// 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.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Security.Cryptography;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.IdentityModel.Tokens;

namespace JwtSample
{
    public class Startup
    {
        private readonly SymmetricSecurityKey SecurityKey = new SymmetricSecurityKey(RandomNumberGenerator.GetBytes(32));
        private readonly JwtSecurityTokenHandler JwtTokenHandler = new JwtSecurityTokenHandler();

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddSignalR();
            services.AddAuthorization(options =>
            {
                options.AddPolicy(JwtBearerDefaults.AuthenticationScheme, policy =>
                {
                    policy.AddAuthenticationSchemes(JwtBearerDefaults.AuthenticationScheme);
                    policy.RequireClaim(ClaimTypes.NameIdentifier);
                });
            });

            services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
                .AddJwtBearer(options =>
                {
                    options.TokenValidationParameters =
                    new TokenValidationParameters
                    {
                        LifetimeValidator = (before, expires, token, parameters) => expires > DateTime.UtcNow,
                        ValidateAudience = false,
                        ValidateIssuer = false,
                        ValidateActor = false,
                        ValidateLifetime = true,
                        IssuerSigningKey = SecurityKey
                    };

                    options.Events = new JwtBearerEvents
                    {
                        OnMessageReceived = context =>
                        {
                            var accessToken = context.Request.Query["access_token"];

                            if (!string.IsNullOrEmpty(accessToken) &&
                                (context.HttpContext.WebSockets.IsWebSocketRequest || context.Request.Headers["Accept"] == "text/event-stream"))
                            {
                                context.Token = context.Request.Query["access_token"];
                            }
                            return Task.CompletedTask;
                        }
                    };
                });
        }

        public void Configure(IApplicationBuilder app)
        {
            app.UseFileServer();

            app.UseRouting();
            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapHub<Broadcaster>("/broadcast");
                endpoints.MapGet("/generatetoken", context =>
                {
                    return context.Response.WriteAsync(GenerateToken(context));
                });
            });
        }

        private string GenerateToken(HttpContext httpContext)
        {
            var claims = new[] { new Claim(ClaimTypes.NameIdentifier, httpContext.Request.Query["user"]) };
            var credentials = new SigningCredentials(SecurityKey, SecurityAlgorithms.HmacSha256);
            var token = new JwtSecurityToken("SignalRTestServer", "SignalRTests", claims, expires: DateTime.UtcNow.AddSeconds(30), signingCredentials: credentials);
            return JwtTokenHandler.WriteToken(token);
        }
    }
}
