/*******************************************************************************
    * Portions created by Sebastian Thomschke are copyright (c) 2005-2012 Sebastian
    * Thomschke.
    * 
    * All Rights Reserved. This program and the accompanying materials
    * are made available under the terms of the Eclipse Public License v1.0
    * which accompanies this distribution, and is available at
    * http://www.eclipse.org/legal/epl-v10.html
    * 
   * Contributors:
   *     Sebastian Thomschke - initial implementation.
   *******************************************************************************/
  package net.sf.oval.expression;
  
  import java.util.Map;
  import java.util.Map.Entry;
  
  import net.sf.oval.exception.ExpressionEvaluationException;
  import net.sf.oval.internal.Log;
  import bsh.EvalError;
  import bsh.Interpreter;
  
  /**
   * @author Sebastian Thomschke
   */
  public class ExpressionLanguageBeanShellImpl implements ExpressionLanguage
  {
  	private static final Log LOG = Log.getLog(ExpressionLanguageBeanShellImpl.class);
  
  	/**
  	 * {@inheritDoc}
  	 */
  	public Object evaluate(final String expression, final Map<String, ? > values) throws ExpressionEvaluationException
  	{
  		LOG.debug("Evaluating BeanShell expression: {1}", expression);
  		try
  		{
  			final Interpreter interpreter = new Interpreter();
  			interpreter.eval("setAccessibility(true)"); // turn off access restrictions
  			for (final Entry<String, ? > entry : values.entrySet())
  				interpreter.set(entry.getKey(), entry.getValue());
  			return interpreter.eval(expression);
  		}
  		catch (final EvalError ex)
  		{
  			throw new ExpressionEvaluationException("Evaluating BeanShell expression failed: " + expression, ex);
  		}
  	}
  
  	/**
  	 * {@inheritDoc}
  	 */
  	public boolean evaluateAsBoolean(final String expression, final Map<String, ? > values)
  			throws ExpressionEvaluationException
  	{
  		final Object result = evaluate(expression, values);
  		if (!(result instanceof Boolean))
  			throw new ExpressionEvaluationException("The script must return a boolean value.");
  		return (Boolean) result;
  	}
  }