using System;
using CSharpFunctionalExtensions;
using WinSCP;

namespace AAC.SettlementEngine.UI.DataAccess.Utilities
{
	public class FtpProcessor
	{
		private readonly string _hostName;
		private readonly string _password;
		private readonly Protocol _protocol;
		private readonly string _userName;


		/// <summary>
		///     Setup Sessions credential
		/// </summary>
		/// <param name="hostName"></param>
		/// <param name="userName"></param>
		/// <param name="password"></param>
		/// <param name="protocol">Default is SFTP (support FTP)</param>
		public FtpProcessor(string hostName, string userName, string password, Protocol protocol = Protocol.Sftp)
		{
			// the client will read the credential
			// information from a configuration file
			_protocol = protocol;
			_hostName = hostName;
			_userName = userName;
			_password = password;
		}

		/// <summary>
		///     Download one file from a remote directory to a local directory.
		///     The method downloads files only. It throws when the source path points to a directory.
		///     If the target local directory does not exist, it is created.
		/// </summary>
		/// <param name="remotePath">
		///     Full path to the remote file to download.
		/// </param>
		/// <param name="downloadPath">
		///     Full path to the local directory to download the file to.
		///     The directory is created, if it does not exist.
		/// </param>
		/// <returns>
		///     Result.Fail if downloading of a file has failed
		///     Result.Success if downloading of a file is successful
		/// </returns>
		public Result RetrieveFile(string remotePath, string downloadPath)
		{
			var sessionOptions = new SessionOptions
			{
				Protocol = _protocol,
				HostName = _hostName,
				UserName = _userName,
				Password = _password
			};

			try
			{
				using (var session = new Session())
				{
					// Connect
					session.Open(sessionOptions);
					
					var transferOptions = new TransferOptions
					{
						TransferMode = TransferMode.Binary
					};

					var fileExist = session.FileExists(remotePath);

					if (fileExist)
					{
						// Download files
						var transferResult = session.GetFiles(remotePath, downloadPath, false, transferOptions);

						// Throw on any error
						transferResult.Check();
					}
					else
					{
						return Result.Failure($"Error: File {remotePath} does not exists.");
					}
				}
			}
			catch (Exception e)
			{
				return Result.Failure($"{e.Message}");
			}


			return Result.Success();
		}
	}
}