
        return HttpResponseBadRequest(_("Enrollment action is invalid"))


def _generate_not_activated_message(user):
    """
    Generates the message displayed on the sign-in screen when a learner attempts to access the
    system with an inactive account.

    Arguments:
        user (User): User object for the learner attempting to sign in.
    """

    support_url = configuration_helpers.get_value(
        'SUPPORT_SITE_LINK',
        settings.SUPPORT_SITE_LINK
    )

    platform_name = configuration_helpers.get_value(
        'PLATFORM_NAME',
        settings.PLATFORM_NAME
    )

    not_activated_msg_template = _('In order to sign in, you need to activate your account.<br /><br />'
                                   'We just sent an activation link to <strong>{email}</strong>.  If '
                                   'you do not receive an email, check your spam folders or '
                                   '<a href="{support_url}">contact {platform} Support</a>.')

    not_activated_message = not_activated_msg_template.format(
        email=user.email,
        support_url=support_url,
        platform=platform_name
    )

    return not_activated_message


# Need different levels of logging
@ensure_csrf_cookie
def login_user(request, error=""):  # pylint: disable=too-many-statements,unused-argument
    """AJAX request to log in the user."""

    backend_name = None
    email = None
    password = None
    redirect_url = None
    response = None
    running_pipeline = None
    third_party_auth_requested = third_party_auth.is_enabled() and pipeline.running(request)
    third_party_auth_successful = False
    trumped_by_first_party_auth = bool(request.POST.get('email')) or bool(request.POST.get('password'))
    user = None
    platform_name = configuration_helpers.get_value("platform_name", settings.PLATFORM_NAME)

    if third_party_auth_requested and not trumped_by_first_party_auth:
        # The user has already authenticated via third-party auth and has not
        # asked to do first party auth by supplying a username or password. We
        # now want to put them through the same logging and cookie calculation
        # logic as with first-party auth.
        running_pipeline = pipeline.get(request)
        username = running_pipeline['kwargs'].get('username')
        backend_name = running_pipeline['backend']
        third_party_uid = running_pipeline['kwargs']['uid']
        requested_provider = provider.Registry.get_from_pipeline(running_pipeline)

        try:
            user = pipeline.get_authenticated_user(requested_provider, username, third_party_uid)
            third_party_auth_successful = True
        except User.DoesNotExist:
            AUDIT_LOG.info(
                u"Login failed - user with username {username} has no social auth "
                "with backend_name {backend_name}".format(
                    username=username, backend_name=backend_name)
            )
            message = _(
                "You've successfully logged into your {provider_name} account, "
                "but this account isn't linked with an {platform_name} account yet."
            ).format(
                platform_name=platform_name,
                provider_name=requested_provider.name,
            )
            message += "<br/><br/>"
            message += _(
                "Use your {platform_name} username and password to log into {platform_name} below, "
                "and then link your {platform_name} account with {provider_name} from your dashboard."
            ).format(
                platform_name=platform_name,
                provider_name=requested_provider.name,
            )
            message += "<br/><br/>"
            message += _(
                "If you don't have an {platform_name} account yet, "
                "click <strong>Register</strong> at the top of the page."
            ).format(
                platform_name=platform_name
            )

            return HttpResponse(message, content_type="text/plain", status=403)

    else:

        if 'email' not in request.POST or 'password' not in request.POST:
            return JsonResponse({
                "success": False,
                # TODO: User error message
                "value": _('There was an error receiving your login information. Please email us.'),
            })  # TODO: this should be status code 400

        email = request.POST['email']
        password = request.POST['password']
        try:
            user = User.objects.get(email=email)
        except User.DoesNotExist:
            if settings.FEATURES['SQUELCH_PII_IN_LOGS']:
                AUDIT_LOG.warning(u"Login failed - Unknown user email")
            else:
                AUDIT_LOG.warning(u"Login failed - Unknown user email: {0}".format(email))

    # check if the user has a linked shibboleth account, if so, redirect the user to shib-login
    # This behavior is pretty much like what gmail does for shibboleth.  Try entering some @stanford.edu
    # address into the Gmail login.
    if settings.FEATURES.get('AUTH_USE_SHIB') and user:
        try:
            eamap = ExternalAuthMap.objects.get(user=user)
            if eamap.external_domain.startswith(openedx.core.djangoapps.external_auth.views.SHIBBOLETH_DOMAIN_PREFIX):
                return JsonResponse({
                    "success": False,
                    "redirect": reverse('shib-login'),
                })  # TODO: this should be status code 301  # pylint: disable=fixme
        except ExternalAuthMap.DoesNotExist:
            # This is actually the common case, logging in user without external linked login
            AUDIT_LOG.info(u"User %s w/o external auth attempting login", user)

    # see if account has been locked out due to excessive login failures
    user_found_by_email_lookup = user
    if user_found_by_email_lookup and LoginFailures.is_feature_enabled():
        if LoginFailures.is_user_locked_out(user_found_by_email_lookup):
            lockout_message = _('This account has been temporarily locked due '
                                'to excessive login failures. Try again later.')
            return JsonResponse({
                "success": False,
                "value": lockout_message,
            })  # TODO: this should be status code 429  # pylint: disable=fixme

    # see if the user must reset his/her password due to any policy settings
    if user_found_by_email_lookup and PasswordHistory.should_user_reset_password_now(user_found_by_email_lookup):
        return JsonResponse({
            "success": False,
            "value": _('Your password has expired due to password policy on this account. You must '
                       'reset your password before you can log in again. Please click the '
                       '"Forgot Password" link on this page to reset your password before logging in again.'),
        })  # TODO: this should be status code 403  # pylint: disable=fixme

    # if the user doesn't exist, we want to set the username to an invalid
    # username so that authentication is guaranteed to fail and we can take
    # advantage of the ratelimited backend
    username = user.username if user else ""

    if not third_party_auth_successful:
        try:
            user = authenticate(username=username, password=password, request=request)
        # this occurs when there are too many attempts from the same IP address
        except RateLimitException:
            return JsonResponse({
                "success": False,
                "value": _('Too many failed login attempts. Try again later.'),
            })  # TODO: this should be status code 429  # pylint: disable=fixme

    if user is None:
        # tick the failed login counters if the user exists in the database
        if user_found_by_email_lookup and LoginFailures.is_feature_enabled():
            LoginFailures.increment_lockout_counter(user_found_by_email_lookup)

        # if we didn't find this username earlier, the account for this email
        # doesn't exist, and doesn't have a corresponding password
        if username != "":
            if settings.FEATURES['SQUELCH_PII_IN_LOGS']:
                loggable_id = user_found_by_email_lookup.id if user_found_by_email_lookup else "<unknown>"
                AUDIT_LOG.warning(u"Login failed - password for user.id: {0} is invalid".format(loggable_id))
            else:
                AUDIT_LOG.warning(u"Login failed - password for {0} is invalid".format(email))
        return JsonResponse({
            "success": False,
            "value": _('Email or password is incorrect.'),
        })  # TODO: this should be status code 400  # pylint: disable=fixme

    # successful login, clear failed login attempts counters, if applicable
    if LoginFailures.is_feature_enabled():
        LoginFailures.clear_lockout_counter(user)

