from datetime import datetime

from django.conf import settings
from django.contrib.auth import authenticate
from django.contrib.auth.backends import RemoteUserBackend
from django.contrib.auth.middleware import RemoteUserMiddleware
from django.contrib.auth.models import User
from django.contrib.auth.tests.utils import skipIfCustomUser
from django.test import TestCase, override_settings
from django.utils import timezone


@skipIfCustomUser
@override_settings(ROOT_URLCONF='django.contrib.auth.tests.urls')
class RemoteUserTest(TestCase):

    middleware = 'django.contrib.auth.middleware.RemoteUserMiddleware'
    backend = 'django.contrib.auth.backends.RemoteUserBackend'
    header = 'REMOTE_USER'

    # Usernames to be passed in REMOTE_USER for the test_known_user test case.
    known_user = 'knownuser'
    known_user2 = 'knownuser2'

    def setUp(self):
        self.curr_middleware = settings.MIDDLEWARE_CLASSES
        self.curr_auth = settings.AUTHENTICATION_BACKENDS
        settings.MIDDLEWARE_CLASSES += (self.middleware,)
        settings.AUTHENTICATION_BACKENDS += (self.backend,)

    def test_no_remote_user(self):
        """
        Tests requests where no remote user is specified and insures that no
        users get created.
        """
        num_users = User.objects.count()

        response = self.client.get('/remote_user/')
        self.assertTrue(response.context['user'].is_anonymous())
        self.assertEqual(User.objects.count(), num_users)

        response = self.client.get('/remote_user/', **{self.header: None})
        self.assertTrue(response.context['user'].is_anonymous())
        self.assertEqual(User.objects.count(), num_users)

        response = self.client.get('/remote_user/', **{self.header: ''})
        self.assertTrue(response.context['user'].is_anonymous())
        self.assertEqual(User.objects.count(), num_users)

    def test_unknown_user(self):
        """
        Tests the case where the username passed in the header does not exist
        as a User.
        """
        num_users = User.objects.count()
        response = self.client.get('/remote_user/', **{self.header: 'newuser'})
        self.assertEqual(response.context['user'].username, 'newuser')
        self.assertEqual(User.objects.count(), num_users + 1)
        User.objects.get(username='newuser')

        # Another request with same user should not create any new users.
        response = self.client.get('/remote_user/', **{self.header: 'newuser'})
        self.assertEqual(User.objects.count(), num_users + 1)

    def test_known_user(self):
        """
        Tests the case where the username passed in the header is a valid User.
        """
        User.objects.create(username='knownuser')
        User.objects.create(username='knownuser2')
        num_users = User.objects.count()
        response = self.client.get('/remote_user/',
                                   **{self.header: self.known_user})
        self.assertEqual(response.context['user'].username, 'knownuser')
        self.assertEqual(User.objects.count(), num_users)
        # Test that a different user passed in the headers causes the new user
        # to be logged in.
        response = self.client.get('/remote_user/',
                                   **{self.header: self.known_user2})
        self.assertEqual(response.context['user'].username, 'knownuser2')
        self.assertEqual(User.objects.count(), num_users)

    def test_last_login(self):
        """
        Tests that a user's last_login is set the first time they make a
        request but not updated in subsequent requests with the same session.
        """
        user = User.objects.create(username='knownuser')
        # Set last_login to something so we can determine if it changes.
        default_login = datetime(2000, 1, 1)
        if settings.USE_TZ:
            default_login = default_login.replace(tzinfo=timezone.utc)
        user.last_login = default_login
        user.save()

        response = self.client.get('/remote_user/',
                                   **{self.header: self.known_user})
        self.assertNotEqual(default_login, response.context['user'].last_login)

        user = User.objects.get(username='knownuser')
        user.last_login = default_login
        user.save()
        response = self.client.get('/remote_user/',
                                   **{self.header: self.known_user})
        self.assertEqual(default_login, response.context['user'].last_login)

