MqttBroker.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading.Tasks;
using Waher.Events;
using Waher.Networking;
using Waher.Networking.MQTT;
using Waher.Runtime.Inventory;
using Waher.Runtime.Timing;
 
namespace Waher.Things.Mqtt.Model
{
    public class MqttBroker : IDisposable
    {
        private static Scheduler scheduler = null;
        private readonly SortedDictionary<string, MqttTopic> topics = new SortedDictionary<string, MqttTopic>();
        private readonly MqttBrokerNode node;
        private MqttClient mqttClient;
        private bool connectionOk = false;
        private readonly string host;
        private readonly int port;
        private readonly bool tls;
        private readonly bool trustServer;
        private readonly string userName;
        private readonly string password;
        private readonly string connectionSubscription;
        private string willTopic;
        private string willData;
        private bool willRetain;
        private MqttQualityOfService willQoS;
        private DateTime nextCheck;
 
        public MqttBroker(MqttBrokerNode Node, string Host, int Port, bool Tls, bool TrustServer, string UserName, string Password,
            string ConnectionSubscription, string WillTopic, string WillData, bool WillRetain, MqttQualityOfService WillQoS)
        {
            this.node = Node;
            this.host = Host;
            this.port = Port;
            this.tls = Tls;
            this.trustServer = TrustServer;
            this.userName = UserName;
            this.password = Password;
            this.connectionSubscription = ConnectionSubscription;
            this.willTopic = WillTopic;
            this.willData = WillData;
            this.willRetain = WillRetain;
            this.willQoS = WillQoS;
 
            this.Open();
        }
 
        internal MqttClient Client => this.mqttClient;
 
        public MqttBrokerNode Node => this.node;
 
        private void Open()
        {
            this.mqttClient = new MqttClient(this.host, this.port, this.tls, this.userName, this.password, this.willTopic,
                this.willQoS, this.willRetain, Encoding.UTF8.GetBytes(this.willData))
            {
                TrustServer = this.trustServer
            };
 
            this.mqttClient.OnConnectionError += this.MqttClient_OnConnectionError;
            this.mqttClient.OnContentReceived += this.MqttClient_OnContentReceived;
            this.mqttClient.OnStateChanged += this.MqttClient_OnStateChanged;
 
            this.nextCheck = Scheduler.Add(DateTime.Now.AddMinutes(1), this.CheckOnline, null);
        }
 
        private async Task Close()
        {
            if (!(this.mqttClient is null))
            {
                Scheduler.Remove(this.nextCheck);
 
                this.mqttClient.OnConnectionError -= this.MqttClient_OnConnectionError;
                this.mqttClient.OnContentReceived -= this.MqttClient_OnContentReceived;
                this.mqttClient.OnStateChanged -= this.MqttClient_OnStateChanged;
 
                await this.mqttClient.DisposeAsync();
                this.mqttClient = null;
            }
        }
 
        [Obsolete("Use the DisposeAsync() method.")]
        public async void Dispose()
        {
            try
            {
                await this.DisposeAsync();
            }
            catch (Exception ex)
            {
                Log.Exception(ex);
            }
        }
 
        public Task DisposeAsync()
        {
            return this.Close();
        }
 
        private async void CheckOnline(object _)
        {
            try
            {
                if (!(this.mqttClient is null) && !NetworkingModule.Stopping)
                {
                    MqttState State = this.mqttClient.State;
                    if (State == MqttState.Offline || State == MqttState.Error || State == MqttState.Authenticating)
                        await this.mqttClient.Reconnect();
                }
            }
            catch (Exception ex)
            {
                Log.Exception(ex);
            }
            finally
            {
                this.nextCheck = Scheduler.Add(DateTime.Now.AddMinutes(1), this.CheckOnline, null);
            }
        }
 
        public Task Publish(string Topic, MqttQualityOfService QoS, bool Retain, byte[] Data)
        {
            return this.Client.PUBLISH(Topic, QoS, Retain, Data);
        }
 
        public Task Publish(string Topic, MqttQualityOfService QoS, bool Retain, string Data)
        {
            return this.Publish(Topic, QoS, Retain, Encoding.UTF8.GetBytes(Data));
        }
 
        public async Task DataReceived(MqttContent Content)
        {
            MqttTopic Topic = await this.GetTopic(Content.Topic, true, true);
            if (!(Topic is null))
                await Topic.DataReported(Content);
        }
 
        public async Task SetWill(string WillTopic, string WillData, bool WillRetain, MqttQualityOfService WillQoS)
        {
            if (this.willTopic != WillTopic || this.willData != WillData || this.willRetain != WillRetain || this.willQoS != WillQoS)
            {
                await this.Close();
 
                this.willTopic = WillTopic;
                this.willData = WillData;
                this.willRetain = WillRetain;
                this.willQoS = WillQoS;
 
                this.Open();
            }
        }
 
        private async Task MqttClient_OnStateChanged(object Sender, MqttState NewState)
        {
            try
            {
                switch (NewState)
                {
                    case MqttState.Connected:
                        this.connectionOk = true;
                        await this.node.RemoveErrorAsync("Offline");
                        await this.node.RemoveErrorAsync("Error");
 
                        if (!string.IsNullOrEmpty(this.connectionSubscription))
                        {
                            string[] Parts = this.connectionSubscription.Split(',');
                            int i, c = Parts.Length;
 
