/*
VisAD system for interactive analysis and visualization of numerical
data.  Copyright (C) 1996 - 2017 Bill Hibbard, Curtis Rueden, Tom
Rink, Dave Glowacki, Steve Emmerson, Tom Whittaker, Don Murray, and
Tommy Jasmin.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA

$Id: FileField.java,v 1.12 2009-03-02 23:35:46 curtis Exp $
*/

package visad.data;


import java.rmi.RemoteException;

import visad.Data;
import visad.FieldImpl;
import visad.FlatField;
import visad.FieldException;
import visad.VisADException;
import visad.FunctionType;


public class FileField extends FieldImpl {
  // note FileField extends FieldImpl but may not inherit
  // any of its methods - it must re-implement all of them
  // through the adapted FieldImpl

  FieldImpl adaptedField;  // won't be null

  // this is the FileAccessor for reading and writing range
  // samples to the adapted file
  FileAccessor fileAccessor;
  // these are the locations in the file for the range samples
  // of this FileField;
  // note fileLocations[index] has type int[] that defines
  // the location for the index-th range sample of this
  // FileField
  int[][] fileLocations;

  public FileField(FieldImpl field, FileAccessor accessor,
                   int[][] locations)
    throws FieldException, VisADException
  {
    super((FunctionType)null, field.getDomainSet());

    if (field instanceof FlatField) {
      throw new FieldException("FileField: cannot adapt FlatField");
    }
    adaptedField = field;
    fileAccessor = accessor;
    fileLocations = locations;
  }

  // must implement all the methods of Data, Function and Field
  //
  // most are simple adapters, like this:
  public Data getSample(int index)
         throws VisADException, RemoteException {
    return adaptedField.getSample(index);
  }

  // setSample changes the contents of this Field,
  // in both the adaptedField and in the file
  public void setSample(int index, Data range)
         throws VisADException, RemoteException {
    // set the index-th range sample in adaptedField
    adaptedField.setSample(index, range);
    // write range sample through to fileAccessor
    fileAccessor.writeFile(fileLocations[index], range);
  }

  // setSamples also changes the file contents;
  // it could be implemented as a series of calls to setSample

  /**
   * Clones this instance.  This implementation always throws a {@link
   * CloneNotSupportedException}.
   *
   * @return                            A clone of this instance.
   * @throws CloneNotSupportedException if cloning isn't supported.
   */
  public Object clone() throws CloneNotSupportedException {
    throw new CloneNotSupportedException();
  }

}