    def test_header_disappears(self):
        """
        Tests that a logged in user is logged out automatically when
        the REMOTE_USER header disappears during the same browser session.
        """
        User.objects.create(username='knownuser')
        # Known user authenticates
        response = self.client.get('/remote_user/',
                                   **{self.header: self.known_user})
        self.assertEqual(response.context['user'].username, 'knownuser')
        # During the session, the REMOTE_USER header disappears. Should trigger logout.
        response = self.client.get('/remote_user/')
        self.assertEqual(response.context['user'].is_anonymous(), True)
        # verify the remoteuser middleware will not remove a user
        # authenticated via another backend
        User.objects.create_user(username='modeluser', password='foo')
        self.client.login(username='modeluser', password='foo')
        authenticate(username='modeluser', password='foo')
        response = self.client.get('/remote_user/')
        self.assertEqual(response.context['user'].username, 'modeluser')

    def test_user_switch_forces_new_login(self):
        """
        Tests that if the username in the header changes between requests
        that the original user is logged out
        """
        User.objects.create(username='knownuser')
        # Known user authenticates
        response = self.client.get('/remote_user/',
                                   **{self.header: self.known_user})
        self.assertEqual(response.context['user'].username, 'knownuser')
        # During the session, the REMOTE_USER changes to a different user.
        response = self.client.get('/remote_user/',
                                   **{self.header: "newnewuser"})
        # Ensure that the current user is not the prior remote_user
        # In backends that create a new user, username is "newnewuser"
        # In backends that do not create new users, it is '' (anonymous user)
        self.assertNotEqual(response.context['user'].username, 'knownuser')

    def tearDown(self):
        """Restores settings to avoid breaking other tests."""
        settings.MIDDLEWARE_CLASSES = self.curr_middleware
        settings.AUTHENTICATION_BACKENDS = self.curr_auth


class RemoteUserNoCreateBackend(RemoteUserBackend):
    """Backend that doesn't create unknown users."""
    create_unknown_user = False


@skipIfCustomUser
class RemoteUserNoCreateTest(RemoteUserTest):
    """
    Contains the same tests as RemoteUserTest, but using a custom auth backend
    class that doesn't create unknown users.
    """

    backend = 'django.contrib.auth.tests.test_remote_user.RemoteUserNoCreateBackend'

    def test_unknown_user(self):
        num_users = User.objects.count()
        response = self.client.get('/remote_user/', **{self.header: 'newuser'})
        self.assertTrue(response.context['user'].is_anonymous())
        self.assertEqual(User.objects.count(), num_users)


class CustomRemoteUserBackend(RemoteUserBackend):
    """
    Backend that overrides RemoteUserBackend methods.
    """

    def clean_username(self, username):
        """
        Grabs username before the @ character.
        """
        return username.split('@')[0]

    def configure_user(self, user):
        """
        Sets user's email address.
        """
        user.email = 'user@example.com'
        user.save()
        return user


@skipIfCustomUser
class RemoteUserCustomTest(RemoteUserTest):
    """
    Tests a custom RemoteUserBackend subclass that overrides the clean_username
    and configure_user methods.
    """

    backend = 'django.contrib.auth.tests.test_remote_user.CustomRemoteUserBackend'
    # REMOTE_USER strings with email addresses for the custom backend to
    # clean.
    known_user = 'knownuser@example.com'
    known_user2 = 'knownuser2@example.com'

    def test_known_user(self):
        """
        The strings passed in REMOTE_USER should be cleaned and the known users
        should not have been configured with an email address.
        """
        super(RemoteUserCustomTest, self).test_known_user()
        self.assertEqual(User.objects.get(username='knownuser').email, '')
        self.assertEqual(User.objects.get(username='knownuser2').email, '')

    def test_unknown_user(self):
        """
        The unknown user created should be configured with an email address.
        """
        super(RemoteUserCustomTest, self).test_unknown_user()
        newuser = User.objects.get(username='newuser')
        self.assertEqual(newuser.email, 'user@example.com')


class CustomHeaderMiddleware(RemoteUserMiddleware):
    """
    Middleware that overrides custom HTTP auth user header.
    """
    header = 'HTTP_AUTHUSER'


@skipIfCustomUser
class CustomHeaderRemoteUserTest(RemoteUserTest):
    """
    Tests a custom RemoteUserMiddleware subclass with custom HTTP auth user
    header.
    """
    middleware = (
        'django.contrib.auth.tests.test_remote_user.CustomHeaderMiddleware'
    )
    header = 'HTTP_AUTHUSER'