    # Track the user's sign in
    if hasattr(settings, 'LMS_SEGMENT_KEY') and settings.LMS_SEGMENT_KEY:
        tracking_context = tracker.get_tracker().resolve_context()
        analytics.identify(
            user.id,
            {
                'email': email,
                'username': username
            },
            {
                # Disable MailChimp because we don't want to update the user's email
                # and username in MailChimp on every page load. We only need to capture
                # this data on registration/activation.
                'MailChimp': False
            }
        )

        analytics.track(
            user.id,
            "edx.bi.user.account.authenticated",
            {
                'category': "conversion",
                'label': request.POST.get('course_id'),
                'provider': None
            },
            context={
                'ip': tracking_context.get('ip'),
                'Google Analytics': {
                    'clientId': tracking_context.get('client_id')
                }
            }
        )
    if user is not None and user.is_active:
        try:
            # We do not log here, because we have a handler registered
            # to perform logging on successful logins.
            login(request, user)
            if request.POST.get('remember') == 'true':
                request.session.set_expiry(604800)
                log.debug("Setting user session to never expire")
            else:
                request.session.set_expiry(0)
        except Exception as exc:  # pylint: disable=broad-except
            AUDIT_LOG.critical("Login failed - Could not create session. Is memcached running?")
            log.critical("Login failed - Could not create session. Is memcached running?")
            log.exception(exc)
            raise

        redirect_url = None  # The AJAX method calling should know the default destination upon success
        if third_party_auth_successful:
            redirect_url = pipeline.get_complete_url(backend_name)

        response = JsonResponse({
            "success": True,
            "redirect_url": redirect_url,
        })

        # Ensure that the external marketing site can
        # detect that the user is logged in.
        return set_logged_in_cookies(request, response, user)

    if settings.FEATURES['SQUELCH_PII_IN_LOGS']:
        AUDIT_LOG.warning(u"Login failed - Account not active for user.id: {0}, resending activation".format(user.id))
    else:
        AUDIT_LOG.warning(u"Login failed - Account not active for user {0}, resending activation".format(username))

    reactivation_email_for_user(user)

    return JsonResponse({
        "success": False,
        "value": _generate_not_activated_message(user),
    })  # TODO: this should be status code 400  # pylint: disable=fixme


@csrf_exempt
@require_POST
@social_utils.psa("social:complete")
def login_oauth_token(request, backend):
    """
    Authenticate the client using an OAuth access token by using the token to
    retrieve information from a third party and matching that information to an
    existing user.
    """
    warnings.warn("Please use AccessTokenExchangeView instead.", DeprecationWarning)

    backend = request.backend
    if isinstance(backend, social_oauth.BaseOAuth1) or isinstance(backend, social_oauth.BaseOAuth2):
        if "access_token" in request.POST:
            # Tell third party auth pipeline that this is an API call
            request.session[pipeline.AUTH_ENTRY_KEY] = pipeline.AUTH_ENTRY_LOGIN_API
            user = None
            access_token = request.POST["access_token"]
            try:
                user = backend.do_auth(access_token)
            except (HTTPError, AuthException):
                pass
            # do_auth can return a non-User object if it fails
            if user and isinstance(user, User):
                login(request, user)
                return JsonResponse(status=204)
            else:
                # Ensure user does not re-enter the pipeline
                request.social_strategy.clean_partial_pipeline(access_token)
                return JsonResponse({"error": "invalid_token"}, status=401)
        else:
            return JsonResponse({"error": "invalid_request"}, status=400)
    raise Http404


@require_GET
@login_required
@ensure_csrf_cookie
def manage_user_standing(request):
    """
    Renders the view used to manage user standing. Also displays a table
    of user accounts that have been disabled and who disabled them.
    """
    if not request.user.is_staff:
        raise Http404
    all_disabled_accounts = UserStanding.objects.filter(
        account_status=UserStanding.ACCOUNT_DISABLED
    )

    all_disabled_users = [standing.user for standing in all_disabled_accounts]

    headers = ['username', 'account_changed_by']
    rows = []
    for user in all_disabled_users:
        row = [user.username, user.standing.changed_by]
        rows.append(row)

    context = {'headers': headers, 'rows': rows}

    return render_to_response("manage_user_standing.html", context)


@require_POST
@login_required
@ensure_csrf_cookie
def disable_account_ajax(request):
    """
    Ajax call to change user standing. Endpoint of the form
    in manage_user_standing.html
    """
    if not request.user.is_staff:
        raise Http404
    username = request.POST.get('username')
    context = {}
    if username is None or username.strip() == '':
        context['message'] = _('Please enter a username')
        return JsonResponse(context, status=400)

    account_action = request.POST.get('account_action')
    if account_action is None:
        context['message'] = _('Please choose an option')
        return JsonResponse(context, status=400)

    username = username.strip()
    try:
        user = User.objects.get(username=username)
    except User.DoesNotExist:
        context['message'] = _("User with username {} does not exist").format(username)
        return JsonResponse(context, status=400)
    else:
        user_account, _success = UserStanding.objects.get_or_create(
            user=user, defaults={'changed_by': request.user},
        )
        if account_action == 'disable':
            user_account.account_status = UserStanding.ACCOUNT_DISABLED
            context['message'] = _("Successfully disabled {}'s account").format(username)
            log.info(u"%s disabled %s's account", request.user, username)
        elif account_action == 'reenable':
            user_account.account_status = UserStanding.ACCOUNT_ENABLED
            context['message'] = _("Successfully reenabled {}'s account").format(username)
            log.info(u"%s reenabled %s's account", request.user, username)
        else:
            context['message'] = _("Unexpected account status")
            return JsonResponse(context, status=400)
        user_account.changed_by = request.user
        user_account.standing_last_changed_at = datetime.datetime.now(UTC)
        user_account.save()

    return JsonResponse(context)


@login_required
@ensure_csrf_cookie
def change_setting(request):
    """JSON call to change a profile setting: Right now, location"""
    # TODO (vshnayder): location is no longer used
    u_prof = UserProfile.objects.get(user=request.user)  # request.user.profile_cache
    if 'location' in request.POST:
        u_prof.location = request.POST['location']
    u_prof.save()

    return JsonResponse({
        "success": True,
        "location": u_prof.location,
    })


class AccountValidationError(Exception):
    def __init__(self, message, field):
        super(AccountValidationError, self).__init__(message)
        self.field = field


@receiver(post_save, sender=User)
def user_signup_handler(sender, **kwargs):  # pylint: disable=unused-argument
    """
    handler that saves the user Signup Source
    when the user is created
    """
    if 'created' in kwargs and kwargs['created']:
        site = configuration_helpers.get_value('SITE_NAME')
        if site:
            user_signup_source = UserSignupSource(user=kwargs['instance'], site=site)
            user_signup_source.save()
            log.info(u'user {} originated from a white labeled "Microsite"'.format(kwargs['instance'].id))


def _do_create_account(form, custom_form=None):
    """
    Given cleaned post variables, create the User and UserProfile objects, as well as the
    registration for this user.

    Returns a tuple (User, UserProfile, Registration).

