def chooser(request):
    Document = get_document_model()

    if permission_policy.user_has_permission(request.user, "add"):
        DocumentForm = get_document_form(Document)
        uploadform = DocumentForm()
    else:
        uploadform = None

    documents = []

    q = None
    is_searching = False
    if "q" in request.GET or "p" in request.GET or "collection_id" in request.GET:
        documents = Document.objects.all()

        collection_id = request.GET.get("collection_id")
        if collection_id:
            documents = documents.filter(collection=collection_id)

        searchform = SearchForm(request.GET)
        if searchform.is_valid():
            q = searchform.cleaned_data["q"]

            documents = documents.search(q)
            is_searching = True
        else:
            documents = documents.order_by("-created_at")
            is_searching = False

        # Pagination
        paginator, documents = paginate(request, documents, per_page=10)

        return render(
            request,
            "wagtaildocs/chooser/results.html",
            {"documents": documents, "query_string": q, "is_searching": is_searching},
        )
    else:
        searchform = SearchForm()

        collections = Collection.objects.all()
        if len(collections) < 2:
            collections = None

        documents = Document.objects.order_by("-created_at")
        paginator, documents = paginate(request, documents, per_page=10)

    return render_modal_workflow(
        request,
        "wagtaildocs/chooser/chooser.html",
        "wagtaildocs/chooser/chooser.js",
        {
            "documents": documents,
            "uploadform": uploadform,
            "searchform": searchform,
            "collections": collections,
            "is_searching": False,
        },
    )

def chooser(request):
    Image = get_image_model()

    if permission_policy.user_has_permission(request.user, 'add'):
        ImageForm = get_image_form(Image)
        uploadform = ImageForm(user=request.user)
    else:
        uploadform = None

    images = Image.objects.order_by('-created_at')

    # allow hooks to modify the queryset
    for hook in hooks.get_hooks('construct_image_chooser_queryset'):
        images = hook(images, request)

    if (
        'q' in request.GET or 'p' in request.GET or 'tag' in request.GET or
        'collection_id' in request.GET
    ):
        # this request is triggered from search, pagination or 'popular tags';
        # we will just render the results.html fragment
        collection_id = request.GET.get('collection_id')
        if collection_id:
            images = images.filter(collection=collection_id)

        searchform = SearchForm(request.GET)
        if searchform.is_valid():
            q = searchform.cleaned_data['q']

            images = images.search(q)
            is_searching = True
        else:
            is_searching = False
            q = None

            tag_name = request.GET.get('tag')
            if tag_name:
                images = images.filter(tags__name=tag_name)

        # Pagination
        paginator, images = paginate(request, images, per_page=12)

        return render(request, "wagtailimages/chooser/results.html", {
            'images': images,
            'is_searching': is_searching,
            'query_string': q,
            'will_select_format': request.GET.get('select_format')
        })
    else:
        paginator, images = paginate(request, images, per_page=12)

        context = get_chooser_context(request)
        context.update({
            'images': images,
            'uploadform': uploadform,
        })
        return render_modal_workflow(
            request, 'wagtailimages/chooser/chooser.html', None, context,
            json_data=get_chooser_js_data()
        )

def chooser(request):
    Document = get_document_model()

    if permission_policy.user_has_permission(request.user, 'add'):
        DocumentForm = get_document_form(Document)
        uploadform = DocumentForm(user=request.user)
    else:
        uploadform = None

    documents = Document.objects.all()

    # allow hooks to modify the queryset
    for hook in hooks.get_hooks('construct_document_chooser_queryset'):
        documents = hook(documents, request)

    q = None
    if 'q' in request.GET or 'p' in request.GET or 'collection_id' in request.GET:

        collection_id = request.GET.get('collection_id')
        if collection_id:
            documents = documents.filter(collection=collection_id)

        searchform = SearchForm(request.GET)
        if searchform.is_valid():
            q = searchform.cleaned_data['q']

            documents = documents.search(q)
            is_searching = True
        else:
            documents = documents.order_by('-created_at')
            is_searching = False

