/*
 * Copyright 2005-2011 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.xmlrouter.impl;

import java.util.concurrent.atomic.AtomicLong;

import org.wamblee.xmlrouter.common.Id;
import org.wamblee.xmlrouter.config.Config;
import org.wamblee.xmlrouter.config.RouterConfig;
import org.wamblee.xmlrouter.config.RouterConfigService;

/**
 * Router configuration service providing an atomic configuration API for the
 * XML router.
 * 
 * @author Erik Brakkee
 */
public class XMLRouterConfigService implements RouterConfigService {

    private AtomicLong sequence;
    private XMLRouterConfiguration config;
    private Config<RouterConfig> routerConfigs;

    public XMLRouterConfigService(XMLRouterConfiguration aConfig) {
        sequence = new AtomicLong(1L);
        config = aConfig;
        routerConfigs = new ConfigImpl<RouterConfig>(sequence) {
            public RouterConfig wrap(Id<RouterConfig> aId, RouterConfig aT) {
                return aT;
            }
        };
    }

    @Override
    public RouterConfig emptyConfig() {
        return new SingleRouterConfig(sequence);
    }

    @Override
    public Id<RouterConfig> apply(RouterConfig aConfig,
        Id<RouterConfig> aOldConfig) {
        config.startConfigurationChange();
        try {
            return applyImpl(aConfig, aOldConfig);
        } finally {
            config.endConfigurationChange();
        }
    }

    private Id<RouterConfig> applyImpl(RouterConfig aConfig,
        Id<RouterConfig> aOldConfig) {
        if (aOldConfig != null) {
            routerConfigs.remove(aOldConfig);
        }
        Id<RouterConfig> id = routerConfigs.add(aConfig);
        update();
        return id;
    }

    @Override
    public void clear(Id<RouterConfig> aConfig) {
        config.startConfigurationChange();
        try {
            clearImpl(aConfig);
        } finally {
            config.endConfigurationChange();
        }
    }

    private void clearImpl(Id<RouterConfig> aConfig) {
        routerConfigs.remove(aConfig);
        update();
    }

    private void update() {
        ExtendedRouterConfig newconfig = new CompositeRouterConfig(
            routerConfigs.map().values());
        config.setRouterConfig(newconfig);
    }

}