public bool CheckFileExtension(string[] extensions, File file, SystemInfoMessage infoMessage)
        {
            string fileExtension = null;

            if (SenderIsPep(infoMessage.SystemInfo.Sender))
            {
                fileExtension = Path.GetExtension(file.ShepFile.Name);
            }
            else
            {
                fileExtension = Path.GetExtension(file.Name);
            }

            if (fileExtension == null)
            {
                return(false);
            }

            foreach (var extension in extensions)
            {
                if (fileExtension.Equals(extension, StringComparison.InvariantCultureIgnoreCase))
                {
                    return(true);
                }
            }
            return(false);
        }
        public bool FileNameIsCorrect(File file, SystemInfoMessage infoMessage)
        {
            if (file == null)
            {
                return(false);
            }

            if (SenderIsPep(infoMessage.SystemInfo.Sender))
            {
                if (file.ShepFile == null || !CheckFileNameCorrect(file.ShepFile.Name))
                {
                    return(false);
                }
            }
            else
            {
                if (file.Content == null || !CheckFileNameCorrect(file.Name))
                {
                    return(false);
                }
            }

            return(true);
        }
        public bool FileIsEmpty(File file, SystemInfoMessage infoMessage)
        {
            if (file == null)
            {
                return(true);
            }

            if (SenderIsPep(infoMessage.SystemInfo.Sender))
            {
                if (string.IsNullOrEmpty(file.ShepFile?.ID))
                {
                    return(true);
                }
            }
            else
            {
                if (file.Content == null || file.Content.Length == 0)
                {
                    return(true);
                }
            }

            return(false);
        }