package sk2;

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.HashSet;

public class NioServ {
    
    ServerSocketChannel ssc;
    Selector sel;
    HashSet<SocketChannel> clients = new HashSet<SocketChannel>();
    ByteBuffer commonReadBuffer = ByteBuffer.allocate(256);
    
    public NioServ(int port) throws Throwable {
        sel = Selector.open();
        ssc = ServerSocketChannel.open();
        ssc.bind(new InetSocketAddress(port));
        ssc.configureBlocking(false);
        ssc.register(sel, SelectionKey.OP_ACCEPT);
    }
    
    private void loop() throws Throwable {
        while(true){
            select();
        }
    }

    private void select() throws Throwable {
        sel.select();
        for(SelectionKey key : sel.selectedKeys()){
            if(key.isAcceptable()){
                accept();
            }
            if(key.isReadable()){
                SocketChannel sc = (SocketChannel) key.channel();
                read(key, sc);
            }
        }
        sel.selectedKeys().clear();
    }

    private void accept() throws Throwable {
        SocketChannel sc = ssc.accept();
        sc.configureBlocking(false);
        sc.register(sel, SelectionKey.OP_READ);
        sendAll("Connected:" + sc.getRemoteAddress().toString() + "\n");
        clients.add(sc);
    }
    
    private void read(SelectionKey key, SocketChannel sc) throws Throwable {
        commonReadBuffer.clear();
        commonReadBuffer.put(sc.getRemoteAddress().toString().getBytes());
        commonReadBuffer.putChar(':');
        commonReadBuffer.putChar(' ');
        
        int count = sc.read(commonReadBuffer);
        
        if(count == 0) return;
        if(count == -1){
            clients.remove(sc);
            sendAll("Disconnected:" + sc.getRemoteAddress().toString() + "\n");
            key.cancel();
            sc.close();
            return;
        }
        
        sendAll(commonReadBuffer);
    }

    private void sendAll(String msg) throws Throwable {
        ByteBuffer bb = ByteBuffer.wrap(msg.getBytes());
        bb.position(bb.limit());
        sendAll(bb);
    }
        
    private void sendAll(ByteBuffer bb) throws Throwable {
        bb.flip();
        for(SocketChannel sc : clients){
            sc.write(bb);
            bb.rewind();
        }
    }

    public static void main(String[] args) throws Throwable{
        NioServ s = new NioServ(Integer.parseInt(args[0]));
        s.loop();
    }

}