isn/Controllers/HomeController.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
using IdentityServer4.Services;
using Microsoft.AspNetCore.DataProtection;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using nuget_host.Entities;
using nuget_host.Models;

namespace nuget_host.Controllers
{
    public class HomeController : Controller
    {
        private readonly IIdentityServerInteractionService _interaction;
        private readonly ILogger _logger;
        readonly IHostingEnvironment _environment;
        public IDataProtector DataProtector { get; } 
        public SmtpSettings Options { get; } //set only via Secret Manager

        public HomeController(
            IOptions<SmtpSettings> smtpSettings,
            IDataProtectionProvider provider, 
            IIdentityServerInteractionService interaction, Microsoft.AspNetCore.Hosting.IHostingEnvironment environment, ILogger<HomeController> logger)
        {
            _interaction = interaction;
            _environment = environment;
            _logger = logger;
            Options = smtpSettings.Value;
            DataProtector = provider.CreateProtector(Options.ProtectionTitle);
        }
        
        public IActionResult Index()
        {
            return View();
        }

        public IActionResult About()
        {
            ViewData["Message"] = "Your application description page.";

            return View();
        }

        public IActionResult Contact()
        {
            ViewData["Message"] = "Your contact page.";

            return View();
        }

        public IActionResult Privacy()
        {
            ViewData["Message"] = "Your Privacy page.";

            return Ok(ViewData);
        }


        /// <summary>
        /// Shows the error page
        /// </summary>
        public async Task<IActionResult> Error(string errorId)
        {
            var vm = new ErrorViewModel();

            // retrieve error details from identityserver
            var message = await _interaction.GetErrorContextAsync(errorId);
            if (message != null)
            {
                vm.Error = message;

                if (!_environment.IsDevelopment())
                {
                    // only show in development
                    message.ErrorDescription = null;
                }
            }

            return View("Error", vm);
        }

    }
}