/* JndiVariableResolver.java

{{IS_NOTE
	Purpose:
		
	Description:
		
	History:
		Mon Dec 1 2007, Created by jeffliu
}}IS_NOTE

Copyright (C) 2006 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
}}IS_RIGHT
*/
package org.zkoss.zkplus.jndi;

import java.util.HashMap;
import java.util.Map;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.zkoss.lang.Objects;
import org.zkoss.util.Maps;
import org.zkoss.xel.VariableResolver;
import org.zkoss.xel.XelException;

/**
 * JndiVariableResolver, a jndi variableResolver 
 * @author Jeff
 *
 */
public class JndiVariableResolver implements VariableResolver {

	private static final Logger log = LoggerFactory.getLogger(JndiVariableResolver.class);

	private String _jndiPrepend = null;

	private Map<String, Object> _jndiMapping = new HashMap<String, Object>();

	/**
	 * This constructor take arguments to initialize JNDI names. 
	 * <ul>
	 * <li>prepend - The prepended part of JNDI name</li>
	 * <li>mapping - The key-value pairs for JNDI name and its corresponding variable name</li>
	 * </ul>
	 * 
	 * The variable will be resolved in following priority
	 * <ol>
	 * <li>java:comp/env</li>
	 * <li>java:comp</li>
	 * <li>java:</li>
	 * <li>The variable will be look up as a sessionBean with prepend.</li>
	 * <li>The key-value pairs which is defined by mapping</li>
	 * </ol>
	 * </p>
	 * 
	 * <p>
	 * For example:
	 * </p>
	 * <p>
	 * By default, session beans will bind to JNDI in the form ejbName/remote for remote interfaces and ejbName/local in the case of local interfaces. When the EJBs are deployed in an .ear file, the default jndi binding will be prepended by the name of the .ear file.
	 * As a result, if the ear file name is foo.ear, prepend is: foo
	 * </p>
	 * </br>
	 * <p>
	 * If you define your own jndi binding, the string should be in key-value pairs format as</br>
	 * "a=custom/MySession,b=custom/MySession2,emf=java:/EntityManagerFactory"
	 * </p>
	 *
	 * @param prepend prepended part of JNDI name
	 * @param mapping key-value pairs for JNDI name and its corresponding variable name
	 */
	public JndiVariableResolver(String prepend, String mapping) {
		_jndiMapping = new HashMap<String, Object>();
		Maps.parse(_jndiMapping, mapping, ',', '=');
		_jndiPrepend = prepend;
	}

	public JndiVariableResolver() {
		//Do Nothing
	}

	/**
	 * Get object from JNDI binding
	 * @param var JNDI binding name
	 * @return bean of context
	 */
	public Object resolveVariable(String var) throws XelException {
		Object variable = null;
		/*
		 * First, find the variable, var in JNDI key-value map. If
		 * not found, look for the variable as a sessionBean
		 */

		variable = jndiLookup("java:comp/env/" + var);

		if (variable == null) {
			variable = jndiLookup("java:comp/" + var);
		}
		if (variable == null) {
			variable = jndiLookup("java:/" + var);
		}
		if (variable == null) {
			variable = defaultBean(var);
		}
		if (!_jndiMapping.isEmpty() && variable == null) {
			Object jndiPattern = _jndiMapping.get(var);
			if (jndiPattern != null) {
				variable = jndiLookup(jndiPattern.toString());
			}
		}
		return variable;
	}

	private Object defaultBean(String name) {
		Object variable = null;

		variable = jndiLookup(_jndiPrepend + "/" + name + "/local");
		//If not found in local, lookup remote
		if (variable == null) {
			variable = jndiLookup(_jndiPrepend + "/" + name + "/remote");
		}
		return variable;
	}

	private Object jndiLookup(String jndiPattern) {
		Object obj = null;
		try {
			Context ctx = new InitialContext();
			obj = ctx.lookup(jndiPattern);
		} catch (NamingException ex) {
			//Not found, logging
			if (log.isDebugEnabled()) {
				log.debug("JNDI binding not found: " + ex);
			}
		}
		return obj;
	}

	public int hashCode() {
		return Objects.hashCode(_jndiMapping) + Objects.hashCode(_jndiPrepend);
	}

	public boolean equals(Object obj) {
		return this == obj || (obj instanceof JndiVariableResolver
				&& Objects.equals(_jndiMapping, ((JndiVariableResolver) obj)._jndiMapping)
				&& Objects.equals(_jndiPrepend, ((JndiVariableResolver) obj)._jndiPrepend));
	}
}