// FileFlatField.java
//

/*
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
*/

package visad.data;

import java.io.IOException;

import java.rmi.RemoteException;

import visad.FlatField;
import visad.*;

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

  // number of FlatFields in cache

       private static final int MAX_FILE_FLAT_FIELDS = 10;

  // array of cached FlatFields

       private static transient FlatField[] adaptedFlatFields =
       new FlatField[MAX_FILE_FLAT_FIELDS];

  // true if cache entry differs from file contents

       private static transient boolean adaptedFlatFieldDirty[] =
       new boolean[MAX_FILE_FLAT_FIELDS];

  // the FileFlatField that owns this cache entry

       private static transient FileFlatField[] adaptedFlatFieldOwner =
       new FileFlatField[MAX_FILE_FLAT_FIELDS];

  // adaptedFlatFieldSizes and adaptedFlatFieldTimes
  // may be useful for cache allocation algorithms
  // approximate sizes of FlatFields in cache

       private static transient long[] adaptedFlatFieldSizes =
       new long[MAX_FILE_FLAT_FIELDS];

  // times of most recent accesses to FlatFields in cache

       private static transient long[] adaptedFlatFieldTimes =
       new long[MAX_FILE_FLAT_FIELDS];

  // index of cache entry owned by this FileFlatField;
  // but only if
  // this == adaptedFlatFieldOwner[adaptedFlatFieldIndex]

       private transient int adaptedFlatFieldIndex;


  // this is the FileAccessor for reading and writing values from
  // and to the adapted file

       transient FileAccessor fileAccessor;

  // this implements a strategy for cache replacement;
  // this separates the cahce strategy algorithm from the logic
  // of FileFlatField

       private transient CacheStrategy cacheStrategy;

  static
  {
    // initialize cache of FlatFields
    if (adaptedFlatFieldOwner != null && adaptedFlatFields != null &&
        adaptedFlatFieldSizes != null && adaptedFlatFieldTimes != null &&
        adaptedFlatFieldDirty != null) {
      for (int i=0; i
   * clone() contract in that the returned object will compare unequal to
   * this instance.  As such, this method should probably not be invoked.
   *
   * @return                            A clone of this instance.
   */
  public Object clone()
  {
    /*
     * This implementation should probably just throw a 
     * CloneNotSupportedException but can't because FlatField.clone() doesn't.
     */
      
    FlatField fld = getAdaptedFlatField();
    if (fld == null) {
      return null;
    }

    return fld.clone();
  }

  public String toString()
  {
    FlatField fld = getAdaptedFlatField();
    if (fld == null) {
      return "Cannot get cached FlatField";
    }

    return fld.toString();
  }

  public String longString(String pre)
  {
    FlatField fld = getAdaptedFlatField();
    if (fld == null) {
      return pre + "Cannot get cached FlatField";
    }

    try {
      return fld.longString(pre);
    } catch (VisADException e) {
      return pre + e.getMessage();
    }
  }

  private void readObject(java.io.ObjectInputStream oos)
    throws ClassNotFoundException, IOException
  {
    throw new java.io.NotSerializableException("FileFlatField is not serializable");
  }

  private void writeObject(java.io.ObjectOutputStream oos)
    throws IOException
  {
    throw new java.io.NotSerializableException("FileFlatField is not serializable");
  }
}