using System;
using System.Linq;
using System.Threading;
using Hangfire;
using LeafWeb.Core.DAL;
using LeafWeb.Core.Entities;
using LeafWeb.Core.Remote;
using NLog;

namespace LeafWeb.Web.Services
{
	public class PiscalQueueManager : IDisposable
	{
		private readonly DataService _dataService;
		private readonly PiscalService _piscalService;
		private readonly EmailNotificationService _emailService;

		public PiscalQueueManager(DataService dataService, PiscalService piscalService, EmailNotificationService emailService)
		{
			_dataService = dataService;
			_piscalService = piscalService;
			_emailService = emailService;
		}

		public PiscalQueueManager() : this(new DataService(), new PiscalService(), new EmailNotificationService()) {}

		private static readonly object ProcessQueueLock = new object();

		public void ProcessQueue()
		{
			var logger = LogManager.GetCurrentClassLogger();

			if (Monitor.TryEnter(ProcessQueueLock))
			{
				logger.Trace("ProcessQueue entered");

				try
				{
					ProcessRunning(logger);

					ProcessQueue(logger);
				}
				finally
				{
					logger.Trace("ProcessQueue exit");

					Monitor.Exit(ProcessQueueLock);
				}
			}
			else
			{
				logger.Trace("ProcessQueue locked, queue already processing");
			}
		}

		private void ProcessQueue(ILogger logger)
		{
			var runningLeafInputs = _dataService.GetLeafInputs(LeafInputStatusType.Running).ToList();
			if (runningLeafInputs.Any())
				return;

			var pending =
				_dataService
					.GetLeafInputs(LeafInputStatusType.Pending)
					.OrderBy(l => l.StatusHistory.Min(sh => sh.DateTime))
					.FirstOrDefault();

			if (pending == null)
				return;

			logger.Info("LeafInputFile: {0}, Start", pending.Id);
			try
			{
				_piscalService.Run(pending);
			}
			catch (PiscalClientException ex)
			{
				logger.Error("LeafInputFile: {0}, ProcessQueue Exception: {1}", pending.Id, ex.Message);
				_dataService.SetLeafInputStatus(pending, LeafInputStatusType.Exception, "Error occurred starting LeafInput", ex.Message);
				logger.Info("LeafInputFile: {0}, Cleanup", pending.Id);
				_piscalService.Cleanup(pending);

				// TODO: re-queue?
				//_dataService.SetLeafInputFileStatus(queuedFile, LeafInputStatusType.Queued, "Re-queuing LeafInput");
			}
			_dataService.SetLeafInputStatus(pending, LeafInputStatusType.Running);
		}

		private void ProcessRunning(ILogger logger)
		{
			var running = _dataService.GetLeafInputs(LeafInputStatusType.Running).ToList();
			foreach (var leafInput in running)
			{
				try
				{
					var status = _piscalService.GetStatus(leafInput);
					switch (status)
					{
						case PiscalStatus.NotStarted:
							logger.Warn("LeafInputFile: {0}, Not Started, re-queueing", leafInput.Id);
							// if it's not started, try to requeue the process - unusual state
							_dataService.SetLeafInputStatus(leafInput, LeafInputStatusType.Pending);
							break;

						case PiscalStatus.Running:
							logger.Trace("LeafInputFile: {0}, Running", leafInput.Id);
							// continue running
							break;

						case PiscalStatus.Complete:
							logger.Info("LeafInputFile: {0}, Complete", leafInput.Id);
							// collect the leaf output
							var leafOutputFiles = _piscalService.RetrieveOutputFiles(leafInput).ToList();
							foreach (var outputFile in leafOutputFiles)
								_dataService.AddLeafOutputFile(outputFile);

							logger.Info("LeafInputFile: {0}, output files: {1}", leafInput.Id,
								string.Join(", ", leafOutputFiles.Select(o => o.Filename)));

							// update db
							_dataService.SetLeafInputStatus(leafInput, LeafInputStatusType.Complete);

							BackgroundJob.Enqueue(() => _emailService.SendLeafWebComplete(leafInput.Id));

							// remove working data from the server
							logger.Info("LeafInputFile: {0}, Cleanup", leafInput.Id);
							_piscalService.Cleanup(leafInput);
							break;
					}
				}
				catch (PiscalClientException ex)
				{
					logger.Error("LeafInputFile: {0}, ProcessRunning Exception: {1}", leafInput.Id, ex.Message);
					_dataService.SetLeafInputStatus(leafInput, LeafInputStatusType.Exception, "Error occurred processing LeafInput", ex.Message);

					// TODO: Send email
					logger.Info("LeafInputFile: {0}, Cleanup", leafInput.Id);
					_piscalService.Cleanup(leafInput);
					// TODO: re-queue ?
				}
			}
		}

		public void Dispose()
		{
			_dataService.Dispose();
		}
	}
}