def edit(request, image_id):
    Image = get_image_model()
    ImageForm = get_image_form(Image)

    image = get_object_or_404(Image, id=image_id)

    if not image.is_editable_by_user(request.user):
        raise PermissionDenied

    if request.POST:
        original_file = image.file
        form = ImageForm(request.POST, request.FILES, instance=image)
        if form.is_valid():
            if 'file' in form.changed_data:
                # if providing a new image file, delete the old one and all renditions.
                # NB Doing this via original_file.delete() clears the file field,
                # which definitely isn't what we want...
                original_file.storage.delete(original_file.name)
                image.renditions.all().delete()

                # Set new image file size
                image.file_size = image.file.size

            form.save()

            # Reindex the image to make sure all tags are indexed
            for backend in get_search_backends():
                backend.add(image)

            messages.success(request, _("Image '{0}' updated.").format(image.title), buttons=[
                messages.button(reverse('wagtailimages:edit', args=(image.id,)), _('Edit again'))
            ])
            return redirect('wagtailimages:index')
        else:
            messages.error(request, _("The image could not be saved due to errors."))
    else:
        form = ImageForm(instance=image)

    # Check if we should enable the frontend url generator
    try:
        reverse('wagtailimages_serve', args=('foo', '1', 'bar'))
        url_generator_enabled = True
    except NoReverseMatch:
        url_generator_enabled = False

    if image.is_stored_locally():
        # Give error if image file doesn't exist
        if not os.path.isfile(image.file.path):
            messages.error(request, _(
                "The source image file could not be found. Please change the source or delete the image."
            ).format(image.title), buttons=[
                messages.button(reverse('wagtailimages:delete', args=(image.id,)), _('Delete'))
            ])

    return render(request, "wagtailimages/images/edit.html", {
        'image': image,
        'form': form,
        'url_generator_enabled': url_generator_enabled,
        'filesize': image.get_file_size(),
    })

def approve_moderation(request, revision_id):
    revision = get_object_or_404(PageRevision, id=revision_id)
    if not revision.page.permissions_for_user(request.user).can_publish():
        raise PermissionDenied

    if not revision.submitted_for_moderation:
        messages.error(
            request,
            _("The page '{0}' is not currently awaiting moderation.").format(revision.page.get_admin_display_title()),
        )
        return redirect("wagtailadmin_home")

    if request.method == "POST":
        revision.approve_moderation()
        messages.success(
            request,
            _("Page '{0}' published.").format(revision.page.get_admin_display_title()),
            buttons=[
                messages.button(revision.page.url, _("View live")),
                messages.button(reverse("wagtailadmin_pages:edit", args=(revision.page.id,)), _("Edit")),
            ],
        )
        if not send_notification(revision.id, "approved", request.user.pk):
            messages.error(request, _("Failed to send approval notifications"))

    return redirect("wagtailadmin_home")

def edit(request, document_id):
    Document = get_document_model()
    DocumentForm = get_document_form(Document)

    doc = get_object_or_404(Document, id=document_id)

    if not permission_policy.user_has_permission_for_instance(request.user, 'change', doc):
        return permission_denied(request)

    if request.POST:
        original_file = doc.file
        form = DocumentForm(request.POST, request.FILES, instance=doc, user=request.user)
        if form.is_valid():
            if 'file' in form.changed_data:
                # if providing a new document file, delete the old one.
                # NB Doing this via original_file.delete() clears the file field,
                # which definitely isn't what we want...
                original_file.storage.delete(original_file.name)
            doc = form.save()

            # Reindex the document to make sure all tags are indexed
            for backend in get_search_backends():
                backend.add(doc)

            messages.success(request, _("Document '{0}' updated").format(doc.title), buttons=[
                messages.button(reverse('wagtaildocs:edit', args=(doc.id,)), _('Edit'))
            ])
            return redirect('wagtaildocs:index')
        else:
            messages.error(request, _("The document could not be saved due to errors."))
    else:
        form = DocumentForm(instance=doc, user=request.user)

    filesize = None

    # Get file size when there is a file associated with the Document object
    if doc.file:
        try:
            filesize = doc.file.size
        except OSError:
            # File doesn't exist
            pass

    if not filesize:
        messages.error(
            request,
            _("The file could not be found. Please change the source or delete the document"),
            buttons=[messages.button(reverse('wagtaildocs:delete', args=(doc.id,)), _('Delete'))]
        )

