InterceptSink.cs :  » Testing » XT-Unit » TeamAgile » ApplicationBlocks » Interception » Internal » C# / CSharp Open Source

using System;
using System.Collections;
using System.Diagnostics;
using System.Reflection;
using System.Runtime.Remoting.Messaging;

namespace TeamAgile.ApplicationBlocks.Interception.Internal{
  class InterceptSink : IMessageSink
  {
    private IMessageSink nextSink;
    private MarshalByRefObject m_target=null;

    [DebuggerStepThrough]
    public InterceptSink(MarshalByRefObject target, IMessageSink nextSink)
    {
      m_target = target;
      this.nextSink = nextSink;
    }

    #region IMessageSink Members

    [DebuggerStepThrough]
    public IMessage SyncProcessMessage(IMessage msg)
    {
      IMethodCallMessage mcm = (msg as IMethodCallMessage);
      this.PreProcess(ref mcm);
      
      IMethodReturnMessage customReturnMessage = 
        mcm.LogicalCallContext.GetData("CustomReturnMessage") as IMethodReturnMessage;
      if(customReturnMessage!=null)
      {
        this.PostProcess(mcm,ref customReturnMessage);
        
        //do not execute anything else
        return customReturnMessage;
      }
      IMessage rtnMsg = nextSink.SyncProcessMessage(mcm);
      IMethodReturnMessage mrm = (rtnMsg as IMethodReturnMessage);
      this.PostProcess(mcm,ref mrm);
      return mrm;
    }

    public IMessageSink NextSink
    {
      get
      {
        return this.nextSink;
      }
    }

    [DebuggerStepThrough]
    public IMessageCtrl AsyncProcessMessage(IMessage msg, IMessageSink replySink)
    {
      IMessageCtrl rtnMsgCtrl = nextSink.AsyncProcessMessage(msg,replySink);
      return rtnMsgCtrl;
    }

    #endregion
    
    [DebuggerStepThrough]
    private void PreProcess(ref IMethodCallMessage callMessage)
    {
      ArrayList attrs = getMethodCallCustomAttributes(callMessage);
      ArrayList newCallMessages = new ArrayList();

      for(int i=0;i<attrs.Count;i++)
      {
        PreProcessEventArgs args = new PreProcessEventArgs(m_target,callMessage);
        ((BaseProcessingAttribute)attrs[i]).PreProcess(this,args);
        //currently handles only a case where one attribute changes the 
        //value of an inside parameter
        if(args.HasNewParameterValues)
        {
          //this should contain a MEthodCallMEssageWrapper object with new parameter values
          newCallMessages.Add(args.MethodCallMessage);
        }
      }

      if(newCallMessages.Count==1)
      {
        callMessage = (IMethodCallMessage) newCallMessages[0];
      }
      if(newCallMessages.Count>1)
      {
        combineMultipleNewParamValuesIntoNewMessage (newCallMessages, ref callMessage);
      }

    }

    private static void combineMultipleNewParamValuesIntoNewMessage (ArrayList newCallMessages, ref IMethodCallMessage callMessage)
    {
      object[] combinedNewValues = new object[callMessage.Args.Length];
  
      foreach (IMethodCallMessage newCallMessage in  newCallMessages)
      {
        //notice that we run the rist that the same parameter can be changed twice
        //in two different places and the last change wins
        for (int i = 0; i < newCallMessage.Args.Length; i++)
        {
          combinedNewValues[i] = newCallMessage.Args[i];
        }  
      }
      MethodCallMessageWrapper newCombinedMessageCall = new MethodCallMessageWrapper(callMessage);
      newCombinedMessageCall.Args = combinedNewValues;
      callMessage = newCombinedMessageCall;
    }

    [DebuggerStepThrough]
    private  ArrayList getMethodCallCustomAttributes(IMethodCallMessage msg)
    {
      ArrayList attribList = new ArrayList();
      Type type = typeof(BaseProcessingAttribute);
      
      BaseProcessingAttribute[] attributes = (BaseProcessingAttribute[])
                          msg.MethodBase.GetCustomAttributes(type,true);
      attribList.AddRange (attributes);
      
      foreach (ParameterInfo pinfo in msg.MethodBase.GetParameters())
      {
        attribList.AddRange (pinfo.GetCustomAttributes(type,true));
      }

      return attribList;
    }

    private  ICollection getMethodCallParamsCustomAttributes(IMethodCallMessage msg)
    {
      ArrayList attribList = new ArrayList();
      Type type = typeof(BaseProcessingAttribute);
        foreach (ParameterInfo pinfo in msg.MethodBase.GetParameters())
      {
        attribList.AddRange (pinfo.GetCustomAttributes(type,true));
      }
      
      return attribList;
    }

    [DebuggerStepThrough]
    private void PostProcess(IMethodCallMessage callMessage, ref IMethodReturnMessage returnMessage)
    {
      ArrayList attrs = getMethodCallCustomAttributes(callMessage);
      PostProcessEventArgs args = new PostProcessEventArgs( m_target,callMessage,returnMessage);
      
      for(int i=0;i<attrs.Count;i++)
      {
        ((BaseProcessingAttribute)attrs[i])
              .PostProcess(this,args);
      }
      returnMessage = args.MethodCallReturnMessage;
    }

  }

}