package com.ruoyi.Dzp;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;

/** One exchange owns its channel, selector, receive buffer and peer address. */
public class MyUdpSocket implements AutoCloseable {
    private final DatagramChannel channel;
    private final Selector selector;
    private int clientPort;
    private String clientIp;
    private final ByteBuffer receiveBuffer = ByteBuffer.allocate(1280);

    public MyUdpSocket(int port) throws IOException {
        channel = DatagramChannel.open();
        Selector opened = null;
        try {
            opened = Selector.open();
            channel.configureBlocking(false);
            channel.bind(new InetSocketAddress(port));
            channel.register(opened, SelectionKey.OP_READ);
            selector = opened;
        } catch (IOException | RuntimeException failure) {
            if (opened != null) {
                try { opened.close(); } catch (IOException close) { failure.addSuppressed(close); }
            }
            try { channel.close(); } catch (IOException close) { failure.addSuppressed(close); }
            throw failure;
        }
    }

    public final void send(String ip, int port, byte[] buffer, int size) throws IOException {
        channel.send(ByteBuffer.wrap(buffer, 0, size), new InetSocketAddress(ip, port));
    }

    @Override
    public final void close() throws IOException {
        try { selector.close(); } finally { channel.close(); }
    }

    public final int get_client_port() { return clientPort; }
    public final String get_client_ip() { return clientIp; }

    public final void get_receive_buffer(byte[] buffer) {
        get_receive_packet(buffer, buffer.length);
    }

    public final int receive() {
        try {
            receiveBuffer.clear();
            if (selector.select(10) != 0) {
                var keys = selector.selectedKeys().iterator();
                while (keys.hasNext()) {
                    SelectionKey key = keys.next();
                    keys.remove();
                    if (!key.isValid() || !key.isReadable()) continue;
                    InetSocketAddress peer = (InetSocketAddress) channel.receive(receiveBuffer);
                    if (peer != null) {
                        clientIp = peer.getAddress().getHostAddress();
                        clientPort = peer.getPort();
                        return receiveBuffer.position();
                    }
                }
            }
            return 0;
        } catch (IOException e) {
            throw new java.io.UncheckedIOException("LED receive failed", e);
        }
    }

    public final void get_receive_packet(byte[] packet, int size) {
        System.arraycopy(receiveBuffer.array(), 0, packet, 0, size);
    }
}