/*
 * Copyright 2008-present MongoDB, Inc.
 *
 * 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 com.mongodb.client;

import com.mongodb.MongoException;
import com.mongodb.diagnostics.logging.Logger;
import com.mongodb.diagnostics.logging.Loggers;

import javax.naming.Context;
import javax.naming.Name;
import javax.naming.RefAddr;
import javax.naming.Reference;
import javax.naming.spi.ObjectFactory;
import java.util.Enumeration;
import java.util.Hashtable;

import static java.lang.String.format;

A JNDI ObjectFactory for MongoClient instances. 
Since:
3.10/**
 * A JNDI ObjectFactory for {@link MongoClient} instances.
 *
 * @since 3.10
 */
public class MongoClientFactory implements ObjectFactory {

    private static final Logger LOGGER = Loggers.getLogger("client");

    private static final String CONNECTION_STRING = "connectionString";

    
This implementation will create instances of MongoClient based on a connection string conforming to the format specified in ConnectionString. 
The connection string is specified in one of two ways:

As the String value of a property in the environment parameter with a key of "connectionString"
As the String value of a RefAddr with type "connectionString" in an obj parameter of type Reference
 Specification of the connection string in the environment parameter takes precedence over specification in the obj parameter. The name and nameCtx parameters are ignored. If a non-empty connection string is not specified in either of these two ways, a MongoException is thrown. 
Returns:
an instance of MongoClient based on the specified connection string/**
     * This implementation will create instances of {@link MongoClient} based on a connection string conforming to the format specified in
     * {@link com.mongodb.ConnectionString}.
     * <p>The connection string is specified in one of two ways:</p>
     * <ul>
     * <li>As the {@code String} value of a property in the {@code environment} parameter with a key of {@code "connectionString"}</li>
     * <li>As the {@code String} value of a {@link RefAddr} with type {@code "connectionString"} in an {@code obj} parameter
     * of type {@link Reference}</li>
     * </ul>
     *
     * Specification of the connection string in the {@code environment} parameter takes precedence over specification in the {@code obj}
     * parameter.  The {@code name} and {@code nameCtx} parameters are ignored.
     *
     * If a non-empty connection string is not specified in either of these two ways, a {@link MongoException} is thrown.
     * @return an instance of {@link MongoClient} based on the specified connection string
     */
    @Override
    public Object getObjectInstance(final Object obj, final Name name, final Context nameCtx, final Hashtable<?, ?> environment) {

        // Some app servers, e.g. Wildfly, use the environment to pass location information to an ObjectFactory
        String connectionString = null;

        if (environment.get(CONNECTION_STRING) instanceof String) {
            connectionString = (String) environment.get(CONNECTION_STRING);
        }

        if (connectionString == null || connectionString.isEmpty()) {
            LOGGER.debug(format("No '%s' property in environment.  Casting 'obj' to java.naming.Reference to look for a "
                                        + "javax.naming.RefAddr with type equal to '%s'", CONNECTION_STRING, CONNECTION_STRING));

            // Some app servers, e.g. Tomcat, pass obj as an instance of javax.naming.Reference and pass location information in a
            // javax.naming.RefAddr
            if (obj instanceof Reference) {
                Enumeration<RefAddr> props = ((Reference) obj).getAll();

                while (props.hasMoreElements()) {
                    RefAddr addr = props.nextElement();
                    if (addr != null) {
                        if (CONNECTION_STRING.equals(addr.getType())) {
                            if (addr.getContent() instanceof String) {
                                connectionString = (String) addr.getContent();
                                break;
                            }
                        }
                    }
                }
            }
        }

        if (connectionString == null || connectionString.isEmpty()) {
            throw new MongoException(format("Could not locate '%s' in either environment or obj", CONNECTION_STRING));
        }

        return MongoClients.create(connectionString);
    }
}