package ch.qos.logback.core.boolex;


import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.List;

import org.codehaus.janino.ExpressionEvaluator;

import ch.qos.logback.core.spi.ContextAwareBase;
import ch.qos.logback.core.spi.LifeCycle;

abstract public class JaninoEventEvaluatorBase extends ContextAwareBase implements
    EventEvaluator, LifeCycle {

  static Class EXPRESSION_TYPE = boolean.class;
  static Class[] THROWN_EXCEPTIONS = new Class[1];

  static {
    THROWN_EXCEPTIONS[0] = EvaluationException.class;
  }
  protected boolean start = false;

  private String name;
  private String expression;

  ExpressionEvaluator ee;

  abstract protected String getDecoratedExpression();
  abstract protected String[] getParameterNames();
  abstract protected Class[] getParameterTypes();
  abstract protected Object[] getParameterValues(Object event);

  protected List<Matcher> matcherList = new ArrayList<Matcher> ();
  
  public boolean isStarted() {
    return start;
  }

  public void stop() {
    start = false;
  }

  public void start() {
    try {
      ee = new ExpressionEvaluator(getDecoratedExpression(),
          EXPRESSION_TYPE, getParameterNames(), getParameterTypes(),
          THROWN_EXCEPTIONS, null);
      start = true;
    } catch (Exception e) {
      addError("Could not start evaluator with expression [" + expression + "]", e);
    }
  }

  public boolean evaluate(Object event) throws NullPointerException,
      EvaluationException {
    try {
      Boolean result = (Boolean) ee.evaluate(getParameterValues(event));
      return result.booleanValue();
    } catch (InvocationTargetException ite) {
      throw new EvaluationException("Evaluator [" + name
          + "] caused an exception", ite);
    }
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    if (this.name != null) {
      throw new IllegalStateException("name has been already set");
    }
    this.name = name;
  }

  public String getExpression() {
    return expression;
  }

  public void setExpression(String expression) {
    this.expression = expression;
  }
  
  public void addMatcher(Matcher matcher) {
    matcherList.add(matcher);
  }
  
  public List getMatcherList() {
    return matcherList;
  }
}
