views.py

"""
Student Views
"""
import datetime
import json
import logging
import re
import urllib
import uuid
import time
from collections import defaultdict
from pytz import UTC

from django.conf import settings
from django.contrib.auth import logout, authenticate, login
from django.contrib.auth.models import User, AnonymousUser
from django.contrib.auth.decorators import login_required
from django.contrib.auth.views import password_reset_confirm
from django.core.cache import cache
from django.core.context_processors import csrf
from django.core.mail import send_mail
from django.core.urlresolvers import reverse
from django.core.validators import validate_email, validate_slug, ValidationError
from django.db import IntegrityError, transaction
from django.http import (HttpResponse, HttpResponseBadRequest, HttpResponseForbidden,
                         Http404)
from django.shortcuts import redirect
from django_future.csrf import ensure_csrf_cookie
from django.utils.http import cookie_date, base36_to_int
from django.utils.translation import ugettext as _
from django.views.decorators.http import require_POST, require_GET

from ratelimitbackend.exceptions import RateLimitException

from edxmako.shortcuts import render_to_response, render_to_string

from course_modes.models import CourseMode
from student.models import (
    Registration, UserProfile, PendingNameChange,
    PendingEmailChange, CourseEnrollment, unique_id_for_user,
    CourseEnrollmentAllowed, UserStanding, LoginFailures
)
from student.forms import PasswordResetFormNoActive
from student.firebase_token_generator import create_token

from verify_student.models import SoftwareSecurePhotoVerification, MidcourseReverificationWindow
from certificates.models import CertificateStatuses, certificate_status_for_student
from dark_lang.models import DarkLangConfig

from xmodule.course_module import CourseDescriptor
from xmodule.modulestore.exceptions import ItemNotFoundError
from xmodule.modulestore.django import modulestore
from xmodule.modulestore import XML_MODULESTORE_TYPE, Location

from collections import namedtuple

from courseware.courses import get_courses, sort_by_announcement
from courseware.access import has_access

from external_auth.models import ExternalAuthMap
import external_auth.views

from bulk_email.models import Optout, CourseAuthorization
import shoppingcart
from user_api.models import UserPreference
from lang_pref import LANGUAGE_KEY

import track.views

from dogapi import dog_stats_api

from util.json_request import JsonResponse

from microsite_configuration.middleware import MicrositeConfiguration

from util.password_policy_validators import (
    validate_password_length, validate_password_complexity,
    validate_password_dictionary
)

log = logging.getLogger("edx.student")
AUDIT_LOG = logging.getLogger("audit")

Article = namedtuple('Article', 'title url author image deck publication publish_date')
ReverifyInfo = namedtuple('ReverifyInfo', 'course_id course_name course_number date status display')  # pylint: disable=C0103


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

    # The course selection work is done in courseware.courses.
    domain = settings.FEATURES.get('FORCE_UNIVERSITY_DOMAIN')  # normally False
    # do explicit check, because domain=None is valid
    if domain is False:
        domain = request.META.get('HTTP_HOST')

    courses = get_courses(user, domain=domain)
    courses = sort_by_announcement(courses)

    context = {'courses': courses}

    context.update(extra_context)
    return render_to_response('index.html', context)


def course_from_id(course_id):
    """Return the CourseDescriptor corresponding to this course_id"""
    course_loc = CourseDescriptor.id_to_location(course_id)
    return modulestore().get_instance(course_id, course_loc)

day_pattern = re.compile(r'\s\d+,\s')
multimonth_pattern = re.compile(r'\s?\-\s?\S+\s')


def _get_date_for_press(publish_date):
    # strip off extra months, and just use the first:
    date = re.sub(multimonth_pattern, ", ", publish_date)
    if re.search(day_pattern, date):
        date = datetime.datetime.strptime(date, "%B %d, %Y").replace(tzinfo=UTC)
    else:
        date = datetime.datetime.strptime(date, "%B, %Y").replace(tzinfo=UTC)
    return date


def press(request):
    json_articles = cache.get("student_press_json_articles")
    if json_articles is None:
        if hasattr(settings, 'RSS_URL'):
            content = urllib.urlopen(settings.PRESS_URL).read()
            json_articles = json.loads(content)
        else:
            content = open(settings.PROJECT_ROOT / "templates" / "press.json").read()
            json_articles = json.loads(content)
        cache.set("student_press_json_articles", json_articles)
    articles = [Article(**article) for article in json_articles]
    articles.sort(key=lambda item: _get_date_for_press(item.publish_date), reverse=True)
    return render_to_response('static_templates/press.html', {'articles': articles})


