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appops black rhino cache impl
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/*
 * AppOps is a Java framework to develop, deploy microservices with ease and is available for free
 * and common use developed by AinoSoft ( www.ainosoft.com )
 *
 * AppOps and AinoSoft are registered trademarks of Aino Softwares private limited, India.
 *
 * Copyright (C) <2016> 
 *
 * This program is free software: you can redistribute it and/or modify it under the terms of the
 * GNU General Public License as published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version along with applicable additional terms as
 * provisioned by GPL 3.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
 * even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License and applicable additional terms
 * along with this program.
 *
 * If not, see  and 
 */

package org.appops.cache.impl;

import com.google.common.collect.HashBasedTable;
import com.google.common.collect.Table;
import java.util.HashSet;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.appops.cache.event.Condition;
import org.appops.cache.event.EventSubscriber;
import org.appops.cache.event.SubscriberRegistry;

/**
 * Storage class which stores all event listeners.
 *
 * @author deba
 * @version $Id: $Id
 */
public class SubscriberRegistryImpl implements SubscriberRegistry {

  private Table> subscriberListenerTable = HashBasedTable.create();
  private static final Condition DEFAULT = new Condition();
  private Logger logger = Logger.getLogger(getClass().getCanonicalName());

  /**
   * Constructor for SubscriberRegistryImpl.
   */
  public SubscriberRegistryImpl() {

  }

  /**
   * {@inheritDoc}
   *
   * Locates and registers listener method(s) from given event subscriber.
   */
  @Override
  public Boolean register(EventSubscriber eventSubscriber) {

    String serviceUrl = eventSubscriber.getServiceUrl();
    String serviceName = eventSubscriber.getServiceName();
    String serviceSubscriber = eventSubscriber.getSubscriber().getMethodName();
    String eventType = eventSubscriber.getSubscriber().getParameterType();
    Condition condition = eventSubscriber.getCondition();
    if (condition == null) {
      condition = DEFAULT;
    }
    String subscriberUrl = generateSubscriberUrl(serviceUrl, serviceName, serviceSubscriber);
    try {
      return addListener(eventType, condition, subscriberUrl);
    } catch (Exception e) {
      logger.log(Level.SEVERE, "Exception occured in " + getClass() + "::register()" + e);
    }
    return false;
  }

  /**
   * It adds the listener and subscriber into registry.
   * 
   * @param eventType event type
   * @param condition condition if any for subscriber
   * @param subscriber event subscriber url
   * @return true, after adding subscriber otherwise false
   */
  private boolean addListener(String eventType, Condition condition, String subscriber) {
    return getSubscribers(eventType, condition).add(subscriber);
  }

  /**
   * It creates url using given parameters and return it.
   * 
   * @param serviceUrl service url
   * @param serviceName service name which have listener
   * @param serviceSubscriber subscriber method name
   * @return url string using given paramaters
   */
  private String generateSubscriberUrl(String serviceUrl, String serviceName,
      String serviceSubscriber) {
    if (!serviceUrl.endsWith("/")) {
      serviceUrl = serviceUrl.concat("/");
    }
    return serviceUrl + "Op/" + serviceName + "/" + serviceSubscriber;
  }

  /**
   * {@inheritDoc}
   *
   * Fetches listeners which are registered against event type and condition provided.
   */
  @Override
  public Set getSubscribers(String eventType, Condition condition) {
    condition = condition == null ? DEFAULT : condition;
    Set listeners = subscriberListenerTable.get(eventType, condition);
    if (listeners == null) {
      listeners = new HashSet<>();
      subscriberListenerTable.put(eventType, condition, listeners);
    }
    return subscriberListenerTable.get(eventType, condition);
  }

}