    Note: this function is also used for creating test users.
    """
    # Check if ALLOW_PUBLIC_ACCOUNT_CREATION flag turned off to restrict user account creation
    if not configuration_helpers.get_value(
            'ALLOW_PUBLIC_ACCOUNT_CREATION',
            settings.FEATURES.get('ALLOW_PUBLIC_ACCOUNT_CREATION', True)
    ):
        raise PermissionDenied()

    errors = {}
    errors.update(form.errors)
    if custom_form:
        errors.update(custom_form.errors)

    if errors:
        raise ValidationError(errors)

    user = User(
        username=form.cleaned_data["username"],
        email=form.cleaned_data["email"],
        is_active=False
    )
    user.set_password(form.cleaned_data["password"])
    registration = Registration()

    # TODO: Rearrange so that if part of the process fails, the whole process fails.
    # Right now, we can have e.g. no registration e-mail sent out and a zombie account
    try:
        with transaction.atomic():
            user.save()
            if custom_form:
                custom_model = custom_form.save(commit=False)
                custom_model.user = user
                custom_model.save()
    except IntegrityError:
        # Figure out the cause of the integrity error
        # TODO duplicate email is already handled by form.errors above as a ValidationError.
        # The checks for duplicate email/username should occur in the same place with an
        # AccountValidationError and a consistent user message returned (i.e. both should
        # return "It looks like {username} belongs to an existing account. Try again with a
        # different username.")
        if len(User.objects.filter(username=user.username)) > 0:
            raise AccountValidationError(
                _("An account with the Public Username '{username}' already exists.").format(username=user.username),
                field="username"
            )
        elif len(User.objects.filter(email=user.email)) > 0:
            raise AccountValidationError(
                _("An account with the Email '{email}' already exists.").format(email=user.email),
                field="email"
            )
        else:
            raise

    # add this account creation to password history
    # NOTE, this will be a NOP unless the feature has been turned on in configuration
    password_history_entry = PasswordHistory()
    password_history_entry.create(user)

    registration.register(user)

    profile_fields = [
        "name", "level_of_education", "gender", "mailing_address", "city", "country", "goals",
        "year_of_birth"
    ]
    profile = UserProfile(
        user=user,
        **{key: form.cleaned_data.get(key) for key in profile_fields}
    )
    extended_profile = form.cleaned_extended_profile
    if extended_profile:
        profile.meta = json.dumps(extended_profile)
    try:
        profile.save()
    except Exception:  # pylint: disable=broad-except
        log.exception("UserProfile creation failed for user {id}.".format(id=user.id))
        raise

    return (user, profile, registration)


def _create_or_set_user_attribute_created_on_site(user, site):
    # Create or Set UserAttribute indicating the microsite site the user account was created on.
    # User maybe created on 'courses.edx.org', or a white-label site
    if site:
        UserAttribute.set_user_attribute(user, 'created_on_site', site.domain)


def create_account_with_params(request, params):
    """
    Given a request and a dict of parameters (which may or may not have come
    from the request), create an account for the requesting user, including
    creating a comments service user object and sending an activation email.
    This also takes external/third-party auth into account, updates that as
    necessary, and authenticates the user for the request's session.

    Does not return anything.

    Raises AccountValidationError if an account with the username or email
    specified by params already exists, or ValidationError if any of the given
    parameters is invalid for any other reason.

    Issues with this code:
    * It is not transactional. If there is a failure part-way, an incomplete
      account will be created and left in the database.
    * Third-party auth passwords are not verified. There is a comment that
      they are unused, but it would be helpful to have a sanity check that
      they are sane.
    * It is over 300 lines long (!) and includes disprate functionality, from
      registration e-mails to all sorts of other things. It should be broken
      up into semantically meaningful functions.
    * The user-facing text is rather unfriendly (e.g. "Username must be a
      minimum of two characters long" rather than "Please use a username of
      at least two characters").
    * Duplicate email raises a ValidationError (rather than the expected
      AccountValidationError). Duplicate username returns an inconsistent
      user message (i.e. "An account with the Public Username '{username}'
      already exists." rather than "It looks like {username} belongs to an
      existing account. Try again with a different username.") The two checks
      occur at different places in the code; as a result, registering with
      both a duplicate username and email raises only a ValidationError for
      email only.
    """
    # Copy params so we can modify it; we can't just do dict(params) because if
    # params is request.POST, that results in a dict containing lists of values
    params = dict(params.items())

    # allow to define custom set of required/optional/hidden fields via configuration
    extra_fields = configuration_helpers.get_value(
        'REGISTRATION_EXTRA_FIELDS',
        getattr(settings, 'REGISTRATION_EXTRA_FIELDS', {})
    )
    # registration via third party (Google, Facebook) using mobile application
    # doesn't use social auth pipeline (no redirect uri(s) etc involved).
    # In this case all related info (required for account linking)
    # is sent in params.
    # `third_party_auth_credentials_in_api` essentially means 'request
    # is made from mobile application'
    third_party_auth_credentials_in_api = 'provider' in params

    is_third_party_auth_enabled = third_party_auth.is_enabled()

    if is_third_party_auth_enabled and (pipeline.running(request) or third_party_auth_credentials_in_api):
        params["password"] = pipeline.make_random_password()

    # in case user is registering via third party (Google, Facebook) and pipeline has expired, show appropriate
    # error message
    if is_third_party_auth_enabled and ('social_auth_provider' in params and not pipeline.running(request)):
        raise ValidationError(
            {'session_expired': [
                _(u"Registration using {provider} has timed out.").format(
                    provider=params.get('social_auth_provider'))
            ]}
        )

    # if doing signup for an external authorization, then get email, password, name from the eamap
    # don't use the ones from the form, since the user could have hacked those
    # unless originally we didn't get a valid email or name from the external auth
    # TODO: We do not check whether these values meet all necessary criteria, such as email length
    do_external_auth = 'ExternalAuthMap' in request.session
    if do_external_auth:
        eamap = request.session['ExternalAuthMap']
        try:
            validate_email(eamap.external_email)
            params["email"] = eamap.external_email
        except ValidationError:
            pass
        if eamap.external_name.strip() != '':
            params["name"] = eamap.external_name
        params["password"] = eamap.internal_password
        log.debug(u'In create_account with external_auth: user = %s, email=%s', params["name"], params["email"])

    extended_profile_fields = configuration_helpers.get_value('extended_profile_fields', [])
    enforce_password_policy = (
        settings.FEATURES.get("ENFORCE_PASSWORD_POLICY", False) and
        not do_external_auth
    )
    # Can't have terms of service for certain SHIB users, like at Stanford
    registration_fields = getattr(settings, 'REGISTRATION_EXTRA_FIELDS', {})
    tos_required = (
        registration_fields.get('terms_of_service') != 'hidden' or
        registration_fields.get('honor_code') != 'hidden'
    ) and (
        not settings.FEATURES.get("AUTH_USE_SHIB") or
        not settings.FEATURES.get("SHIB_DISABLE_TOS") or
        not do_external_auth or
        not eamap.external_domain.startswith(openedx.core.djangoapps.external_auth.views.SHIBBOLETH_DOMAIN_PREFIX)
    )

    form = AccountCreationForm(
        data=params,
        extra_fields=extra_fields,
        extended_profile_fields=extended_profile_fields,
        enforce_username_neq_password=True,
        enforce_password_policy=enforce_password_policy,
        tos_required=tos_required,
    )
    custom_form = get_registration_extension_form(data=params)

