/*
* 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.formula.function.information;

import org.pentaho.reporting.libraries.formula.EvaluationException;
import org.pentaho.reporting.libraries.formula.FormulaContext;
import org.pentaho.reporting.libraries.formula.LibFormulaErrorValue;
import org.pentaho.reporting.libraries.formula.function.Function;
import org.pentaho.reporting.libraries.formula.function.ParameterCallback;
import org.pentaho.reporting.libraries.formula.lvalues.ContextLookup;
import org.pentaho.reporting.libraries.formula.lvalues.LValue;
import org.pentaho.reporting.libraries.formula.lvalues.TypeValuePair;
import org.pentaho.reporting.libraries.formula.typing.coretypes.LogicalType;

/**
 * Document me!
 *
 * @author : Thomas Morgner
 */
public class IsBlankFunction implements Function {
  private static final TypeValuePair RETURN_FALSE = new TypeValuePair(
    LogicalType.TYPE, Boolean.FALSE );

  private static final TypeValuePair RETURN_TRUE = new TypeValuePair(
    LogicalType.TYPE, Boolean.TRUE );
  private static final long serialVersionUID = 3352413434463488403L;

  public IsBlankFunction() {
  }

  public String getCanonicalName() {
    return "ISBLANK";
  }

  public TypeValuePair evaluate( final FormulaContext context,
                                 final ParameterCallback parameters ) throws EvaluationException {
    final int parameterCount = parameters.getParameterCount();
    if ( parameterCount < 1 ) {
      throw EvaluationException.getInstance( LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE );
    }
    try {
      final Object value = parameters.getValue( 0 );
      final LValue raw = parameters.getRaw( 0 );
      if ( raw instanceof ContextLookup ) {
        if ( value == null ) {
          return RETURN_TRUE;
        }
      }
    } catch ( EvaluationException e ) {
      if ( e.getErrorValue().getErrorCode() == LibFormulaErrorValue.ERROR_NA ) {
        return RETURN_TRUE;
      }
      return RETURN_FALSE;
    }

    return RETURN_FALSE;
  }
}