using System;
using System.Collections.Generic;
using System.Data.Common;
using System.IO;
using System.Linq;
using LeafWeb.Core.Utility;
using NLog;
using Renci.SshNet;

namespace LeafWeb.Core.Remote
{
	public class PiscalSshClient : IPiscalClient
	{
		private const string BaseDirectory = "./LeafWeb";
		private const string RemoteScriptPath = BaseDirectory + "/piscal_manager.sh";
		private readonly PasswordConnectionInfo _connectionInfo;

		private const string StatusComplete = "complete";
		private const string StatusRunning = "running";
		private const string StatusNotStarted = "not started";

		Logger _logger = LogManager.GetCurrentClassLogger();

		public PiscalSshClient(string connectionString)
		{
			var conn = new DbConnectionStringBuilder {ConnectionString = connectionString};

			var host = conn["host"] as string;
			var username = conn["username"] as string;
			var password = conn["password"] as string;
			_connectionInfo = new PasswordConnectionInfo(host, username, password);
		}

		private SshClient GetSshClient()
		{
			return new SshClient(_connectionInfo);
		}

		private ScpClient GetScpClient()
		{
			return new ScpClient(_connectionInfo);
		}

		private void CopyLeafInput(PiscalLeafInput leafInput, string directory)
		{
			// copy files
			using (var scp = GetScpClient())
			foreach (var file in leafInput.InputFiles)
			{
				var inputPath = $"{directory}/input/{file.Filename}";
				using (var stream = new MemoryStream(file.Contents))
				{
					_logger.Trace("Copying " + inputPath);
					scp.Connect();
					scp.Upload(stream, inputPath);
					scp.Disconnect();
				}
			}
		}

		public void RunLeafInput(PiscalLeafInput leafInput)
		{
			var inputDirectory = $"{BaseDirectory}/{leafInput.DirectoryName}";

			CopyLeafInput(leafInput, inputDirectory);

			// begin processing
			using (var ssh = GetSshClient())
			{
				ssh.Connect();
				var commandText = $"{RemoteScriptPath} -d {leafInput.DirectoryName} -p {leafInput.PhotosyntheticType} -s";
				var command = ssh.CreateCommand(commandText);
				command.Execute();
				ssh.Disconnect();

				if (command.ExitStatus != 0)
					throw new PiscalClientException(leafInput.LeafInputId, command.Result);

				_logger.Debug("RunLeafInput result: " + command.Result);
			}
		}

		public PiscalStatus GetLeafInputStatus(PiscalLeafInput leafInput)
		{
			var statusRaw = GetLeafInputStatusRaw(leafInput);

			switch (statusRaw[0])
			{
				case StatusRunning:
					return PiscalStatus.Running;
				case StatusComplete:
					return PiscalStatus.Complete;
				case StatusNotStarted:
					return PiscalStatus.NotStarted;
				default:
					throw new PiscalClientException(leafInput.LeafInputId, "Unknown status: " + statusRaw[0]);
			}
		}

		private string[] GetLeafInputStatusRaw(PiscalLeafInput leafInput)
		{
			using (var ssh = GetSshClient())
			{
				ssh.Connect();
				var commandText = $"{RemoteScriptPath} -d {leafInput.DirectoryName}";
				var command = ssh.CreateCommand(commandText);
				command.Execute();
				ssh.Disconnect();

				if (command.ExitStatus != 0)
					throw new PiscalClientException(leafInput.LeafInputId, command.Result);

				return command.Result
					.SplitNewLine()
					.Where(s => s.Length > 0)
					.Select(s => s.Trim()).ToArray();
			}
		}

		/// <summary>
		/// Gets the leaf output from piscal, only run on if result status is success
		/// </summary>
		public IEnumerable<PiscalLeafOutputFile> RetrieveLeafOutput(PiscalLeafInput leafInput)
		{
			// get output files
			var status = GetLeafInputStatusRaw(leafInput);
			if (status[0] != StatusComplete)
				throw new PiscalClientException(leafInput.LeafInputId, "output not available, status is " + status[0]);

			var filePaths = status.Skip(1);

			using (var scp = GetScpClient())
			{
				scp.Connect();
				foreach (var filePath in filePaths)
				{
					using (var stream = new MemoryStream())
					{
						scp.Download(filePath, stream);
						yield return 
							new PiscalLeafOutputFile
							{
								Contents = stream.ToArray(),
								Filename = filePath.FilenameFromPath(),
								DirectoryName = leafInput.DirectoryName
							};
					}
				}

				scp.Disconnect();
			}
		}
		
		public void CleanupLeafProcess(PiscalLeafInput leafInput)
		{
			using (var ssh = GetSshClient())
			{
				ssh.Connect();
				var commandText = $"{RemoteScriptPath} -d {leafInput.DirectoryName} -c";
				var command = ssh.CreateCommand(commandText);
				command.Execute();
				ssh.Disconnect();

				if (command.ExitStatus != 0)
					throw new PiscalClientException(leafInput.LeafInputId, command.Error);
			}
		}
	}
}