text: from __future__ import unicode_literals
  
  import warnings
  
  from django import forms
  from django.conf import settings
  from django.contrib.admin.templatetags.admin_static import static
  from django.contrib.admin.utils import (
      display_for_field, flatten_fieldsets, help_text_for_field, label_for_field,
      lookup_field,
  )
  from django.core.exceptions import ObjectDoesNotExist
  from django.db.models.fields.related import ManyToManyRel
  from django.forms.utils import flatatt
  from django.template.defaultfilters import capfirst, linebreaksbr
  from django.utils import six
  from django.utils.deprecation import RemovedInDjango20Warning
  from django.utils.encoding import force_text, smart_text
  from django.utils.functional import cached_property
  from django.utils.html import conditional_escape, format_html
  from django.utils.safestring import mark_safe
  from django.utils.translation import ugettext_lazy as _
  
  ACTION_CHECKBOX_NAME = '_selected_action'
  
  
  class ActionForm(forms.Form):
      action = forms.ChoiceField(label=_('Action:'))
      select_across = forms.BooleanField(label='', required=False, initial=0,
          widget=forms.HiddenInput({'class': 'select-across'}))
  
  checkbox = forms.CheckboxInput({'class': 'action-select'}, lambda value: False)
  
  
  class AdminForm(object):
      def __init__(self, form, fieldsets, prepopulated_fields, readonly_fields=None, model_admin=None):
          self.form, self.fieldsets = form, fieldsets
          self.prepopulated_fields = [{
              'field': form[field_name],
              'dependencies': [form[f] for f in dependencies]
          } for field_name, dependencies in prepopulated_fields.items()]
          self.model_admin = model_admin
          if readonly_fields is None:
              readonly_fields = ()
          self.readonly_fields = readonly_fields
  
      def __iter__(self):
          for name, options in self.fieldsets:
              yield Fieldset(
                  self.form, name,
                  readonly_fields=self.readonly_fields,
                  model_admin=self.model_admin,
                  **options
              )
  
      def _media(self):
          media = self.form.media
          for fs in self:
              media = media + fs.media
          return media
      media = property(_media)
  
  
  class Fieldset(object):
      def __init__(self, form, name=None, readonly_fields=(), fields=(), classes=(),
        description=None, model_admin=None):
          self.form = form
          self.name, self.fields = name, fields
          self.classes = ' '.join(classes)
          self.description = description
          self.model_admin = model_admin
          self.readonly_fields = readonly_fields
  
      def _media(self):
          if 'collapse' in self.classes:
              extra = '' if settings.DEBUG else '.min'
              js = ['jquery%s.js' % extra,
                    'jquery.init.js',
                    'collapse%s.js' % extra]
              return forms.Media(js=[static('admin/js/%s' % url) for url in js])
          return forms.Media()
      media = property(_media)
  
      def __iter__(self):
          for field in self.fields:
              yield Fieldline(self.form, field, self.readonly_fields, model_admin=self.model_admin)
  
  
  class Fieldline(object):
      def __init__(self, form, field, readonly_fields=None, model_admin=None):
          self.form = form  # A django.forms.Form instance
          if not hasattr(field, "__iter__") or isinstance(field, six.text_type):
              self.fields = [field]
          else:
              self.fields = field
          self.has_visible_field = not all(field in self.form.fields and
                                           self.form.fields[field].widget.is_hidden
                                           for field in self.fields)
          self.model_admin = model_admin
          if readonly_fields is None:
              readonly_fields = ()
          self.readonly_fields = readonly_fields
  
      def __iter__(self):
          for i, field in enumerate(self.fields):
              if field in self.readonly_fields:
                  yield AdminReadonlyField(self.form, field, is_first=(i == 0),
                      model_admin=self.model_admin)
              else:
                  yield AdminField(self.form, field, is_first=(i == 0))
  
      def errors(self):
          return mark_safe(
              '\n'.join(self.form[f].errors.as_ul()
              for f in self.fields if f not in self.readonly_fields).strip('\n')
          )
  
  
  class AdminField(object):
      def __init__(self, form, field, is_first):
          self.field = form[field]  # A django.forms.BoundField instance
          self.is_first = is_first  # Whether this field is first on the line
          self.is_checkbox = isinstance(self.field.field.widget, forms.CheckboxInput)
          self.is_readonly = False
  