    return render(request, "wagtaildocs/documents/edit.html", {
        'document': doc,
        'filesize': filesize,
        'form': form,
        'user_can_delete': permission_policy.user_has_permission_for_instance(
            request.user, 'delete', doc
        ),
    })

def edit(request, group_id):
    group = get_object_or_404(Group, id=group_id)
    if request.method == 'POST':
        form = GroupForm(request.POST, instance=group)
        permission_panels = [
            cls(request.POST, instance=group)
            for cls in get_permission_panel_classes()
        ]
        if form.is_valid() and all(panel.is_valid() for panel in permission_panels):
            form.save()

            for panel in permission_panels:
                panel.save()

            messages.success(request, _("Group '{0}' updated.").format(group), buttons=[
                messages.button(reverse('wagtailusers_groups:edit', args=(group.id,)), _('Edit'))
            ])
            return redirect('wagtailusers_groups:index')
        else:
            messages.error(request, _("The group could not be saved due to errors."))
    else:
        form = GroupForm(instance=group)
        permission_panels = [
            cls(instance=group)
            for cls in get_permission_panel_classes()
        ]

    return render(request, 'wagtailusers/groups/edit.html', {
        'group': group,
        'form': form,
        'permission_panels': permission_panels,
    })

    def form_valid(self, form):
        """
        Processes a valid form submittal.

        :param form: the form instance.
        :rtype: django.http.HttpResponse.
        """
        #noinspection PyAttributeOutsideInit
        self.object = form.save()
        meta        = getattr(self.object, '_meta')

        # Index the object.
        for backend in get_search_backends():
            backend.add(object)

        #noinspection PyUnresolvedReferences
        messages.success(
            self.request,
            _(u'{0} "{1}" saved.').format(
                meta.verbose_name,
                str(self.object)
            ),
            buttons=[messages.button(
                reverse(
                    '{0}:edit'.format(self.url_namespace),
                    args=(self.object.id,)
                ),
                _(u'Edit')
            )]
        )

        return redirect(self.get_success_url())

def create(request):
    GroupPagePermissionFormSet = inlineformset_factory(
        Group,
        GroupPagePermission,
        formset=BaseGroupPagePermissionFormSet,
        extra=0
    )
    if request.POST:
        form = GroupForm(request.POST)
        formset = GroupPagePermissionFormSet(request.POST)
        if form.is_valid() and formset.is_valid():
            group = form.save()
            formset.instance = group
            formset.save()
            messages.success(request, _("Group '{0}' created.").format(group), buttons = [
                messages.button(reverse('wagtailusers_groups_edit', args=(group.id,)), _('Edit'))
            ])
            return redirect('wagtailusers_groups_index')
        else:
            messages.error(request, _("The group could not be created due to errors."))
    else:
        form = GroupForm()
        formset = GroupPagePermissionFormSet()

    return render(request, 'wagtailusers/groups/create.html', {
        'form': form,
        'formset': formset,
    })

def edit(request, group_id):
    group = get_object_or_404(Group, id=group_id)
    GroupPagePermissionFormSet = inlineformset_factory(
        Group,
        GroupPagePermission,
        formset=BaseGroupPagePermissionFormSet,
        extra=0
    )
    if request.POST:
        form = GroupForm(request.POST, instance=group)
        formset = GroupPagePermissionFormSet(request.POST, instance=group)
        if form.is_valid() and formset.is_valid():
            group = form.save()
            formset.save()
            messages.success(request, _("Group '{0}' updated.").format(group), buttons = [
                messages.button(reverse('wagtailusers_groups_edit', args=(group.id,)), _('Edit'))
            ])
            return redirect('wagtailusers_groups_index')
        else:
            messages.error(request, _("The group could not be saved due to errors."))
    else:
        form = GroupForm(instance=group)
        formset = GroupPagePermissionFormSet(instance=group)

    return render(request, 'wagtailusers/groups/edit.html', {
        'group': group,
        'form': form,
        'formset': formset,
    })

def edit(request, redirect_id):
    theredirect = get_object_or_404(models.Redirect, id=redirect_id)

    if not permission_policy.user_has_permission_for_instance(
        request.user, 'change', theredirect
    ):
        return permission_denied(request)

    if request.method == 'POST':
        form = RedirectForm(request.POST, request.FILES, instance=theredirect)
        if form.is_valid():
            form.save()
            messages.success(request, _("Redirect '{0}' updated.").format(theredirect.title), buttons=[
                messages.button(reverse('wagtailredirects:edit', args=(theredirect.id,)), _('Edit'))
            ])
            return redirect('wagtailredirects:index')
        else:
            messages.error(request, _("The redirect could not be saved due to errors."))
    else:
        form = RedirectForm(instance=theredirect)