    # Perform operations within a transaction that are critical to account creation
    with transaction.atomic():
        # first, create the account
        (user, profile, registration) = _do_create_account(form, custom_form)

        # If a 3rd party auth provider and credentials were provided in the API, link the account with social auth
        # (If the user is using the normal register page, the social auth pipeline does the linking, not this code)

        # Note: this is orthogonal to the 3rd party authentication pipeline that occurs
        # when the account is created via the browser and redirect URLs.

        if is_third_party_auth_enabled and third_party_auth_credentials_in_api:
            backend_name = params['provider']
            request.social_strategy = social_utils.load_strategy(request)
            redirect_uri = reverse('social:complete', args=(backend_name, ))
            request.backend = social_utils.load_backend(request.social_strategy, backend_name, redirect_uri)
            social_access_token = params.get('access_token')
            if not social_access_token:
                raise ValidationError({
                    'access_token': [
                        _("An access_token is required when passing value ({}) for provider.").format(
                            params['provider']
                        )
                    ]
                })
            request.session[pipeline.AUTH_ENTRY_KEY] = pipeline.AUTH_ENTRY_REGISTER_API
            pipeline_user = None
            error_message = ""
            try:
                pipeline_user = request.backend.do_auth(social_access_token, user=user)
            except AuthAlreadyAssociated:
                error_message = _("The provided access_token is already associated with another user.")
            except (HTTPError, AuthException):
                error_message = _("The provided access_token is not valid.")
            if not pipeline_user or not isinstance(pipeline_user, User):
                # Ensure user does not re-enter the pipeline
                request.social_strategy.clean_partial_pipeline(social_access_token)
                raise ValidationError({'access_token': [error_message]})

    # Perform operations that are non-critical parts of account creation
    _create_or_set_user_attribute_created_on_site(user, request.site)

    preferences_api.set_user_preference(user, LANGUAGE_KEY, get_language())

    if settings.FEATURES.get('ENABLE_DISCUSSION_EMAIL_DIGEST'):
        try:
            enable_notifications(user)
        except Exception:  # pylint: disable=broad-except
            log.exception("Enable discussion notifications failed for user {id}.".format(id=user.id))

    dog_stats_api.increment("common.student.account_created")

    # If the user is registering via 3rd party auth, track which provider they use
    third_party_provider = None
    running_pipeline = None
    if is_third_party_auth_enabled and pipeline.running(request):
        running_pipeline = pipeline.get(request)
        third_party_provider = provider.Registry.get_from_pipeline(running_pipeline)

    # Track the user's registration
    if hasattr(settings, 'LMS_SEGMENT_KEY') and settings.LMS_SEGMENT_KEY:
        tracking_context = tracker.get_tracker().resolve_context()
        identity_args = [
            user.id,  # pylint: disable=no-member
            {
                'email': user.email,
                'username': user.username,
                'name': profile.name,
                # Mailchimp requires the age & yearOfBirth to be integers, we send a sane integer default if falsey.
                'age': profile.age or -1,
                'yearOfBirth': profile.year_of_birth or datetime.datetime.now(UTC).year,
                'education': profile.level_of_education_display,
                'address': profile.mailing_address,
                'gender': profile.gender_display,
                'country': unicode(profile.country),
            }
        ]

        if hasattr(settings, 'MAILCHIMP_NEW_USER_LIST_ID'):
            identity_args.append({
                "MailChimp": {
                    "listId": settings.MAILCHIMP_NEW_USER_LIST_ID
                }
            })

        analytics.identify(*identity_args)

        analytics.track(
            user.id,
            "edx.bi.user.account.registered",
            {
                'category': 'conversion',
                'label': params.get('course_id'),
                'provider': third_party_provider.name if third_party_provider else None
            },
            context={
                'ip': tracking_context.get('ip'),
                'Google Analytics': {
                    'clientId': tracking_context.get('client_id')
                }
            }
        )

    # Announce registration
    REGISTER_USER.send(sender=None, user=user, registration=registration)

    create_comments_service_user(user)

    # Check if we system is configured to skip activation email for the current user.
    skip_email = skip_activation_email(
        user, do_external_auth, running_pipeline, third_party_provider,
    )

    if skip_email:
        registration.activate()
        _enroll_user_in_pending_courses(user)  # Enroll student in any pending courses
    else:
        compose_and_send_activation_email(user, profile, registration)

    # Immediately after a user creates an account, we log them in. They are only
    # logged in until they close the browser. They can't log in again until they click
    # the activation link from the email.
    new_user = authenticate(username=user.username, password=params['password'])
    login(request, new_user)
    request.session.set_expiry(0)

    try:
        record_registration_attributions(request, new_user)
    # Don't prevent a user from registering due to attribution errors.
    except Exception:   # pylint: disable=broad-except
        log.exception('Error while attributing cookies to user registration.')

    # TODO: there is no error checking here to see that the user actually logged in successfully,
    # and is not yet an active user.
    if new_user is not None:
        AUDIT_LOG.info(u"Login success on new account creation - {0}".format(new_user.username))

    if do_external_auth:
        eamap.user = new_user
        eamap.dtsignup = datetime.datetime.now(UTC)
        eamap.save()
        AUDIT_LOG.info(u"User registered with external_auth %s", new_user.username)
        AUDIT_LOG.info(u'Updated ExternalAuthMap for %s to be %s', new_user.username, eamap)

        if settings.FEATURES.get('BYPASS_ACTIVATION_EMAIL_FOR_EXTAUTH'):
            log.info('bypassing activation email')
            new_user.is_active = True
            new_user.save()
            AUDIT_LOG.info(u"Login activated on extauth account - {0} ({1})".format(new_user.username, new_user.email))

    return new_user


def skip_activation_email(user, do_external_auth, running_pipeline, third_party_provider):
    """
    Return `True` if activation email should be skipped.

    Skip email if we are:
        1. Doing load testing.
        2. Random user generation for other forms of testing.
        3. External auth bypassing activation.
        4. Have the platform configured to not require e-mail activation.
        5. Registering a new user using a trusted third party provider (with skip_email_verification=True)

    Note that this feature is only tested as a flag set one way or
    the other for *new* systems. we need to be careful about
    changing settings on a running system to make sure no users are
    left in an inconsistent state (or doing a migration if they are).

    Arguments:
        user (User): Django User object for the current user.
        do_external_auth (bool): True if external authentication is in progress.
        running_pipeline (dict): Dictionary containing user and pipeline data for third party authentication.
        third_party_provider (ProviderConfig): An instance of third party provider configuration.

