/*
 * 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><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="jakarta.mail.Session"
 *           mail.smtp.host="mail.mycompany.com"
 *           /&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";


    @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((PrivilegedAction<Session>) () -> {

            // 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
            return Session.getInstance(props, auth);
        });
    }
}
