package node;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;

import util.BufferUtil;

public class UDPHandler implements Runnable {
    private final static Logger LOGGER = Logger.getLogger(Node.class.getName());

    public static final int BUF_SIZE = 512;

    // How long do we remember broadcast packets (ms)?
    private static final int BROADCAST_TIMEOUT = 10000;

    private Map<Integer, Long> broadcastPackets = new HashMap<>();

    private volatile boolean running = true;
    private ByteBuffer buf = ByteBuffer.allocate(BUF_SIZE);

    private Node node;

    public UDPHandler(Node node) {
        this.node = node;
    }

    private void receiveInvite(SocketAddress from) {
        LOGGER.log(Level.INFO, "{0}: received invite from {1}", new Object[] {
                node.getName(), from.toString() });
        int ack_id = buf.getInt();
        node.sendAck(from, ack_id);
        node.addNeighbor(from);
    }

    private void receiveAck(SocketAddress from) {
        int ack_id = buf.getInt();

        LOGGER.log(Level.INFO, "{0}: received ack ({1}) from {2}",
                new Object[] {
                node.getName(), ack_id, from.toString() });

        if (node.hasAck(ack_id)) {
            Ack theAck = node.getAck(ack_id);
            if (theAck.check(from)) {
                // theAck.setReceived();
                // node.removeAck(theAck.getId());
                node.removeAck(ack_id).setReceived();
            }
        }
    }

    private void receiveLeave(SocketAddress from) {
        LOGGER.log(Level.INFO, "{0}: {1} is leaving. Deleting...",
                new Object[] { node.getName(), from.toString() });

        if (node.removeNeighbor(from)) {
            int ack_id = buf.getInt();
            node.sendAck(from, ack_id);
        }
        // If we don't know that neighbor, we don't have to
        // ack
    }

    private void receiveBroadcast(SocketAddress from) {
        int packet_id = buf.getInt();
        byte command = buf.get();
        if (isNewBroadcast(packet_id)) {
            // Save packet id so we don't forward a packet multiple times
            broadcastPackets.put(packet_id, System.currentTimeMillis());

            switch (command) {
            case MessageType.STATUS:
                InetSocketAddress originalSender = readIPFromBuffer();

                // Broadcast to my neighbors
                node.sendBroadcast(packet_id, command,
                        BufferUtil.addrToBytes(originalSender));

                LOGGER.log(
                        Level.INFO,
                        "{0}: received status broadcast packet from {1}. original sender: {2}",
                        new Object[] { node.getName(), from.toString(),
                                originalSender.toString() });

                node.sendStatus(originalSender);

                break;
            default:
                LOGGER.log(
                        Level.INFO,
                        "{0}: received unknown broadcast packet from {1}. id: {2} type: {3}",
                        new Object[] { node.getName(), from.toString(),
                                packet_id, command });
                break;
            }
        } else {
            LOGGER.log(Level.INFO,
                    "{0}: Received duplicate broadcast packet ({0}). Discarding...",
                    new Object[] { node.getName(), packet_id });
        }
    }

    private void receiveStatus(SocketAddress receivedFrom) {
        List<SocketAddress> neighbors = new ArrayList<SocketAddress>();

        while (buf.hasRemaining()) {
            neighbors.add(readIPFromBuffer());
        }

        // Keep track of all neighbors..
    }

    private InetSocketAddress readIPFromBuffer() {
        StringBuilder theAddr = new StringBuilder();
        // Read 4 Bytes and 1 Integer = 1 IP address
        for (int i = 0; i < 4; i++) {
            theAddr.append(buf.get());
            if (i < 3) {
                theAddr.append(".");
            }
        }
        int port = buf.getInt();

        return new InetSocketAddress(theAddr.toString(), port);
    }

    private void receiveNewNeighbor(SocketAddress from) {
        int ack_id = buf.getInt();

        InetSocketAddress newNeighbor = readIPFromBuffer();

        node.addNeighbor(newNeighbor);

        LOGGER.log(
                Level.INFO,
                "{0}: from {1} received new neighbor:{2}",
                new Object[] { node.getName(), from.toString(),
                        newNeighbor.toString() });

        node.sendAck(from, ack_id);
    }

    private boolean isNewBroadcast(int id) {
        boolean isNew = true;
        if (broadcastPackets.containsKey(id)) {
            long receivedAt = broadcastPackets.get(id);
            if (receivedAt < System.currentTimeMillis() + BROADCAST_TIMEOUT) {
                isNew = false;
            }
        }
        return isNew;
    }

    public void run() {
        SocketAddress receivedFrom = null;

        while (running) {
            try {
                receivedFrom = node.getChannel().receive(buf);

                // channel.receive() is non blocking. So we need to check if
                // something actually has been written to the buffer
                if (buf.remaining() != BUF_SIZE) {
                    buf.flip();

                    byte messageType = buf.get();

                    switch (messageType) {
                    case MessageType.INVITE:
                        receiveInvite(receivedFrom);
                        break;
                    case MessageType.ACK:
                        receiveAck(receivedFrom);
                        break;
                    case MessageType.LEAVE:
                        receiveLeave(receivedFrom);
                        break;
                    case MessageType.NEW_NEIGHBOR:
                        receiveNewNeighbor(receivedFrom);
                        break;
                    case MessageType.BROADCAST:
                        receiveBroadcast(receivedFrom);
                        break;
                    case MessageType.STATUS:
                        receiveStatus(receivedFrom);
                        break;
                    default:
                        LOGGER.log(
                                Level.INFO,
                                "{0}: received unknown command from {1}: [{2}]{3}",
                                new Object[] { node.getName(),
                                        receivedFrom.toString(), messageType,
                                        new String(buf.array()) });
                    }
                } else {
                    try {
                        Thread.sleep(10);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                buf.clear();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public void terminate() {
        running = false;
    }
}