/*
 * 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.usergrid.mongo.commands;


import java.util.concurrent.ConcurrentHashMap;

import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.MessageEvent;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.StringUtils;
import org.apache.usergrid.mongo.MongoChannelHandler;
import org.apache.usergrid.mongo.protocol.OpQuery;
import org.apache.usergrid.mongo.protocol.OpReply;


public abstract class MongoCommand {

    private static final Logger logger = LoggerFactory.getLogger( MongoCommand.class );

    static ConcurrentHashMap<String, MongoCommand> commands = new ConcurrentHashMap<String, MongoCommand>();


    @SuppressWarnings("unchecked")
    public static MongoCommand getCommand( String commandName ) {
        MongoCommand command = commands.get( commandName );
        if ( command != null ) {
            return command;
        }

        String clazz = "org.apache.usergrid.mongo.commands." + StringUtils.capitalize( commandName );

        Class<MongoCommand> cls = null;

        try {
            cls = ( Class<MongoCommand> ) Class.forName( clazz );
        }
        catch ( ClassNotFoundException e ) {
            logger.error( "Couldn't find command class", e );
        }
        logger.debug( "using MongoCommand class {}", clazz );
        try {
            if ( cls != null ) {
                command = cls.newInstance();
            }
        }
        catch ( Exception e ) {
            logger.error( "Couldn't find instantiate class", e );
        }

        if ( command != null ) {
            MongoCommand oldCommand = commands.putIfAbsent( commandName, command );
            if ( oldCommand != null ) {
                command = oldCommand;
            }
        }
        else {
            logger.warn( "Mongo command handler not found for " + commandName );
        }

        return command;
    }


    public abstract OpReply execute( MongoChannelHandler handler, ChannelHandlerContext ctx, MessageEvent e,
                                     OpQuery opQuery );
}