    return render(request, "wagtailredirects/edit.html", {
        'redirect': theredirect,
        'form': form,
        'user_can_delete': permission_policy.user_has_permission(request.user, 'delete'),
    })

def unpublish(request, page_id):
    page = get_object_or_404(Page, id=page_id).specific

    user_perms = UserPagePermissionsProxy(request.user)
    if not user_perms.for_page(page).can_unpublish():
        raise PermissionDenied

    next_url = get_valid_next_url_from_request(request)

    if request.method == "POST":
        include_descendants = request.POST.get("include_descendants", False)

        page.unpublish()

        if include_descendants:
            live_descendant_pages = page.get_descendants().live().specific()
            for live_descendant_page in live_descendant_pages:
                if user_perms.for_page(live_descendant_page).can_unpublish():
                    live_descendant_page.unpublish()

        messages.success(
            request,
            _("Page '{0}' unpublished.").format(page.get_admin_display_title()),
            buttons=[messages.button(reverse("wagtailadmin_pages:edit", args=(page.id,)), _("Edit"))],
        )

        if next_url:
            return redirect(next_url)
        return redirect("wagtailadmin_explore", page.get_parent().id)

    return render(
        request,
        "wagtailadmin/pages/confirm_unpublish.html",
        {"page": page, "next": next_url, "live_descendant_count": page.get_descendants().live().count()},
    )

def create(request):
    group = Group()
    if request.POST:
        form = GroupForm(request.POST, instance=group)
        permission_panels = [
            cls(request.POST, instance=group)
            for cls in get_permission_panel_classes()
        ]
        if form.is_valid() and all(panel.is_valid() for panel in permission_panels):
            form.save()

            for panel in permission_panels:
                panel.save()

            messages.success(request, _("Group '{0}' created.").format(group), buttons=[
                messages.button(reverse('wagtailusers_groups:edit', args=(group.id,)), _('Edit'))
            ])
            return redirect('wagtailusers_groups:index')
        else:
            messages.error(request, _("The group could not be created due to errors."))
    else:
        form = GroupForm(instance=group)
        permission_panels = [
            cls(instance=group)
            for cls in get_permission_panel_classes()
        ]

    return render(request, 'wagtailusers/groups/create.html', {
        'form': form,
        'permission_panels': permission_panels,
    })

def edit(request, document_id):
    doc = get_object_or_404(Document, id=document_id)

    if not doc.is_editable_by_user(request.user):
        raise PermissionDenied

    if request.POST:
        original_file = doc.file
        form = DocumentForm(request.POST, request.FILES, instance=doc)
        if form.is_valid():
            if 'file' in form.changed_data:
                # if providing a new document file, delete the old one.
                # NB Doing this via original_file.delete() clears the file field,
                # which definitely isn't what we want...
                original_file.storage.delete(original_file.name)
            doc = form.save()

            # Reindex the document to make sure all tags are indexed
            for backend in get_search_backends():
                backend.add(doc)

            messages.success(request, _("Document '{0}' updated").format(doc.title), buttons=[
                messages.button(reverse('wagtaildocs_edit_document', args=(doc.id,)), _('Edit'))
            ])
            return redirect('wagtaildocs_index')
        else:
            messages.error(request, _("The document could not be saved due to errors."))
    else:
        form = DocumentForm(instance=doc)

    return render(request, "wagtaildocs/documents/edit.html", {
        'document': doc,
        'form': form
    })

def add(request):
    ImageModel = get_image_model()
    ImageForm = get_image_form(ImageModel)

    if request.POST:
        image = ImageModel(uploaded_by_user=request.user)
        form = ImageForm(request.POST, request.FILES, instance=image)
        if form.is_valid():
            # Set image file size
            image.file_size = image.file.size

            form.save()

