/*!
* 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) 2002-2013 Pentaho Corporation..  All rights reserved.
*/

package org.pentaho.reporting.libraries.formula.function.userdefined;

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.Sequence;
import org.pentaho.reporting.libraries.formula.typing.Type;
import org.pentaho.reporting.libraries.formula.typing.TypeRegistry;
import org.pentaho.reporting.libraries.formula.typing.coretypes.AnyType;
import org.pentaho.reporting.libraries.formula.typing.sequence.RecursiveSequence;

import java.util.ArrayList;

public class ArrayLeftFunction implements Function {
  public ArrayLeftFunction() {
  }

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

  public TypeValuePair evaluate( final FormulaContext context,
                                 final ParameterCallback parameters ) throws EvaluationException {
    final int parameterCount = parameters.getParameterCount();
    if ( parameterCount < 1 || parameterCount > 2 ) {
      throw EvaluationException.getInstance( LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE );
    }
    final TypeRegistry typeRegistry = context.getTypeRegistry();

    final Object textValue = parameters.getValue( 0 );

    final Sequence text = new RecursiveSequence( textValue, context );
    final int length;
    if ( parameterCount == 2 ) {
      final Type lengthType = parameters.getType( 1 );
      final Object lengthValue = parameters.getValue( 1 );
      final Number lengthConv = typeRegistry.convertToNumber( lengthType, lengthValue );
      if ( lengthConv.doubleValue() < 0 ) {
        throw EvaluationException.getInstance( LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE );
      }

      length = lengthConv.intValue();
    } else {
      length = 1;
    }

    final ArrayList retval = new ArrayList( length );
    if ( length > 0 ) {
      while ( text.hasNext() ) {
        final Object o = text.next();
        retval.add( o );
        if ( retval.size() == length ) {
          break;
        }
      }
    }
    // Note that MID(T;1;Length) produces the same results as LEFT(T;Length).
    return new TypeValuePair( AnyType.ANY_ARRAY, retval.toArray() );
  }
}