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):
    """
    Get the certificate info needed to render the dashboard section for the given
    student and course.  Returns a dictionary with keys:

    'status': one of 'generating', 'ready', 'notpassing', 'processing', 'restricted'
    'show_download_url': bool
    'download_url': url, only present if show_download_url is True
    'show_disabled_download_button': bool -- true if state is 'generating'
    'show_survey_button': bool
    'survey_url': url, only if show_survey_button is True
    'grade': if status is not 'processing'
    """
    if not course.has_ended():
        return {}

    return _cert_info(user, course, certificate_status_for_student(user, course.id))


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

    Args:
        course_enrollment_pairs (list): list of (course, enrollment) tuples
        user (User): the user whose information we want
        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)
    for (course, enrollment) in course_enrollment_pairs:
        info = single_course_reverification_info(user, course, enrollment)
        if info:
            reverifications[info.status].append(info)

    # 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 single_course_reverification_info(user, course, enrollment):  # pylint: disable=invalid-name
    """Returns midcourse reverification-related information for user with enrollment in course.

    If a course has an open re-verification window, and that user has a verified enrollment in
    the course, we return a tuple with relevant information. Returns None if there is no info..

    Args:
        user (User): the user we want to get information for
        course (Course): the course in which the student is enrolled
        enrollment (CourseEnrollment): the object representing the type of enrollment user has in course

    Returns:
        ReverifyInfo: (course_id, course_name, course_number, date, status)
        OR, None: None if there is no re-verification info for this enrollment
    """
    window = MidcourseReverificationWindow.get_window(course.id, datetime.datetime.now(UTC))

    # If there's no window OR the user is not verified, we don't get reverification info
    if (not window) or (enrollment.mode != "verified"):
        return None
    return ReverifyInfo(
        course.id, course.display_name, course.number,
        window.end_date.strftime('%B %d, %Y %X %p'),
        SoftwareSecurePhotoVerification.user_status(user, window)[0],
        SoftwareSecurePhotoVerification.display_status(user, window),
    )


def get_course_enrollment_pairs(user, course_org_filter, org_filter_out_set):
    """
    Get the relevant set of (Course, CourseEnrollment) pairs to be displayed on
    a student's dashboard.
    """
    for enrollment in CourseEnrollment.enrollments_for_user(user):
        try:
            course = course_from_id(enrollment.course_id)

            # if we are in a Microsite, then filter out anything that is not
            # attributed (by ORG) to that Microsite
            if course_org_filter and course_org_filter != course.location.org:
                continue
            # Conversely, if we are not in a Microsite, then let's filter out any enrollments
            # with courses attributed (by ORG) to Microsites
            elif course.location.org in org_filter_out_set:
                continue

            yield (course, enrollment)
        except ItemNotFoundError:
            log.error("User {0} enrolled in non-existent course {1}"
                      .format(user.username, enrollment.course_id))


def _cert_info(user, course, cert_status):
    """
    Implements the logic for cert_info -- split out for testing.
    """
    default_status = 'processing'

    default_info = {'status': default_status,
                    'show_disabled_download_button': False,
                    'show_download_url': False,
                    'show_survey_button': False,
                    }

    if cert_status is None:
        return default_info

    # simplify the status for the template using this lookup table
    template_state = {
        CertificateStatuses.generating: 'generating',
        CertificateStatuses.regenerating: 'generating',
        CertificateStatuses.downloadable: 'ready',
        CertificateStatuses.notpassing: 'notpassing',
        CertificateStatuses.restricted: 'restricted',
    }

    status = template_state.get(cert_status['status'], default_status)

    d = {'status': status,
         'show_download_url': status == 'ready',
         'show_disabled_download_button': status == 'generating',
         'mode': cert_status.get('mode', None)}

