/*
 * The MIT License
 * Copyright © 2014-2019 Ilkka Seppälä
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package com.iluwatar.databus;

import java.util.HashSet;
import java.util.Set;

/**
 * The Data-Bus implementation.
 *
 * <p>This implementation uses a Singleton.</p>
 *
 * @author Paul Campbell (pcampbell@kemitix.net)
 */
public class DataBus {

  private static final DataBus INSTANCE = new DataBus();

  private final Set<Member> listeners = new HashSet<>();

  public static DataBus getInstance() {
    return INSTANCE;
  }

  /**
   * Register a member with the data-bus to start receiving events.
   *
   * @param member The member to register
   */
  public void subscribe(final Member member) {
    this.listeners.add(member);
  }

  /**
   * Deregister a member to stop receiving events.
   *
   * @param member The member to deregister
   */
  public void unsubscribe(final Member member) {
    this.listeners.remove(member);
  }

  /**
   * Publish and event to all members.
   *
   * @param event The event
   */
  public void publish(final DataType event) {
    event.setDataBus(this);
    listeners.forEach(listener -> listener.accept(event));
  }
}
