hass-workstation-service/hass-workstation-service/Domain/Sensors/AbstractSensor.cs

using System;
using System.Threading.Tasks;
using hass_workstation_service.Communication;
using MQTTnet;

namespace hass_workstation_service.Domain.Sensors
{
    public abstract class AbstractSensor : AbstractDiscoverable
    {
        /// <summary>
        /// The update interval in seconds. It checks state only if the interval has passed.
        /// </summary>
        public int UpdateInterval { get; protected set; }
        public DateTime? LastUpdated { get; protected set; }
        public string PreviousPublishedState { get; protected set; }
        public MqttPublisher Publisher { get; protected set; }
        public override string Domain { get => "sensor"; }

        public AbstractSensor(MqttPublisher publisher, string name, int updateInterval = 10, Guid id = default)
        {
            Id = id == Guid.Empty ? Guid.NewGuid() : id;
            Name = name;
            Publisher = publisher;
            UpdateInterval = updateInterval;
        }

        public abstract string GetState();

        public async Task PublishStateAsync()
        {
            // dont't even check the state if the update interval hasn't passed
            if (LastUpdated.HasValue && LastUpdated.Value.AddSeconds(UpdateInterval) > DateTime.UtcNow)
                return;

            string state = GetState();
            // don't publish the state if it hasn't changed
            if (PreviousPublishedState == state)
                return;

            var message = new MqttApplicationMessageBuilder()
                .WithTopic(GetAutoDiscoveryConfig().State_topic)
                .WithPayload(state)
                //.WithExactlyOnceQoS()
                //.WithRetainFlag()
                .Build();
            await Publisher.Publish(message);
            PreviousPublishedState = state;
            LastUpdated = DateTime.UtcNow;
        }

        public async void PublishAutoDiscoveryConfigAsync() => await Publisher.AnnounceAutoDiscoveryConfig(this);

        public async Task UnPublishAutoDiscoveryConfigAsync()
        {
            await Publisher.AnnounceAutoDiscoveryConfig(this, true);
            this._autoDiscoveryConfigModel = null;
        }

        protected SensorDiscoveryConfigModel _autoDiscoveryConfigModel;
        protected SensorDiscoveryConfigModel SetAutoDiscoveryConfigModel(SensorDiscoveryConfigModel config)
        {
            _autoDiscoveryConfigModel = config;
            return config;
        }
    }
}