//
//  Class:			BSMDPopClient
//	Current CLR:	4.0.30319.34209
//	System:			Microsoft Visual Studio 10.0
//	Author:			dani
// 	Created:		6/15/2015 8:43:41 PM
//
//	Copyright (c) 2015 Informatikbüro Daniel Schick. All rights reserved.

using System;
using System.IO;
using OpenPop.Pop3;
using OpenPop.Mime;
using log4net;
using System.Security.Cryptography.X509Certificates;
using System.Net.Security;

namespace bsmd.email
{
    public class BSMDPopClient : IDisposable
    {

        #region Fields

        private readonly Pop3Client pop3Client;
        private readonly ILog _log = LogManager.GetLogger(typeof(BSMDPopClient));
        private int currentMail = 1;

        #endregion

        #region Construction / Destruction

        public BSMDPopClient()
        {
            try
            {
                this.pop3Client = new Pop3Client();

                this.pop3Client.Connect(Properties.Settings.Default.POP3Server, Properties.Settings.Default.POP3Port, true, 
                    60000, 60000, new System.Net.Security.RemoteCertificateValidationCallback(ValidateServerCertificate));

                this.pop3Client.Authenticate(Properties.Settings.Default.POP3User, Properties.Settings.Default.POP3Password);
                this.IsConnected = true;
            }
            catch (Exception ex)
            {
                _log.ErrorFormat("Error connecting to POP3 Server: {0}", ex.Message);
                _log.DebugFormat("User:{0} Pw:{1}", Properties.Settings.Default.POP3User, Properties.Settings.Default.POP3Password);
            }
        }

        public void Dispose()
        {
            if (this.pop3Client != null)
            {
                if (this.pop3Client.Connected)
                    this.pop3Client.Disconnect();
                this.pop3Client.Dispose();
            }
        }

        #endregion

        #region Hack

        /// <summary>
        /// Diese Funktion validiert *jedes* Zertifikat und ist eigentlich scheiße. Das geht nur so im abgeschlossenen BSMD Netz!
        /// </summary>        
        public static bool ValidateServerCertificate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
        {
            return true;
        }

        #endregion

        #region Properties

        public bool IsConnected { get; } = false;

        #endregion

        #region E-Mail receive helper / convenience funcs

        public bool ReceiveSingleMailText(out string messageId, out string sender, out string subject, out string body)
        {
            messageId = null;
            sender = null;
            subject = null;
            body = null;

            if (!IsConnected) return false;
            int messageCount = this.pop3Client.GetMessageCount();

            if (messageCount > (this.currentMail - 1))
            {
                Message mailMessage = this.pop3Client.GetMessage(this.currentMail);

                if (mailMessage.Headers.Sender?.HasValidMailAddress == true)
                    sender = mailMessage.Headers.Sender.MailAddress.Address;
                if ((sender == null) && (mailMessage.Headers.From?.HasValidMailAddress == true))
                    sender = mailMessage.Headers.From.MailAddress.Address;

                MessagePart aPart = mailMessage.FindFirstPlainTextVersion();
                body = aPart?.GetBodyAsText();
                messageId = mailMessage.Headers.MessageId;
                subject = mailMessage.Headers.Subject;
                this.currentMail++; // advance message pointer

                return true;
            }
            else
            {
                return false;
            }
        }

        public bool ReceiveSingleMail(out string attachmentLocalFile, out string messageId, out string sender, out string subject)
        {
            attachmentLocalFile = null;
            messageId = null;
            sender = null;
            subject = null;

            if (!IsConnected) return false;

            int messageCount = this.pop3Client.GetMessageCount();
            if (messageCount > (this.currentMail - 1))
            {
                Message mailMessage = this.pop3Client.GetMessage(this.currentMail);

                if (mailMessage.Headers.Sender?.HasValidMailAddress == true)
                    sender = mailMessage.Headers.Sender.MailAddress.Address;
                if ((sender == null) && (mailMessage.Headers.From?.HasValidMailAddress == true))
                    sender = mailMessage.Headers.From.MailAddress.Address;

                messageId = mailMessage.Headers.MessageId;
                subject = mailMessage.Headers.Subject;

                foreach(MessagePart part in mailMessage.FindAllAttachments())
                {
                    _log.InfoFormat("found attachment named {0}, ContentType {1}", part.FileName, part.ContentType);
                    if (part.FileName.EndsWith(".xls", StringComparison.InvariantCultureIgnoreCase))
                    {
                        attachmentLocalFile = Path.Combine(Properties.Settings.Default.ArchiveFolder, part.FileName);
                        part.Save(new FileInfo(attachmentLocalFile));
                    }
                    else if (part.FileName.EndsWith(".xlsx", StringComparison.InvariantCultureIgnoreCase))
                    {
                        attachmentLocalFile = Path.Combine(Properties.Settings.Default.ArchiveFolder, part.FileName);
                        part.Save(new FileInfo(attachmentLocalFile));
                    }
                }

                this.currentMail++; // advance message pointer

                return true;
            }
            else
            {
                _log.Info("no new mail on server");
                return false;
            }            
        }

        public string GetNameOfFirstMailEmailPDFAttachment(string messageId)
        {
            if (IsConnected)
            {
                int messageCount = this.pop3Client.GetMessageCount();

                // Run through each of these messages and download the headers
                for (int messageIndex = messageCount; messageIndex > 0; messageIndex--)
                {
                    // If the Message ID of the current message is the same as the parameter given, delete that message
                    if (this.pop3Client.GetMessageHeaders(messageIndex).MessageId.Equals(messageId))
                    {
                        // gefunden, Nachricht laden
                        Message mailMessage = this.pop3Client.GetMessage(messageIndex);
                        foreach (MessagePart part in mailMessage.FindAllAttachments())
                        {
                            if (part.FileName.EndsWith(".pdf", StringComparison.InvariantCultureIgnoreCase))
                                return part.FileName;
                        }
                    }
                }
            }
            return null;
        }

        #endregion

        #region delete designated email

        /// <summary>
        /// deletes message referenced by messageId
        /// </summary>        
        /// <returns>true if successful</returns>
        public bool DeleteMessageByMessageId(string messageId)
        {
            if (!IsConnected) return false;

            // Get the number of messages on the POP3 server
            int messageCount = this.pop3Client.GetMessageCount();

            // Run trough each of these messages and download the headers
            for (int messageItem = messageCount; messageItem > 0; messageItem--)
            {
                // If the Message ID of the current message is the same as the parameter given, delete that message
                if (this.pop3Client.GetMessageHeaders(messageItem).MessageId.Equals(messageId))
                {
                    // Delete
                    this.pop3Client.DeleteMessage(messageItem);
                    return true;
                }
            }

            // We did not find any message with the given messageId, report this back
            return false;            
        }

        #endregion
        
    }
}