        # Pagination
        paginator, documents = paginate(request, documents, per_page=10)

        return render(request, "wagtaildocs/chooser/results.html", {
            'documents': documents,
            'query_string': q,
            'is_searching': is_searching,
        })
    else:
        searchform = SearchForm()

        collections = Collection.objects.all()
        if len(collections) < 2:
            collections = None

        documents = documents.order_by('-created_at')
        paginator, documents = paginate(request, documents, per_page=10)

        return render_modal_workflow(request, 'wagtaildocs/chooser/chooser.html', 'wagtaildocs/chooser/chooser.js', {
            'documents': documents,
            'uploadform': uploadform,
            'searchform': searchform,
            'collections': collections,
            'is_searching': False,
            'uploadid': uuid.uuid4(),
        })

def chooser(request):
    VideoForm = get_video_form(Video)
    uploadform = VideoForm()

    videos = Video.objects.order_by('-created_at')

    q = None
    if (
        'q' in request.GET or 'p' in request.GET or 'tag' in request.GET or
        'collection_id' in request.GET
    ):
        # this request is triggered from search, pagination or 'popular tags';
        # we will just render the results.html fragment
        collection_id = request.GET.get('collection_id')
        if collection_id:
            videos = videos.filter(collection=collection_id)

        searchform = SearchForm(request.GET)
        if searchform.is_valid():
            q = searchform.cleaned_data['q']

            videos = videos.search(q)
            is_searching = True
        else:
            is_searching = False

            tag_name = request.GET.get('tag')
            if tag_name:
                videos = videos.filter(tags__name=tag_name)

        # Pagination
        paginator, videos = paginate(request, videos, per_page=12)

        return render(request, "wagtailvideos/chooser/results.html", {
            'videos': videos,
            'is_searching': is_searching,
            'query_string': q,
        })
    else:
        searchform = SearchForm()

        collections = Collection.objects.all()
        if len(collections) < 2:
            collections = None

        paginator, videos = paginate(request, videos, per_page=12)

    return render_modal_workflow(request, 'wagtailvideos/chooser/chooser.html', 'wagtailvideos/chooser/chooser.js', {
        'videos': videos,
        'uploadform': uploadform,
        'searchform': searchform,
        'is_searching': False,
        'query_string': q,
        'popular_tags': popular_tags_for_model(Video),
        'collections': collections,
    })

def chooser(request):
    Image = get_image_model()

    if request.user.has_perm('wagtailimages.add_image'):
        ImageForm = get_image_form(Image)
        uploadform = ImageForm()
    else:
        uploadform = None

    images = Image.objects.order_by('-created_at')

    q = None
    if 'q' in request.GET or 'p' in request.GET or 'tag' in request.GET:
        # this request is triggered from search, pagination or 'popular tags';
        # we will just render the results.html fragment

        searchform = SearchForm(request.GET)
        if searchform.is_valid():
            q = searchform.cleaned_data['q']

            images = images.search(q)
            is_searching = True
        else:
            is_searching = False

            tag_name = request.GET.get('tag')
            if tag_name:
                images = images.filter(tags__name=tag_name)

        # Pagination
        paginator, images = paginate(request, images, per_page=12)

        return render(request, "wagtailimages/chooser/results.html", {
            'images': images,
            'is_searching': is_searching,
            'query_string': q,
            'will_select_format': request.GET.get('select_format')
        })
    else:
        searchform = SearchForm()

        paginator, images = paginate(request, images, per_page=12)

    return render_modal_workflow(request, 'wagtailimages/chooser/chooser.html', 'wagtailimages/chooser/chooser.js', {
        'images': images,
        'uploadform': uploadform,
        'searchform': searchform,
        'is_searching': False,
        'query_string': q,
        'will_select_format': request.GET.get('select_format'),
        'popular_tags': Image.popular_tags(),
    })

def chooser(request):
    EmbedVideo = get_embed_video_model()

