/*
 * 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.function;

import org.pentaho.reporting.engine.classic.core.ReportElement;
import org.pentaho.reporting.engine.classic.core.style.ElementStyleKeys;
import org.pentaho.reporting.libraries.base.util.ObjectUtilities;

/**
 * Hides the specified elements if the given field contains empty strings or zero numbers.
 *
 * @author Thomas Morgner
 * @deprecated This should be done using Style-Expressions.
 */
public class HideNullValuesFunction extends AbstractElementFormatFunction {
  /**
   * The name of the data-row column that is checked for null-values.
   */
  private String field;

  /**
   * Default Constructor.
   */
  public HideNullValuesFunction() {
  }

  /**
   * Returns the field used by the function. The field name corresponds to a column name in the report's data-row.
   *
   * @return The field name.
   */
  public String getField() {
    return field;
  }

  /**
   * Sets the field name for the function. The field name corresponds to a column name in the report's data-row.
   *
   * @param field
   *          the field name.
   */
  public void setField( final String field ) {
    this.field = field;
  }

  protected boolean evaluateElement( final ReportElement e ) {
    if ( ObjectUtilities.equal( e.getName(), getElement() ) ) {
      final boolean visible = computeVisibility();
      e.getStyle().setStyleProperty( ElementStyleKeys.VISIBLE, visible );
      return true;
    }
    return false;
  }

  /**
   * Computes the visiblity of the specified element.
   *
   * @return true, if the element should be visible, false otherwise.
   */
  protected boolean computeVisibility() {
    final Object value = getDataRow().get( getField() );
    if ( value == null ) {
      return false;
    }
    if ( value instanceof String ) {
      final String strValue = (String) value;
      return strValue.trim().length() > 0;
    }
    if ( value instanceof Number ) {
      final Number numValue = (Number) value;
      return numValue.doubleValue() != 0;
    }
    return true;
  }
}