text: from django.db import transaction
  from django.conf import settings
  from django.conf.urls import url
  from django.contrib import admin
  from django.contrib.admin.options import IS_POPUP_VAR
  from django.contrib.auth import update_session_auth_hash
  from django.contrib.auth.forms import (UserCreationForm, UserChangeForm,
      AdminPasswordChangeForm)
  from django.contrib.auth.models import User, Group
  from django.contrib import messages
  from django.core.exceptions import PermissionDenied
  from django.http import HttpResponseRedirect, Http404
  from django.shortcuts import get_object_or_404
  from django.template.response import TemplateResponse
  from django.utils.html import escape
  from django.utils.decorators import method_decorator
  from django.utils.translation import ugettext, ugettext_lazy as _
  from django.views.decorators.csrf import csrf_protect
  from django.views.decorators.debug import sensitive_post_parameters
  
  csrf_protect_m = method_decorator(csrf_protect)
  sensitive_post_parameters_m = method_decorator(sensitive_post_parameters())
  
  
  class GroupAdmin(admin.ModelAdmin):
      search_fields = ('name',)
      ordering = ('name',)
      filter_horizontal = ('permissions',)
  
      def formfield_for_manytomany(self, db_field, request=None, **kwargs):
          if db_field.name == 'permissions':
              qs = kwargs.get('queryset', db_field.rel.to.objects)
              # Avoid a major performance hit resolving permission names which
              # triggers a content_type load:
              kwargs['queryset'] = qs.select_related('content_type')
          return super(GroupAdmin, self).formfield_for_manytomany(
              db_field, request=request, **kwargs)
  
  
  class UserAdmin(admin.ModelAdmin):
      add_form_template = 'admin/auth/user/add_form.html'
      change_user_password_template = None
      fieldsets = (
          (None, {'fields': ('username', 'password')}),
          (_('Personal info'), {'fields': ('first_name', 'last_name', 'email')}),
          (_('Permissions'), {'fields': ('is_active', 'is_staff', 'is_superuser',
                                         'groups', 'user_permissions')}),
          (_('Important dates'), {'fields': ('last_login', 'date_joined')}),
      )
      add_fieldsets = (
          (None, {
              'classes': ('wide',),
              'fields': ('username', 'password1', 'password2'),
          }),
      )
      form = UserChangeForm
      add_form = UserCreationForm
      change_password_form = AdminPasswordChangeForm
      list_display = ('username', 'email', 'first_name', 'last_name', 'is_staff')
      list_filter = ('is_staff', 'is_superuser', 'is_active', 'groups')
      search_fields = ('username', 'first_name', 'last_name', 'email')
      ordering = ('username',)
      filter_horizontal = ('groups', 'user_permissions',)
  
      def get_fieldsets(self, request, obj=None):
          if not obj:
              return self.add_fieldsets
          return super(UserAdmin, self).get_fieldsets(request, obj)
  
      def get_form(self, request, obj=None, **kwargs):
          """
          Use special form during user creation
          """
          defaults = {}
          if obj is None:
              defaults['form'] = self.add_form
          defaults.update(kwargs)
          return super(UserAdmin, self).get_form(request, obj, **defaults)
  
      def get_urls(self):
          return [
              url(r'^(\d+)/password/$', self.admin_site.admin_view(self.user_change_password)),
          ] + super(UserAdmin, self).get_urls()
  
      def lookup_allowed(self, lookup, value):
          # See #20078: we don't want to allow any lookups involving passwords.
          if lookup.startswith('password'):
              return False
          return super(UserAdmin, self).lookup_allowed(lookup, value)
  
      @sensitive_post_parameters_m
      @csrf_protect_m
      @transaction.atomic
      def add_view(self, request, form_url='', extra_context=None):
          # It's an error for a user to have add permission but NOT change
          # permission for users. If we allowed such users to add users, they
          # could create superusers, which would mean they would essentially have
          # the permission to change users. To avoid the problem entirely, we
          # disallow users from adding users if they don't have change
          # permission.
          if not self.has_change_permission(request):
              if self.has_add_permission(request) and settings.DEBUG:
                  # Raise Http404 in debug mode so that the user gets a helpful
                  # error message.
                  raise Http404(
                      'Your user does not have the "Change user" permission. In '
                      'order to add users, Django requires that your user '
                      'account have both the "Add user" and "Change user" '
                      'permissions set.')
              raise PermissionDenied
          if extra_context is None:
              extra_context = {}
          username_field = self.model._meta.get_field(self.model.USERNAME_FIELD)
          defaults = {
              'auto_populated_fields': (),
              'username_help_text': username_field.help_text,
          }
          extra_context.update(defaults)
          return super(UserAdmin, self).add_view(request, form_url,
                                                 extra_context)
  
      @sensitive_post_parameters_m
      def user_change_password(self, request, id, form_url=''):
          if not self.has_change_permission(request):
              raise PermissionDenied
          user = get_object_or_404(self.get_queryset(request), pk=id)
          if request.method == 'POST':
              form = self.change_password_form(user, request.POST)
              if form.is_valid():
                  form.save()
                  change_message = self.construct_change_message(request, form, None)
                  self.log_change(request, request.user, change_message)
                  msg = ugettext('Password changed successfully.')
                  messages.success(request, msg)
                  update_session_auth_hash(request, form.user)
                  return HttpResponseRedirect('..')
          else:
              form = self.change_password_form(user)
  
          fieldsets = [(None, {'fields': list(form.base_fields)})]
          adminForm = admin.helpers.AdminForm(form, fieldsets, {})
  
          context = {
              'title': _('Change password: %s') % escape(user.get_username()),
              'adminForm': adminForm,
              'form_url': form_url,
              'form': form,
              'is_popup': (IS_POPUP_VAR in request.POST or
                           IS_POPUP_VAR in request.GET),
              'add': True,
              'change': False,
              'has_delete_permission': False,
              'has_change_permission': True,
              'has_absolute_url': False,
              'opts': self.model._meta,
              'original': user,
              'save_as': False,
              'show_save': True,
          }
          context.update(admin.site.each_context())
          return TemplateResponse(request,
              self.change_user_password_template or
              'admin/auth/user/change_password.html',
              context, current_app=self.admin_site.name)
  
      def response_add(self, request, obj, post_url_continue=None):
          """
          Determines the HttpResponse for the add_view stage. It mostly defers to
          its superclass implementation but is customized because the User model
          has a slightly different workflow.
          """
          # We should allow further modification of the user just added i.e. the
          # 'Save' button should behave like the 'Save and continue editing'
          # button except in two scenarios:
          # * The user has pressed the 'Save and add another' button
          # * We are adding a user in a popup
          if '_addanother' not in request.POST and IS_POPUP_VAR not in request.POST:
              request.POST['_continue'] = 1
          return super(UserAdmin, self).response_add(request, obj,
                                                     post_url_continue)
  
  admin.site.register(Group, GroupAdmin)
  admin.site.register(User, UserAdmin)
  