/*
* JBoss, the OpenSource J2EE webOS
*
* Distributable under LGPL license.
* See terms of license at gnu.org.
*/
package org.jboss.invocation;

import java.io.DataOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.lang.reflect.Method;
import java.security.DigestOutputStream;
import java.security.MessageDigest;
import java.security.Principal;
import java.util.Map;
import java.util.Iterator;
import java.util.HashMap;
import java.util.WeakHashMap;
import javax.transaction.Transaction;

import org.jboss.invocation.Invocation;

/**
 * The MarshalledInvocation is an invocation that travels.  As such it serializes
 * its payload because of lack of ClassLoader visibility.
 * As such it contains Marshalled data representing the byte[] of the Invocation object it extends
 * Besides handling the specifics of "marshalling" the payload, which could be done at the Invocation level
 * the Marshalled Invocation can hold optimization and needed code for distribution for example the
 * TransactionPropagationContext which is a serialization of the TX for distribution purposes as
 * well as the "hash" for the methods that we send, as opposed to sending Method objects.
 * Serialization "optimizations" should be coded here in the externalization implementation of the class
 *
 *   @see <related>
 *   @author  <a href="mailto:marc@jboss.org">Marc Fleury</a>
 *   @version $Revision: 1.11.2.5 $
 *   Revisions:
 *
 *   <p><b>Revisions:</b>
 *
 *   <p><b>2001120 marc fleury:</b>
 *   <ul>
 *   <li> Initial check-in
 *   </ul>
 *   <p><b>20020113 Sacha Labourey:</b>
 *   <ul>
 *   <li> Make Externalizable calls (writeExternal) idempotent: until now,
 *  serialization on a MarshalledInvocation could only performed once (transaction was removed
 *  and METHOD type was modified). If another call was re-using the same object (in
 *  clustering for example), the call was making a ClassCastException because of
 *  the changed METHOD type in the Map that occured in the previous call to writeExternal)
 *   </ul>
 *   <p><b>20020911 Bill Burke:</b>
 *   <ul>
 *   <li> Optimize access to certain variables.  Avoid hash lookups.
 *   </ul>
 */
public class MarshalledInvocation
        extends Invocation
        implements java.io.Externalizable
{
   // Constants -----------------------------------------------------

   /** Serial Version Identifier. */
   static final long serialVersionUID = -718723094688127810L;

   // The Transaction Propagation Context for distribution
   protected Object tpc;

   // The Map of methods used by this Invocation
   protected transient Map methodMap;

   // These are here to avoid unneeded hash lookup
   protected transient long methodHash = 0;
   protected transient MarshalledValue marshalledArgs = null;

   // Static --------------------------------------------------------
   static Map hashMap = new WeakHashMap();

   /**
    * Calculate method hashes. This algo is taken from RMI.
    *
    * @param   intf
    * @return
    */
   public static Map getInterfaceHashes(Class intf)
   {
      // Create method hashes
      Method[] methods = intf.getDeclaredMethods();
      HashMap map = new HashMap();
      for (int i = 0; i < methods.length; i++)
      {
         Method method = methods[i];
         Class[] parameterTypes = method.getParameterTypes();
         String methodDesc = method.getName() + "(";
         for (int j = 0; j < parameterTypes.length; j++)
         {
            methodDesc += getTypeString(parameterTypes[j]);
         }
         methodDesc += ")" + getTypeString(method.getReturnType());

         try
         {
            long hash = 0;
            ByteArrayOutputStream bytearrayoutputstream = new ByteArrayOutputStream(512);
            MessageDigest messagedigest = MessageDigest.getInstance("SHA");
            DataOutputStream dataoutputstream = new DataOutputStream(new DigestOutputStream(bytearrayoutputstream, messagedigest));
            dataoutputstream.writeUTF(methodDesc);
            dataoutputstream.flush();
            byte abyte0[] = messagedigest.digest();
            for (int j = 0; j < Math.min(8, abyte0.length); j++)
               hash += (long) (abyte0[j] & 0xff) << j * 8;
            map.put(method.toString(), new Long(hash));
         }
         catch (Exception e)
         {
            e.printStackTrace();
         }
      }

