/* DelegatingVariableResolver.java
{{IS_NOTE
	Purpose:
		
	Description:
		
	History:
		Dec 31, 2009 10:56:14 AM, Created by henrichen
}}IS_NOTE

Copyright (C) 2009 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
	This program is distributed under GPL Version 3.0 in the hope that
	it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.zkplus.cdi;

import java.util.Set;

import javax.enterprise.context.spi.CreationalContext;
import javax.enterprise.inject.spi.Bean;
import javax.enterprise.inject.spi.BeanManager;

import org.zkoss.lang.Objects;
import org.zkoss.xel.VariableResolverX;
import org.zkoss.xel.XelContext;
import org.zkoss.xel.XelException;

/**
 * Generic CDI EL named managed bean resolver.
 * <p>Applicable to CDI version 1.0 or later</p>
 * @author henrichen
 *
 */
public class DelegatingVariableResolver implements VariableResolverX {

	private BeanManager _beanMgr;

	public DelegatingVariableResolver() {
		_beanMgr = CDIUtil.getBeanManager();
	}

	public Object resolveVariable(String name) throws XelException {
		return resolveVariable(null, null, name);
	}

	@SuppressWarnings("rawtypes")
	public Object resolveVariable(XelContext ctx, Object base, Object name) throws XelException {
		if (base != null || !(name instanceof String))
			return null;

		final Set<Bean<?>> beans = _beanMgr.getBeans((String) name);
		if (beans == null || beans.size() == 0)
			return null;

		//I(Dennis) think we don't need to check(if there are more than one bean has same name), CDI should check this when startup
		//However, Since it returns a Set, so I just check it.
		//Note, I do some test, the alternative bean will not be returned by the getBeans api with the name.
		Bean bean = null;
		for (Bean b : beans) {
			if (b.isAlternative())
				continue; //(Ian Tsai) alternative is the bean with explicit declaration in bean.xml. they are reserved for Bean 
			if (bean != null) {
				throw new XelException(
						"more than one non-alternative bean have same name " + bean + " and " + b + ", name " + name);
			}
			bean = b;
		}
		if (bean == null)
			return null;

		CreationalContext context = _beanMgr.createCreationalContext(null);
		/*
		 * Ian Tsai & Dennis
		 * 
		 * We are not sure what is the best way to handle the life cycle of CreationalContext.
		 * CreationalContext is the context designed to serve a specific contextual bean type, 
		 * we are using null here, so we got no contextual concept.
		 */
		//		CreationalContext context = ctx==null?
		//			null:(CreationalContext)ctx.getAttribute(CREATIONAL_CONTEXT);
		//		if(context==null){
		//			System.out.println(">>>>>create a new CreationalContext");
		//			context = _beanMgr.createCreationalContext(null);
		//			if(ctx!=null){
		//				ctx.setAttribute(CREATIONAL_CONTEXT,context);
		//			}else{
		//				
		//			}
		//		}
		Object value = _beanMgr.getReference(bean, bean.getBeanClass(), context);

		// follow the old implementation, we won't handle preDestroy of creationalContext in dependent scope.
		// we cannot call release() before user get the returned value and use it.
		//		context.release();

		return value;
	}

	public int hashCode() {
		return Objects.hashCode(_beanMgr);
	}

	public boolean equals(Object o) {
		return this == o || (o instanceof DelegatingVariableResolver
				&& Objects.equals(_beanMgr, ((DelegatingVariableResolver) o)._beanMgr));
	}
}