using System;
using System.Threading.Tasks;
using Makaretu.Dns;
using MQTTnet;
using MQTTnet.Server;
using UnityEngine;

namespace SicknessReduction.Haptic
{
    public sealed class DataBroker
    {
        private readonly IMqttServer server;
        private readonly Task serverStarted;
        private bool disposed;

        private DataBroker()
        {
            server = new MqttFactory().CreateMqttServer();
            var service = new ServiceProfile("VRCyclingControllers", "_mqtt._tcp", 1883,
                new[] {Helpers.GetIPAddress()});
            var sd = new ServiceDiscovery();
            sd.Advertise(service);
            serverStarted = server.StartAsync(new MqttServerOptions());
            server.ClientSubscribedTopicHandler =
                new MqttServerClientSubscribedHandlerDelegate(OnClientSubscribedTopic);
            Debug.Log($"Mqtt Server started at {Helpers.GetIPAddress()}");
            //await PublishBla();
        }

        public Action<string, string> onClientSubscribed { set; get; }

        public async Task AwaitServerStarted()
        {
            await serverStarted;
        }

        public async Task Publish(string topic, string payload)
        {
            Debug.Assert(server.IsStarted);
            await server.PublishAsync(new MqttApplicationMessageBuilder().WithTopic(topic)
                .WithPayload($"{payload}\0").Build());
        }

        private void OnClientSubscribedTopic(MqttServerClientSubscribedTopicEventArgs args)
        {
            Debug.Log($"Client {args.ClientId} subscribed to topic {args.TopicFilter.Topic}");
            onClientSubscribed?.Invoke(args.ClientId, args.TopicFilter.Topic);
        }

        private async void Dispose()
        {
            if (server == null || !server.IsStarted) return;
            await server.StopAsync();
            disposed = true;
        }

        #region signleton

        private static readonly Lazy<DataBroker>
            lazy =
                new Lazy<DataBroker>
                    (() => new DataBroker());

        public static DataBroker Instance => lazy.Value;

        public static void DisposeInstance()
        {
            if (!Instance.disposed) Instance.Dispose();
        }

        #endregion
    }
}