/*
 * Copyright 2005 the original author or authors.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */ 

package org.wamblee.security.servlet;

import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.security.auth.Subject;

import ognl.Ognl;
import ognl.OgnlException;

/**
 * Locating the authenticated subject in a JBoss application server.  
 */
public class JBossSubjectLocator implements SubjectLocator {
    
    /**
     * Name of the property of the JBoss security manager that returns the subject. 
     */
    private static final String OGNL_EXPRESSION = "activeSubject"; 
    
    /**
     * JBoss security domain. 
     */
    private String _realm; 
    
    public JBossSubjectLocator(String aRealm) {
        _realm = aRealm;     
    }
    
    /* (non-Javadoc)
     * @see org.wamblee.security.servlet.SubjectLocator#getSubject()
     */
    public Subject getSubject() {
        Object securityMgr = null; 
        try {
            InitialContext context = new InitialContext();
            securityMgr = context.lookup("java:/jaas/" + _realm);
            Object value = Ognl.getValue(OGNL_EXPRESSION, securityMgr);
            return (Subject)value;
        } catch (NamingException e) { 
            throw new RuntimeException("Could not locate security manager for realm '" + _realm + "'. Is the realm configured correctly?",
                    e);
        } catch (OgnlException e) { 
            throw new RuntimeException("The obtained security manager '" + securityMgr + "' does not provide access to the subject", e); 
        }
    }
}