    if (status in ('generating', 'ready', 'notpassing', 'restricted') and
            course.end_of_course_survey_url is not None):
        d.update({
            'show_survey_button': True,
            'survey_url': process_survey_link(course.end_of_course_survey_url, user)})
    else:
        d['show_survey_button'] = False

    if status == 'ready':
        if 'download_url' not in cert_status:
            log.warning("User %s has a downloadable cert for %s, but no download url",
                        user.username, course.id)
            return default_info
        else:
            d['download_url'] = cert_status['download_url']

    if status in ('generating', 'ready', 'notpassing', 'restricted'):
        if 'grade' not in cert_status:
            # 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
        else:
            d['grade'] = cert_status['grade']

    return d


@ensure_csrf_cookie
def signin_user(request):
    """
    This view will display the non-modal login form
    """
    if (settings.FEATURES['AUTH_USE_CERTIFICATES'] and
            external_auth.views.ssl_get_cert_from_request(request)):
        # SSL login doesn't require a view, so redirect
        # branding and allow that to process the login if it
        # is enabled and the header is in the request.
        return redirect(reverse('root'))
    if request.user.is_authenticated():
        return redirect(reverse('dashboard'))

    context = {
        'course_id': request.GET.get('course_id'),
        'enrollment_action': request.GET.get('enrollment_action'),
        'platform_name': MicrositeConfiguration.get_microsite_configuration_value(
            'platform_name',
            settings.PLATFORM_NAME
        ),
    }
    return render_to_response('login.html', context)


@ensure_csrf_cookie
def register_user(request, extra_context=None):
    """
    This view will display the non-modal registration form
    """
    if request.user.is_authenticated():
        return redirect(reverse('dashboard'))
    if settings.FEATURES.get('AUTH_USE_CERTIFICATES_IMMEDIATE_SIGNUP'):
        # Redirect to branding to process their certificate if SSL is enabled
        # and registration is disabled.
        return redirect(reverse('root'))

    context = {
        'course_id': request.GET.get('course_id'),
        'enrollment_action': request.GET.get('enrollment_action'),
        'platform_name': MicrositeConfiguration.get_microsite_configuration_value(
            'platform_name',
            settings.PLATFORM_NAME
        ),
    }
    if extra_context is not None:
        context.update(extra_context)

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


def complete_course_mode_info(course_id, enrollment):
    """
    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
    """
    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 verified and if verified is an
    # option
    if 'verified' in modes and enrollment.mode != 'verified':
        mode_info['show_upsell'] = True
        # 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


@login_required
@ensure_csrf_cookie
def dashboard(request):
    user = request.user

    # for microsites, we want to filter and only show enrollments for courses within
    # the microsites 'ORG'
    course_org_filter = MicrositeConfiguration.get_microsite_configuration_value('course_org_filter')

    # Let's filter out any courses in an "org" that has been declared to be
    # in a Microsite
    org_filter_out_set = MicrositeConfiguration.get_all_microsite_orgs()

    # remove our current Microsite from the "filter out" list, if applicable
    if course_org_filter:
        org_filter_out_set.remove(course_org_filter)

    # Build our (course, enrollment) list for the user, but ignore any courses that no
    # longer exist (because the course IDs have changed). Still, we don't delete those
    # enrollments, because it could have been a data push snafu.
    course_enrollment_pairs = list(get_course_enrollment_pairs(user, course_org_filter, org_filter_out_set))

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

    message = ""
    if not user.is_active:
        message = render_to_string('registration/activate_account_notice.html', {'email': user.email})

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

    show_courseware_links_for = frozenset(course.id for course, _enrollment in course_enrollment_pairs
                                          if has_access(request.user, course, 'load'))

    course_modes = {course.id: complete_course_mode_info(course.id, enrollment) for course, enrollment in course_enrollment_pairs}
    cert_statuses = {course.id: cert_info(request.user, course) for course, _enrollment in course_enrollment_pairs}

    # only show email settings for Mongo course and when bulk email is turned on
    show_email_settings_for = frozenset(
        course.id for course, _enrollment in course_enrollment_pairs if (
            settings.FEATURES['ENABLE_INSTRUCTOR_EMAIL'] and
            modulestore().get_modulestore_type(course.id) != XML_MODULESTORE_TYPE and
            CourseAuthorization.instructor_email_enabled(course.id)
        )
    )

