using System.Net;
using System.Text;
using FinalFactory.Rendezvous.TestClient;
using LiteNetLib;

namespace FinalFactory.Rendezvous.Tests.TestClient;

public sealed class DirectEchoProtocolTests
{
    [Fact]
    public async Task HostReleasesPendingNonceWhenPeerDisconnectsBeforeAcknowledgement()
    {
        using CancellationTokenSource timeout = new(TimeSpan.FromSeconds(3));
        EventBasedNetListener hostEvents = new();
        EventBasedNetListener clientEvents = new();
        hostEvents.ConnectionRequestEvent += request => request.Accept();
        NetPeer? clientPeer = null;
        clientEvents.PeerConnectedEvent += peer => clientPeer = peer;
        NetManager hostManager = new(hostEvents);
        NetManager clientManager = new(clientEvents);
        try
        {
            Assert.True(hostManager.Start(0));
            Assert.True(clientManager.Start(0));
            clientManager.Connect(
                new IPEndPoint(IPAddress.Loopback, hostManager.LocalPort),
                "echo-test");
            await PumpUntilAsync(
                () => clientPeer is not null,
                hostManager,
                clientManager,
                clientManager,
                timeout.Token);
            using DirectEchoProtocol host = new(hostEvents, host: true);
            clientPeer!.Send(
                Encoding.ASCII.GetBytes("rv1-ping:00112233445566778899aabbccddeeff"),
                DeliveryMethod.ReliableOrdered);
            await PumpUntilAsync(
                () => host.PendingHostExchangeCount == 1,
                hostManager,
                clientManager,
                clientManager,
                timeout.Token);

            clientPeer.Disconnect();
            await PumpUntilAsync(
                () => host.PendingHostExchangeCount == 0,
                hostManager,
                clientManager,
                clientManager,
                timeout.Token);

            Assert.Equal(0, host.PendingHostExchangeCount);
        }
        finally
        {
            clientManager.Stop();
            hostManager.Stop();
        }
    }

    [Fact]
    public async Task HostVerifiesOverlappingPeersAgainstTheirOwnNonces()
    {
        using CancellationTokenSource timeout = new(TimeSpan.FromSeconds(3));
        EventBasedNetListener hostEvents = new();
        EventBasedNetListener firstEvents = new();
        EventBasedNetListener secondEvents = new();
        hostEvents.ConnectionRequestEvent += request => request.Accept();
        NetPeer? firstPeer = null;
        NetPeer? secondPeer = null;
        firstEvents.PeerConnectedEvent += peer => firstPeer = peer;
        secondEvents.PeerConnectedEvent += peer => secondPeer = peer;
        NetManager hostManager = new(hostEvents);
        NetManager firstManager = new(firstEvents);
        NetManager secondManager = new(secondEvents);
        try
        {
            Assert.True(hostManager.Start(0));
            Assert.True(firstManager.Start(0));
            Assert.True(secondManager.Start(0));
            IPEndPoint hostEndpoint = new(IPAddress.Loopback, hostManager.LocalPort);
            firstManager.Connect(hostEndpoint, "echo-test");
            secondManager.Connect(hostEndpoint, "echo-test");
            await PumpUntilAsync(
                () => firstPeer is not null && secondPeer is not null,
                hostManager,
                firstManager,
                secondManager,
                timeout.Token);

            using DirectEchoProtocol host = new(hostEvents, host: true);
            using DirectEchoProtocol first = new(firstEvents, host: false);
            using DirectEchoProtocol second = new(secondEvents, host: false);
            int hostCompletions = 0;
            host.ExchangeCompleted += _ => hostCompletions++;
            first.BeginJoin(firstPeer!);
            second.BeginJoin(secondPeer!);

            await PumpUntilAsync(
                () => first.Completion.IsCompleted
                    && second.Completion.IsCompleted
                    && hostCompletions == 2,
                hostManager,
                firstManager,
                secondManager,
                timeout.Token);

            Assert.Equal(2, hostCompletions);
        }
        finally
        {
            firstManager.Stop();
            secondManager.Stop();
            hostManager.Stop();
        }
    }

    private static async Task PumpUntilAsync(
        Func<bool> predicate,
        NetManager host,
        NetManager first,
        NetManager second,
        CancellationToken cancellationToken)
    {
        while (!predicate())
        {
            cancellationToken.ThrowIfCancellationRequested();
            host.PollEvents();
            first.PollEvents();
            second.PollEvents();
            await Task.Delay(2, cancellationToken);
        }
    }
}