    Returns:
        (bool): `True` if account activation email should be skipped, `False` if account activation email should be
            sent.
    """
    sso_pipeline_email = running_pipeline and running_pipeline['kwargs'].get('details', {}).get('email')

    # Email is valid if the SAML assertion email matches the user account email or
    # no email was provided in the SAML assertion. Some IdP's use a callback
    # to retrieve additional user account information (including email) after the
    # initial account creation.
    valid_email = (
        sso_pipeline_email == user.email or (
            sso_pipeline_email is None and
            third_party_provider and
            getattr(third_party_provider, "identity_provider_type", None) == SAP_SUCCESSFACTORS_SAML_KEY
        )
    )

    return (
        settings.FEATURES.get('SKIP_EMAIL_VALIDATION', None) or
        settings.FEATURES.get('AUTOMATIC_AUTH_FOR_TESTING') or
        (settings.FEATURES.get('BYPASS_ACTIVATION_EMAIL_FOR_EXTAUTH') and do_external_auth) or
        (third_party_provider and third_party_provider.skip_email_verification and valid_email)
    )


def _enroll_user_in_pending_courses(student):
    """
    Enroll student in any pending courses he/she may have.
    """
    ceas = CourseEnrollmentAllowed.objects.filter(email=student.email)
    for cea in ceas:
        if cea.auto_enroll:
            enrollment = CourseEnrollment.enroll(student, cea.course_id)
            manual_enrollment_audit = ManualEnrollmentAudit.get_manual_enrollment_by_email(student.email)
            if manual_enrollment_audit is not None:
                # get the enrolled by user and reason from the ManualEnrollmentAudit table.
                # then create a new ManualEnrollmentAudit table entry for the same email
                # different transition state.
                ManualEnrollmentAudit.create_manual_enrollment_audit(
                    manual_enrollment_audit.enrolled_by, student.email, ALLOWEDTOENROLL_TO_ENROLLED,
                    manual_enrollment_audit.reason, enrollment
                )


def record_affiliate_registration_attribution(request, user):
    """
    Attribute this user's registration to the referring affiliate, if
    applicable.
    """
    affiliate_id = request.COOKIES.get(settings.AFFILIATE_COOKIE_NAME)
    if user and affiliate_id:
        UserAttribute.set_user_attribute(user, REGISTRATION_AFFILIATE_ID, affiliate_id)


def record_utm_registration_attribution(request, user):
    """
    Attribute this user's registration to the latest UTM referrer, if
    applicable.
    """
    utm_cookie_name = RegistrationCookieConfiguration.current().utm_cookie_name
    utm_cookie = request.COOKIES.get(utm_cookie_name)
    if user and utm_cookie:
        utm = json.loads(utm_cookie)
        for utm_parameter_name in REGISTRATION_UTM_PARAMETERS:
            utm_parameter = utm.get(utm_parameter_name)
            if utm_parameter:
                UserAttribute.set_user_attribute(
                    user,
                    REGISTRATION_UTM_PARAMETERS.get(utm_parameter_name),
                    utm_parameter
                )
        created_at_unixtime = utm.get('created_at')
        if created_at_unixtime:
            # We divide by 1000 here because the javascript timestamp generated is in milliseconds not seconds.
            # PYTHON: time.time()      => 1475590280.823698
            # JS: new Date().getTime() => 1475590280823
            created_at_datetime = datetime.datetime.fromtimestamp(int(created_at_unixtime) / float(1000), tz=UTC)
            UserAttribute.set_user_attribute(
                user,
                REGISTRATION_UTM_CREATED_AT,
                created_at_datetime
            )


def record_registration_attributions(request, user):
    """
    Attribute this user's registration based on referrer cookies.
    """
    record_affiliate_registration_attribution(request, user)
    record_utm_registration_attribution(request, user)


@csrf_exempt
def create_account(request, post_override=None):
    """
    JSON call to create new edX account.
    Used by form in signup_modal.html, which is included into header.html
    """
    # Check if ALLOW_PUBLIC_ACCOUNT_CREATION flag turned off to restrict user account creation
    if not configuration_helpers.get_value(
            'ALLOW_PUBLIC_ACCOUNT_CREATION',
            settings.FEATURES.get('ALLOW_PUBLIC_ACCOUNT_CREATION', True)
    ):
        return HttpResponseForbidden(_("Account creation not allowed."))

    warnings.warn("Please use RegistrationView instead.", DeprecationWarning)

    try:
        user = create_account_with_params(request, post_override or request.POST)
    except AccountValidationError as exc:
        return JsonResponse({'success': False, 'value': exc.message, 'field': exc.field}, status=400)
    except ValidationError as exc:
        field, error_list = next(exc.message_dict.iteritems())
        return JsonResponse(
            {
                "success": False,
                "field": field,
                "value": error_list[0],
            },
            status=400
        )

    redirect_url = None  # The AJAX method calling should know the default destination upon success

    # Resume the third-party-auth pipeline if necessary.
    if third_party_auth.is_enabled() and pipeline.running(request):
        running_pipeline = pipeline.get(request)
        redirect_url = pipeline.get_complete_url(running_pipeline['backend'])

    response = JsonResponse({
        'success': True,
        'redirect_url': redirect_url,
    })
    set_logged_in_cookies(request, response, user)
    return response


def str2bool(s):
    s = str(s)
    return s.lower() in ('yes', 'true', 't', '1')


def _clean_roles(roles):
    """ Clean roles.

    Strips whitespace from roles, and removes empty items.

    Args:
        roles (str[]): List of role names.

    Returns:
        str[]
    """
    roles = [role.strip() for role in roles]
    roles = [role for role in roles if role]
    return roles


def auto_auth(request):
    """
    Create or configure a user account, then log in as that user.

    Enabled only when
    settings.FEATURES['AUTOMATIC_AUTH_FOR_TESTING'] is true.

    Accepts the following querystring parameters:
    * `username`, `email`, and `password` for the user account
    * `full_name` for the user profile (the user's full name; defaults to the username)
    * `staff`: Set to "true" to make the user global staff.
    * `course_id`: Enroll the student in the course with `course_id`
    * `roles`: Comma-separated list of roles to grant the student in the course with `course_id`
    * `no_login`: Define this to create the user but not login
    * `redirect`: Set to "true" will redirect to the `redirect_to` value if set, or
        course home page if course_id is defined, otherwise it will redirect to dashboard
    * `redirect_to`: will redirect to to this url
    * `is_active` : make/update account with status provided as 'is_active'
    If username, email, or password are not provided, use
    randomly generated credentials.
    """

    # Generate a unique name to use if none provided
    generated_username = uuid.uuid4().hex[0:30]

    # Use the params from the request, otherwise use these defaults
    username = request.GET.get('username', generated_username)
    password = request.GET.get('password', username)
    email = request.GET.get('email', username + "@example.com")
    full_name = request.GET.get('full_name', username)
    is_staff = str2bool(request.GET.get('staff', False))
    is_superuser = str2bool(request.GET.get('superuser', False))
    course_id = request.GET.get('course_id')
    redirect_to = request.GET.get('redirect_to')
    is_active = str2bool(request.GET.get('is_active', True))

    # Valid modes: audit, credit, honor, no-id-professional, professional, verified
    enrollment_mode = request.GET.get('enrollment_mode', 'honor')

    # Parse roles, stripping whitespace, and filtering out empty strings
    roles = _clean_roles(request.GET.get('roles', '').split(','))
    course_access_roles = _clean_roles(request.GET.get('course_access_roles', '').split(','))

    redirect_when_done = str2bool(request.GET.get('redirect', '')) or redirect_to
    login_when_done = 'no_login' not in request.GET

    form = AccountCreationForm(
        data={
            'username': username,
            'email': email,
            'password': password,
            'name': full_name,
        },
        tos_required=False
    )

    # Attempt to create the account.
    # If successful, this will return a tuple containing
    # the new user object.
    try:
        user, profile, reg = _do_create_account(form)
    except (AccountValidationError, ValidationError):
        # Attempt to retrieve the existing user.
        user = User.objects.get(username=username)
        user.email = email
        user.set_password(password)
        user.is_active = is_active
        user.save()
        profile = UserProfile.objects.get(user=user)
        reg = Registration.objects.get(user=user)
    except PermissionDenied:
        return HttpResponseForbidden(_('Account creation not allowed.'))

