/*
 * 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) 2001 - 2013 Object Refinery Ltd, Pentaho Corporation and Contributors..  All rights reserved.
 */

package org.pentaho.reporting.engine.classic.core.modules.parser.ext.factory.base;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

/**
 * An object description for simple collection objects, like java.util.List or java.util.Set.
 *
 * @author Thomas Morgner
 */
public class CollectionObjectDescription extends AbstractObjectDescription {

  private static final Log logger = LogFactory.getLog( CollectionObjectDescription.class );

  /**
   * Creates a list object description for the given collection class.
   * <p/>
   * Throws <code>ClassCastException</code> if the given class is no collection instance.
   *
   * @param c
   *          the class of the collection implementation.
   */
  public CollectionObjectDescription( final Class c ) {
    super( c );
    if ( !Collection.class.isAssignableFrom( c ) ) {
      throw new ClassCastException( "The given class is no Collection instance" );
    }
  }

  /**
   * Tries to parse the given parameter string into a positive integer. Returns -1 if the parsing failed for some
   * reason.
   *
   * @param name
   *          the name of the parameter.
   * @return the parsed int value or -1 on errors.
   */
  private int parseParameterName( final String name ) {
    try {
      return Integer.parseInt( name );
    } catch ( Exception e ) {
      return -1;
    }
  }

  /**
   * Returns a parameter definition. If the parameter is invalid, this function returns null.
   *
   * @param name
   *          the definition name.
   * @return The parameter class or null, if the parameter is not defined.
   */
  public Class getParameterDefinition( final String name ) {
    if ( "size".equals( name ) ) {
      return Integer.TYPE;
    }
    final int par = parseParameterName( name );
    if ( par < 0 ) {
      return null;
    }
    return Object.class;
  }

  /**
   * Returns an iterator for the parameter names.
   *
   * @return The iterator.
   */
  public synchronized Iterator getParameterNames() {
    final Integer size = (Integer) getParameter( "size" );
    if ( size == null ) {
      return getDefinedParameterNames();
    } else {
      final ArrayList l = new ArrayList();
      l.add( "size" );
      for ( int i = 0; i < size.intValue(); i++ ) {
        l.add( String.valueOf( i ) );
      }
      return l.iterator();
    }
  }

  /**
   * Creates an object based on the description.
   *
   * @return The object.
   */
  public Object createObject() {
    try {
      final Collection l = (Collection) getObjectClass().newInstance();
      int counter = 0;
      while ( getParameterDefinition( String.valueOf( counter ) ) != null ) {
        final Object value = getParameter( String.valueOf( counter ) );
        if ( value == null ) {
          break;
        }

        l.add( value );
        counter += 1;
      }
      return l;
    } catch ( Exception ie ) {
      CollectionObjectDescription.logger.warn( "Unable to instantiate Object", ie );
      return null;
    }
  }

  /**
   * Sets the parameters of this description object to match the supplied object.
   *
   * @param o
   *          the object.
   * @throws ObjectFactoryException
   *           if there is a problem while reading the properties of the given object.
   */
  public void setParameterFromObject( final Object o ) throws ObjectFactoryException {
    if ( o == null ) {
      throw new NullPointerException( "Given object is null" );
    }
    final Class c = getObjectClass();
    if ( !c.isInstance( o ) ) {
      throw new ObjectFactoryException( "Object is no instance of " + c + "(is " + o.getClass() + ')' );
    }

    final Collection l = (Collection) o;
    final Iterator it = l.iterator();
    int counter = 0;
    while ( it.hasNext() ) {
      final Object ob = it.next();
      setParameter( String.valueOf( counter ), ob );
      counter++;
    }
  }
}