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

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

    show_refund_option_for = frozenset(course.id for course, _enrollment in course_enrollment_pairs
                                       if _enrollment.refundable())

    # get info w.r.t ExternalAuthMap
    external_auth_map = None
    try:
        external_auth_map = ExternalAuthMap.objects.get(user=user)
    except ExternalAuthMap.DoesNotExist:
        pass

    # 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"])

    language_options = DarkLangConfig.current().released_languages_list

    # add in the default language if it's not in the list of released languages
    if settings.LANGUAGE_CODE not in language_options:
        language_options.append(settings.LANGUAGE_CODE)

    # try to get the prefered language for the user
    cur_lang_code = UserPreference.get_preference(request.user, LANGUAGE_KEY)
    if cur_lang_code:
        # if the user has a preference, get the name from the code
        current_language = settings.LANGUAGE_DICT[cur_lang_code]
    else:
        # if the user doesn't have a preference, use the default language
        current_language = settings.LANGUAGE_DICT[settings.LANGUAGE_CODE]

    context = {
        'course_enrollment_pairs': course_enrollment_pairs,
        'course_optouts': course_optouts,
        'message': message,
        'external_auth_map': external_auth_map,
        'staff_access': staff_access,
        'errored_courses': errored_courses,
        'show_courseware_links_for': show_courseware_links_for,
        'all_course_modes': course_modes,
        'cert_statuses': cert_statuses,
        'show_email_settings_for': show_email_settings_for,
        'reverifications': reverifications,
        'verification_status': verification_status,
        'verification_msg': verification_msg,
        'show_refund_option_for': show_refund_option_for,
        'denied_banner': denied_banner,
        'billing_email': settings.PAYMENT_SUPPORT_EMAIL,
        'language_options': language_options,
        'current_language': current_language,
        'current_language_code': cur_lang_code,
    }

    return render_to_response('dashboard.html', context)


def try_change_enrollment(request):
    """
    This method calls change_enrollment if the necessary POST
    parameters are present, but does not return anything. It
    simply logs the result or exception. This is usually
    called after a registration or login, as secondary action.
    It should not interrupt a successful registration or login.
    """
    if 'enrollment_action' in request.POST:
        try:
            enrollment_response = change_enrollment(request)
            # There isn't really a way to display the results to the user, so we just log it
            # We expect the enrollment to be a success, and will show up on the dashboard anyway
            log.info(
                "Attempted to automatically enroll after login. Response code: {0}; response body: {1}".format(
                    enrollment_response.status_code,
                    enrollment_response.content
                )
            )
            if enrollment_response.content != '':
                return enrollment_response.content
        except Exception, e:
            log.exception("Exception automatically enrolling after login: {0}".format(str(e)))


@require_POST
def change_enrollment(request):
    """
    Modify the enrollment status for the logged-in user.

    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 or
    as a post-login/registration helper, so the error messages in the responses
    should never actually be user-visible.
    """
    user = request.user

    action = request.POST.get("enrollment_action")
    course_id = request.POST.get("course_id")
    if course_id is None:
        return HttpResponseBadRequest(_("Course id not specified"))

    if not user.is_authenticated():
        return HttpResponseForbidden()

    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
        try:
            course = course_from_id(course_id)
        except ItemNotFoundError:
            log.warning("User {0} tried to enroll in non-existent course {1}"
                        .format(user.username, course_id))
            return HttpResponseBadRequest(_("Course id is invalid"))

        if not has_access(user, course, 'enroll'):
            return HttpResponseBadRequest(_("Enrollment is closed"))

        # see if we have already filled up all allowed enrollments
        is_course_full = CourseEnrollment.is_course_full(course)

        if is_course_full:
            return HttpResponseBadRequest(_("Course is full"))

        # If this course is available in multiple modes, redirect them to a page
        # where they can choose which mode they want.
        available_modes = CourseMode.modes_for_course(course_id)
        if len(available_modes) > 1:
            return HttpResponse(
                reverse("course_modes_choose", kwargs={'course_id': course_id})
            )

        current_mode = available_modes[0]

        course_id_dict = Location.parse_course_id(course_id)
        dog_stats_api.increment(
            "common.student.enrollment",
            tags=[u"org:{org}".format(**course_id_dict),
                  u"course:{course}".format(**course_id_dict),
                  u"run:{name}".format(**course_id_dict)]
        )

