/*
    * 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.BufferedReader;
  import java.io.IOException;
  import java.io.Reader;
  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 reads from the octave process. 
   * Used in {@link OctaveExec#evalRW(WriteFunctor, ReadFunctor)} only. 
   */
  final class OctaveReaderCallable implements Callable<Void> {
  
      private static final String MSG_IOE_READ = 
  	"IOException from ReadFunctor";
      private static final String MSG_IOE_CLS = 
  	"IOException during close";
  
      private static final Log LOG = LogFactory
  	.getLog(OctaveReaderCallable.class);
  
  
      private final BufferedReader processReader;
  
      private final ReadFunctor readFunctor;
  
      private final String spacer;
  
      /**
       * @param processReader
       * @param readFunctor
       * @param spacer
       */
      OctaveReaderCallable(final BufferedReader processReader, 
  			 final ReadFunctor readFunctor, 
  			 final String spacer) {
          this.processReader = processReader;
          this.readFunctor   = readFunctor;
          this.spacer        = spacer;
      }
  
      /**
       * Calling reads from an {@link OctaveExecuteReader} 
       * made up from {@link #processReader} 
       * with end of stream sign {@link #spacer}. 
       * Exceptions are logged on {@link #LOG}. 
       *
       * @throws OctaveIOException 
       *    if underlying readers/read functors 
       *    have thrown an {@link IOException}. 
       */
      @Override
      public Void call() {
          final Reader reader = new OctaveExecuteReader(this.processReader, 
  						      this.spacer);
          try {
              this.readFunctor.doReads(reader);
          } catch (final IOException e) {
  	    LOG.debug(MSG_IOE_READ, e);
              throw new OctaveIOException(MSG_IOE_READ, e);
          } finally { // NOPMD
              try {
                  reader.close();
              } catch (final IOException e) {
                  LOG.debug(MSG_IOE_CLS, e);
                  throw new OctaveIOException(MSG_IOE_CLS, e);
              }
          }
          return null;
      }
  
  }