Program.cs

using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;
using Microsoft.IdentityModel.Tokens;
using StackOverflow;
using StackOverflow.Data;
using StackOverflow.Models;
using StackOverflow.Services;
using System.Text.Json.Serialization;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
var connectionString = builder.Configuration.GetConnectionString("DefaultConnection");
builder.Services.AddDbContext<ApplicationDbContext>(options =>
    options.UseSqlServer(connectionString));
builder.Services.AddDatabaseDeveloperPageExceptionFilter();

builder.Services
    .AddIdentity<ApplicationUser, IdentityRole>(options => options.SignIn.RequireConfirmedAccount = true)
    .AddRoleManager<RoleManager<IdentityRole>>()
    .AddDefaultUI()
    .AddEntityFrameworkStores<ApplicationDbContext>()
    .AddDefaultTokenProviders();

builder.Services.AddIdentityServer()
    .AddApiAuthorization<ApplicationUser, ApplicationDbContext>();

builder.Services.AddControllersWithViews().AddJsonOptions(x => x.JsonSerializerOptions.ReferenceHandler = ReferenceHandler.IgnoreCycles);
builder.Services.AddRazorPages();

builder.Services.AddScoped<AnswersService>();
builder.Services.AddScoped<AnswerVotesService>();
builder.Services.AddScoped<ApplicationUsersService>();
builder.Services.AddScoped<QuestionsService>();
builder.Services.AddScoped<QuestionTagsService>();
builder.Services.AddScoped<QuestionVotesService>();
builder.Services.AddScoped<TagsService>();

builder.Services.AddAuthentication(auth =>
{
    auth.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
    auth.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
})
.AddJwtBearer(options =>
{
    options.TokenValidationParameters = new TokenValidationParameters();
});

var app = builder.Build();

AdminInitializer.Initialize(app.Services.CreateScope().ServiceProvider);

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseMigrationsEndPoint();
}
else
{
    // 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.UseCors(x => x
            .AllowAnyOrigin()
            .AllowAnyMethod()
            .AllowAnyHeader());

app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();

app.UseAuthentication();
app.UseIdentityServer();
app.UseAuthorization();
app.UseMiddleware<JwtMiddleware>();

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

app.MapFallbackToFile("index.html"); ;

app.Run();