    user.is_staff = is_staff
    user.is_superuser = is_superuser
    user.save()

    if is_active:
        reg.activate()
        reg.save()

    # ensure parental consent threshold is met
    year = datetime.date.today().year
    age_limit = settings.PARENTAL_CONSENT_AGE_LIMIT
    profile.year_of_birth = (year - age_limit) - 1
    profile.save()

    _create_or_set_user_attribute_created_on_site(user, request.site)

    # Enroll the user in a course
    course_key = None
    if course_id:
        course_key = CourseLocator.from_string(course_id)
        CourseEnrollment.enroll(user, course_key, mode=enrollment_mode)

        # Apply the roles
        for role in roles:
            assign_role(course_key, user, role)

        for role in course_access_roles:
            CourseAccessRole.objects.update_or_create(user=user, course_id=course_key, org=course_key.org, role=role)

    # Log in as the user
    if login_when_done:
        user = authenticate(username=username, password=password)
        login(request, user)

    create_comments_service_user(user)

    if redirect_when_done:
        if redirect_to:
            # Redirect to page specified by the client
            redirect_url = redirect_to
        elif course_id:
            # Redirect to the course homepage (in LMS) or outline page (in Studio)
            try:
                redirect_url = reverse(course_home_url_name(course_key), kwargs={'course_id': course_id})
            except NoReverseMatch:
                redirect_url = reverse('course_handler', kwargs={'course_key_string': course_id})
        else:
            # Redirect to the learner dashboard (in LMS) or homepage (in Studio)
            try:
                redirect_url = reverse('dashboard')
            except NoReverseMatch:
                redirect_url = reverse('home')

        return redirect(redirect_url)
    else:
        response = JsonResponse({
            'created_status': 'Logged in' if login_when_done else 'Created',
            'username': username,
            'email': email,
            'password': password,
            'user_id': user.id,  # pylint: disable=no-member
            'anonymous_id': anonymous_id_for_user(user, None),
        })
    response.set_cookie('csrftoken', csrf(request)['csrf_token'])
    return response


@ensure_csrf_cookie
def activate_account(request, key):
    """When link in activation e-mail is clicked"""

    # If request is in Studio call the appropriate view
    if theming_helpers.get_project_root_name().lower() == u'cms':
        return activate_account_studio(request, key)

    try:
        registration = Registration.objects.get(activation_key=key)
    except (Registration.DoesNotExist, Registration.MultipleObjectsReturned):
        messages.error(
            request,
            HTML(_(
                '{html_start}Your account could not be activated{html_end}'
                'Something went wrong, please <a href="{support_url}">contact support</a> to resolve this issue.'
            )).format(
                support_url=configuration_helpers.get_value('SUPPORT_SITE_LINK', settings.SUPPORT_SITE_LINK),
                html_start=HTML('<p class="message-title">'),
                html_end=HTML('</p>'),
            ),
            extra_tags='account-activation aa-icon'
        )
    else:
        if not registration.user.is_active:
            registration.activate()
            # Success message for logged in users.
            message = _('{html_start}Success{html_end} You have activated your account.')

            if not request.user.is_authenticated():
                # Success message for logged out users
                message = _(
                    '{html_start}Success! You have activated your account.{html_end}'
                    'You will now receive email updates and alerts from us related to'
                    ' the courses you are enrolled in. Sign In to continue.'
                )

            # Add message for later use.
            messages.success(
                request,
                HTML(message).format(
                    html_start=HTML('<p class="message-title">'),
                    html_end=HTML('</p>'),
                ),
                extra_tags='account-activation aa-icon',
            )
        else:
            messages.info(
                request,
                HTML(_('{html_start}This account has already been activated.{html_end}')).format(
                    html_start=HTML('<p class="message-title">'),
                    html_end=HTML('</p>'),
                ),
                extra_tags='account-activation aa-icon',
            )

        # Enroll student in any pending courses he/she may have if auto_enroll flag is set
        _enroll_user_in_pending_courses(registration.user)

    return redirect('dashboard')


@ensure_csrf_cookie
def activate_account_studio(request, key):
    """
    When link in activation e-mail is clicked and the link belongs to studio.
    """
    try:
        registration = Registration.objects.get(activation_key=key)
    except (Registration.DoesNotExist, Registration.MultipleObjectsReturned):
        return render_to_response(
            "registration/activation_invalid.html",
            {'csrf': csrf(request)['csrf_token']}
        )
    else:
        user_logged_in = request.user.is_authenticated()
        already_active = True
        if not registration.user.is_active:
            registration.activate()
            already_active = False

        # Enroll student in any pending courses he/she may have if auto_enroll flag is set
        _enroll_user_in_pending_courses(registration.user)

        return render_to_response(
            "registration/activation_complete.html",
            {
                'user_logged_in': user_logged_in,
                'already_active': already_active
            }
        )


@csrf_exempt
@require_POST
def password_reset(request):
    """ Attempts to send a password reset e-mail. """
    # Add some rate limiting here by re-using the RateLimitMixin as a helper class
    limiter = BadRequestRateLimiter()
    if limiter.is_rate_limit_exceeded(request):
        AUDIT_LOG.warning("Rate limit exceeded in password_reset")
        return HttpResponseForbidden()

    form = PasswordResetFormNoActive(request.POST)
    if form.is_valid():
        form.save(use_https=request.is_secure(),
                  from_email=configuration_helpers.get_value('email_from_address', settings.DEFAULT_FROM_EMAIL),
                  request=request)
        # When password change is complete, a "edx.user.settings.changed" event will be emitted.
        # But because changing the password is multi-step, we also emit an event here so that we can
        # track where the request was initiated.
        tracker.emit(
            SETTING_CHANGE_INITIATED,
            {
                "setting": "password",
                "old": None,
                "new": None,
                "user_id": request.user.id,
            }
        )
        destroy_oauth_tokens(request.user)
    else:
        # bad user? tick the rate limiter counter
        AUDIT_LOG.info("Bad password_reset user passed in.")
        limiter.tick_bad_request_counter(request)

    return JsonResponse({
        'success': True,
        'value': render_to_string('registration/password_reset_done.html', {}),
    })


def uidb36_to_uidb64(uidb36):
    """
    Needed to support old password reset URLs that use base36-encoded user IDs
    https://github.com/django/django/commit/1184d077893ff1bc947e45b00a4d565f3df81776#diff-c571286052438b2e3190f8db8331a92bR231
    Args:
        uidb36: base36-encoded user ID

    Returns: base64-encoded user ID. Otherwise returns a dummy, invalid ID
    """
    try:
        uidb64 = force_text(urlsafe_base64_encode(force_bytes(base36_to_int(uidb36))))
    except ValueError:
        uidb64 = '1'  # dummy invalid ID (incorrect padding for base64)
    return uidb64


def validate_password(password):
    """
    Validate password overall strength if ENFORCE_PASSWORD_POLICY is enable
    otherwise only validate the length of the password.

    Args:
        password: the user's proposed new password.

