// ***************************************************************
// <copyright file="EdgeTransportLogging.cs" company="Microsoft">
//     Copyright (C) Microsoft Corporation.  All rights reserved.
// </copyright>
// <summary>
// A simple agent that logs messages on an Edge Transport server.
// </summary>
// ***************************************************************

namespace Microsoft.Exchange.Samples.Agents.EdgeTransportLogging
{
    using System;
    using System.IO;
    using System.Diagnostics;
    using System.Reflection;
    using System.Text;
    using Microsoft.Exchange.Data.Transport;
    using Microsoft.Exchange.Data.Transport.Smtp;
	using System.Globalization;

    public class MessageLoggerFactory : SmtpReceiveAgentFactory
    {
        public override SmtpReceiveAgent CreateAgent(SmtpServer server)
        {
            return new MessageLogger();
        }
    }

    public class MessageLogger : SmtpReceiveAgent
    {
        // The agent uses the fileLock object to synchronize access to the log file
        private object fileLock = new object();        

        // The agent uses the agentAsyncContext object when the agent uses asynchronous execution.
        // The AgentAsyncContext.Complete() method must be invoked
        // before the server will continue processing a message.
        private AgentAsyncContext agentAsyncContext;

        public MessageLogger()
        {
            //Register an OnEndOfData event handler
            this.OnEndOfData += new EndOfDataEventHandler(this.OnEndOfDataHandler);
        }

        // The OnEndOfDataHandler method is invoked when the entire message has been received
        public void OnEndOfDataHandler(ReceiveEventSource source, EndOfDataEventArgs eodArgs)
        {
            // Begin a background thread that will save the message to disk
            System.Threading.ThreadPool.QueueUserWorkItem(this.LogMessage, eodArgs.MailItem);

            // GetAgentAsyncContext causes the server to wait for this agent
            // to invoke the returned callback before continuing to 
            // process the current message.
            this.agentAsyncContext = this.GetAgentAsyncContext();

            return;
        }

        // Append the given stream to the message log
        public void LogMessage(object state)
        {
			MailItem mailItem = state as MailItem;
			using (Stream messageStream = mailItem.GetMimeReadStream())
			{
				lock (fileLock)
				{
					try
					{
						string filename = mailItem.Message.MessageId;
						foreach (char pathChar in Path.GetInvalidFileNameChars())
							filename = filename.Replace(pathChar, '-');
						filename = String.Concat(DateTime.Now.ToString("yyyy-MM-dd_HHmmss", CultureInfo.InvariantCulture), "_", filename, ".log");
						string logDir = Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location) + @"\Log";
						string logFile = Path.Combine(logDir, filename);

						if (!Directory.Exists(logDir))
						{
							Directory.CreateDirectory(logDir);
						}

						if (!File.Exists(logFile))
						{
							File.CreateText(logFile).Close();
						}

						using (FileStream fileStream = new FileStream(logFile, FileMode.Create, FileAccess.Write, FileShare.Read))
						using (BinaryWriter writer = new BinaryWriter(fileStream))
						{
							const int bufferSize = 4096;
							byte[] buffer = new byte[bufferSize];
							messageStream.Seek(0, SeekOrigin.Begin);
							int dataSize = 0;
							while ((dataSize = messageStream.Read(buffer, 0, bufferSize)) > 0)
								fileStream.Write(buffer, 0, dataSize);
						}
					}
					catch (System.IO.IOException ex)
					{
						Debug.WriteLine(ex.ToString());
					}
				}
			}

            this.agentAsyncContext.Complete();
            this.agentAsyncContext = null;
        }
    }
}