var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddControllersWithViews();

// Like with Microsoft.AspNetCore.SpaProxy, a 'spa.proxy.json' file gets generated based on the values in the project file (SpaRoot, SpaProxyClientUrl, SpaProxyLaunchCommand).
// This file gets not published when using "dotnet publish".
// The services get not added and the proxy is not used when the file does not exist.
builder.Services.AddSpaYarp();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
    // 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.MapControllerRoute(
    name: "default",
    pattern: "{controller}/{action=Index}/{id?}");

// The middlewares get only added if the 'spa.proxy.json' file exists and the SpaYarp services were added.
app.UseSpaYarp();

// If the SPA proxy is used, this will never be reached.
app.MapFallbackToFile("index.html");

app.Run();

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.AddControllersWithViews();

        // Like with Microsoft.AspNetCore.SpaProxy, a 'spa.proxy.json' file gets generated based on the values in the project file (SpaRoot, SpaProxyClientUrl, SpaProxyLaunchCommand).
        // This file gets not published when using "dotnet publish".
        // The services get not added and the proxy is not used when the file does not exist.
        services.AddSpaYarp();
    }

    // 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("/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();

        // The middleware gets only added if the 'spa.proxy.json' file exists and the SpaYarp services were added.
        app.UseSpaYarpMiddleware();

        app.UseRouting();

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

            // The route endpoint gets only added if the 'spa.proxy.json' file exists and the SpaYarp services were added.
            endpoints.MapSpaYarp();

            // If the SPA proxy is used, this will never be reached.
            endpoints.MapFallbackToFile("index.html");
        });
    }
}

// First
builder.Services.AddSpaYarp()

//Second
app.UseSpaYarp();