monorepo/LCU.API.Internal.FTP/LCU.Api.Internal.FTP/Services/FtpOpertionServices/WinScpSftpDownloadFilesService.cs

using System;
using System.Collections.Generic;
using System.Linq;
using Newtonsoft.Json;
using Serilog;
using WinSCP;
using System.Text.RegularExpressions;
using LCU.Api.Internal.FTP.Helpers;
using LCU.Api.Internal.FTPLib.Models;
using LCU.Library.Internal.FileOperationsModels.Shared;
namespace LCU.Api.Internal.FTP.Services.FtpOpertionServices;

public class WinScpSftpDownloadFilesService : IWinScpSftpDownloadFilesService
{
    private readonly IWinScpListDirectoryService _winScpListDirectoryService;
    public WinScpSftpDownloadFilesService(IWinScpListDirectoryService winScpListDirectoryService)
    {
        _winScpListDirectoryService = winScpListDirectoryService;
    }

    public FtpRequestResponse ExecuteAction(QueueRequest queueRequest)
    {
        var ftpRequestResponse = new FtpRequestResponse();
        try
        {
            ArgumentNullException.ThrowIfNull(queueRequest);
            var request = JsonConvert.DeserializeObject<SftpDownloadFileRequest>(queueRequest.Request);
            ArgumentNullException.ThrowIfNull(request);
            ftpRequestResponse.ReturnResponse = request;
            ftpRequestResponse = TransferFiles(request, ftpRequestResponse);
        }
        catch (Exception exception)
        {
            ftpRequestResponse.IsSuccessful = false;
            ftpRequestResponse.MessageStack.Add(exception.Message);
        }
        return ftpRequestResponse;
    }

    private FtpRequestResponse TransferFiles(SftpDownloadFileRequest winScpDownloadFileRequest, FtpRequestResponse ftpRequestResponse)
    {
        try
        {
            var listDirectoryRequest = new ListDirectoryRequest()
            {
                SessionInformation = winScpDownloadFileRequest.SessionInformation,
                RemotePath = winScpDownloadFileRequest.FinalRemoteFilePath
            };
            var filesInDirectory = _winScpListDirectoryService.GetListOfFilesInDirectory(listDirectoryRequest);
            var remoteFileNameRegex = winScpDownloadFileRequest.DynamicNameSetting != null ? 
                                                RegexNameHandler.BuildRegexName(winScpDownloadFileRequest.FinalRemoteFileName, winScpDownloadFileRequest.DynamicNameSetting) : 
                                                new Regex(winScpDownloadFileRequest.FinalRemoteFileName);

            var matchedDirectoryFiles = filesInDirectory.Where(fileName => remoteFileNameRegex.IsMatch(fileName)).ToList();
            if (!matchedDirectoryFiles.Any())
            {
                ftpRequestResponse.MessageStack.Add($"No files available to be downloaded.  " +
                                                        $"RegexFileName: {remoteFileNameRegex}.  " +
                                                        $"Succeed On Empty?: {winScpDownloadFileRequest.SucceedOnEmpty}");
                ftpRequestResponse.IsSuccessful = winScpDownloadFileRequest.SucceedOnEmpty;
                return ftpRequestResponse;
            }

            var sessionOptions = WinScpSessionOptionsHelper.CreateSessionOptions(winScpDownloadFileRequest.SessionInformation);
            WinScpFile(sessionOptions, winScpDownloadFileRequest, matchedDirectoryFiles);            
        }
        catch (Exception exception)
        {
            ftpRequestResponse.MessageStack.Add($"Failed to download file with WinSCP. " +
                                $"Host: {winScpDownloadFileRequest.SessionInformation.HostName}, " +
                                $"RemotePath: {winScpDownloadFileRequest.FinalRemoteFilePath} " +
                                $"ExceptionMessage: { exception.Message }");
            ftpRequestResponse.IsSuccessful = false;
        }

        return ftpRequestResponse;
    }

    private void WinScpFile(SessionOptions sessionOptions, SftpDownloadFileRequest winScpDownloadFileRequest, List<string> remoteFileNames)
    {
        using (var session = new Session())
        {
            session.Open(sessionOptions);
            var transferOptions = new TransferOptions { TransferMode = TransferMode.Binary, PreserveTimestamp = false };

            if (!winScpDownloadFileRequest.ResumeSupportStateOn)
            {
                transferOptions.ResumeSupport.State = TransferResumeSupportState.Off;
            }

            foreach(string remoteFileName in remoteFileNames)
            {
                var addedSlash = winScpDownloadFileRequest.FinalRemoteFilePath.EndsWith('/') ? "" : "/";
                var remotefilePath = $"{winScpDownloadFileRequest.FinalRemoteFilePath}{addedSlash}{remoteFileName}";
                var transferResult = session.GetFiles(remotefilePath, winScpDownloadFileRequest.FinalLocalFilePath, winScpDownloadFileRequest.ShouldRemove, transferOptions);
                transferResult.Check();
                foreach (TransferEventArgs transfer in transferResult.Transfers)
                {
                    Log.Debug($"Download of {transfer.FileName} succeeded");
                }
            }            
        }
    }
}