using System;
using System.Configuration;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Mail;
using LeafWeb.Core.DAL;
using LeafWeb.Core.Entities;
using LeafWeb.Core.Utility;
using NLog;

namespace LeafWeb.Web.Services
{
	public class EmailNotificationService : IDisposable
	{
		private static readonly Logger Logger = LogManager.GetCurrentClassLogger();

		private readonly string _emailFromAddress;

		private const string EmailSuccessSubject = "LeafWeb Results";
		private const string EmailErrorSubject = "LeafWeb processing error";

		/// <summary>
		/// Comma separated values
		/// </summary>
		private readonly string _adminEmailAddresses;

		private readonly SmtpClient _smtpClient;

		private readonly DataService _dataService;

		private readonly DownloadUrlService _downloadUrlService;

		public EmailNotificationService(DataService dataService)
		{
			_dataService = dataService;

			_downloadUrlService = new DownloadUrlService();

			_smtpClient = new SmtpClient(
				ConfigurationManager.AppSettings["SmtpHost"],
				Convert.ToInt32(ConfigurationManager.AppSettings["SmtpPort"]));

			if (!string.IsNullOrEmpty(ConfigurationManager.AppSettings["SmtpUserName"]))
				_smtpClient.Credentials = new NetworkCredential(
					ConfigurationManager.AppSettings["SmtpUserName"],
					ConfigurationManager.AppSettings["SmtpPassword"]
					);

			_emailFromAddress = ConfigurationManager.AppSettings["EmailFromAddress"];
			_adminEmailAddresses = ConfigurationManager.AppSettings["AdminEmailAddresses"];
		}

		public EmailNotificationService() : this(new DataService())
		{ }

		public void SendLeafWebComplete(int leafInputId)
		{
			var leafInput = _dataService.GetLeafInput(leafInputId);

			var outputErrorMessage = leafInput.OutputErrorMessage;
			if (outputErrorMessage != null)
				SendLeafWebError(leafInput, outputErrorMessage.Contents.GetString());
			else
				SendLeafWebSuccess(leafInput);
		}

		public void SendAdministratorMessage(string subject, string body)
		{
			var message = new MailMessage(_emailFromAddress, _adminEmailAddresses, subject, body);
			SendMessage(message);
		}

		private void SendLeafWebSuccess(LeafInput leafInput)
		{
			var body = $"Your leaf analysis job, {leafInput.Identifier}, has completed. ";

			body += FormatWarningMessage(leafInput);

			if (true)
			{
				var downloadUrl = _downloadUrlService.GetDownloadUrl(leafInput);

				body += 
					"Download results with the following link:" 
					+ Environment.NewLine + Environment.NewLine 
					+ downloadUrl;

				var message = new MailMessage(_emailFromAddress, leafInput.Email, EmailSuccessSubject, body);
				SendMessage(message);
			}
			else
			{
				body += "Please see the attached results.";

				var message = new MailMessage(_emailFromAddress, leafInput.Email, EmailSuccessSubject, body);

				var fileStreams =
					(from outputFile in
						leafInput.OutputFiles
						select Tuple.Create(outputFile, new MemoryStream(outputFile.Contents))).ToList();
				try
				{
					foreach (var fileStream in fileStreams)
					{
						var attachment = new Attachment(fileStream.Item2, fileStream.Item1.Filename);
						message.Attachments.Add(attachment);
					}

					SendMessage(message);
				}
				finally
				{
					// can't dispose those memory streams until the message is sent
					foreach (var stream in fileStreams.Select(f => f.Item2))
					{
						stream.Dispose();
					}
				}
			}
		}

		private void SendLeafWebError(LeafInput leafInput, string errorMessage)
		{
			var body = $"Your leaf analysis job, {leafInput.Identifier}, encountered the following errors." + Environment.NewLine
			           + Environment.NewLine + Environment.NewLine
			           + errorMessage
					   + Environment.NewLine + Environment.NewLine
					   + "You will need to correct your input and resubmit.";

			body += FormatWarningMessage(leafInput);

			var message = new MailMessage(_emailFromAddress, leafInput.Email, EmailErrorSubject, body);
			SendMessage(message);
		}

		private string FormatWarningMessage(LeafInput leafInput)
		{
			if (leafInput.OutputWarningMessage != null)
				return Environment.NewLine + Environment.NewLine
					+ "The following warning message was generated."
					+ Environment.NewLine + Environment.NewLine
					+ leafInput.OutputWarningMessage.Contents.GetString()
					+ Environment.NewLine;
			return string.Empty;
		}

		private void SendMessage(MailMessage mailMessage)
		{
			try
			{
				Logger.Debug("Email sending to " + mailMessage.To + ", subject: " + mailMessage.Subject);
				_smtpClient.Send(mailMessage);
			}
			catch (SmtpException ex)
			{
				Logger.Error(ex, "Failed to send mail: {0}", ex.Message);
			}
		}

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