    Returns:
        err_msg: an error message if there's a violation of one of the password
            checks. Otherwise, `None`.
    """

    try:
        if settings.FEATURES.get('ENFORCE_PASSWORD_POLICY', False):
            validate_password_strength(password)
        else:
            validate_password_length(password)

    except ValidationError as err:
        return _('Password: ') + '; '.join(err.messages)


def validate_password_security_policy(user, password):
    """
    Tie in password policy enforcement as an optional level of
    security protection

    Args:
        user: the user object whose password we're checking.
        password: the user's proposed new password.

    Returns:
        err_msg: an error message if there's a violation of one of the password
            checks. Otherwise, `None`.
    """

    err_msg = None
    # also, check the password reuse policy
    if not PasswordHistory.is_allowable_password_reuse(user, password):
        if user.is_staff:
            num_distinct = settings.ADVANCED_SECURITY_CONFIG['MIN_DIFFERENT_STAFF_PASSWORDS_BEFORE_REUSE']
        else:
            num_distinct = settings.ADVANCED_SECURITY_CONFIG['MIN_DIFFERENT_STUDENT_PASSWORDS_BEFORE_REUSE']
        # Because of how ngettext is, splitting the following into shorter lines would be ugly.
        # pylint: disable=line-too-long
        err_msg = ungettext(
            "You are re-using a password that you have used recently. You must have {num} distinct password before reusing a previous password.",
            "You are re-using a password that you have used recently. You must have {num} distinct passwords before reusing a previous password.",
            num_distinct
        ).format(num=num_distinct)

    # also, check to see if passwords are getting reset too frequent
    if PasswordHistory.is_password_reset_too_soon(user):
        num_days = settings.ADVANCED_SECURITY_CONFIG['MIN_TIME_IN_DAYS_BETWEEN_ALLOWED_RESETS']
        # Because of how ngettext is, splitting the following into shorter lines would be ugly.
        # pylint: disable=line-too-long
        err_msg = ungettext(
            "You are resetting passwords too frequently. Due to security policies, {num} day must elapse between password resets.",
            "You are resetting passwords too frequently. Due to security policies, {num} days must elapse between password resets.",
            num_days
        ).format(num=num_days)

    return err_msg


def password_reset_confirm_wrapper(request, uidb36=None, token=None):
    """
    A wrapper around django.contrib.auth.views.password_reset_confirm.
    Needed because we want to set the user as active at this step.
    We also optionally do some additional password policy checks.
    """
    # convert old-style base36-encoded user id to base64
    uidb64 = uidb36_to_uidb64(uidb36)
    platform_name = {
        "platform_name": configuration_helpers.get_value('platform_name', settings.PLATFORM_NAME)
    }
    try:
        uid_int = base36_to_int(uidb36)
        user = User.objects.get(id=uid_int)
    except (ValueError, User.DoesNotExist):
        # if there's any error getting a user, just let django's
        # password_reset_confirm function handle it.
        return password_reset_confirm(
            request, uidb64=uidb64, token=token, extra_context=platform_name
        )

    if request.method == 'POST':
        password = request.POST['new_password1']
        valid_link = False
        error_message = validate_password_security_policy(user, password)
        if not error_message:
            # if security is not violated, we need to validate password
            error_message = validate_password(password)
            if error_message:
                # password reset link will be valid if there is no security violation
                valid_link = True

        if error_message:
            # We have a password reset attempt which violates some security
            # policy, or any other validation. Use the existing Django template to communicate that
            # back to the user.
            context = {
                'validlink': valid_link,
                'form': None,
                'title': _('Password reset unsuccessful'),
                'err_msg': error_message,
            }
            context.update(platform_name)
            return TemplateResponse(
                request, 'registration/password_reset_confirm.html', context
            )

        # remember what the old password hash is before we call down
        old_password_hash = user.password

        response = password_reset_confirm(
            request, uidb64=uidb64, token=token, extra_context=platform_name
        )

        # If password reset was unsuccessful a template response is returned (status_code 200).
        # Check if form is invalid then show an error to the user.
        # Note if password reset was successful we get response redirect (status_code 302).
        if response.status_code == 200:
            form_valid = response.context_data['form'].is_valid() if response.context_data['form'] else False
            if not form_valid:
                log.warning(
                    u'Unable to reset password for user [%s] because form is not valid. '
                    u'A possible cause is that the user had an invalid reset token',
                    user.username,
                )
                response.context_data['err_msg'] = _('Error in resetting your password. Please try again.')
                return response

        # get the updated user
        updated_user = User.objects.get(id=uid_int)

        # did the password hash change, if so record it in the PasswordHistory
        if updated_user.password != old_password_hash:
            entry = PasswordHistory()
            entry.create(updated_user)

    else:
        response = password_reset_confirm(
            request, uidb64=uidb64, token=token, extra_context=platform_name
        )

        response_was_successful = response.context_data.get('validlink')
        if response_was_successful and not user.is_active:
            user.is_active = True
            user.save()

    return response


def reactivation_email_for_user(user):
    try:
        registration = Registration.objects.get(user=user)
    except Registration.DoesNotExist:
        return JsonResponse({
            "success": False,
            "error": _('No inactive user with this e-mail exists'),
        })  # TODO: this should be status code 400  # pylint: disable=fixme

    try:
        context = generate_activation_email_context(user, registration)
    except ObjectDoesNotExist:
        log.error(
            u'Unable to send reactivation email due to unavailable profile for the user "%s"',
            user.username,
            exc_info=True
        )
        return JsonResponse({
            "success": False,
            "error": _('Unable to send reactivation email')
        })

    subject = render_to_string('emails/activation_email_subject.txt', context)
    subject = ''.join(subject.splitlines())
    message = render_to_string('emails/activation_email.txt', context)
    from_address = configuration_helpers.get_value('email_from_address', settings.DEFAULT_FROM_EMAIL)
    from_address = configuration_helpers.get_value('ACTIVATION_EMAIL_FROM_ADDRESS', from_address)

    try:
        user.email_user(subject, message, from_address)
    except Exception:  # pylint: disable=broad-except
        log.error(
            u'Unable to send reactivation email from "%s" to "%s"',
            from_address,
            user.email,
            exc_info=True
        )
        return JsonResponse({
            "success": False,
            "error": _('Unable to send reactivation email')
        })  # TODO: this should be status code 500  # pylint: disable=fixme

    return JsonResponse({"success": True})


def validate_new_email(user, new_email):
    """
    Given a new email for a user, does some basic verification of the new address If any issues are encountered
    with verification a ValueError will be thrown.
    """
    try:
        validate_email(new_email)
    except ValidationError:
        raise ValueError(_('Valid e-mail address required.'))

    if new_email == user.email:
        raise ValueError(_('Old email is the same as the new email.'))

    if User.objects.filter(email=new_email).count() != 0:
        raise ValueError(_('An account with this e-mail already exists.'))


def do_email_change_request(user, new_email, activation_key=None):
    """
    Given a new email for a user, does some basic verification of the new address and sends an activation message
    to the new address. If any issues are encountered with verification or sending the message, a ValueError will
    be thrown.
    """
    pec_list = PendingEmailChange.objects.filter(user=user)
    if len(pec_list) == 0:
        pec = PendingEmailChange()
        pec.user = user
    else:
        pec = pec_list[0]

    # if activation_key is not passing as an argument, generate a random key
    if not activation_key:
        activation_key = uuid.uuid4().hex

    pec.new_email = new_email
    pec.activation_key = activation_key
    pec.save()

    context = {
        'key': pec.activation_key,
        'old_email': user.email,
        'new_email': pec.new_email
    }

    subject = render_to_string('emails/email_change_subject.txt', context)
    subject = ''.join(subject.splitlines())

    message = render_to_string('emails/email_change.txt', context)

    from_address = configuration_helpers.get_value(
        'email_from_address',
        settings.DEFAULT_FROM_EMAIL
    )
    try:
        mail.send_mail(subject, message, from_address, [pec.new_email])
    except Exception:  # pylint: disable=broad-except
        log.error(u'Unable to send email activation link to user from "%s"', from_address, exc_info=True)
        raise ValueError(_('Unable to send email activation link. Please try again later.'))