            # Reindex the image to make sure all tags are indexed
            for backend in get_search_backends():
                backend.add(image)

            messages.success(request, _("Image '{0}' added.").format(image.title), buttons=[
                messages.button(reverse('wagtailimages:edit', args=(image.id,)), _('Edit'))
            ])
            return redirect('wagtailimages:index')
        else:
            messages.error(request, _("The image could not be created due to errors."))
    else:
        form = ImageForm()

    return render(request, "wagtailimages/images/add.html", {
        'form': form,
    })

def edit(request, embed_video_id):
    EmbedVideo = get_embed_video_model()
    EmbedVideoForm = get_embed_video_form(EmbedVideo)

    embed_video = get_object_or_404(EmbedVideo, id=embed_video_id)

    if not embed_video.is_editable_by_user(request.user):
        raise PermissionDenied

    if request.POST:
        form = EmbedVideoForm(request.POST, request.FILES, instance=embed_video)
        if form.is_valid():
            form.save()

            # Reindex the embed_video to make sure all tags are indexed
            for backend in get_search_backends():
                backend.add(embed_video)

            messages.success(request, _("Embed video '{0}' updated.").format(embed_video.title), buttons=[
                messages.button(reverse('wagtail_embed_videos_edit_embed_video', args=(embed_video.id,)), _('Edit again'))
            ])
            return redirect('wagtail_embed_videos_index')
        else:
            messages.error(request, _("The embed video could not be saved due to errors."))
    else:
        form = EmbedVideoForm(instance=embed_video)

    return render(request, "wagtail_embed_videos/embed_videos/edit.html", {
        'embed_video': embed_video,
        'form': form,
    })

def add(request):
    EmbedVideoModel = get_embed_video_model()
    EmbedVideoForm = get_embed_video_form(EmbedVideoModel)

    if request.method == 'POST':
        embed_video = EmbedVideoModel(uploaded_by_user=request.user)
        form = EmbedVideoForm(request.POST, request.FILES, instance=embed_video, user=request.user)
        if form.is_valid():
            form.save()

            # Reindex the embed video to make sure all tags are indexed
            search_index.insert_or_update_object(embed_video)

            messages.success(
                request,
                _("Video '{0}' added.").format(embed_video.title),
                buttons=[
                    messages.button(
                        reverse(
                            'wagtail_embed_videos:edit',
                            args=(embed_video.id,)
                        ),
                        _('Edit')
                    )
                ]
            )
            return redirect('wagtail_embed_videos:index')
        else:
            messages.error(request, _("The video could not be created due to errors."))
    else:
        form = EmbedVideoForm(user=request.user)

    return render(request, "wagtail_embed_videos/embed_videos/add.html", {
        'form': form,
    })

def add(request):
    if request.POST:
        # Get query
        query_form = search_forms.QueryForm(request.POST)
        if query_form.is_valid():
            query = Query.get(query_form['query_string'].value())

            # Save search picks
            searchpicks_formset = forms.SearchPromotionsFormSet(request.POST, instance=query)
            if save_searchpicks(query, query, searchpicks_formset):
                messages.success(request, _("Editor's picks for '{0}' created.").format(query), buttons=[
                    messages.button(reverse('wagtailsearchpromotions:edit', args=(query.id,)), _('Edit'))
                ])
                return redirect('wagtailsearchpromotions:index')
            else:
                if len(searchpicks_formset.non_form_errors()):
                    # formset level error (e.g. no forms submitted)
                    messages.error(request, " ".join(error for error in searchpicks_formset.non_form_errors()))
                else:
                    # specific errors will be displayed within form fields
                    messages.error(request, _("Recommendations have not been created due to errors"))
        else:
            searchpicks_formset = forms.SearchPromotionsFormSet()
    else:
        query_form = search_forms.QueryForm()
        searchpicks_formset = forms.SearchPromotionsFormSet()

    return render(request, 'wagtailsearchpromotions/add.html', {
        'query_form': query_form,
        'searchpicks_formset': searchpicks_formset,
    })

def edit(request, redirect_id):
    theredirect = get_object_or_404(models.Redirect, id=redirect_id)

    if not permission_policy.user_has_permission_for_instance(request.user, "change", theredirect):
        return permission_denied(request)

    if request.POST:
        form = RedirectForm(request.POST, request.FILES, instance=theredirect)
        if form.is_valid():
            form.save()
            messages.success(
                request,
                _("Redirect '{0}' updated.").format(theredirect.title),
                buttons=[messages.button(reverse("wagtailredirects:edit", args=(theredirect.id,)), _("Edit"))],
            )
            return redirect("wagtailredirects:index")
        else:
            messages.error(request, _("The redirect could not be saved due to errors."))
    else:
        form = RedirectForm(instance=theredirect)

    return render(
        request,
        "wagtailredirects/edit.html",
        {
            "redirect": theredirect,
            "form": form,
            "user_can_delete": permission_policy.user_has_permission(request.user, "delete"),
        },
    )

