/* ImplicitObjectELResolver.java

	Purpose:
		
	Description:
		
	History:
		Mary 29, 2012 3:18:34 PM, Created by dennis

Copyright (C) 2012 Potix Corporation. All Rights Reserved.
*/

package org.zkoss.bind.xel.zel;

import java.beans.FeatureDescriptor;
import java.util.Iterator;
import java.util.Map;

import org.zkoss.bind.BindContext;
import org.zkoss.zel.ELContext;
import org.zkoss.zel.ELException;
import org.zkoss.zel.ELResolver;
import org.zkoss.zel.PropertyNotFoundException;
import org.zkoss.zel.PropertyNotWritableException;
import org.zkoss.zel.impl.lang.EvaluationContext;

/**
 * ELResolver for implicit object that is not supported in zk el
 * @author dennis
 * @since 6.0.1
 */
public class ImplicitObjectELResolver extends ELResolver {

	public static final String IMPLICIT_OBJECTS = "$IMPLICIT_OBJECTS$"; //the implicit objects

	@SuppressWarnings("unchecked")
	public Object getValue(ELContext context, Object base, Object property)
			throws NullPointerException, PropertyNotFoundException, ELException {
		if (context == null) {
			throw new NullPointerException();
		}
		BindContext ctx;
		if (base == null && (ctx = getBindContext(context)) != null) {
			Map<String, Object> implicit = (Map<String, Object>) ctx.getAttribute(IMPLICIT_OBJECTS);
			if (implicit != null && implicit.containsKey(property)) {
				//have to check contains to know it is resolved or not.
				context.setPropertyResolved(true);
				return implicit.get(property);
			}
		}
		return null;
	}

	private BindELContext getBindELContext(ELContext context) {
		if (context instanceof EvaluationContext) {
			ELContext ctx = ((EvaluationContext) context).getELContext();
			return ctx instanceof BindELContext ? (BindELContext) ctx : null;
		}
		return null;
	}

	private BindContext getBindContext(ELContext context) {
		BindELContext ctx = getBindELContext(context);
		return ctx == null ? null : ctx.getBindContext();
	}

	public Class<?> getType(ELContext context, Object base, Object property)
			throws NullPointerException, PropertyNotFoundException, ELException {
		//get type is called by setValue,see AstValue#setValue, 
		//since this is ready only resolver, we don't need to implement it.
		return null;
	}

	public void setValue(ELContext context, Object base, Object property, Object value)
			throws NullPointerException, PropertyNotFoundException, PropertyNotWritableException, ELException {
	}

	public boolean isReadOnly(ELContext context, Object base, Object property)
			throws NullPointerException, PropertyNotFoundException, ELException {
		return true;
	}

	public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base) {
		return null;
	}

	public Class<?> getCommonPropertyType(ELContext context, Object base) {
		return null;
	}
}