/*
* 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.loader.file;

import org.pentaho.reporting.libraries.resourceloader.ResourceData;
import org.pentaho.reporting.libraries.resourceloader.ResourceKey;
import org.pentaho.reporting.libraries.resourceloader.ResourceLoadingException;
import org.pentaho.reporting.libraries.resourceloader.ResourceManager;
import org.pentaho.reporting.libraries.resourceloader.loader.AbstractResourceData;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;

/**
 * A simple file reader. This class, as all core implementation, does not hold any references to the data read from the
 * file. Caching is left to the cache provider.
 *
 * @author Thomas Morgner
 */
public class FileResourceData extends AbstractResourceData {
  private ResourceKey key;
  private File file;
  private volatile int length;
  private static final long serialVersionUID = -5719048997437795736L;

  public FileResourceData( final ResourceKey key ) throws ResourceLoadingException {
    if ( key == null ) {
      throw new NullPointerException();
    }
    final File file = (File) key.getIdentifier();
    if ( file.exists() == false ) {
      throw new ResourceLoadingException
        ( "File-handle given does not point to an existing file." );
    }
    if ( file.isFile() == false ) {
      throw new ResourceLoadingException
        ( "File-handle given does not point to a regular file." );
    }
    if ( file.canRead() == false ) {
      throw new ResourceLoadingException
        ( "File '" + file + "' is not readable." );
    }
    this.key = key;
    this.file = file;
  }

  public InputStream getResourceAsStream( final ResourceManager caller ) throws ResourceLoadingException {
    if ( caller == null ) {
      throw new NullPointerException();
    }
    try {
      final int buffer = (int) Math.max( 4096, Math.min( file.length(), 128 * 1024 ) );
      return new BufferedInputStream( new FileInputStream( file ), buffer );
    } catch ( FileNotFoundException e ) {
      throw new ResourceLoadingException( "Unable to open Stream: ", e );
    }
  }

  public Object getAttribute( final String attrkey ) {
    if ( attrkey == null ) {
      throw new NullPointerException();
    }
    if ( attrkey.equals( ResourceData.FILENAME ) ) {
      return file.getName();
    }
    if ( attrkey.equals( ResourceData.CONTENT_LENGTH ) ) {
      return new Long( file.length() );
    }
    return null;
  }

  public long getVersion( final ResourceManager caller )
    throws ResourceLoadingException {
    if ( caller == null ) {
      throw new NullPointerException();
    }
    return file.lastModified();
  }

  public ResourceKey getKey() {
    return key;
  }
}