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 package com.sun.grizzly.filter;

 import com.sun.grizzly.Context;

 import com.sun.grizzly.Context.AttributeScope;

 import com.sun.grizzly.ProtocolFilter;

 import com.sun.grizzly.ProtocolParser;

 import com.sun.grizzly.util.AttributeHolder;

 import com.sun.grizzly.util.WorkerThread;

 import java.io.IOException;

 import java.nio.ByteBuffer;

 import java.nio.channels.SelectionKey;

 import com.sun.grizzly.util.ThreadAttachment;

 import com.sun.grizzly.util.ThreadAttachment.Mode;

 /**

  * Simple ProtocolFilter implementation which read the available bytes

  * and delegate the decision of reading more bytes or not to a ProtocolParser.

  * The ProtocolParser will decide if more bytes are required before continuing

  * the invokation of the ProtocolChain.

  *

  * @author Jeanfrancois Arcand

  */

 public abstract class ParserProtocolFilter extends ReadFilter{

     /**

      * Should ParserProtocolFilter read the data from channel

      */

     protected boolean isSkipRead;

     public ParserProtocolFilter() {

     }

     /**

      * Read available bytes and delegate the processing of them to the next

      * ProtocolFilter in the ProtocolChain.

      * @return <tt>true</tt> if the next ProtocolFilter on the ProtocolChain

      * need to be invoked.

      */

     @Override

     public boolean execute(Context ctx) throws IOException {

         ProtocolParser parser = null;

         // Remove Parser from Connection related attributes (if it was there)

         AttributeHolder connectionAttrs =

                 ctx.getAttributeHolderByScope(AttributeScope.CONNECTION);

         if (connectionAttrs != null) {

             parser = (ProtocolParser) connectionAttrs.removeAttribute(ProtocolParser.PARSER);

         }

         if (parser == null) {

             parser = (ProtocolParser) ctx.getAttribute(ProtocolParser.PARSER);

             if (parser == null) {

                 parser = newProtocolParser();

                 ctx.setAttribute(ProtocolParser.PARSER, parser);

             }

         } else {

             ctx.setAttribute(ProtocolParser.PARSER, parser);

         }

         boolean isExpectingMoreData = parser.isExpectingMoreData();

         if (isExpectingMoreData || !parser.hasMoreBytesToParse()) {

             if (isExpectingMoreData) {

                 // Saved ByteBuffer was restored. May be we will not need it next time

                 ((WorkerThread) Thread.currentThread()).updateAttachment(Mode.ATTRIBUTES_ONLY);

             }

             boolean continueExecution = isSkipRead || super.execute(ctx);

             WorkerThread workerThread = (WorkerThread)Thread.currentThread();

             ByteBuffer byteBuffer = workerThread.getByteBuffer();

             parser.startBuffer(byteBuffer);

             if (!continueExecution){

                 return continueExecution;

             }

         }

         if (!parser.hasNextMessage()) {

             return false;

         }

         return invokeProtocolParser(ctx, parser);

     }

     /**

      * Invoke the {@link ProtocolParser}. If more bytes are required,

      * register the {@link SelectionKey} back to its associated

      * {@link SelectorHandler}

      * @param ctx the Context object.

      * @return <tt>true</tt> if no more bytes are needed.

      */

     protected boolean invokeProtocolParser(Context ctx, ProtocolParser parser) {

         if (parser == null){

             throw new IllegalStateException("ProcotolParser cannot be null");

         }

         Object o = parser.getNextMessage();

         ctx.setAttribute(ProtocolParser.MESSAGE, o);

         return true;

     }

     @Override

     public boolean postExecute(Context context) throws IOException {

         ProtocolParser parser = (ProtocolParser)

                 context.getAttribute(ProtocolParser.PARSER);

         if (parser == null) return true;

         if (parser != null && parser.hasMoreBytesToParse()) {

             // Need to say that we read successfully since bytes are left

             context.setAttribute(ProtocolFilter.SUCCESSFUL_READ, Boolean.TRUE);

             return true;

         }

         SelectionKey key = context.getSelectionKey();

         if (parser.isExpectingMoreData()) {

             if (parser.releaseBuffer()) {

                 saveParser(key, parser);

             }

             saveByteBuffer(key);

             // Register to get more bytes.

             context.getSelectorHandler().register(key,SelectionKey.OP_READ);

             return false;

         } 

         if (parser.releaseBuffer()) {

             saveParser(key, parser);

         }

         return super.postExecute(context);

     }

     /**

      * Return a new or cached ProtocolParser instance.

      */

     public abstract ProtocolParser newProtocolParser();

     private void saveByteBuffer(SelectionKey key) {

         WorkerThread workerThread = (WorkerThread) Thread.currentThread();

         // Detach the current Thread data.

         ThreadAttachment threadAttachment =

                 workerThread.updateAttachment(Mode.BYTE_BUFFER);

         // Attach it to the SelectionKey so the it can be resumed latter.

         key.attach(threadAttachment);

     }

     private void saveParser(SelectionKey key, ProtocolParser parser) {

         WorkerThread workerThread = (WorkerThread) Thread.currentThread();

         // Detach the current Thread data.

         ThreadAttachment threadAttachment = workerThread.getAttachment();

         threadAttachment.setAttribute(ProtocolParser.PARSER, parser);

         // Attach it to the SelectionKey so the it can be resumed latter.

         key.attach(threadAttachment);

     }

     /**

      * Method returns true, if this Filter perform channel read operation on

      * execute, or false - Filter assumes the data was read by previous Filters in

      * a chain.

      * 

      * @return true, if Filter will perform channel read operation on execute.

      * False - Filter assumes the data was read by previous Filters in a chain. 

      */

     protected boolean isSkipRead() {

         return isSkipRead;

     }

     /**

      * Method set if this Filter should perform channel read operation on

      * execute, or should assumes the data was read by previous Filters in

      * a chain.

      * 

      * @param isSkipRead If isSkipRead is true, this Filter will perform 

      * channel read operation on execute. If false - Filter assumes the data 

      * was read by previous Filters in a chain.

      */

     protected void setSkipRead(boolean isSkipRead) {

         this.isSkipRead = isSkipRead;

     }

 }