                            for (i = 0; i < c; i++)
                                Parts[i] = Parts[i].Trim();
 
                            await this.mqttClient.SUBSCRIBE(MqttQualityOfService.AtLeastOnce, Parts);
                        }
                        break;
 
                    case MqttState.Error:
                        await this.node.LogErrorAsync("Error", "Connection to broker failed.");
 
                        if (!NetworkingModule.Stopping)
                            await this.Reconnect();
                        break;
 
                    case MqttState.Offline:
                        await this.node.LogErrorAsync("Offline", "Connection is closed.");
 
                        if (!!NetworkingModule.Stopping)
                            await this.Reconnect();
                        break;
                }
            }
            catch (Exception ex)
            {
                Log.Exception(ex);
            }
        }
 
        private Task MqttClient_OnContentReceived(object Sender, MqttContent Content)
        {
            lock (this.topics)
            {
                if (this.processing)
                {
                    this.queue.AddLast(Content);
                    return Task.CompletedTask;
                }
                else
                    this.processing = true;
            }
 
            this.Process(Content);
 
            return Task.CompletedTask;
        }
 
        private readonly LinkedList<MqttContent> queue = new LinkedList<MqttContent>();
        private bool processing = false;
 
        private async void Process(MqttContent Content)
        {
            try
            {
                while (true)
                {
                    MqttTopic Topic = await this.GetTopic(Content.Topic, true, true);
                    if (!(Topic is null))
                        await Topic.DataReported(Content);
 
                    lock (this.topics)
                    {
                        if (this.queue.First is null)
                        {
                            this.processing = false;
                            break;
                        }
                        else
                        {
                            Content = this.queue.First.Value;
                            this.queue.RemoveFirst();
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                Log.Exception(ex);
                this.processing = false;
            }
        }
 
        private async Task MqttClient_OnConnectionError(object Sender, Exception Exception)
        {
            if (!NetworkingModule.Stopping)
                await this.Reconnect();
        }
 
        private async Task Reconnect()
        {
            if (this.connectionOk)
            {
                this.connectionOk = false;
 
                if (!(this.mqttClient is null) && !NetworkingModule.Stopping)
                    await this.mqttClient.Reconnect();
            }
        }
 
        public async Task<MqttTopic> GetTopic(string TopicString, bool CreateNew, bool IgnoreGuids)
        {
            if (string.IsNullOrEmpty(TopicString))
                return null;
 
            MqttTopicRepresentation Representation = new MqttTopicRepresentation(TopicString, TopicString.Split('/'), 0);
            MqttTopic Topic = await this.GetLocalTopic(Representation, CreateNew);
 
            if (Topic is null)
                return null;
            else if (Representation.MoveNext(Topic))
                return await Topic.GetTopic(Representation, CreateNew, IgnoreGuids, this);
            else
                return Topic;
        }
 
        private async Task<MqttTopic> GetLocalTopic(MqttTopicRepresentation Representation, bool CreateNew)
        {
            string CurrentSegment = Representation.CurrentSegment;
            MqttTopic Topic, Topic2;
 
            lock (this.topics)
            {
                if (this.topics.TryGetValue(CurrentSegment, out Topic))
                    return Topic;
            }
 
            if (Guid.TryParse(CurrentSegment.Replace('_', '-'), out Guid _))
                return null;
 
            if (this.node.HasChildren)
            {
                foreach (INode Child in await this.node.ChildNodes)
                {
                    if (Child is IMqttTopicNode TopicNode && TopicNode.LocalTopic == CurrentSegment)
                    {
                        lock (this.topics)
                        {
                            if (this.topics.TryGetValue(CurrentSegment, out Topic2))
                                return Topic2;
                            else
                            {
                                Topic = new MqttTopic(TopicNode, CurrentSegment, CurrentSegment, null, this);
                                this.topics[CurrentSegment] = Topic;
                                return Topic;
                            }
                        }
                    }
                }
            }
 
            if (!CreateNew)
                return null;
 
            IMqttTopicNode AddNode = Types.FindBest<IMqttTopicNode, MqttTopicRepresentation>(Representation);
            if (AddNode is null)
                return null;
 
            AddNode = await AddNode.CreateNew(Representation);
            Topic = new MqttTopic(AddNode, AddNode.LocalTopic, AddNode.LocalTopic, null, this);
 
            lock (this.topics)
            {
                if (this.topics.TryGetValue(CurrentSegment, out Topic2))
                    return Topic2;
                else
                    this.topics[CurrentSegment] = Topic;
            }
 
            await this.node.AddAsync(AddNode);
 
            return Topic;
        }
 
        public bool Remove(string LocalTopic)
        {
            if (!(LocalTopic is null))
            {
                lock (this.topics)
                {
                    return this.topics.Remove(LocalTopic);
                }
            }
            else
                return false;
        }
 
        public static Scheduler Scheduler
        {
            get
            {
                if (scheduler is null)
                {
                    if (Types.TryGetModuleParameter("Scheduler", out object Obj) && Obj is Scheduler Scheduler)
                        scheduler = Scheduler;
                    else
                    {
                        scheduler = new Scheduler();
 
                        Log.Terminating += (Sender, e) =>
                        {
                            scheduler?.Dispose();
                            scheduler = null;
                        };
                    }
                }
 
                return scheduler;
            }
        }
 
    }
}