RhSolutions-AddIn/RhSolutions.AddIn/AddIn/RhSolutionsAddIn.cs

using ExcelDna.Integration;
using ExcelDna.IntelliSense;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Office.Interop.Excel;
using RhSolutions.Services;
using System;
using System.Net;

namespace RhSolutions.AddIn
{
    public class RhSolutionsAddIn : IExcelAddIn
    {
        public static Application Excel { get; private set; }
        public static ServiceProvider ServiceProvider { get; set; }
        public static IAddInConfiguration Configuration { get; set; }

        public void AutoOpen()
        {
            IServiceCollection Services = new ServiceCollection();
            Excel = (Application)ExcelDnaUtil.Application;

            Services.AddHttpClient()
                .AddSingleton<IDatabaseClient, RhDatabaseClient>()
                .AddSingleton<IAddInConfiguration, AddInConfiguration>();

            ServiceProvider = Services.BuildServiceProvider();
            Configuration = ServiceProvider.GetService<IAddInConfiguration>();
                        
            IntelliSenseServer.Install();
            EventsUtil.Initialize();

            ServicePointManager.SecurityProtocol =
                SecurityProtocolType.Tls12;
        }

        public void AutoClose()
        {
            IntelliSenseServer.Uninstall();
            EventsUtil.Uninitialize();
        }
    }
}