      def label_tag(self):
          classes = []
          contents = conditional_escape(force_text(self.field.label))
          if self.is_checkbox:
              classes.append('vCheckboxLabel')
  
          if self.field.field.required:
              classes.append('required')
          if not self.is_first:
              classes.append('inline')
          attrs = {'class': ' '.join(classes)} if classes else {}
          # checkboxes should not have a label suffix as the checkbox appears
          # to the left of the label.
          return self.field.label_tag(contents=mark_safe(contents), attrs=attrs,
                                      label_suffix='' if self.is_checkbox else None)
  
      def errors(self):
          return mark_safe(self.field.errors.as_ul())
  
  
  class AdminReadonlyField(object):
      def __init__(self, form, field, is_first, model_admin=None):
          # Make self.field look a little bit like a field. This means that
          # {{ field.name }} must be a useful class name to identify the field.
          # For convenience, store other field-related data here too.
          if callable(field):
              class_name = field.__name__ if field.__name__ != '<lambda>' else ''
          else:
              class_name = field
  
          if form._meta.labels and class_name in form._meta.labels:
              label = form._meta.labels[class_name]
          else:
              label = label_for_field(field, form._meta.model, model_admin)
  
          if form._meta.help_texts and class_name in form._meta.help_texts:
              help_text = form._meta.help_texts[class_name]
          else:
              help_text = help_text_for_field(class_name, form._meta.model)
  
          self.field = {
              'name': class_name,
              'label': label,
              'help_text': help_text,
              'field': field,
          }
          self.form = form
          self.model_admin = model_admin
          self.is_first = is_first
          self.is_checkbox = False
          self.is_readonly = True
          self.empty_value_display = model_admin.get_empty_value_display()
  
      def label_tag(self):
          attrs = {}
          if not self.is_first:
              attrs["class"] = "inline"
          label = self.field['label']
          return format_html('<label{}>{}:</label>',
                             flatatt(attrs),
                             capfirst(force_text(label)))
  
      def contents(self):
          from django.contrib.admin.templatetags.admin_list import _boolean_icon
          field, obj, model_admin = self.field['field'], self.form.instance, self.model_admin
          try:
              f, attr, value = lookup_field(field, obj, model_admin)
          except (AttributeError, ValueError, ObjectDoesNotExist):
              result_repr = self.empty_value_display
          else:
              if f is None:
                  boolean = getattr(attr, "boolean", False)
                  if boolean:
                      result_repr = _boolean_icon(value)
                  else:
                      result_repr = smart_text(value)
                      if getattr(attr, "allow_tags", False):
                          result_repr = mark_safe(result_repr)
                      else:
                          result_repr = linebreaksbr(result_repr)
              else:
                  if isinstance(f.remote_field, ManyToManyRel) and value is not None:
                      result_repr = ", ".join(map(six.text_type, value.all()))
                  else:
                      result_repr = display_for_field(value, f, self.empty_value_display)
          return conditional_escape(result_repr)
  
  
  class InlineAdminFormSet(object):
      """
      A wrapper around an inline formset for use in the admin system.
      """
      def __init__(self, inline, formset, fieldsets, prepopulated_fields=None,
              readonly_fields=None, model_admin=None):
          self.opts = inline
          self.formset = formset
          self.fieldsets = fieldsets
          self.model_admin = model_admin
          if readonly_fields is None:
              readonly_fields = ()
          self.readonly_fields = readonly_fields
          if prepopulated_fields is None:
              prepopulated_fields = {}
          self.prepopulated_fields = prepopulated_fields
  
      def __iter__(self):
          for form, original in zip(self.formset.initial_forms, self.formset.get_queryset()):
              view_on_site_url = self.opts.get_view_on_site_url(original)
              yield InlineAdminForm(self.formset, form, self.fieldsets,
                  self.prepopulated_fields, original, self.readonly_fields,
                  model_admin=self.opts, view_on_site_url=view_on_site_url)
          for form in self.formset.extra_forms:
              yield InlineAdminForm(self.formset, form, self.fieldsets,
                  self.prepopulated_fields, None, self.readonly_fields,
                  model_admin=self.opts)
          yield InlineAdminForm(self.formset, self.formset.empty_form,
              self.fieldsets, self.prepopulated_fields, None,
              self.readonly_fields, model_admin=self.opts)
  
