/*
* 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.math;

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.TypeValuePair;
import org.pentaho.reporting.libraries.formula.typing.Type;
import org.pentaho.reporting.libraries.formula.typing.coretypes.NumberType;

import java.math.BigDecimal;

/**
 * This function returns the rounding a number up to the nearest odd integer, where "up" means "away from 0".
 *
 * @author Cedric Pronzato
 */
public class OddFunction implements Function {
  private static final long serialVersionUID = -7438242687193650125L;

  public OddFunction() {
  }

  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 );
    }
    final Type type1 = parameters.getType( 0 );
    final Object value1 = parameters.getValue( 0 );
    final Number result = context.getTypeRegistry().convertToNumber( type1, value1 );

    return new TypeValuePair( NumberType.GENERIC_NUMBER, compute( result ) );
  }

  private static BigDecimal compute( final Number result ) {
    final int intValue;
    final double v = result.doubleValue();
    if ( v < 0 ) {
      intValue = (int) Math.floor( v );
    } else {
      intValue = (int) Math.ceil( v );
    }

    final BigDecimal ret;
    if ( intValue == 0 ) {
      if ( v < 0 ) {
        ret = new BigDecimal( -1 );
      } else {
        ret = new BigDecimal( 1 );
      }
    } else if ( intValue % 2 != 0 ) // already odd
    {
      ret = new BigDecimal( intValue );
    } else // number is even
    {
      if ( v < 0 ) {
        ret = new BigDecimal( intValue - 1 );
      } else {
        ret = new BigDecimal( intValue + 1 );
      }
    }
    return ret;
  }


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