        CourseEnrollment.enroll(user, course.id, mode=current_mode.slug)

        return HttpResponse()

    elif action == "add_to_cart":
        # Pass the request handling to shoppingcart.views
        # The view in shoppingcart.views performs error handling and logs different errors.  But this elif clause
        # is only used in the "auto-add after user reg/login" case, i.e. it's always wrapped in try_change_enrollment.
        # This means there's no good way to display error messages to the user.  So we log the errors and send
        # the user to the shopping cart page always, where they can reasonably discern the status of their cart,
        # whether things got added, etc

        shoppingcart.views.add_course_to_cart(request, course_id)
        return HttpResponse(
            reverse("shoppingcart.views.show_cart")
        )

    elif action == "unenroll":
        if not CourseEnrollment.is_enrolled(user, course_id):
            return HttpResponseBadRequest(_("You are not enrolled in this course"))
        CourseEnrollment.unenroll(user, course_id)
        course_id_dict = Location.parse_course_id(course_id)
        dog_stats_api.increment(
            "common.student.unenrollment",
            tags=[u"org:{org}".format(**course_id_dict),
                  u"course:{course}".format(**course_id_dict),
                  u"run:{name}".format(**course_id_dict)]
        )
        return HttpResponse()
    else:
        return HttpResponseBadRequest(_("Enrollment action is invalid"))


def _parse_course_id_from_string(input_str):
    """
    Helper function to determine if input_str (typically the queryparam 'next') contains a course_id.
    @param input_str:
    @return: the course_id if found, None if not
    """
    m_obj = re.match(r'^/courses/(?P<course_id>[^/]+/[^/]+/[^/]+)', input_str)
    if m_obj:
        return m_obj.group('course_id')
    return None


def _get_course_enrollment_domain(course_id):
    """
    Helper function to get the enrollment domain set for a course with id course_id
    @param course_id:
    @return:
    """
    try:
        course = course_from_id(course_id)
        return course.enrollment_domain
    except ItemNotFoundError:
        return None


@ensure_csrf_cookie
def accounts_login(request):
    """
    This view is mainly used as the redirect from the @login_required decorator.  I don't believe that
    the login path linked from the homepage uses it.
    """
    if settings.FEATURES.get('AUTH_USE_CAS'):
        return redirect(reverse('cas-login'))
    if settings.FEATURES['AUTH_USE_CERTIFICATES']:
        # SSL login doesn't require a view, so redirect
        # to branding and allow that to process the login.
        return redirect(reverse('root'))
    # see if the "next" parameter has been set, whether it has a course context, and if so, whether
    # there is a course-specific place to redirect
    redirect_to = request.GET.get('next')
    if redirect_to:
        course_id = _parse_course_id_from_string(redirect_to)
        if course_id and _get_course_enrollment_domain(course_id):
            return external_auth.views.course_specific_login(request, course_id)

    context = {
        'platform_name': settings.PLATFORM_NAME,
    }
    return render_to_response('login.html', context)


# Need different levels of logging
@ensure_csrf_cookie
def login_user(request, error=""):
    """AJAX request to log in the user."""
    if 'email' not in request.POST or 'password' not in request.POST:
        return JsonResponse({
            "success": False,
            "value": _('There was an error receiving your login information. Please email us.'),  # TODO: User error message
        })  # TODO: this should be status code 400  # pylint: disable=fixme

    email = request.POST['email']
    password = request.POST['password']
    try:
        user = User.objects.get(email=email)
    except User.DoesNotExist:
        AUDIT_LOG.warning(u"Login failed - Unknown user email: {0}".format(email))
        user = None

    # 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(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("User %s w/o external auth attempting login", user)

    # see if account has been locked out due to excessive login failres
    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):
            return JsonResponse({
                "success": False,
                "value": _('This account has been temporarily locked due to excessive login failures. Try again later.'),
            })  # TODO: this should be status code 429  # 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 ""
    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 != "":
            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)

