package NIO;

import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.channels.spi.SelectorProvider;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class NIOServer {
	private Selector selector;
	private ExecutorService tp = Executors.newCachedThreadPool();
	public static Map<Socket, Long> time_start = new HashMap<Socket, Long>(1024);

	public static void main(String[] args) {

	}

	private void startServer() throws Exception {
		// 工厂方法获取selector
		selector = SelectorProvider.provider().openSelector();
		// 服务器端SocketChannel实例
		ServerSocketChannel ssc = ServerSocketChannel.open();
		// 设置为非阻塞模式
		ssc.configureBlocking(false);

		InetSocketAddress isa = new InetSocketAddress(InetAddress.getLocalHost(), 8000);
		// InetSocketAddress isa = new InetSocketAddress(8000);
		// 将套接字绑定到本地地址
		ssc.socket().bind(isa);
		// 将SocketChannel绑定到Seletor
		ssc.register(selector, SelectionKey.OP_ACCEPT);
		// 等待分发网络消息
		for (;;) {
			// 阻塞方法,若数据没有等待好则等待,否则就返回SelectionKey的数量
			selector.select();
			// 获取准备好的SelectionKey
			Set readKeys = selector.selectedKeys();
			Iterator iterator = readKeys.iterator();
			long e = 0;
			while (iterator.hasNext()) {
				SelectionKey sk = (SelectionKey) iterator.next();
				// 处理完后移除SelectionKey,防止重复处理
				iterator.remove();
				if (sk.isAcceptable()) {
					doAccpet(sk);
				} else if (sk.isValid() && sk.isReadable()) {
					if (!time_start.containsKey(((SocketChannel) sk.channel()).socket())) {
						time_start.put(((SocketChannel) sk.channel()).socket(), System.currentTimeMillis());
					}
					doRead(sk);
				} else if (sk.isValid() && sk.isWritable()) {
					doWrite(sk);
					e = System.currentTimeMillis();
					long b = time_start.remove(((SocketChannel) sk.channel()).socket());
					System.out.println("spend:" + (e - b) + "ms");

				}
			}
		}
	}

	private void doWrite(SelectionKey sk) {
		SocketChannel channel = (SocketChannel) sk.channel();
		EchoClient echoClient = (EchoClient) sk.attachment();
		LinkedList<ByteBuffer> ouqt = echoClient.getOutputQueue();
		ByteBuffer bb = ouqt.getLast();
		try {
			int len = channel.write(bb);
			if (len == -1) {
				disconnect(sk);
				return;
			}
			// 写入完成,移除,remaining返回当前位置与限制之间的元素数
			if (bb.remaining() == 0) {
				ouqt.removeLast();
			}
		} catch (IOException e) {
			System.out.println("Failed to write to client");
			e.printStackTrace();
			disconnect(sk);
		}
		if (ouqt.size() == 0) {
			sk.interestOps(SelectionKey.OP_READ);
		}
	}

	private void doRead(SelectionKey sk) {
		SocketChannel channel = (SocketChannel) sk.channel();
		ByteBuffer bb = ByteBuffer.allocate(8192);
		int len;
		try {
			len = channel.read(bb);
			if (len < 0) {
				disconnect(sk);
				return;
			}
		} catch (IOException e) {
			System.out.println("failed to read from client");
			e.printStackTrace();
			disconnect(sk);
			return;
		}
		// 反转此缓冲区
		bb.flip();
		tp.execute(new HandlerMsg(sk, bb));
	}

	private void disconnect(SelectionKey sk) {
		if (sk != null) {
			sk.cancel();
			sk = null;
		}
	}

	/**
	 * @param sk
	 * 进行客户端接受
	 */
	private void doAccpet(SelectionKey sk) {
		ServerSocketChannel server = (ServerSocketChannel) sk.channel();
		SocketChannel clientChannel;
		try {
			// 客户端通信通道
			clientChannel = server.accept();
			clientChannel.configureBlocking(false);
			SelectionKey clientKey = clientChannel.register(selector, SelectionKey.OP_READ);
			EchoClient echoClient = new EchoClient();
			clientKey.attach(echoClient);
			InetAddress clientAddress = clientChannel.socket().getInetAddress();
			System.out.println("Accept connection form " + clientAddress.getHostAddress() + ".");
		} catch (IOException e) {
			System.out.println("Failed to accept new client.");
			e.printStackTrace();
		}

	}

	class HandlerMsg implements Runnable {
		SelectionKey sk;
		ByteBuffer bb;

		public HandlerMsg(SelectionKey sk, ByteBuffer bb) {
			this.sk = sk;
			this.bb = bb;
		}

		@Override
		public void run() {
			EchoClient echoClient = (EchoClient) sk.attachment();
			echoClient.enqueue(bb);
			sk.interestOps(SelectionKey.OP_READ | SelectionKey.OP_WRITE);
			// 强迫selector立即返回
			selector.wakeup();
		}
	}

}