using Microsoft.Extensions.DependencyInjection;

using Microsoft.Extensions.Hosting;

using Microsoft.Extensions.Logging;

​

using OpenTelemetry.Metrics;

using OpenTelemetry.Resources;

​

using System;

using System.Threading;

using System.Threading.Tasks;

​

using System.Diagnostics;

using System.Diagnostics.Metrics;

​

using System.Collections.Generic;

​

​

/*

<Project Sdk="Microsoft.NET.Sdk">

​

  <PropertyGroup>

    <OutputType>Exe</OutputType>

    <TargetFramework>net8.0</TargetFramework>

    <ImplicitUsings>enable</ImplicitUsings>

    <Nullable>enable</Nullable>

  </PropertyGroup>

​

  <ItemGroup>

    <PackageReference Include="Microsoft.Extensions.Hosting" Version="7.0.1" />

    <PackageReference Include="OpenTelemetry.Exporter.Console" Version="1.4.0" />

    <PackageReference Include="OpenTelemetry.Exporter.Prometheus.HttpListener" Version="1.5.0-alpha.1" />

    <PackageReference Include="OpenTelemetry.Extensions.Hosting" Version="1.4.0" />

  </ItemGroup>

​

</Project>

​

*/

​

namespace OtlpMetrics;

​

internal class Program

{

    private static async Task Main(string[] args)

    {

        var host = Host

            .CreateDefaultBuilder()

            .ConfigureLogging(logger => logger.AddConsole())

            .ConfigureServices(services =>

            {

                services.AddOpenTelemetry()

                    .WithMetrics(metricsBuilder =>

                    {

                        metricsBuilder.ConfigureResource(resourceBuilder =>

                        {

                            resourceBuilder

                                .AddService("ClickService")

                                .AddAttributes(new[]

                                {

                                    new KeyValuePair<string, object>("dc", Environment.GetEnvironmentVariable("dc") ?? "il3"),

                                    new KeyValuePair<string, object>("env", Environment.GetEnvironmentVariable("env") ?? "local"),

                                })

                                .AddTelemetrySdk();

                        });

                        var meterProviderBuilder = metricsBuilder.AddMeter("custom-console-meter");

​

                        metricsBuilder.AddConsoleExporter();

​

                        metricsBuilder.AddPrometheusHttpListener(httpListenerOptions =>

                        {

                            httpListenerOptions.UriPrefixes = new[] { "http://localhost:9464/" };

                        });

                    });

​

                services.AddHostedService<ClickAppHost>();

            });

​

        await host.RunConsoleAsync();

    }

}

​

// a simple application the loops until a CTRL-C combination is not added

// counts the number of clicked buttons

public class ClickAppHost : IHostedService

{

    private readonly CancellationTokenSource _work = new();

​

    public Task StartAsync(CancellationToken cancellationToken)

    {

        Console.CancelKeyPress += (sender, args) =>

        {

            Console.WriteLine("cancellation requested");

            _work.Cancel();

        };

​

        while (!_work.Token.IsCancellationRequested)

        {

            Console.WriteLine("Click a key");

            var sw = Stopwatch.GetTimestamp();

            var key = Console.ReadKey(intercept: true);

            var elapsed = Stopwatch.GetElapsedTime(sw);

            var combination = GetKeyLabel(key);

            Console.WriteLine($"Clicked: {combination}");

​

            Meters.ClickInstrument.Add(1,

                new KeyValuePair<string, object?>("key", combination));

            Meters.DurationInstrumentation.Record((long)elapsed.TotalMilliseconds);

        }

​

        return Task.CompletedTask;

​

        static string GetKeyLabel(ConsoleKeyInfo keyInfo)

            => keyInfo.Modifiers != ConsoleModifiers.None

                ? $"{keyInfo.Modifiers}-{keyInfo.KeyChar}"

                : keyInfo.KeyChar.ToString();

    }

​

    public Task StopAsync(CancellationToken cancellationToken)

    {

        _work.Cancel();

​

        return Task.CompletedTask;

    }

}

​

public static class Meters

{

    private static readonly Meter _applicationMeter = new("custom-console-meter", "1.0.0");

​

    public static readonly Counter<int> ClickInstrument

        = _applicationMeter.CreateCounter<int>("click_c", "clicks_total", "count the number of clicks");

​

    public static readonly Histogram<long> DurationInstrumentation

        = _applicationMeter.CreateHistogram<long>("click_t", "ms", "time to click after prompted");

}