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package com.bluejeans.utils.zookeeper;

import java.io.IOException;
import java.util.List;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.recipes.cache.ChildData;
import org.apache.curator.framework.recipes.cache.PathChildrenCache;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheListener;

public class ServiceLocator implements PathChildrenCacheListener {

    private final PathChildrenCache pathChildrenCache;
    private final MODE mode;
    
    private int rrIndex = 0;

    public ServiceLocator(CuratorFramework zkClient, String path) {
        this(zkClient, path, MODE.ROUND_ROBIN);
    }
    
    public ServiceLocator(CuratorFramework zkClient, String path, MODE mode) {
        this.mode = mode;
        this.pathChildrenCache = ZookeeperUtils.getPathChildrenCache(zkClient, path, true);
    }

    @Override
    public void childEvent(CuratorFramework client, PathChildrenCacheEvent evt)
            throws Exception {
        System.out.println("childEvent in zkLoadBalancer");
    }
    
    public String getHost() {
        String path = null;
        ChildData response = getChild();
        if(response!=null){
            path = response.getPath();
            path = path.substring(path.lastIndexOf('/')+1);
        }
        return path;
    }

    private ChildData getChild(){
        switch(mode){
            case RANDOM:
            case LEAST_LOADED:
            case ROUND_ROBIN: 
            default: return roundRobinChild();

        }
    }
    
    private synchronized ChildData roundRobinChild() {
        List children = pathChildrenCache.getCurrentData();
        if(children.isEmpty())
            return null;
        if(rrIndex>=children.size())
            rrIndex=0;
        
        ChildData data = children.get(rrIndex++);
        return data;
    }

    public enum MODE {
        ROUND_ROBIN,
        RANDOM,
        LEAST_LOADED
    }
    
    public void close() {
        try {
            pathChildrenCache.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}