      return map;
   }

   static String getTypeString(Class cl)
   {
      if (cl == Byte.TYPE)
      {
         return "B";
      }
      else if (cl == Character.TYPE)
      {
         return "C";
      }
      else if (cl == Double.TYPE)
      {
         return "D";
      }
      else if (cl == Float.TYPE)
      {
         return "F";
      }
      else if (cl == Integer.TYPE)
      {
         return "I";
      }
      else if (cl == Long.TYPE)
      {
         return "J";
      }
      else if (cl == Short.TYPE)
      {
         return "S";
      }
      else if (cl == Boolean.TYPE)
      {
         return "Z";
      }
      else if (cl == Void.TYPE)
      {
         return "V";
      }
      else if (cl.isArray())
      {
         return "[" + getTypeString(cl.getComponentType());
      }
      else
      {
         return "L" + cl.getName().replace('.', '/') + ";";
      }
   }

   /*
   * The use of hashCode is not enough to differenciate methods
   * we override the hashCode
   *
   * The hashes are cached in a static for efficiency
   * RO: WeakHashMap needed to support undeploy
   */
   public static long calculateHash(Method method)
   {
      Map methodHashes = (Map) hashMap.get(method.getDeclaringClass());

      if (methodHashes == null)
      {
         // Add the method hashes for the class
         methodHashes = getInterfaceHashes(method.getDeclaringClass());
         synchronized (hashMap)
         {
            hashMap.put(method.getDeclaringClass(), methodHashes);
         }
      }

      Long hash = (Long) methodHashes.get(method.toString());
      return hash.longValue();
   }

   /** Remove all method hashes for the declaring class
    * @param declaringClass a class for which a calculateHash(Method) was called
    */
   public static void removeHashes(Class declaringClass)
   {
      synchronized (hashMap)
      {
         hashMap.remove(declaringClass);
      }
   }

   // Constructors --------------------------------------------------
   public MarshalledInvocation()
   {
      // For externalization to work
   }

   public MarshalledInvocation(Invocation invocation)
   {
      this.payload = invocation.payload;
      this.as_is_payload = invocation.as_is_payload;
      this.method = invocation.getMethod();
      this.objectName = invocation.getObjectName();
      this.args = invocation.getArguments();
      this.invocationType = invocation.getType();
   }


   /*
   public MarshalledInvocation(Map payload)
   {
      super(payload);
   }

   public MarshalledInvocation(Map payload, Map as_is_payload)
   {
      super(payload);
      this.as_is_payload = as_is_payload;
   }
   */
   public MarshalledInvocation(
           Object id,
           Method m,
           Object[] args,
           Transaction tx,
           Principal identity,
           Object credential)
   {
      super(id, m, args, tx, identity, credential);
   }
   // Public --------------------------------------------------------


   public Method getMethod()
   {
      if (this.method != null)
         return this.method;

      // Try the hash, the methodMap should be set
      this.method = (Method) methodMap.get(new Long(methodHash));

      // Keep it in the payload
      if (this.method == null)
      {
         throw new IllegalStateException("Failed to find method for hash:" + methodHash);
      }
      return this.method;
   }

   public void setMethodMap(Map methods)
   {
      methodMap = methods;
   }

   // The transaction propagation context for the Invocation that travels (distributed tx only)
   public void setTransactionPropagationContext(Object tpc)
   {
      this.tpc = tpc;
   }

   public Object getTransactionPropagationContext()
   {
      return tpc;
   }

   // Invocation overwrite -----------------------------------------

   /** A Marshalled invocation has serialized data in the form of
    MarshalledValue objects. We overwrite the "getValue" to deserialize the
    data, this assume that the thread context class loader has visibility
    on the classes.
    */
   public Object getValue(Object key)
   {

      Object value = super.getValue(key);