    if request.user.has_perm('wagtail_embed_videos.add_embedvideo'):
        can_add = True
    else:
        can_add = False

    q = None
    embed_videos = EmbedVideo.objects.order_by('-created_at')
    if 'q' in request.GET or 'p' in request.GET:
        searchform = SearchForm(request.GET)
        if searchform.is_valid():
            q = searchform.cleaned_data['q']

            embed_videos = embed_videos.search(q)

            is_searching = True

        else:
            is_searching = False
            q = None

        # Pagination
        paginator, embed_videos = paginate(request, embed_videos, per_page=12)

        return render(request, "wagtail_embed_videos/chooser/results.html", {
            'embed_videos': embed_videos,
            'is_searching': is_searching,
            'can_add': can_add,
            'query_string': q,
        })
    else:
        paginator, embed_videos = paginate(request, embed_videos, per_page=12)

        searchform = SearchForm()

    return render_modal_workflow(
        request,
        'wagtail_embed_videos/chooser/chooser.html',
        'wagtail_embed_videos/chooser/chooser.js',
        {
            'embed_videos': embed_videos,
            'searchform': searchform,
            'is_searching': False,
            'can_add': can_add,
            'query_string': q,
            'popular_tags': popular_tags_for_model(EmbedVideo),
        }
    )

def choose(request, app_label, model_name):
    model = get_model_or_404(app_label, model_name)
    objects = model.objects.all()

    q = None
    if ('q' in request.GET or 'p' in request.GET):
        # this request is triggered from search or pagination
        # we will just render the results.html fragment

        searchform = SearchForm(request.GET)
        if searchform.is_valid():
            q = searchform.cleaned_data['q']

            objects = objects.search(q)
            is_searching = True
        else:
            is_searching = False

        # Pagination
        paginator, objects = paginate(request, objects, per_page=12)

        return render(request, "modeladminutils/chooser/results.html", {
            'objects': objects,
            'is_searching': is_searching,
            'query_string': q,
            'will_select_format': request.GET.get('select_format'),
            'app_label': app_label,
            'model_name': model_name,
            'model_verbose_name_plural': model._meta.verbose_name_plural,
        })
    else:
        searchform = SearchForm()

        paginator, objects = paginate(request, objects, per_page=12)

    return render_modal_workflow(
        request,
        'modeladminutils/chooser/chooser.html',
        'modeladminutils/chooser/chooser.js',
        {
            'objects': objects,
            'searchform': searchform,
            'is_searching': False,
            'query_string': q,
            'app_label': app_label,
            'model_name': model_name,
            'model_verbose_name': model._meta.verbose_name,
        }
    )

def chooser(request):
    Media = get_media_model()

    media_files = []

    q = None
    is_searching = False
    if 'q' in request.GET or 'p' in request.GET or 'collection_id' in request.GET:
        media_files = Media.objects.all()

        collection_id = request.GET.get('collection_id')
        if collection_id:
            media_files = media_files.filter(collection=collection_id)

        searchform = SearchForm(request.GET)
        if searchform.is_valid():
            q = searchform.cleaned_data['q']

            media_files = media_files.search(q)
            is_searching = True
        else:
            media_files = media_files.order_by('-created_at')
            is_searching = False

        # Pagination
        paginator, media_files = paginate(request, media_files, per_page=10)

        return render(request, "wagtailmedia/chooser/results.html", {
            'media_files': media_files,
            'query_string': q,
            'is_searching': is_searching,
        })
    else:
        searchform = SearchForm()

        collections = Collection.objects.all()
        if len(collections) < 2:
            collections = None

        media_files = Media.objects.order_by('-created_at')
        paginator, media_files = paginate(request, media_files, per_page=10)

    return render_modal_workflow(request, 'wagtailmedia/chooser/chooser.html', 'wagtailmedia/chooser/chooser.js', {
        'media_files': media_files,
        'searchform': searchform,
        'collections': collections,
        'is_searching': False,
    })

def chooser_upload(request):
    VideoForm = get_video_form(Video)

    searchform = SearchForm()

    if request.POST:
        video = Video(uploaded_by_user=request.user)
        form = VideoForm(request.POST, request.FILES, instance=video)

        if form.is_valid():
            video.uploaded_by_user = request.user
            video.save()

