AcManager.LargeFilesSharing.GoogleDrive.GoogleDriveUploader.GetDirectories C# (CSharp) Method

        public override async Task<DirectoryEntry[]> GetDirectories(CancellationToken cancellation) {
            await Prepare(cancellation);

            if (_authToken == null) {
                throw new Exception(ToolsStrings.Uploader_AuthenticationTokenIsMissing);
            }

            const string query = "mimeType='application/vnd.google-apps.folder' and trashed = false and 'me' in writers";
            const string fields = "items(id,parents(id,isRoot),title)";
            var data = await Request.Get<SearchResult>(
                    @"https://www.googleapis.com/drive/v2/files?maxResults=1000&orderBy=title&" +
                            $"q={HttpUtility.UrlEncode(query)}&fields={HttpUtility.UrlEncode(fields)}",
                    _authToken.AccessToken, cancellation);
            
            if (data == null) {
                throw new Exception(ToolsStrings.Uploader_RequestFailed);
            }

            var directories = data.Items.Select(x => new DirectoryEntry {
                Id = x.Id,
                DisplayName = x.Title
            }).ToList();

            foreach (var directory in directories) {
                directory.Children = data.Items.Where(x => x.Parents.Any(y => !y.IsRoot && y.Id == directory.Id))
                                         .Select(x => directories.GetById(x.Id)).ToArray();
            }
            
            return new [] {
                new DirectoryEntry {
                    Id = null,
                    DisplayName = ToolsStrings.Uploader_RootDirectory,
                    Children = data.Items.Where(x => x.Parents.All(y => y.IsRoot)).Select(x => directories.GetById(x.Id)).ToArray()
                }
            };
        }