/*
    * 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;
      }
  
  }