/*
 * Copyright (C) 2009-2018 Lightbend Inc. <https://www.lightbend.com>
 */

package jdocs.io;

import akka.actor.ActorRef;
import akka.actor.ActorSystem;
import akka.actor.Props;
import akka.io.Udp;
import akka.testkit.SocketUtil;

import jdocs.AbstractJavaTest;
import akka.testkit.javadsl.TestKit;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.util.*;


public class JavaUdpMulticastTest extends AbstractJavaTest {

    static ActorSystem system;

    @BeforeClass
    public static void setup() {
        system = ActorSystem.create("JavaUdpMulticastTest");
    }

    @Test
    public void testUdpMulticast() throws Exception {
        new TestKit(system) {{
            List<NetworkInterface> ipv6Ifaces = new ArrayList<>();
            for (Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces(); interfaces.hasMoreElements(); ) {
                NetworkInterface interf = interfaces.nextElement();
                if (interf.isUp() && interf.supportsMulticast()) {
                    for (Enumeration<InetAddress> addresses = interf.getInetAddresses(); addresses.hasMoreElements(); ) {
                        InetAddress address = addresses.nextElement();
                        if (address instanceof Inet6Address) {
                            ipv6Ifaces.add(interf);
                        }
                    }
                }
            }
            if (ipv6Ifaces.isEmpty()) {
                system.log().info("JavaUdpMulticastTest skipped since no ipv6 interface supporting multicast could be found");
            } else {
                // lots of problems with choosing the wrong interface for this test depending
                // on the platform (awsdl0 can't be used on OSX, docker[0-9] can't be used in a docker machine etc.)
                // therefore: try hard to find an interface that _does_ work, and only fail if there was any potentially
                // working interfaces but all failed
                for (Iterator<NetworkInterface> interfaceIterator = ipv6Ifaces.iterator(); interfaceIterator.hasNext(); ) {
                    NetworkInterface ipv6Iface = interfaceIterator.next();
                    // host assigned link local multicast address http://tools.ietf.org/html/rfc3307#section-4.3.2
                    // generate a random 32 bit multicast address with the high order bit set
                    final String randomAddress = Long.toHexString(((long) Math.abs(new Random().nextInt())) | (1L << 31)).toUpperCase();
                    final StringBuilder groupBuilder = new StringBuilder("FF02:");
                    for (int i = 0; i < 2; i += 1) {
                        groupBuilder.append(":");
                        groupBuilder.append(randomAddress.subSequence(i * 4, i * 4 + 4));
                    }
                    final String group = groupBuilder.toString();
                    final Integer port = SocketUtil.temporaryUdpIpv6Port(ipv6Iface);
                    final String msg = "ohi";
                    final ActorRef sink = getRef();
                    final String iface = ipv6Iface.getName();

                    final ActorRef listener = system.actorOf(Props.create(JavaUdpMulticast.Listener.class, iface, group, port, sink));

                    try {
                        expectMsgClass(Udp.Bound.class);
                        final ActorRef sender = system.actorOf(Props.create(JavaUdpMulticast.Sender.class, iface, group, port, msg));
                        expectMsgEquals(msg);
                        // success with one interface is enough
                        break;

                    } catch (AssertionError ex) {
                        if (!interfaceIterator.hasNext()) throw ex;
                        else {
                            system.log().info("Failed to run test on interface {}", ipv6Iface.getDisplayName());
                        }
                    } finally {
                        // unbind
                        system.stop(listener);
                    }
                }
            }
        }};
    }

    @AfterClass
    public static void tearDown() {
        TestKit.shutdownActorSystem(system);
        system = null;
    }
}
