/*
 * 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.date;

import org.pentaho.reporting.engine.classic.core.function.AbstractExpression;

import java.util.Date;

/**
 * Computes the difference date between the start and the end date.
 *
 * @author Thomas Morgner
 * @deprecated This can be solved using a plain formula.
 */
public class DateSpanExpression extends AbstractExpression {
  /**
   * The field that contains the start-date.
   */
  private String startDateField;
  /**
   * The field that contains the end-date.
   */
  private String endDateField;

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

  /**
   * Returns the name of the field that contains the start-date.
   *
   * @return the start-date fieldname
   */
  public String getStartDateField() {
    return startDateField;
  }

  /**
   * Defines the name of the field that contains the start-date.
   *
   * @param startDateField
   *          the start-date fieldname
   */
  public void setStartDateField( final String startDateField ) {
    this.startDateField = startDateField;
  }

  /**
   * Returns the name of the field that contains the end-date.
   *
   * @return the end-date fieldname
   */
  public String getEndDateField() {
    return endDateField;
  }

  /**
   * Defines the name of the field that contains the end-date.
   *
   * @param endDateField
   *          the start-date fieldname
   */
  public void setEndDateField( final String endDateField ) {
    this.endDateField = endDateField;
  }

  /**
   * Computes the difference between the start and the end date. The start-field and end-field must contain either Date
   * objects or Number objects. If the fields contain number objects, the number will be interpreted as milliseconds
   * since 01-Jan-1970.
   *
   * @return the difference between start and end or null, if the difference could not be computed.
   */
  public Object getValue() {
    if ( startDateField == null ) {
      return null;
    }
    if ( endDateField == null ) {
      return null;
    }

    final Object startRaw = getDataRow().get( startDateField );
    final long startTime;
    if ( startRaw instanceof Date ) {
      final Date start = (Date) startRaw;
      startTime = start.getTime();
    } else if ( startRaw instanceof Number ) {
      final Number start = (Number) startRaw;
      startTime = start.longValue();
    } else {
      return null;
    }

    final Object endRaw = getDataRow().get( startDateField );
    final long endTime;
    if ( endRaw instanceof Date ) {
      final Date end = (Date) endRaw;
      endTime = end.getTime();
    } else if ( endRaw instanceof Number ) {
      final Number end = (Number) endRaw;
      endTime = end.longValue();
    } else {
      return null;
    }
    return new Date( endTime - startTime );
  }
}