/*
* This program is free software; you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
* Foundation.
*
* You should have received a copy of the GNU Lesser General Public License along with this
* program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
* or from the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* This program 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 Lesser General Public License for more details.
*
* Copyright (c) 2006 - 2013 Pentaho Corporation and Contributors.  All rights reserved.
*/

package org.pentaho.reporting.libraries.resourceloader;

import java.io.InputStream;

/**
 * A resource data object encapsulates the raw data of an resource at a given point in the past.
 * <p/>
 * Any change to the resource increases the version number. Version numbers are not needed to be checked regulary, but
 * must be checked on each call to 'getVersion()'.
 * <p/>
 * This definitly does *not* solve the problem of concurrent modifications; if you need to be sure that the resource has
 * not been altered between the last call to 'getVersion' and 'getResource..' external locking mechanism have to be
 * implemented.
 *
 * @author Thomas Morgner
 */
public interface ResourceData {
  public static final String CONTENT_LENGTH = "content-length";
  public static final String CONTENT_TYPE = "content-type";
  public static final String FILENAME = "filename";

  public InputStream getResourceAsStream( ResourceManager caller ) throws ResourceLoadingException;

  /**
   * This is dangerous, especially if the resource is large.
   *
   * @param caller
   * @return
   * @throws ResourceLoadingException
   */
  public byte[] getResource( ResourceManager caller ) throws ResourceLoadingException;

  /**
   * Tries to read data into the given byte-array.
   *
   * @param caller
   * @param target
   * @param offset
   * @param length
   * @return the number of bytes read or -1 if no more data can be read.
   * @throws ResourceLoadingException
   */
  public int getResource( ResourceManager caller, byte[] target, long offset, int length )
    throws ResourceLoadingException;

  public long getLength();

  public Object getAttribute( String key );

  public ResourceKey getKey();

  public long getVersion( ResourceManager caller ) throws ResourceLoadingException;

}