Program.cs

using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;
using netdotro.Data;
using SeedIdentity.Data;

internal class Program
{
    private static void CheckSameSite(HttpContext httpContext, CookieOptions options)
    {
        if (options.SameSite == SameSiteMode.None)
        {
            var userAgent = httpContext.Request.Headers["User-Agent"].ToString();

            if (DisallowsSameSiteNone(userAgent))
            {
                options.SameSite = SameSiteMode.Unspecified;
                options.Secure = true;
            }
        }
    }

    //  Read comments in https://docs.microsoft.com/en-us/aspnet/core/security/samesite?view=aspnetcore-3.1
    public static bool DisallowsSameSiteNone(string userAgent)
    {
        // Check if a null or empty string has been passed in, since this
        // will cause further interrogation of the useragent to fail.
        if (String.IsNullOrWhiteSpace(userAgent))
            return false;

        // Cover all iOS based browsers here. This includes:
        // - Safari on iOS 12 for iPhone, iPod Touch, iPad
        // - WkWebview on iOS 12 for iPhone, iPod Touch, iPad
        // - Chrome on iOS 12 for iPhone, iPod Touch, iPad
        // All of which are broken by SameSite=None, because they use the iOS networking
        // stack.
        if (userAgent.Contains("CPU iPhone OS 12") ||
            userAgent.Contains("iPad; CPU OS 12"))
        {
            return true;
        }

        // Cover Mac OS X based browsers that use the Mac OS networking stack. 
        // This includes:
        // - Safari on Mac OS X.
        // This does not include:
        // - Chrome on Mac OS X
        // Because they do not use the Mac OS networking stack.
        if (userAgent.Contains("Macintosh; Intel Mac OS X 10_14") &&
            userAgent.Contains("Version/") && userAgent.Contains("Safari"))
        {
            return true;
        }

        // Cover Chrome 50-69, because some versions are broken by SameSite=None, 
        // and none in this range require it.
        // Note: this covers some pre-Chromium Edge versions, 
        // but pre-Chromium Edge does not require SameSite=None.
        if (userAgent.Contains("Chrome"))
        {
            return true;
        }

        return false;
    }

    private static void Main(string[] args)
    {
        var builder = WebApplication.CreateBuilder(args);
        builder.Services.Configure<CookiePolicyOptions>(options =>
        {
            options.MinimumSameSitePolicy = SameSiteMode.Unspecified;
            options.OnAppendCookie = cookieContext =>
                CheckSameSite(cookieContext.Context, cookieContext.CookieOptions);
            options.OnDeleteCookie = cookieContext =>
                CheckSameSite(cookieContext.Context, cookieContext.CookieOptions);
        });

        // Add services to the container.
        var connectionString = builder.Configuration.GetConnectionString("DefaultConnection") ?? throw new InvalidOperationException("Connection string 'DefaultConnection' not found.");
        builder.Services.AddDbContext<ApplicationDbContext>(options =>
            options.UseSqlite(connectionString));
        builder.Services.AddDatabaseDeveloperPageExceptionFilter();

        builder.Services.AddIdentity<ApplicationUser, IdentityRole>(options =>
        {
            options.SignIn.RequireConfirmedAccount = false;
            options.Stores.MaxLengthForKeys = 128;
        })
        .AddEntityFrameworkStores<ApplicationDbContext>()
        .AddRoles<IdentityRole>()
        .AddDefaultUI()
        .AddDefaultTokenProviders();

        builder.Services.Configure<IdentityOptions>(options =>
        {
            // Password settings.
            options.Password.RequireDigit = false;
            options.Password.RequireLowercase = false;
            options.Password.RequireNonAlphanumeric = false;
            options.Password.RequireUppercase = false;
            options.Password.RequiredLength = 8;
            options.Password.RequiredUniqueChars = 2;

            // Lockout settings.
            options.Lockout.DefaultLockoutTimeSpan = TimeSpan.FromMinutes(5);
            options.Lockout.MaxFailedAccessAttempts = 10;
            options.Lockout.AllowedForNewUsers = true;

            // User settings.
            options.User.AllowedUserNameCharacters =
            "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._@+";
            options.User.RequireUniqueEmail = true;
        });

        builder.Services.ConfigureApplicationCookie(options =>
        {
            // Cookie settings
            options.Cookie.HttpOnly = true;
            options.ExpireTimeSpan = TimeSpan.FromMinutes(5);

            options.LoginPath = "/Identity/Account/Login";
            options.AccessDeniedPath = "/Identity/Account/AccessDenied";
            options.SlidingExpiration = true;
        });

        builder.Services.AddAuthorization();

        // builder.Services.AddAuthentication().AddGoogle(googleOptions =>
        // {
        //     if (googleOptions != null && builder.Configuration != null)
        //     {
        //         googleOptions.ClientId = builder.Configuration["Authentication:Google:ClientId"]
        //                                 ?? throw new ArgumentNullException("Authentication:Google:ClientId");
        //         googleOptions.ClientSecret = builder.Configuration["Authentication:Google:ClientSecret"]
        //                                     ?? throw new ArgumentNullException("Authentication:Google:ClientSecret"); ;
        //     }
        // });

        builder.Services.AddRazorPages();
        var app = builder.Build();

        // Configure the HTTP request pipeline.
        if (!app.Environment.IsDevelopment())
        {
            app.UseExceptionHandler("/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.UseCookiePolicy();
        app.UseAuthentication();
        app.UseAuthorization();

        app.MapRazorPages();

        using (var scope = app.Services.CreateScope())
        {
            var services = scope.ServiceProvider;

            var context = services.GetRequiredService<ApplicationDbContext>();

            context.Database.Migrate();

            var userMgr = services.GetRequiredService<UserManager<ApplicationUser>>();
            var roleMgr = services.GetRequiredService<RoleManager<IdentityRole>>();

            IdentitySeedData.Initialize(context, userMgr, roleMgr).Wait();
        }

        app.Run();
    }
}