// This example shows how to implement reading from edge node metrics using a single overriden method.
//
// You can use any Sparkplug application, including our SparkplugCmd utility and the SparkplugApplicationConsoleDemo
// program, to subscribe to the edge node data. 
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-ConnectivityStudio/Latest/examples.html .
// Sparkplug examples in C# on GitHub: https://github.com/OPCLabs/Examples-ConnectivityStudio-CSharp .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

using System;
using OpcLabs.EasySparkplug;
using OpcLabs.EasySparkplug.OperationModel;

namespace SparkplugDocExamples.EdgeNode._EasySparkplugEdgeNode
{
    class OnRead
    {
        /// <summary>
        /// A sparkplug edge node, with specialized read behavior for its metrics.
        /// </summary>
        class EdgeNodeWithOnRead : EasySparkplugEdgeNode
        {
            /// <summary>
            /// Obtains the data for Sparkplug read.
            /// </summary>
            /// <param name="eventArgs">The event arguments.</param>
            protected override void OnRead(SparkplugMetricReadEventArgs eventArgs)
            {
                // Obtain the state associated with the metric that is being read.
                object state = eventArgs.Metric.State;

                // The state is null in metrics that we have not created, such as the "node rebirth" metric.
                if (state is null)
                    return;

                // Use the state as the offset for the random value, so that each metric generates values in a unique range.
                int offset = (int)state * 100;

                // Generate a random value, indicate that the read has been handled, and return the generated value.
                eventArgs.HandleAndReturn(Random.Next(offset, offset + 100));
            }

            static private readonly Random Random = new Random();
        }
        
        static public void Main1()
        {
            // Note that the default port for the "mqtt" scheme is 1883.
            var hostDescriptor = new SparkplugHostDescriptor("mqtt://localhost");

            // Instantiate our derived edge node object and hook events.
            var edgeNode = new EdgeNodeWithOnRead
            {
                EdgeNodeId = "easySparkplugDemo",
                GroupId = "easyGroup",
                SystemDescriptor = hostDescriptor
            };
            edgeNode.SystemConnectionStateChanged += (sender, eventArgs) =>
            {
                // Display the new connection state (such as when the connection to the broker succeeds or fails).
                Console.WriteLine($"{nameof(EasySparkplugEdgeNode.SystemConnectionStateChanged)}: {eventArgs}");
            };

            // Create metrics in the folder. Distinguish them by their state.
            edgeNode.Add(new SparkplugMetric("MyMetric1").ValueType<int>().SetState(1));
            edgeNode.Add(new SparkplugMetric("MyMetric2").ValueType<int>().SetState(2));
            edgeNode.Add(new SparkplugMetric("MyMetric3").ValueType<int>().SetState(3));
            edgeNode.Add(new SparkplugMetric("MyMetric4").ValueType<int>().SetState(4));
            edgeNode.Add(new SparkplugMetric("MyMetric5").ValueType<int>().SetState(5));

            // Start the edge node.
            Console.WriteLine("The edge node is starting...");
            edgeNode.Start();

            Console.WriteLine("The edge node is started.");
            Console.WriteLine();

            // Let the user decide when to stop.
            Console.WriteLine("Press Enter to stop the edge node...");
            Console.ReadLine();

            // Stop the edge node.
            Console.WriteLine("The edge node is stopping...");
            edgeNode.Stop();

            Console.WriteLine("The edge node is stopped.");
        }
    }
}