package net;

import java.nio.channels.*;
import java.nio.channels.ServerSocketChannel;
import java.net.*;
import java.util.*;
import java.io.*;

/**
 * 反應器<br>
 * 通過構造方法產生一個反應器（選擇器），構造Unix系統常用的網絡通信select架構<br>
 * 通過KVM內部的select結構，對網絡事件做出反應，比如連接，讀，寫等。
 *
 * <p>Title: </p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2006</p>
 * <p>Company: </p>
 * @author not attributable
 * @version 1.0
 */
public class Reactor
    implements Runnable {

  private final Selector selector;
  private final ServerSocketChannel serverSocketChannel;
  private final NetListener processor;

  private boolean shutdown = false;

  /**
   * 構造方法
   *
   * @param port int
   * @param processor AcceptionListener
   * @throws IOException
   */
  public Reactor(int port, NetListener processor) throws IOException {
    this.processor = processor;
    selector = Selector.open();
    serverSocketChannel = ServerSocketChannel.open();
    InetSocketAddress isa = new InetSocketAddress(port);
    serverSocketChannel.socket().bind(isa); //綁定
    serverSocketChannel.configureBlocking(false); //非阻塞
    SelectionKey sk = serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT); //注冊監聽選擇器
    sk.attach(new Acceptor());
  }

  public void shutdown() {
    shutdown = true;
  }

  /**
   * 選擇器線程，此線程會對所有連接的讀寫進行響應，通過回調Handle和Acceptor的run()方法實現。
   */
  public void run() {
    try {
      while (!shutdown) {
        int num = selector.select();
        //select方法可能返回為0

        //所以加上此判斷
        if (num > 0) {
          Set selected = selector.selectedKeys();
          Iterator it = selected.iterator();
          while (it.hasNext()) {
            dispatch( (SelectionKey) it.next());
          }
          selected.clear();
        }
        synchronized (this) {
          try {
            wait(100);
          }
          catch (InterruptedException ex) {
          }
        }
      } //end while
    }
    catch (IOException e) {
    }
  }

  /**
   * 任務分發
   * @param k SelectionKey
   */
  private void dispatch(SelectionKey k) {
    Runnable r = (Runnable) k.attachment();
    if (r != null) {
      r.run();
    }
  }

  /**
   * 接收者,當監聽到一個連接請求時，產生一個接收者
   *
   * 這個任務產生一個Handle，Handle實際上是一個連接的管理器，負責對一個客戶的所有通信進行管理
   * <p>Title: </p>
   * <p>Description: </p>
   * <p>Copyright: Copyright (c) 2006</p>
   * <p>Company: </p>
   * @author not attributable
   * @version 1.0
   */
  class Acceptor
      implements Runnable {

    /**
     * 反應器回調接口
     */
    public void run() {
      try {
        System.out.println("Acceptor:" + this);
        SocketChannel sc = serverSocketChannel.accept();
        sc.configureBlocking(false);
        if (sc != null) {
          //accpet后將key的attach轉到handle上面
          Handler h = new Handler(selector, sc);

          //如果網絡監聽器不為空，則執行定制操作
          if (processor != null) {
            processor.onAccept(h);
          }
        }
      }
      catch (IOException e) {
      }
    }
  }
}