using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Linq;
using System.IO;
using System.ServiceProcess;
using System.Text;
using System.Timers;
using System.Threading.Tasks;

using OpenPop;
using log4net;
using bsmd.database;

namespace bsmd.EMailReceiveService
{

    /// <summary>
    /// Simpler Windows-Service zum Abruf von NSW Antworten via E-mail. Ich verwende OpenPop.NET Library (via NuGet)
    /// http://hpop.sourceforge.net/
    ///
    /// </summary>
    public partial class EmailReceiveService : ServiceBase
    {

        private Timer _timer;
        private object _timerlock = new object();
        private bool processRunning = false;
        private ILog _log = LogManager.GetLogger(typeof(EmailReceiveService));

        public EmailReceiveService()
        {
            Directory.SetCurrentDirectory(AppDomain.CurrentDomain.BaseDirectory);
            InitializeComponent();
        }

        protected override void OnStart(string[] args)
        {
            this.EventLog.Source = this.ServiceName;
            this.EventLog.Log = "Application";
            this.EventLog.BeginInit();
            if (!EventLog.SourceExists(this.EventLog.Source, this.EventLog.Log))
                EventLog.CreateEventSource(this.EventLog.Source, this.EventLog.Log);
            this.EventLog.EndInit();

            this.Init(args);

            this.EventLog.WriteEntry("NSW EMail Receive Service started.", EventLogEntryType.Information);
        }

        protected override void OnStop()
        {
            _log.Info("EmailReceiveService stopped");
        }

        public void Init(string[] args)
        {
            this._timer = new Timer();
            this._timer.Interval = 600000; // 10 Min, TODO: Settings
            this._timer.Elapsed += _timer_Elapsed;
            this._timer.Enabled = true;

            if (Debugger.IsAttached)
                this._timer_Elapsed(null, null);
        }

        void _timer_Elapsed(object sender, ElapsedEventArgs e)
        {
            lock (this._timerlock)
            {
                if (this.processRunning) return;
                else this.processRunning = true;
            }

            if (DBManager.Instance.Connect(Properties.Settings.Default.ConnectionString))
            {
                try
                {

                    // dbh E-Mail aus Postfach abrufen
                    using (OpenPop.Pop3.Pop3Client client = new OpenPop.Pop3.Pop3Client())
                    {
                        client.Connect(Properties.Settings.Default.Host, Properties.Settings.Default.Port, true);
                        client.Authenticate(Properties.Settings.Default.User, Properties.Settings.Default.Password);

                        int messageNum = client.GetMessageCount();
                        _log.DebugFormat("Mail Server has {0} messages", messageNum);

                        if (messageNum > 0)
                        {
                            // We want to download all messages
                            List<OpenPop.Mime.Message> allMessages = new List<OpenPop.Mime.Message>(messageNum);

                            // Messages are numbered in the interval: [1, messageCount]
                            // Ergo: message numbers are 1-based.
                            // Most servers give the latest message the highest number
                            for (int i = 1; i <= messageNum; i++)
                            {
                                allMessages.Add(client.GetMessage(i));
                            }

                            for (int i = 0; i < allMessages.Count; i++)
                            {
                                // XML Anhang extrahieren und in einen string schreiben
                                OpenPop.Mime.Message message = allMessages[i];

                                List<OpenPop.Mime.MessagePart> messageParts = message.FindAllAttachments();
                                for (int partIndex = 0; partIndex < messageParts.Count; partIndex++)                                
                                {
                                    OpenPop.Mime.MessagePart part = messageParts[partIndex];
                                    _log.DebugFormat("{0} Encoding: {1}", partIndex, part.ContentTransferEncoding);

                                    switch (part.ContentTransferEncoding)
                                    {
                                        case OpenPop.Mime.Header.ContentTransferEncoding.Base64:
                                            // decode base64 body

                                            break;
                                        default:
                                            break;
                                    }

                                }


                                // E-Mail entfernen

                                // client.DeleteMessage(i+1);
                            }
                        }
                    }
                }
                catch (Exception ex)
                {
                    _log.ErrorFormat("Exception occurred: {0}", ex.ToString());
                }
            }
            else
            {
                this.EventLog.WriteEntry("FormService stopped: DB connection failed", EventLogEntryType.Error);
                this.Stop();
            }            

            lock (this._timerlock)
            {
                this.processRunning = false;
            }           
        }
    }
}