    # When the email address change is complete, a "edx.user.settings.changed" event will be emitted.
    # But because changing the email address is multi-step, we also emit an event here so that we can
    # track where the request was initiated.
    tracker.emit(
        SETTING_CHANGE_INITIATED,
        {
            "setting": "email",
            "old": context['old_email'],
            "new": context['new_email'],
            "user_id": user.id,
        }
    )


@ensure_csrf_cookie
def confirm_email_change(request, key):  # pylint: disable=unused-argument
    """
    User requested a new e-mail. This is called when the activation
    link is clicked. We confirm with the old e-mail, and update
    """
    with transaction.atomic():
        try:
            pec = PendingEmailChange.objects.get(activation_key=key)
        except PendingEmailChange.DoesNotExist:
            response = render_to_response("invalid_email_key.html", {})
            transaction.set_rollback(True)
            return response

        user = pec.user
        address_context = {
            'old_email': user.email,
            'new_email': pec.new_email
        }

        if len(User.objects.filter(email=pec.new_email)) != 0:
            response = render_to_response("email_exists.html", {})
            transaction.set_rollback(True)
            return response

        subject = render_to_string('emails/email_change_subject.txt', address_context)
        subject = ''.join(subject.splitlines())
        message = render_to_string('emails/confirm_email_change.txt', address_context)
        u_prof = UserProfile.objects.get(user=user)
        meta = u_prof.get_meta()
        if 'old_emails' not in meta:
            meta['old_emails'] = []
        meta['old_emails'].append([user.email, datetime.datetime.now(UTC).isoformat()])
        u_prof.set_meta(meta)
        u_prof.save()
        # Send it to the old email...
        try:
            user.email_user(
                subject,
                message,
                configuration_helpers.get_value('email_from_address', settings.DEFAULT_FROM_EMAIL)
            )
        except Exception:    # pylint: disable=broad-except
            log.warning('Unable to send confirmation email to old address', exc_info=True)
            response = render_to_response("email_change_failed.html", {'email': user.email})
            transaction.set_rollback(True)
            return response

        user.email = pec.new_email
        user.save()
        pec.delete()
        # And send it to the new email...
        try:
            user.email_user(
                subject,
                message,
                configuration_helpers.get_value('email_from_address', settings.DEFAULT_FROM_EMAIL)
            )
        except Exception:  # pylint: disable=broad-except
            log.warning('Unable to send confirmation email to new address', exc_info=True)
            response = render_to_response("email_change_failed.html", {'email': pec.new_email})
            transaction.set_rollback(True)
            return response

        response = render_to_response("email_change_successful.html", address_context)
        return response


@require_POST
@login_required
@ensure_csrf_cookie
def change_email_settings(request):
    """Modify logged-in user's setting for receiving emails from a course."""
    user = request.user

    course_id = request.POST.get("course_id")
    course_key = CourseKey.from_string(course_id)
    receive_emails = request.POST.get("receive_emails")
    if receive_emails:
        optout_object = Optout.objects.filter(user=user, course_id=course_key)
        if optout_object:
            optout_object.delete()
        log.info(
            u"User %s (%s) opted in to receive emails from course %s",
            user.username,
            user.email,
            course_id,
        )
        track.views.server_track(
            request,
            "change-email-settings",
            {"receive_emails": "yes", "course": course_id},
            page='dashboard',
        )
    else:
        Optout.objects.get_or_create(user=user, course_id=course_key)
        log.info(
            u"User %s (%s) opted out of receiving emails from course %s",
            user.username,
            user.email,
            course_id,
        )
        track.views.server_track(
            request,
            "change-email-settings",
            {"receive_emails": "no", "course": course_id},
            page='dashboard',
        )

    return JsonResponse({"success": True})


class LogoutView(TemplateView):
    """
    Logs out user and redirects.

    The template should load iframes to log the user out of OpenID Connect services.
    See http://openid.net/specs/openid-connect-logout-1_0.html.
    """
    oauth_client_ids = []
    template_name = 'logout.html'

    # Keep track of the page to which the user should ultimately be redirected.
    default_target = reverse_lazy('cas-logout') if settings.FEATURES.get('AUTH_USE_CAS') else '/'

    @property
    def target(self):
        """
        If a redirect_url is specified in the querystring for this request, and the value is a url
        with the same host, the view will redirect to this page after rendering the template.
        If it is not specified, we will use the default target url.
        """
        target_url = self.request.GET.get('redirect_url')

        if target_url and is_safe_url(target_url, self.request.META.get('HTTP_HOST')):
            return target_url
        else:
            return self.default_target

    def dispatch(self, request, *args, **kwargs):  # pylint: disable=missing-docstring
        # We do not log here, because we have a handler registered to perform logging on successful logouts.
        request.is_from_logout = True

        # Get the list of authorized clients before we clear the session.
        self.oauth_client_ids = request.session.get(edx_oauth2_provider.constants.AUTHORIZED_CLIENTS_SESSION_KEY, [])

        logout(request)

        # If we don't need to deal with OIDC logouts, just redirect the user.
        if self.oauth_client_ids:
            response = super(LogoutView, self).dispatch(request, *args, **kwargs)
        else:
            response = redirect(self.target)

        # Clear the cookie used by the edx.org marketing site
        delete_logged_in_cookies(response)

        return response

    def _build_logout_url(self, url):
        """
        Builds a logout URL with the `no_redirect` query string parameter.

        Args:
            url (str): IDA logout URL

        Returns:
            str
        """
        scheme, netloc, path, query_string, fragment = urlsplit(url)
        query_params = parse_qs(query_string)
        query_params['no_redirect'] = 1
        new_query_string = urlencode(query_params, doseq=True)
        return urlunsplit((scheme, netloc, path, new_query_string, fragment))

    def get_context_data(self, **kwargs):
        context = super(LogoutView, self).get_context_data(**kwargs)

        # Create a list of URIs that must be called to log the user out of all of the IDAs.
        uris = Client.objects.filter(client_id__in=self.oauth_client_ids,
                                     logout_uri__isnull=False).values_list('logout_uri', flat=True)

        referrer = self.request.META.get('HTTP_REFERER', '').strip('/')
        logout_uris = []

        for uri in uris:
            if not referrer or (referrer and not uri.startswith(referrer)):
                logout_uris.append(self._build_logout_url(uri))

        context.update({
            'target': self.target,
            'logout_uris': logout_uris,
        })

        return context