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

            return render_modal_workflow(
                request, None, 'wagtailvideos/chooser/video_chosen.js',
                {'video_json': get_video_json(video)}
            )
    else:
        form = VideoForm()

    videos = Video.objects.order_by('title')
    paginator, videos = paginate(request, videos, per_page=12)

    return render_modal_workflow(
        request, 'wagtailvideos/chooser/chooser.html', 'wagtailvideos/chooser/chooser.js',
        {'videos': videos, 'uploadform': form, 'searchform': searchform}
    )

def chooser(request, get_results=False):
    # Get most popular queries
    queries = models.Query.get_most_popular()

    # If searching, filter results by query string
    query_string = None
    if 'q' in request.GET:
        searchform = SearchForm(request.GET)
        if searchform.is_valid():
            query_string = searchform.cleaned_data['q']
            queries = queries.filter(query_string__icontains=normalise_query_string(query_string))
    else:
        searchform = SearchForm()

    paginator, queries = paginate(request, queries, per_page=10)

    # Render
    if get_results:
        return render(request, "wagtailsearch/queries/chooser/results.html", {
            'queries': queries,
        })
    else:
        return render_modal_workflow(
            request, 'wagtailsearch/queries/chooser/chooser.html', None, {
                'queries': queries,
                'searchform': searchform,
            }, json_data={'step': 'chooser'}
        )

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

    paginator, used_by = paginate(request, doc.get_usage())

    return render(request, "wagtaildocs/documents/usage.html", {"document": doc, "used_by": used_by})

def chooser(request, get_results=False):
    # Get most popular queries
    queries = models.Query.get_most_popular()

    # If searching, filter results by query string
    query_string = None
    if "q" in request.GET:
        searchform = SearchForm(request.GET)
        if searchform.is_valid():
            query_string = searchform.cleaned_data["q"]
            queries = queries.filter(query_string__icontains=normalise_query_string(query_string))
    else:
        searchform = SearchForm()

    paginator, queries = paginate(request, queries, per_page=10)

    # Render
    if get_results:
        return render(request, "wagtailsearch/queries/chooser/results.html", {"queries": queries})
    else:
        return render_modal_workflow(
            request,
            "wagtailsearch/queries/chooser/chooser.html",
            "wagtailsearch/queries/chooser/chooser.js",
            {"queries": queries, "searchform": searchform},
        )

def browse(request, parent_page_id=None):
    # Find parent page
    if parent_page_id:
        parent_page = get_object_or_404(Page, id=parent_page_id)
    else:
        parent_page = Page.get_first_root_node()

    # Get children of parent page
    pages = parent_page.get_children()

    # Filter them by page type
    # A missing or empty page_type parameter indicates 'all page types' (i.e. descendants of wagtailcore.page)
    page_type_string = request.GET.get('page_type') or 'wagtailcore.page'
    if page_type_string != 'wagtailcore.page':
        try:
            desired_classes = page_models_from_string(page_type_string)
        except (ValueError, LookupError):
            raise Http404

        # restrict the page listing to just those pages that:
        # - are of the given content type (taking into account class inheritance)
        # - or can be navigated into (i.e. have children)
        choosable_pages = filter_page_type(pages, desired_classes)
        descendable_pages = pages.filter(numchild__gt=0)
        pages = choosable_pages | descendable_pages
    else:
        desired_classes = (Page, )

    can_choose_root = request.GET.get('can_choose_root', False)

    # Parent page can be chosen if it is a instance of desired_classes
    parent_page.can_choose = issubclass(parent_page.specific_class or Page, desired_classes) and (can_choose_root or not parent_page.is_root())

