import copy
import operator
from collections import OrderedDict
from functools import partial, reduce, update_wrapper

from django import forms
from django.conf import settings
from django.contrib import messages
from django.contrib.admin import helpers, widgets
from django.contrib.admin.checks import (
    BaseModelAdminChecks, InlineModelAdminChecks, ModelAdminChecks,
)
from django.contrib.admin.exceptions import DisallowedModelAdminToField
from django.contrib.admin.templatetags.admin_static import static
from django.contrib.admin.templatetags.admin_urls import add_preserved_filters
from django.contrib.admin.utils import (
    NestedObjects, flatten_fieldsets, get_deleted_objects,
    lookup_needs_distinct, model_format_dict, quote, unquote,
)
from django.contrib.auth import get_permission_codename
from django.core.exceptions import (
    FieldDoesNotExist, FieldError, PermissionDenied, ValidationError,
)
from django.core.paginator import Paginator
from django.core.urlresolvers import reverse
from django.db import models, router, transaction
from django.db.models.constants import LOOKUP_SEP
from django.db.models.fields import BLANK_CHOICE_DASH
from django.forms.formsets import DELETION_FIELD_NAME, all_valid
from django.forms.models import (
    BaseInlineFormSet, inlineformset_factory, modelform_defines_fields,
    modelform_factory, modelformset_factory,
)
from django.forms.widgets import CheckboxSelectMultiple, SelectMultiple
from django.http import Http404, HttpResponseRedirect
from django.http.response import HttpResponseBase
from django.template.response import SimpleTemplateResponse, TemplateResponse
from django.utils import six
from django.utils.decorators import method_decorator
from django.utils.encoding import force_text, python_2_unicode_compatible
from django.utils.html import escape
from django.utils.http import urlencode
from django.utils.safestring import mark_safe
from django.utils.text import capfirst, get_text_list
from django.utils.translation import string_concat, ugettext as _, ungettext
from django.views.decorators.csrf import csrf_protect
from django.views.generic import RedirectView

IS_POPUP_VAR = '_popup'
TO_FIELD_VAR = '_to_field'


HORIZONTAL, VERTICAL = 1, 2


def get_content_type_for_model(obj):
    # 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(obj, for_concrete_model=False)


def get_ul_class(radio_style):
    return 'radiolist' if radio_style == VERTICAL else 'radiolist inline'


class IncorrectLookupParameters(Exception):
    pass

# Defaults for formfield_overrides. ModelAdmin subclasses can change this
# by adding to ModelAdmin.formfield_overrides.

FORMFIELD_FOR_DBFIELD_DEFAULTS = {
    models.DateTimeField: {
        'form_class': forms.SplitDateTimeField,
        'widget': widgets.AdminSplitDateTime
    },
    models.DateField: {'widget': widgets.AdminDateWidget},
    models.TimeField: {'widget': widgets.AdminTimeWidget},
    models.TextField: {'widget': widgets.AdminTextareaWidget},
    models.URLField: {'widget': widgets.AdminURLFieldWidget},
    models.IntegerField: {'widget': widgets.AdminIntegerFieldWidget},
    models.BigIntegerField: {'widget': widgets.AdminBigIntegerFieldWidget},
    models.CharField: {'widget': widgets.AdminTextInputWidget},
    models.ImageField: {'widget': widgets.AdminFileWidget},
    models.FileField: {'widget': widgets.AdminFileWidget},
    models.EmailField: {'widget': widgets.AdminEmailInputWidget},
}

csrf_protect_m = method_decorator(csrf_protect)


class BaseModelAdmin(six.with_metaclass(forms.MediaDefiningClass)):
    """Functionality common to both ModelAdmin and InlineAdmin."""

    raw_id_fields = ()
    fields = None
    exclude = None
    fieldsets = None
    form = forms.ModelForm
    filter_vertical = ()
    filter_horizontal = ()
    radio_fields = {}
    prepopulated_fields = {}
    formfield_overrides = {}
    readonly_fields = ()
    ordering = None
    view_on_site = True
    show_full_result_count = True
    checks_class = BaseModelAdminChecks

    def check(self, **kwargs):
        return self.checks_class().check(self, **kwargs)

    def __init__(self):
        overrides = FORMFIELD_FOR_DBFIELD_DEFAULTS.copy()
        overrides.update(self.formfield_overrides)
        self.formfield_overrides = overrides

    def formfield_for_dbfield(self, db_field, **kwargs):
        """
        Hook for specifying the form Field instance for a given database Field
        instance.

