/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.naming.factory;

import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Properties;

import javax.mail.Authenticator;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.naming.Context;
import javax.naming.Name;
import javax.naming.RefAddr;
import javax.naming.Reference;
import javax.naming.spi.ObjectFactory;

/**
 * <p>Factory class that creates a JNDI named JavaMail Session factory,
 * which can be used for managing inbound and outbound electronic mail
 * messages via JavaMail APIs.  All messaging environment properties
 * described in the JavaMail Specification may be passed to the Session
 * factory; however the following properties are the most commonly used:</p>
 * <ul>
 * <li>
 * <li><strong>mail.smtp.host</strong> - Hostname for outbound transport
 *     connections.  Defaults to <code>localhost</code> if not specified.</li>
 * </ul>
 *
 * <p>This factory can be configured in a
 * <code>&lt;Context&gt;</code> element in your <code>conf/server.xml</code>
 * configuration file.  An example of factory configuration is:</p>
 * <pre>
 * &lt;Resource name="mail/smtp" auth="CONTAINER"
 *           type="javax.mail.Session"/&gt;
 * &lt;ResourceParams name="mail/smtp"&gt;
 *   &lt;parameter&gt;
 *     &lt;name&gt;factory&lt;/name&gt;
 *     &lt;value&gt;org.apache.naming.factory.MailSessionFactory&lt;/value&gt;
 *   &lt;/parameter&gt;
 *   &lt;parameter&gt;
 *     &lt;name&gt;mail.smtp.host&lt;/name&gt;
 *     &lt;value&gt;mail.mycompany.com&lt;/value&gt;
 *   &lt;/parameter&gt;
 * &lt;/ResourceParams&gt;
 * </pre>
 *
 * @author Craig R. McClanahan
 */
public class MailSessionFactory implements ObjectFactory {


    /**
     * The Java type for which this factory knows how to create objects.
     */
    protected static final String factoryType = "javax.mail.Session";


    /**
     * Create and return an object instance based on the specified
     * characteristics.
     *
     * @param refObj Reference information containing our parameters, or null
     *  if there are no parameters
     * @param name The name of this object, relative to context, or null
     *  if there is no name
     * @param context The context to which name is relative, or null if name
     *  is relative to the default initial context
     * @param env Environment variables, or null if there are none
     *
     * @exception Exception if an error occurs during object creation
     */
    @Override
    public Object getObjectInstance(Object refObj, Name name, Context context,
            Hashtable<?,?> env) throws Exception {

        // Return null if we cannot create an object of the requested type
        final Reference ref = (Reference) refObj;
        if (!ref.getClassName().equals(factoryType))
            return null;

        // Create a new Session inside a doPrivileged block, so that JavaMail
        // can read its default properties without throwing Security
        // exceptions.
        //
        // Bugzilla 31288, 33077: add support for authentication.
        return AccessController.doPrivileged(new PrivilegedAction<Session>() {
                @Override
                public Session run() {

                    // Create the JavaMail properties we will use
                    Properties props = new Properties();
                    props.put("mail.transport.protocol", "smtp");
                    props.put("mail.smtp.host", "localhost");

                    String password = null;

                    Enumeration<RefAddr> attrs = ref.getAll();
                    while (attrs.hasMoreElements()) {
                        RefAddr attr = attrs.nextElement();
                        if ("factory".equals(attr.getType())) {
                            continue;
                        }

                        if ("password".equals(attr.getType())) {
                            password = (String) attr.getContent();
                            continue;
                        }

                        props.put(attr.getType(), attr.getContent());
                    }

                    Authenticator auth = null;
                    if (password != null) {
                        String user = props.getProperty("mail.smtp.user");
                        if(user == null) {
                            user = props.getProperty("mail.user");
                        }

                        if(user != null) {
                            final PasswordAuthentication pa = new PasswordAuthentication(user, password);
                            auth = new Authenticator() {
                                    @Override
                                    protected PasswordAuthentication getPasswordAuthentication() {
                                        return pa;
                                    }
                                };
                        }
                    }

                    // Create and return the new Session object
                    Session session = Session.getInstance(props, auth);
                    return session;

                }
        } );
    }
}