package fr.istic.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
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.util.Set;
import java.util.Iterator;

public class PingPong {

	private static final int PORT_NUMBER = 6969;

	// Phrase ACCEPT
	private static void accept(SocketChannel sc, SelectionKey key) throws IOException {
		sc.configureBlocking(false);
		ByteBuffer buffer = ByteBuffer.allocate(64);
		sc.register(key.selector(), SelectionKey.OP_READ, buffer);
	}

	// Phrase READ
	private static void read(SelectionKey key) throws IOException {
		SocketChannel client = (SocketChannel) key.channel();
		ByteBuffer buffer = (ByteBuffer) key.attachment();
		if (client.read(buffer) < 0) {
			client.close();
			return;
		} else {
			buffer.flip();
			byte[] bytes = new byte[buffer.remaining()];
			buffer.get(bytes, 0, buffer.remaining());
			String message = new String(bytes);
			String[] splited = message.split("\\s+");
			if (splited[0].equals("PING") && splited.length == 2) {
				// On récupère le nombre pour bien le traiter sinon
				// message.remplace est plus vite que ça mais c'est ptet un PING STRING
				int number = Integer.parseInt(splited[1]);
				buffer.clear();
				// C'est plus facile quand on a déjà le nombre ici que le transferer
				// dans la partie write, donc on le fait buffer write ici
				String pong = "PONG " + number;
				buffer.put(pong.getBytes());
				// flip pour envoyer le buffer
				buffer.flip();
				key.interestOps(SelectionKey.OP_WRITE);

			}
		}
	}

	// Phrase WRITE
	private static void write(SelectionKey key) throws IOException {
		SocketChannel client = (SocketChannel) key.channel();
		ByteBuffer buffer = (ByteBuffer) key.attachment();
		client.write(buffer);
		buffer.clear();
		key.interestOps(SelectionKey.OP_READ);
	}

	public static void main(String[] args) throws IOException {
		ServerSocketChannel server = ServerSocketChannel.open();
		server.socket().bind(new InetSocketAddress(PORT_NUMBER));
		server.socket().setReuseAddress(true);
		// Mode non bloquant
		server.configureBlocking(false);

		// Création du sélecteur
		Selector selector = Selector.open();
		server.register(selector, SelectionKey.OP_ACCEPT);

		while (true) {
			int channelcount = selector.select();
			if (channelcount > 0) {
				Set<SelectionKey> keys = selector.selectedKeys();
				Iterator<SelectionKey> iterator = keys.iterator();
				while (iterator.hasNext()) {
					SelectionKey key = iterator.next();
					iterator.remove();
					if (!key.isValid()) {
						continue;
					}
					if (key.isAcceptable()) {
						SocketChannel client = server.accept();
						accept(client, key);
					} else if (key.isReadable()) {
						read(key);
					} else if (key.isWritable()) {
						write(key);
					}
				}
			}
		}
	}
}