/* BindingImpl.java

	Purpose:
		
	Description:
		
	History:
		Aug 5, 2011 11:02:23 AM, Created by henrichen

Copyright (C) 2011 Potix Corporation. All Rights Reserved.
*/

package org.zkoss.bind.impl;

import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

import org.zkoss.bind.BindContext;
import org.zkoss.bind.Binder;
import org.zkoss.bind.sys.Binding;
import org.zkoss.zk.ui.Component;

/**
 * Base implementation for implementing a {@link Binding}
 * @author henrichen
 * @since 6.0.0
 */
public class BindingImpl implements Binding, Serializable {
	private static final long serialVersionUID = 1463169907348730644L;
	//http://tracker.zkoss.org/browse/ZK-869, It is OK to not use WeakReference here, 
	//A binding is always associated with a component, and was removed after a component is detached from the view
	private final Component _comp;
	private final Binder _binder;
	private final Map<String, Object> _args;

	protected BindingImpl(Binder binder, Component comp, Map<String, Object> args) {
		_comp = comp;
		_binder = binder;
		_args = args;
	}

	public Component getComponent() {
		return _comp;
	}

	public Binder getBinder() {
		return _binder;
	}

	public Map<String, Object> getArgs() {
		return _args;
	}

	protected Object setAttribute(BindContext ctx, Object key, Object value) {
		Map<Object, Object> bindingBag = getBindingAttribute(ctx);
		if (bindingBag == null) {
			bindingBag = new HashMap<Object, Object>();
			ctx.setAttribute(this, bindingBag);
		}
		return bindingBag.put(key, value);
	}

	protected Object getAttribute(BindContext ctx, Object key) {
		Map<Object, Object> bindingBag = getBindingAttribute(ctx);
		return bindingBag != null ? bindingBag.get(key) : null;
	}

	protected boolean containsAttribute(BindContext ctx, Object key) {
		Map<Object, Object> bindingBag = getBindingAttribute(ctx);
		return bindingBag != null ? bindingBag.containsKey(key) : false;
	}

	@SuppressWarnings("unchecked")
	private Map<Object, Object> getBindingAttribute(BindContext ctx) {
		return (Map<Object, Object>) ctx.getAttribute(this);
	}
}