      def fields(self):
          fk = getattr(self.formset, "fk", None)
          for i, field_name in enumerate(flatten_fieldsets(self.fieldsets)):
              if fk and fk.name == field_name:
                  continue
              if field_name in self.readonly_fields:
                  yield {
                      'label': label_for_field(field_name, self.opts.model, self.opts),
                      'widget': {
                          'is_hidden': False
                      },
                      'required': False,
                      'help_text': help_text_for_field(field_name, self.opts.model),
                  }
              else:
                  yield self.formset.form.base_fields[field_name]
  
      def _media(self):
          media = self.opts.media + self.formset.media
          for fs in self:
              media = media + fs.media
          return media
      media = property(_media)
  
  
  class InlineAdminForm(AdminForm):
      """
      A wrapper around an inline form for use in the admin system.
      """
      def __init__(self, formset, form, fieldsets, prepopulated_fields, original,
        readonly_fields=None, model_admin=None, view_on_site_url=None):
          self.formset = formset
          self.model_admin = model_admin
          self.original = original
          self.show_url = original and view_on_site_url is not None
          self.absolute_url = view_on_site_url
          super(InlineAdminForm, self).__init__(form, fieldsets, prepopulated_fields,
              readonly_fields, model_admin)
  
      @cached_property
      def original_content_type_id(self):
          warnings.warn(
              'InlineAdminForm.original_content_type_id is deprecated and will be '
              'removed in Django 2.0. If you were using this attribute to construct '
              'the "view on site" URL, use the `absolute_url` attribute instead.',
              RemovedInDjango20Warning, stacklevel=2
          )
          if self.original is not None:
              # Since this module gets imported in the application's root package,
              # it cannot import models from other applications at the module level.
              from django.contrib.contenttypes.models import ContentType
              return ContentType.objects.get_for_model(self.original).pk
          raise AttributeError
  
      def __iter__(self):
          for name, options in self.fieldsets:
              yield InlineFieldset(self.formset, self.form, name,
                  self.readonly_fields, model_admin=self.model_admin, **options)
  
      def needs_explicit_pk_field(self):
          # Auto fields are editable (oddly), so need to check for auto or non-editable pk
          if self.form._meta.model._meta.has_auto_field or not self.form._meta.model._meta.pk.editable:
              return True
          # Also search any parents for an auto field. (The pk info is propagated to child
          # models so that does not need to be checked in parents.)
          for parent in self.form._meta.model._meta.get_parent_list():
              if parent._meta.has_auto_field:
                  return True
          return False
  
      def pk_field(self):
          return AdminField(self.form, self.formset._pk_field.name, False)
  
      def fk_field(self):
          fk = getattr(self.formset, "fk", None)
          if fk:
              return AdminField(self.form, fk.name, False)
          else:
              return ""
  
      def deletion_field(self):
          from django.forms.formsets import DELETION_FIELD_NAME
          return AdminField(self.form, DELETION_FIELD_NAME, False)
  
      def ordering_field(self):
          from django.forms.formsets import ORDERING_FIELD_NAME
          return AdminField(self.form, ORDERING_FIELD_NAME, False)
  
  
  class InlineFieldset(Fieldset):
      def __init__(self, formset, *args, **kwargs):
          self.formset = formset
          super(InlineFieldset, self).__init__(*args, **kwargs)
  
      def __iter__(self):
          fk = getattr(self.formset, "fk", None)
          for field in self.fields:
              if fk and fk.name == field:
                  continue
              yield Fieldline(self.form, field, self.readonly_fields,
                  model_admin=self.model_admin)
  
  
  class AdminErrorList(forms.utils.ErrorList):
      """
      Stores all errors for the form/formsets in an add/change stage view.
      """
      def __init__(self, form, inline_formsets):
          super(AdminErrorList, self).__init__()
  
          if form.is_bound:
              self.extend(form.errors.values())
              for inline_formset in inline_formsets:
                  self.extend(inline_formset.non_form_errors())
                  for errors_in_inline_form in inline_formset.errors:
                      self.extend(errors_in_inline_form.values())
  