    # Pagination
    # We apply pagination first so we don't need to walk the entire list
    # in the block below
    paginator, pages = paginate(request, pages, per_page=25)

    # Annotate each page with can_choose/can_decend flags
    for page in pages:
        if desired_classes == (Page, ):
            page.can_choose = True
        else:
            page.can_choose = issubclass(page.specific_class or Page, desired_classes)

        page.can_descend = page.get_children_count()

    # Render
    return render_modal_workflow(
        request,
        'wagtailadmin/chooser/browse.html', 'wagtailadmin/chooser/browse.js',
        shared_context(request, {
            'parent_page': parent_page,
            'pages': pages,
            'search_form': SearchForm(),
            'page_type_string': page_type_string,
            'page_type_names': [desired_class.get_verbose_name() for desired_class in desired_classes],
            'page_types_restricted': (page_type_string != 'wagtailcore.page')
        })
    )

def search(request):
    pages = []
    q = None

    if "q" in request.GET:
        form = SearchForm(request.GET)
        if form.is_valid():
            q = form.cleaned_data["q"]

            pages = Page.objects.all().prefetch_related("content_type").search(q)
            paginator, pages = paginate(request, pages)
    else:
        form = SearchForm()

    if request.is_ajax():
        return render(
            request,
            "wagtailadmin/pages/search_results.html",
            {"pages": pages, "query_string": q, "pagination_query_params": ("q=%s" % q) if q else ""},
        )
    else:
        return render(
            request,
            "wagtailadmin/pages/search.html",
            {
                "search_form": form,
                "pages": pages,
                "query_string": q,
                "pagination_query_params": ("q=%s" % q) if q else "",
            },
        )

def search(request, parent_page_id=None):
    # A missing or empty page_type parameter indicates 'all page types' (i.e. descendants of wagtailcore.page)
    page_type_string = request.GET.get('page_type') or 'wagtailcore.page'

    try:
        desired_classes = page_models_from_string(page_type_string)
    except (ValueError, LookupError):
        raise Http404

    search_form = SearchForm(request.GET)
    if search_form.is_valid() and search_form.cleaned_data['q']:
        pages = Page.objects.exclude(
            depth=1  # never include root
        )
        pages = filter_page_type(pages, desired_classes)
        pages = pages.search(search_form.cleaned_data['q'], fields=['title'])
    else:
        pages = Page.objects.none()

    paginator, pages = paginate(request, pages, per_page=25)

    for page in pages:
        page.can_choose = True

    return render(
        request, 'wagtailadmin/chooser/_search_results.html',
        shared_context(request, {
            'searchform': search_form,
            'pages': pages,
            'page_type_string': page_type_string,
        })
    )

def move_choose_destination(request, page_to_move_id, viewed_page_id=None):
    page_to_move = get_object_or_404(Page, id=page_to_move_id)
    page_perms = page_to_move.permissions_for_user(request.user)
    if not page_perms.can_move():
        raise PermissionDenied

    if viewed_page_id:
        viewed_page = get_object_or_404(Page, id=viewed_page_id)
    else:
        viewed_page = Page.get_first_root_node()

    viewed_page.can_choose = page_perms.can_move_to(viewed_page)

    child_pages = []
    for target in viewed_page.get_children():
        # can't move the page into itself or its descendants
        target.can_choose = page_perms.can_move_to(target)

        target.can_descend = (
            not(target == page_to_move or
                target.is_child_of(page_to_move)) and
            target.get_children_count()
        )

        child_pages.append(target)

    # Pagination
    paginator, child_pages = paginate(request, child_pages, per_page=50)

    return render(request, 'wagtailadmin/pages/move_choose_destination.html', {
        'page_to_move': page_to_move,
        'viewed_page': viewed_page,
        'child_pages': child_pages,
    })

def index(request):
    submissions = Submission.objects.all()

    # Ordering
    if request.GET.get('ordering') in ['title', '-submitted_at']:
        ordering = request.GET['ordering']
    else:
        ordering = '-submitted_at'
    submissions = submissions.order_by(ordering)

