/*

  * Copyright 2008, 2009 Ange Optimization ApS

  *

  * Licensed under the Apache License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  *

  *     http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package eu.simuline.octave.exec;

 import java.io.IOException;

 import java.io.Writer;

 import java.util.concurrent.Callable;

 import eu.simuline.octave.exception.OctaveIOException;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 /**

  * Callable that writes to the octave process. 

  * Used in {@link OctaveExec#evalRW(WriteFunctor, ReadFunctor)} only. 

  */

 final class OctaveWriterCallable implements Callable<Void> {

     private static final Log LOG = LogFactory

         .getLog(OctaveWriterCallable.class);

     static final String EXCEPTION_MESSAGE_FUNCTOR = 

         "IOException from WriteFunctor";

     static final String EXCEPTION_MESSAGE_SPACER = 

         "IOException when writing spacer";

     private final Writer processWriter;

     private final WriteFunctor writeFunctor;

     private final String spacer;

     /**

      * @param processWriter

      * @param writeFunctor

      * @param spacer

      */

     OctaveWriterCallable(final Writer processWriter, 

                          final WriteFunctor writeFunctor, 

                          final String spacer) {

         this.processWriter = processWriter;

         this.writeFunctor  = writeFunctor;

         this.spacer        = spacer;

     }

     /**

      * Calling writes to {@link #processWriter}: 

      * first according to {@link #writeFunctor} 

      * then printf of {@link #spacer} and then flush. 

      * Exceptions are logged on {@link #LOG}. 

      */

     @Override

     public Void call() {

         // Write to process

         try {

             this.writeFunctor.doWrites(this.processWriter);

         } catch (final IOException e) {

             LOG.debug(EXCEPTION_MESSAGE_FUNCTOR, e);

             throw new OctaveIOException(EXCEPTION_MESSAGE_FUNCTOR, e);

         }

         try {

             this.processWriter.write("\nprintf(\"\\n%s\\n\", \"" + 

                                      this.spacer + "\");\n");

             this.processWriter.flush();

         } catch (final IOException e) {

             LOG.debug(EXCEPTION_MESSAGE_SPACER, e);

             throw new OctaveIOException(EXCEPTION_MESSAGE_SPACER, e);

         }

         LOG.debug("Has written all");

         return null;

     }

 }