private IEnumerator ShowLoadDialogCoroutine()
        {
            // Show a load file dialog and wait for a response from user
            // Load file/folder: file, Initial path: default (Documents), Title: "Load File", submit button text: "Load"
            yield return(FileBrowser.WaitForLoadDialog(FileBrowser.PickMode.Files, false, null, "Load Book", "Load"));

            if (FileBrowser.Success)
            {
                foreach (string path in FileBrowser.Result)
                {
                    string fileName   = FileBrowserHelpers.GetFilename(path);
                    string targetPath = Application.persistentDataPath + _sourceFolder + fileName;
                    FileBrowserHelpers.MoveFile(path, targetPath);

                    ImportFiles();
                }
            }

            onFB2Loaded?.Invoke();
        }
        private async void ImportFiles()
        {
            string path = Application.persistentDataPath + _sourceFolder;

            try
            {
                if (!Directory.Exists(path))
                {
                    Directory.CreateDirectory(path);
                }
            }
            catch (IOException ex)
            {
                Debug.Log(ex.Message);
                return;
            }

            var files = FileBrowserHelpers.GetEntriesInDirectory(path);

            foreach (var file in files)
            {
                string fileName  = string.Empty;
                string filePath  = string.Empty;
                string imagePath = string.Empty;

                string   text      = string.Empty;
                string   finalText = string.Empty;
                byte[]   imageData = null;
                FileData newBook   = null;

                if (!file.IsDirectory)
                {
                    switch (file.Extension)
                    {
                    case ".fb2":
                        fileName = FileBrowserHelpers.GetFilename(file.Path);
                        text     = FileBrowserHelpers.ReadTextFromFile(file.Path);

                        FB2File fb2File = await new FB2Reader().ReadAsync(text);
                        var     lines   = await _fB2SampleConverter.ConvertAsync(fb2File);

                        finalText = _fB2SampleConverter.GetLinesAsText();

                        imageData = _fB2SampleConverter.GetCoverImageData();

                        if (imageData != null)
                        {
                            imagePath = Application.persistentDataPath + _targetFolder + fileName + ".jpg";;

                            try
                            {
                                File.WriteAllBytes(imagePath, imageData);

                                Debug.Log("Image is saved. Path: " + imagePath);
                            }
                            catch
                            {
                                Debug.LogError("Loading image is error!");
                            }

                            imagePath = imagePath.Replace("/", "\\");
                        }

                        filePath = (Application.persistentDataPath + _targetFolder + fileName).Replace("/", "\\");

                        newBook = new FileData(fileName, filePath, imagePath, FileData.FileType.Book);

                        SaveFile(newBook, finalText);

                        FileBrowserHelpers.DeleteFile(file.Path);
                        break;

                    case ".epub":
                        EpubBook epubFile = EpubReader.ReadBook(file.Path);

                        fileName = epubFile.Title + " (" + epubFile.Author + ")";

                        foreach (EpubTextContentFile textContentFile in epubFile.ReadingOrder)
                        {
                            HtmlDocument htmlDocument = new HtmlDocument();
                            htmlDocument.LoadHtml(textContentFile.Content);

                            StringBuilder sb = new StringBuilder();
                            foreach (HtmlNode node in htmlDocument.DocumentNode.SelectNodes("//text()"))
                            {
                                sb.AppendLine(node.InnerText.Replace("\n", "").Replace("\r", ""));
                            }

                            finalText += sb.ToString();
                        }

                        imageData = epubFile.CoverImage;

                        var imageName = string.Empty;

                        if (imageData == null)
                        {
                            imageData = epubFile.Content.Images.FirstOrDefault().Value.Content;
                            imageName = epubFile.Content.Images.FirstOrDefault().Key;
                        }
                        else
                        {
                            imageName = epubFile.Content.Cover.FileName;
                        }

                        if (imageData != null)
                        {
                            imagePath = Application.persistentDataPath + _targetFolder + imageName;

                            try
                            {
                                File.WriteAllBytes(imagePath, imageData);

                                Debug.Log("Image is saved. Path: " + imagePath);
                            }
                            catch
                            {
                                Debug.LogError("Loading image is error!");
                            }

                            imagePath = imagePath.Replace("/", "\\");
                        }

                        filePath = (Application.persistentDataPath + _targetFolder + fileName).Replace("/", "\\");

                        newBook = new FileData(fileName, filePath, imagePath, FileData.FileType.Book);

                        SaveFile(newBook, finalText);

                        FileBrowserHelpers.DeleteFile(file.Path);
                        break;

                    case ".pdf":
                        var document = PdfiumViewer.PdfDocument.Load(file.Path);
                        var title    = document.GetInformation().Title;

                        if (FilesData.Files.Any(x => x.Name == title))
                        {
                            return;
                        }

                        fileName = FileBrowserHelpers.GetFilename(file.Path);
                        filePath = Application.persistentDataPath + _targetFolder + fileName;

                        imagePath = Application.persistentDataPath + _targetFolder + fileName.Remove(fileName.Length - 4) + ".png";

                        var image = document.Render(0, 72, 72, false);
                        image.Save(imagePath, System.Drawing.Imaging.ImageFormat.Png);

                        imagePath = imagePath.Replace("/", "\\");
                        filePath  = filePath.Replace("/", "\\");

                        document.Dispose();

                        FileBrowserHelpers.MoveFile(file.Path, filePath);

                        newBook = new FileData(title, filePath, imagePath, FileData.FileType.PdfFile);

                        SaveFile(newBook);

                        break;
                    }
                }
                else
                {
                    FileBrowserHelpers.DeleteDirectory(file.Path);
                }
            }
        }