    # Search
    query_string = None
    if 'q' in request.GET:
        form = SearchForm(request.GET, placeholder=_("Search submissions"))
        if form.is_valid():
            query_string = form.cleaned_data['q']
            submissions = submissions.search(query_string)
    else:
        form = SearchForm(placeholder=_("Search submissions"))

    # Pagination
    paginator, submissions = paginate(request, submissions)

    return render(request, 'submissions/admin/index.html', {
        'submissions': submissions,
        'ordering': ordering,
        'query_string': query_string,
        'is_searching': bool(query_string),
        'search_form': form,
    })

def search(request):
    pages = []
    q = None

    if 'q' in request.GET:
        form = SearchForm(request.GET)
        if form.is_valid():
            q = form.cleaned_data['q']

            pages = Page.objects.all().prefetch_related('content_type').search(q)
            paginator, pages = paginate(request, pages)
    else:
        form = SearchForm()

    if request.is_ajax():
        return render(request, "wagtailadmin/pages/search_results.html", {
            'pages': pages,
            'query_string': q,
            'pagination_query_params': ('q=%s' % q) if q else ''
        })
    else:
        return render(request, "wagtailadmin/pages/search.html", {
            'search_form': form,
            'pages': pages,
            'query_string': q,
            'pagination_query_params': ('q=%s' % q) if q else ''
        })

def index(request):
    q = None
    is_searching = False

    model_fields = [f.name for f in User._meta.get_fields()]

    if 'q' in request.GET:
        form = SearchForm(request.GET, placeholder=_("Search users"))
        if form.is_valid():
            q = form.cleaned_data['q']
            is_searching = True
            conditions = Q()

            if 'username' in model_fields:
                conditions |= Q(username__icontains=q)

            if 'first_name' in model_fields:
                conditions |= Q(first_name__icontains=q)

            if 'last_name' in model_fields:
                conditions |= Q(last_name__icontains=q)

            if 'email' in model_fields:
                conditions |= Q(email__icontains=q)

            users = User.objects.filter(conditions)
    else:
        form = SearchForm(placeholder=_("Search users"))

    if not is_searching:
        users = User.objects.all()

    if 'last_name' in model_fields and 'first_name' in model_fields:
        users = users.order_by('last_name', 'first_name')

    if 'ordering' in request.GET:
        ordering = request.GET['ordering']

        if ordering == 'username':
            users = users.order_by(User.USERNAME_FIELD)
    else:
        ordering = 'name'

    paginator, users = paginate(request, users)

    if request.is_ajax():
        return render(request, "wagtailusers/users/results.html", {
            'users': users,
            'is_searching': is_searching,
            'query_string': q,
            'ordering': ordering,
        })
    else:
        return render(request, "wagtailusers/users/index.html", {
            'search_form': form,
            'users': users,
            'is_searching': is_searching,
            'ordering': ordering,
            'query_string': q,
        })

def index(request):
    query_string = request.GET.get('q', "")
    ordering = request.GET.get('ordering', 'old_path')

    redirects = models.Redirect.objects.prefetch_related('redirect_page', 'site')

    # Search
    if query_string:
        redirects = redirects.filter(old_path__icontains=query_string)

    # Ordering (A bit useless at the moment as only 'old_path' is allowed)
    if ordering not in ['old_path']:
        ordering = 'old_path'

    if ordering != 'old_path':
        redirects = redirects.order_by(ordering)

    # Pagination
    paginator, redirects = paginate(request, redirects)

    # Render template
    if request.is_ajax():
        return render(request, "wagtailredirects/results.html", {
            'ordering': ordering,
            'redirects': redirects,
            'query_string': query_string,
        })
    else:
        return render(request, "wagtailredirects/index.html", {
            'ordering': ordering,
            'redirects': redirects,
            'query_string': query_string,
            'search_form': SearchForm(data=dict(q=query_string) if query_string else None, placeholder=_("Search redirects")),
        })