MqttBrokers.cs

using System.Collections.Generic;
using System.Text;
using System.Threading.Tasks;
using Waher.Networking.MQTT;
using Waher.Security;
 
namespace Waher.Things.Mqtt.Model
{
    public static class MqttBrokers
    {
        private static readonly Dictionary<string, MqttBroker> brokers = new Dictionary<string, MqttBroker>();
 
        public static string GetKey(string Host, int Port, bool Tls, bool TrustServer, string UserName, string Password, string ConnectionSubscription)
        {
            StringBuilder sb = new StringBuilder();
 
            sb.AppendLine(Host);
            sb.AppendLine(Port.ToString());
            sb.AppendLine(Tls.ToString());
            sb.AppendLine(TrustServer.ToString());
            sb.AppendLine(UserName);
            sb.AppendLine(Password);
            sb.AppendLine(ConnectionSubscription);
 
            return Hashes.ComputeSHA1HashString(Encoding.UTF8.GetBytes(sb.ToString()));
        }
 
        public static MqttBroker GetCachedBroker(string Key)
        {
            lock (brokers)
            {
                if (brokers.TryGetValue(Key, out MqttBroker Broker))
                    return Broker;
                else
                    return null;
            }
        }
 
        public static async Task<MqttBroker> GetBroker(MqttBrokerNode Node, string Key, string Host, int Port, bool Tls, bool TrustServer,
            string UserName, string Password, string ConnectionSubscription, string WillTopic, string WillData, bool WillRetain, 
            MqttQualityOfService WillQoS)
        {
            MqttBroker Broker;
 
            lock (brokers)
            {
                if (!brokers.TryGetValue(Key, out Broker))
                    Broker = null;
            }
 
            if (!(Broker is null))
            {
                await Broker.SetWill(WillTopic, WillData, WillRetain, WillQoS);
                return Broker;
            }
            else
            {
                Broker = new MqttBroker(Node, Host, Port, Tls, TrustServer, UserName, Password, ConnectionSubscription,
                    WillTopic, WillData, WillRetain, WillQoS);
 
                MqttBroker Result;
                MqttBroker Obsolete;
 
                lock (brokers)
                {
                    if (brokers.TryGetValue(Key, out Result))
                        Obsolete = Broker;
                    else
                    {
                        brokers[Key] = Result = Broker;
                        Obsolete = null;
                    }
                }
 
                if (!(Obsolete is null))
                    await Obsolete.DisposeAsync();
 
                return Result;
            }
        }
 
        public static Task DestroyBroker(string Key)
        {
            MqttBroker Broker;
 
            lock (brokers)
            {
                if (!brokers.TryGetValue(Key, out Broker))
                    return Task.CompletedTask;
 
                brokers.Remove(Key);
            }
 
            return Broker.DisposeAsync();
        }
 
    }
}