        If kwargs are given, they're passed to the form Field's constructor.
        """
        request = kwargs.pop("request", None)

        # If the field specifies choices, we don't need to look for special
        # admin widgets - we just need to use a select widget of some kind.
        if db_field.choices:
            return self.formfield_for_choice_field(db_field, request, **kwargs)

        # ForeignKey or ManyToManyFields
        if isinstance(db_field, (models.ForeignKey, models.ManyToManyField)):
            # Combine the field kwargs with any options for formfield_overrides.
            # Make sure the passed in **kwargs override anything in
            # formfield_overrides because **kwargs is more specific, and should
            # always win.
            if db_field.__class__ in self.formfield_overrides:
                kwargs = dict(self.formfield_overrides[db_field.__class__], **kwargs)

            # Get the correct formfield.
            if isinstance(db_field, models.ForeignKey):
                formfield = self.formfield_for_foreignkey(db_field, request, **kwargs)
            elif isinstance(db_field, models.ManyToManyField):
                formfield = self.formfield_for_manytomany(db_field, request, **kwargs)

            # For non-raw_id fields, wrap the widget with a wrapper that adds
            # extra HTML -- the "add other" interface -- to the end of the
            # rendered output. formfield can be None if it came from a
            # OneToOneField with parent_link=True or a M2M intermediary.
            if formfield and db_field.name not in self.raw_id_fields:
                related_modeladmin = self.admin_site._registry.get(db_field.remote_field.model)
                wrapper_kwargs = {}
                if related_modeladmin:
                    wrapper_kwargs.update(
                        can_add_related=related_modeladmin.has_add_permission(request),
                        can_change_related=related_modeladmin.has_change_permission(request),
                        can_delete_related=related_modeladmin.has_delete_permission(request),
                    )
                formfield.widget = widgets.RelatedFieldWidgetWrapper(
                    formfield.widget, db_field.remote_field, self.admin_site, **wrapper_kwargs
                )

            return formfield

        # If we've got overrides for the formfield defined, use 'em. **kwargs
        # passed to formfield_for_dbfield override the defaults.
        for klass in db_field.__class__.mro():
            if klass in self.formfield_overrides:
                kwargs = dict(copy.deepcopy(self.formfield_overrides[klass]), **kwargs)
                return db_field.formfield(**kwargs)

        # For any other type of field, just call its formfield() method.
        return db_field.formfield(**kwargs)

    def formfield_for_choice_field(self, db_field, request=None, **kwargs):
        """
        Get a form Field for a database Field that has declared choices.
        """
        # If the field is named as a radio_field, use a RadioSelect
        if db_field.name in self.radio_fields:
            # Avoid stomping on custom widget/choices arguments.
            if 'widget' not in kwargs:
                kwargs['widget'] = widgets.AdminRadioSelect(attrs={
                    'class': get_ul_class(self.radio_fields[db_field.name]),
                })
            if 'choices' not in kwargs:
                kwargs['choices'] = db_field.get_choices(
                    include_blank=db_field.blank,
                    blank_choice=[('', _('None'))]
                )
        return db_field.formfield(**kwargs)

    def get_field_queryset(self, db, db_field, request):
        """
        If the ModelAdmin specifies ordering, the queryset should respect that
        ordering.  Otherwise don't specify the queryset, let the field decide
        (returns None in that case).
        """
        related_admin = self.admin_site._registry.get(db_field.remote_field.model)
        if related_admin is not None:
            ordering = related_admin.get_ordering(request)
            if ordering is not None and ordering != ():
                return db_field.remote_field.model._default_manager.using(db).order_by(*ordering)
        return None

    def formfield_for_foreignkey(self, db_field, request=None, **kwargs):
        """
        Get a form Field for a ForeignKey.
        """
        db = kwargs.get('using')
        if db_field.name in self.raw_id_fields:
            kwargs['widget'] = widgets.ForeignKeyRawIdWidget(db_field.remote_field,
                                    self.admin_site, using=db)
        elif db_field.name in self.radio_fields:
            kwargs['widget'] = widgets.AdminRadioSelect(attrs={
                'class': get_ul_class(self.radio_fields[db_field.name]),
            })
            kwargs['empty_label'] = _('None') if db_field.blank else None