    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 e:
            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(e)
            raise

        redirect_url = try_change_enrollment(request)

        dog_stats_api.increment("common.student.successful_login")
        response = JsonResponse({
            "success": True,
            "redirect_url": redirect_url,
        })

        # set the login cookie for the edx marketing site
        # we want this cookie to be accessed via javascript
        # so httponly is set to None

        if request.session.get_expire_at_browser_close():
            max_age = None
            expires = None
        else:
            max_age = request.session.get_expiry_age()
            expires_time = time.time() + max_age
            expires = cookie_date(expires_time)

        response.set_cookie(
            settings.EDXMKTG_COOKIE_NAME, 'true', max_age=max_age,
            expires=expires, domain=settings.SESSION_COOKIE_DOMAIN,
            path='/', secure=None, httponly=None,
        )

        return response

    AUDIT_LOG.warning(u"Login failed - Account not active for user {0}, resending activation".format(username))

    reactivation_email_for_user(user)
    not_activated_msg = _("This account has not been activated. We have sent another activation message. Please check your e-mail for the activation instructions.")
    return JsonResponse({
        "success": False,
        "value": not_activated_msg,
    })  # TODO: this should be status code 400  # pylint: disable=fixme


@ensure_csrf_cookie
def logout_user(request):
    """
    HTTP request to log out the user. Redirects to marketing page.
    Deletes both the CSRF and sessionid cookies so the marketing
    site can determine the logged in state of the user
    """
    # We do not log here, because we have a handler registered
    # to perform logging on successful logouts.
    logout(request)
    if settings.FEATURES.get('AUTH_USE_CAS'):
        target = reverse('cas-logout')
    else:
        target = '/'
    response = redirect(target)
    response.delete_cookie(
        settings.EDXMKTG_COOKIE_NAME,
        path='/', domain=settings.SESSION_COOKIE_DOMAIN,
    )
    return response


@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.all()[0].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("{} disabled {}'s account".format(request.user, username))
        elif account_action == 'reenable':
            user_account.account_status = UserStanding.ACCOUNT_ENABLED
            context['message'] = _("Successfully reenabled {}'s account").format(username)
            log.info("{} reenabled {}'s account".format(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
    up = UserProfile.objects.get(user=request.user)  # request.user.profile_cache
    if 'location' in request.POST:
        up.location = request.POST['location']
    up.save()

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


def _do_create_account(post_vars):
    """
    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.
    """
    user = User(username=post_vars['username'],
                email=post_vars['email'],
                is_active=False)
    user.set_password(post_vars['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:
        user.save()
    except IntegrityError:
        js = {'success': False}
        # Figure out the cause of the integrity error
        if len(User.objects.filter(username=post_vars['username'])) > 0:
            js['value'] = _("An account with the Public Username '{username}' already exists.").format(username=post_vars['username'])
            js['field'] = 'username'
            return JsonResponse(js, status=400)

        if len(User.objects.filter(email=post_vars['email'])) > 0:
            js['value'] = _("An account with the Email '{email}' already exists.").format(email=post_vars['email'])
            js['field'] = 'email'
            return JsonResponse(js, status=400)

        raise

    registration.register(user)

    profile = UserProfile(user=user)
    profile.name = post_vars['name']
    profile.level_of_education = post_vars.get('level_of_education')
    profile.gender = post_vars.get('gender')
    profile.mailing_address = post_vars.get('mailing_address')
    profile.city = post_vars.get('city')
    profile.country = post_vars.get('country')
    profile.goals = post_vars.get('goals')

    try:
        profile.year_of_birth = int(post_vars['year_of_birth'])
    except (ValueError, KeyError):
        # If they give us garbage, just ignore it instead
        # of asking them to put an integer.
        profile.year_of_birth = None
    try:
        profile.save()
    except Exception:
        log.exception("UserProfile creation failed for user {id}.".format(id=user.id))
    return (user, profile, registration)


@ensure_csrf_cookie
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 navigation.html
    """
    js = {'success': False}

    post_vars = post_override if post_override else request.POST
    extra_fields = getattr(settings, 'REGISTRATION_EXTRA_FIELDS', {})

    # 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
    DoExternalAuth = 'ExternalAuthMap' in request.session
    if DoExternalAuth: