def handle_listing(listing, node):
            if not listing:
                return
            
            nodes_successfully_listed.add(node.id)

            for folder, items in listing['items'].iteritems():
                for item in items:
                    relative_parent_path = '/'.join(item['path'].split('/')[:-1])
                    item_path = '/'.join(x for x in [path.decode('utf-8'), item['path']] if x)
                    
                    href = '%s/%s' % (base_url, urllib.quote(item['path'].encode('utf-8')))
                    rel = 'file'
                    
                    if 'stream_depth' in level_setup and level_setup['stream_depth'] < path_depth(relative_parent_path) and item['type'] == 'file':
                        continue
                    
                    if 'stream_depth' not in level_setup or level_setup['stream_depth'] >= path_depth(item['path']) or self.extra_folder and self.extra_folder.match(item['name']):
                        rel = 'folder'
                    else:
                        href += '?node=%s' % node.id
                    
                    item_data = self._create_item(rel, href, item['modified'], item['name'], item)
                    
                    for f in self.get_services('listing_result_item'):
                        yield defer.maybeDeferred(f, self, user, item_path, item_data)
                    path_pointers[relative_parent_path].append(item_data)
                    
                    if rel == 'folder':
                        folder_listing_skiplist[item_path].add(node.id)
            
            item_data = self._create_item('folder', base_url, listing['modified'], listing['name'], listing)
            for f in self.get_services('listing_result_item'):
                yield defer.maybeDeferred(f, self, user, '', item_data)
            root.append(item_data)
    def list(self, user, path, config):
        level = path_depth(path)
        
        if level not in self.levels:
            defer.returnValue(ErrorPage(http.BAD_REQUEST, 'Unknown level', 'The path you have requested is at a depth that this section does not support'))
        
        level_setup = self.get_level(level)
        
        path_pointers = defaultdict(list)
        root = []
        
        base_url = '/'.join(x for x in [
                urljoin(settings.BASE_URL, '/section'),
                urllib.quote(self.id),
                urllib.quote(path)]
            if x)
        
        if 'filter_paths' in config:
            config['filter_paths'] = [('/'.join(y.split('/')[:-1]), y.split('/')[-1]) for y in config['filter_paths']]
        
        folder_listing_skiplist = defaultdict(set)
        nodes_successfully_listed = set()
        
        @defer.inlineCallbacks
        def handle_listing(listing, node):
            if not listing:
                return
            
            nodes_successfully_listed.add(node.id)

            for folder, items in listing['items'].iteritems():
                for item in items:
                    relative_parent_path = '/'.join(item['path'].split('/')[:-1])
                    item_path = '/'.join(x for x in [path.decode('utf-8'), item['path']] if x)
                    
                    href = '%s/%s' % (base_url, urllib.quote(item['path'].encode('utf-8')))
                    rel = 'file'
                    
                    if 'stream_depth' in level_setup and level_setup['stream_depth'] < path_depth(relative_parent_path) and item['type'] == 'file':
                        continue
                    
                    if 'stream_depth' not in level_setup or level_setup['stream_depth'] >= path_depth(item['path']) or self.extra_folder and self.extra_folder.match(item['name']):
                        rel = 'folder'
                    else:
                        href += '?node=%s' % node.id
                    
                    item_data = self._create_item(rel, href, item['modified'], item['name'], item)
                    
                    for f in self.get_services('listing_result_item'):
                        yield defer.maybeDeferred(f, self, user, item_path, item_data)
                    path_pointers[relative_parent_path].append(item_data)
                    
                    if rel == 'folder':
                        folder_listing_skiplist[item_path].add(node.id)
            
            item_data = self._create_item('folder', base_url, listing['modified'], listing['name'], listing)
            for f in self.get_services('listing_result_item'):
                yield defer.maybeDeferred(f, self, user, '', item_data)
            root.append(item_data)
        
        nodes = self.nodes
        
        # checking if we can skip listing some nodes
        skipitems_path = path.split(u'/')
        while True:
            skipitems_key = u'skipitems:%s' % u'/'.join(skipitems_path)
            if skipitems_key in cache and path in cache[skipitems_key]:
                nodes = [node for node in self.nodes if node.id not in cache[skipitems_key][path]]
                break
            
            if not skipitems_path:
                break
            
            skipitems_path.pop()
        
        d = []
        for node in nodes:
            d.append(defer.maybeDeferred(node.list, path).addCallback(handle_listing, node))
        
        yield defer.DeferredList(d)
        
        if not root:
            defer.returnValue(NoResource('Unknown path'))

        for f in self.get_services('listing_result'):
            yield defer.maybeDeferred(f, self, user, path, path_pointers)
        
        # the first listing is fast for scanning and adding new elements
        #
        # the final listing is good for browsing around and solves some short-comings
        # that the other listing suffers from
        root = self.merge_items(root)
        root['result'] = []
        root['overwrite_title'] = self.levels.get(level, {}).get('overwrite_title', True)
        if level == 0:
            root['name'] = self.id
        
        item_pointer = {'': root}
        for item_parent_path in sorted(path_pointers.keys()):
            items = path_pointers[item_parent_path]
            
            for item in items:
                if 'filter_paths' in config and (item_parent_path, item['name']) not in config['filter_paths']:
                    continue
                
                if item['rel'] == 'file':
                    if 'result' not in item_pointer[item_parent_path]:
                        item_pointer[item_parent_path]['result'] = []
                        item_pointer[item_parent_path]['overwrite_title'] = root['overwrite_title']
                    
                    item_pointer[item_parent_path]['result'].append(item)
                
                elif item['rel'] == 'folder':
                    if item_parent_path:
                        item_path = '%s/%s' % (item_parent_path, item['name'])
                    else:
                        item_path = item['name']
                    
                    if item_path in item_pointer:
                        item_pointer[item_path] = self.merge_items([item_pointer[item_path], item])
                    else:
                        item_pointer[item_path] = item
        
        # remove empty itamz
        
        for item_path in sorted(item_pointer.keys())[1:]:
            item = item_pointer[item_path]
            parent_item_path = '/'.join(item_path.split('/')[:-1])
            parent_item = item_pointer[parent_item_path]
            
            if 'result' not in parent_item:
                parent_item['result'] = []
            
            parent_item['result'].append(item)
        
        for items in item_pointer.values():
            if 'result' not in items:
                continue
            self.filter(items['result'])
            self.sort(items['result'], config.get('order_by', 'name'))
            self.clean_items(items['result'])
        
        del root['_original_item']
        
        if 'content_type' in level_setup:
            root['content_type'] = level_setup['content_type']
        
        # create skiplist for subfolder listings
        if len(nodes_successfully_listed) > 1:
            final_folder_listing_skiplist = {}
            for item_path, nodes in folder_listing_skiplist.iteritems():
                nodes = nodes_successfully_listed - nodes
                if not nodes:
                    continue
                
                final_folder_listing_skiplist[item_path] = nodes
            
            if final_folder_listing_skiplist:
                cache.set(u'skipitems:%s' % path, final_folder_listing_skiplist, timedelta(hours=2))
        
        defer.returnValue(json.dumps(root))