        if 'queryset' not in kwargs:
            queryset = self.get_field_queryset(db, db_field, request)
            if queryset is not None:
                kwargs['queryset'] = queryset

        return db_field.formfield(**kwargs)

    def formfield_for_manytomany(self, db_field, request=None, **kwargs):
        """
        Get a form Field for a ManyToManyField.
        """
        # If it uses an intermediary model that isn't auto created, don't show
        # a field in admin.
        if not db_field.remote_field.through._meta.auto_created:
            return None
        db = kwargs.get('using')

        if db_field.name in self.raw_id_fields:
            kwargs['widget'] = widgets.ManyToManyRawIdWidget(db_field.remote_field,
                                    self.admin_site, using=db)
            kwargs['help_text'] = ''
        elif db_field.name in (list(self.filter_vertical) + list(self.filter_horizontal)):
            kwargs['widget'] = widgets.FilteredSelectMultiple(
                db_field.verbose_name,
                db_field.name in self.filter_vertical
            )

        if 'queryset' not in kwargs:
            queryset = self.get_field_queryset(db, db_field, request)
            if queryset is not None:
                kwargs['queryset'] = queryset

        form_field = db_field.formfield(**kwargs)
        if isinstance(form_field.widget, SelectMultiple) and not isinstance(form_field.widget, CheckboxSelectMultiple):
            msg = _('Hold down "Control", or "Command" on a Mac, to select more than one.')
            help_text = form_field.help_text
            form_field.help_text = string_concat(help_text, ' ', msg) if help_text else msg
        return form_field

    def get_view_on_site_url(self, obj=None):
        if obj is None or not self.view_on_site:
            return None

        if callable(self.view_on_site):
            return self.view_on_site(obj)
        elif self.view_on_site and hasattr(obj, 'get_absolute_url'):
            # use the ContentType lookup if view_on_site is True
            return reverse('admin:view_on_site', kwargs={
                'content_type_id': get_content_type_for_model(obj).pk,
                'object_id': obj.pk
            })

    def get_empty_value_display(self):
        """
        Return the empty_value_display set on ModelAdmin or AdminSite.
        """
        try:
            return mark_safe(self.empty_value_display)
        except AttributeError:
            return mark_safe(self.admin_site.empty_value_display)

    def get_fields(self, request, obj=None):
        """
        Hook for specifying fields.
        """
        return self.fields

    def get_fieldsets(self, request, obj=None):
        """
        Hook for specifying fieldsets.
        """
        if self.fieldsets:
            return self.fieldsets
        return [(None, {'fields': self.get_fields(request, obj)})]

    def get_ordering(self, request):
        """
        Hook for specifying field ordering.
        """
        return self.ordering or ()  # otherwise we might try to *None, which is bad ;)

    def get_readonly_fields(self, request, obj=None):
        """
        Hook for specifying custom readonly fields.
        """
        return self.readonly_fields

    def get_prepopulated_fields(self, request, obj=None):
        """
        Hook for specifying custom prepopulated fields.
        """
        return self.prepopulated_fields

    def get_queryset(self, request):
        """
        Returns a QuerySet of all model instances that can be edited by the
        admin site. This is used by changelist_view.
        """
        qs = self.model._default_manager.get_queryset()
        # TODO: this should be handled by some parameter to the ChangeList.
        ordering = self.get_ordering(request)
        if ordering:
            qs = qs.order_by(*ordering)
        return qs

    def lookup_allowed(self, lookup, value):
        from django.contrib.admin.filters import SimpleListFilter

        model = self.model
        # Check FKey lookups that are allowed, so that popups produced by
        # ForeignKeyRawIdWidget, on the basis of ForeignKey.limit_choices_to,
        # are allowed to work.
        for l in model._meta.related_fkey_lookups:
            # As ``limit_choices_to`` can be a callable, invoke it here.
            if callable(l):
                l = l()
            for k, v in widgets.url_params_from_lookup_dict(l).items():
                if k == lookup and v == value:
                    return True

        relation_parts = []
        prev_field = None
        for part in lookup.split(LOOKUP_SEP):