def add(request):
    theredirect = models.Redirect()

    form_class = REDIRECT_EDIT_HANDLER.get_form_class(models.Redirect)
    if request.POST:
        form = form_class(request.POST, request.FILES)
        if form.is_valid():
            theredirect = form.save(commit=False)
            theredirect.site = request.site
            theredirect.save()

            messages.success(request, _("Redirect '{0}' added.").format(theredirect.title), buttons=[
                messages.button(reverse('wagtailredirects_edit_redirect', args=(theredirect.id,)), _('Edit'))
            ])
            return redirect('wagtailredirects_index')
        else:
            messages.error(request, _("The redirect could not be created due to errors."))
            edit_handler = REDIRECT_EDIT_HANDLER(instance=theredirect, form=form)
    else:
        form = form_class()
        edit_handler = REDIRECT_EDIT_HANDLER(instance=theredirect, form=form)

    return render(request, "wagtailredirects/add.html", {
        'edit_handler': edit_handler,
    })

def edit(request, query_id):
    query = get_object_or_404(Query, id=query_id)

    if request.POST:
        # Get query
        query_form = search_forms.QueryForm(request.POST)
        # and the recommendations
        searchpicks_formset = forms.SearchPromotionsFormSet(request.POST, instance=query)

        if query_form.is_valid():
            new_query = Query.get(query_form['query_string'].value())

            # Save search picks
            if save_searchpicks(query, new_query, searchpicks_formset):
                messages.success(request, _("Editor's picks for '{0}' updated.").format(new_query), buttons=[
                    messages.button(reverse('wagtailsearchpromotions:edit', args=(query.id,)), _('Edit'))
                ])
                return redirect('wagtailsearchpromotions:index')
            else:
                if len(searchpicks_formset.non_form_errors()):
                    messages.error(request, " ".join(error for error in searchpicks_formset.non_form_errors()))
                    # formset level error (e.g. no forms submitted)
                else:
                    messages.error(request, _("Recommendations have not been saved due to errors"))
                    # specific errors will be displayed within form fields

    else:
        query_form = search_forms.QueryForm(initial=dict(query_string=query.query_string))
        searchpicks_formset = forms.SearchPromotionsFormSet(instance=query)

    return render(request, 'wagtailsearchpromotions/edit.html', {
        'query_form': query_form,
        'searchpicks_formset': searchpicks_formset,
        'query': query,
    })

def add(request):
    ImageModel = get_image_model()
    ImageForm = get_image_form(ImageModel)

    if request.method == "POST":
        image = ImageModel(uploaded_by_user=request.user)
        form = ImageForm(request.POST, request.FILES, instance=image, user=request.user)
        if form.is_valid():
            # Set image file size
            image.file_size = image.file.size

            form.save()

            # Reindex the image to make sure all tags are indexed
            search_index.insert_or_update_object(image)

            messages.success(
                request,
                _("Image '{0}' added.").format(image.title),
                buttons=[messages.button(reverse("wagtailimages:edit", args=(image.id,)), _("Edit"))],
            )
            return redirect("wagtailimages:index")
        else:
            messages.error(request, _("The image could not be created due to errors."))
    else:
        form = ImageForm(user=request.user)

    return render(request, "wagtailimages/images/add.html", {"form": form})

def unpublish(request, page_id):
    page = get_object_or_404(Page, id=page_id).specific

    user_perms = UserPagePermissionsProxy(request.user)
    if not user_perms.for_page(page).can_unpublish():
        raise PermissionDenied

    next_url = get_valid_next_url_from_request(request)

    if request.method == 'POST':
        include_descendants = request.POST.get("include_descendants", False)

        page.unpublish()

        if include_descendants:
            live_descendant_pages = page.get_descendants().live().specific()
            for live_descendant_page in live_descendant_pages:
                if user_perms.for_page(live_descendant_page).can_unpublish():
                    live_descendant_page.unpublish()

        messages.success(request, _("Page '{0}' unpublished.").format(page.title), buttons=[
            messages.button(reverse('wagtailadmin_pages:edit', args=(page.id,)), _('Edit'))
        ])

        if next_url:
            return redirect(next_url)
        return redirect('wagtailadmin_explore', page.get_parent().id)

    return render(request, 'wagtailadmin/pages/confirm_unpublish.html', {
        'page': page,
        'next': next_url,
        'live_descendant_count': page.get_descendants().live().count(),
    })