Startup.cs

using Compendium.Models;
using Compendium.Services;
using Microsoft.AspNetCore.Authentication.OpenIdConnect;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Mvc.Authorization;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Options;
using Microsoft.Identity.Web;
using Microsoft.Identity.Web.UI;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Compendium
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.Configure<CompendiumDatabaseSettings>(
                Configuration.GetSection(nameof(CompendiumDatabaseSettings)));

            services.AddSingleton<ICompendiumDatabaseSettings>(sp =>
                sp.GetRequiredService<IOptions<CompendiumDatabaseSettings>>().Value);

            services.AddSingleton<InteractionsService>();

            services.AddSingleton<CharactersService>();

            services.AddSingleton<SourcesService>();

            services.AddAuthentication(OpenIdConnectDefaults.AuthenticationScheme)
                .AddMicrosoftIdentityWebApp(Configuration.GetSection("AzureAd"));

            services.AddControllersWithViews();

            //services.AddControllersWithViews(options =>
            //{
            //    var policy = new AuthorizationPolicyBuilder()
            //        .RequireAuthenticatedUser()
            //        .Build();
            //    options.Filters.Add(new AuthorizeFilter(policy));
            //});

            services.AddRazorPages()
                 .AddMicrosoftIdentityUI();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseRouting();

            app.UseAuthentication();
            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}