// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Net;
using System.Net.Security;
using System.Security.Authentication;
using System.Security.Cryptography.X509Certificates;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Connections.Features;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.AspNetCore.Server.Kestrel.Https;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
 
namespace SampleApp;
 
public class Startup
{
    public void Configure(IApplicationBuilder app, ILoggerFactory loggerFactory)
    {
        var logger = loggerFactory.CreateLogger("Default");
 
        app.UseClientCertBuffering();
 
        // Add an exception handler that prevents throwing due to large request body size
        app.Use(async (context, next) =>
        {
            // Limit the request body to 1kb
            context.Features.Get<IHttpMaxRequestBodySizeFeature>().MaxRequestBodySize = 1024;
 
            try
            {
                await next.Invoke(context);
            }
            catch (Microsoft.AspNetCore.Http.BadHttpRequestException ex) when (ex.StatusCode == StatusCodes.Status413RequestEntityTooLarge) { }
        });
 
        app.Run(async context =>
        {
            // Drain the request body
            // await context.Request.Body.CopyToAsync(Stream.Null);
 
            var cert = await context.Connection.GetClientCertificateAsync();
 
            var connectionFeature = context.Connection;
            logger.LogDebug($"Peer: {connectionFeature.RemoteIpAddress?.ToString()}:{connectionFeature.RemotePort}"
                + $"{Environment.NewLine}"
                + $"Sock: {connectionFeature.LocalIpAddress?.ToString()}:{connectionFeature.LocalPort}"
                + $"{Environment.NewLine}"
                + cert);
 
            var response = $"hello, world{Environment.NewLine}";
            context.Response.ContentLength = response.Length;
            context.Response.ContentType = "text/plain";
            await context.Response.WriteAsync(response);
        });
    }
 
    public static Task Main(string[] args)
    {
        TaskScheduler.UnobservedTaskException += (sender, e) =>
        {
            Console.WriteLine("Unobserved exception: {0}", e.Exception);
        };
 
        var hostBuilder = new HostBuilder()
            .ConfigureWebHost(webHostBuilder =>
            {
                webHostBuilder
                    .UseKestrel((context, options) =>
                    {
                        if (context.HostingEnvironment.IsDevelopment())
                        {
                            ShowConfig(context.Configuration);
                        }
 
                        var basePort = context.Configuration.GetValue<int?>("BASE_PORT") ?? 5000;
 
                        options.ConfigureHttpsDefaults(httpsOptions =>
                        {
                            httpsOptions.SslProtocols = SslProtocols.Tls12;
 
                            if (!OperatingSystem.IsMacOS())
                            {
                                // Delayed client certificate negotiation is not supported on macOS.
                                httpsOptions.ClientCertificateMode = ClientCertificateMode.DelayCertificate;
                            }
                        });
 
                        options.Listen(IPAddress.Loopback, basePort, listenOptions =>
                        {
                            // Uncomment the following to enable Nagle's algorithm for this endpoint.
                            //listenOptions.NoDelay = false;
 
                            listenOptions.UseConnectionLogging();
                        });
 
                        options.Listen(IPAddress.Loopback, basePort + 1, listenOptions =>
                        {
                            listenOptions.Protocols = Microsoft.AspNetCore.Server.Kestrel.Core.HttpProtocols.Http1;
                            listenOptions.UseHttps();
                            listenOptions.UseConnectionLogging();
                        });
 
                        options.ListenLocalhost(basePort + 2, listenOptions =>
                        {
                            // Use default dev cert
                            listenOptions.UseHttps();
                        });
 
                        options.ListenAnyIP(basePort + 3);
 
                        options.ListenAnyIP(basePort + 4, listenOptions =>
                        {
                            listenOptions.UseHttps(StoreName.My, "localhost", allowInvalid: true);
                        });
 
                        options.ListenAnyIP(basePort + 5, listenOptions =>
                        {
                            var localhostCert = CertificateLoader.LoadFromStoreCert("localhost", "My", StoreLocation.CurrentUser, allowInvalid: true);
 
                            listenOptions.UseHttps((stream, clientHelloInfo, state, cancellationToken) =>
                            {
                                // Here you would check the name, select an appropriate cert, and provide a fallback or fail for null names.
                                var serverName = clientHelloInfo.ServerName;
                                if (serverName != null && serverName != "localhost")
                                {
                                    throw new AuthenticationException($"The endpoint is not configured for server name '{clientHelloInfo.ServerName}'.");
                                }
 
                                return new ValueTask<SslServerAuthenticationOptions>(new SslServerAuthenticationOptions
                                {
                                    ServerCertificate = localhostCert
                                });
                            }, state: null);
                        });
 
                        options
                            .Configure()
                            .Endpoint(IPAddress.Loopback, basePort + 6)
                            .LocalhostEndpoint(basePort + 7)
                            .Load();
 
                        // reloadOnChange: true is the default
                        options
                        .Configure(context.Configuration.GetSection("Kestrel"), reloadOnChange: true)
                        .Endpoint("NamedEndpoint", opt =>
                        {
 
                        })
                        .Endpoint("NamedHttpsEndpoint", opt =>
                        {
                            opt.HttpsOptions.SslProtocols = SslProtocols.Tls12;
                        });
 
                        options.UseSystemd();
 
                        // The following section should be used to demo sockets
                        //options.ListenUnixSocket("/tmp/kestrel-test.sock");
                    })
                    .UseContentRoot(Directory.GetCurrentDirectory())
                    .UseStartup<Startup>();
            })
            .ConfigureLogging((_, factory) =>
            {
                factory.SetMinimumLevel(LogLevel.Debug);
                factory.AddConsole();
            })
            .ConfigureAppConfiguration((hostingContext, config) =>
            {
                var env = hostingContext.HostingEnvironment;
                config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                      .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true);
            });
 
        return hostBuilder.Build().RunAsync();
    }
 
    private static void ShowConfig(IConfiguration config)
    {
        foreach (var pair in config.GetChildren())
        {
            Console.WriteLine($"{pair.Path} - {pair.Value}");
            ShowConfig(pair);
        }
    }
}