      // The map may contain serialized values of the fields
      if (value instanceof MarshalledValue)
      {
         try
         {
            MarshalledValue mv = (MarshalledValue) value;
            value = mv.get();
         }
                 // Barf and return null
         catch (Exception e)
         {
            e.printStackTrace();
            value = null;
         }
      }
      return value;
   }

   /** A Marshalled invocation has serialized data in the form of
    MarshalledValue objects. We overwrite the "getValue" to deserialize the
    data, this assume that the thread context class loader has visibility
    on the classes.
    */
   public Object getPayloadValue(Object key)
   {

      Object value = getPayload().get(key);

      // The map may contain serialized values of the fields
      if (value instanceof MarshalledValue)
      {
         try
         {
            MarshalledValue mv = (MarshalledValue) value;
            value = mv.get();
         }
                 // Barf and return null
         catch (Exception e)
         {
            e.printStackTrace();
            value = null;
         }
      }
      return value;
   }

   public Object[] getArguments()
   {
      if (this.args == null)
      {
         try
         {
            this.args = (Object[]) marshalledArgs.get();
         }
         catch (Exception e)
         {
            e.printStackTrace();
         }
      }
      return args;
   }

   // Externalizable implementation ---------------------------------
   public void writeExternal(java.io.ObjectOutput out)
           throws IOException
   {
      // TODO invocationType should be removed from as is payload
      // for now, it is in there for binary compatibility
      getAsIsPayload().put(InvocationKey.TYPE, invocationType);
      // FIXME marcf: the "specific" treatment of Transactions should be abstracted.
      // Write the TPC, not the local transaction
      out.writeObject(tpc);

      long methodHash = calculateHash(this.method);
      out.writeLong(methodHash);

      out.writeObject(this.objectName);
      out.writeObject(new MarshalledValue(this.args));


      // Write out payload hashmap
      // Don't use hashmap serialization to avoid not-needed data being
      // marshalled
      // The map contains only serialized representations of every other object
      // Everything else is possibly tied to classloaders that exist inside the
      // server but not in the generic JMX land. they will travel in the  payload
      // as MarshalledValue objects, see the Invocation getter logic
      //
      if (payload == null)
         out.writeInt(0);
      else
      {
         out.writeInt(payload.size());
         Iterator keys = payload.keySet().iterator();
         while (keys.hasNext())
         {
            Object currentKey = keys.next();

            // This code could be if (object.getClass().getName().startsWith("java")) then don't serialize.
            // Bench the above for speed.

            out.writeObject(currentKey);
            out.writeObject(new MarshalledValue(payload.get(currentKey)));
         }
      }

      // This map is "safe" as is
      //out.writeObject(as_is_payload);
      if (as_is_payload == null)
         out.writeInt(0);
      else
      {
         out.writeInt(as_is_payload.size());

         Iterator keys = as_is_payload.keySet().iterator();
         while (keys.hasNext())
         {
            Object currentKey = keys.next();
            out.writeObject(currentKey);
            out.writeObject(as_is_payload.get(currentKey));
         }
      }
   }

   public void readExternal(java.io.ObjectInput in)
           throws IOException, ClassNotFoundException
   {
      tpc = in.readObject();
      this.methodHash = in.readLong();

      this.objectName = in.readObject();

      marshalledArgs = (MarshalledValue) in.readObject();

      int payloadSize = in.readInt();
      if (payloadSize > 0)
      {
         payload = new HashMap();
         for (int i = 0; i < payloadSize; i++)
         {
            Object key = in.readObject();
            Object value = in.readObject();
            payload.put(key, value);
         }
      }

      int as_is_payloadSize = in.readInt();
      if (as_is_payloadSize > 0)
      {
         as_is_payload = new HashMap();
         for (int i = 0; i < as_is_payloadSize; i++)
         {
            Object key = in.readObject();
            Object value = in.readObject();
            as_is_payload.put(key, value);
         }
      }
      // TODO invocationType should be removed from as is payload
      // for now, it is in there for binary compatibility
      invocationType = (InvocationType)getAsIsValue(InvocationKey.TYPE);
   }
}