IdentityShroud/IdentityShroud.Api/Apis/OpenIdEndpoints.cs

using IdentityShroud.Api.Apis;
using IdentityShroud.Api.Apis.ISResults;
using IdentityShroud.Api.Helpers;
using IdentityShroud.Api.Mappers;
using IdentityShroud.Core.Contracts;
using IdentityShroud.Core.Messages;
using IdentityShroud.Core.Model;
using IdentityShroud.Core.Services.OpenId;
using Microsoft.AspNetCore.Http.HttpResults;
using Microsoft.AspNetCore.Mvc;

namespace IdentityShroud.Api;

public static class OpenIdEndpoints
{
    // openid: auth/realms/{realmSlug}/.well-known/openid-configuration
    // openid: auth/realms/{realmSlug}/openid-connect/(auth|token|jwks)
    public static void MapEndpoints(this IEndpointRouteBuilder erp)
    {
        var realmsGroup = erp.MapGroup("/auth/realms");
        
        var realmSlugGroup = realmsGroup.MapGroup("{realmSlug}")
            .AddEndpointFilter<RealmSlugValidationFilter>();
        realmSlugGroup.MapGet(".well-known/openid-configuration", GetOpenIdConfiguration);

        var openidConnect = realmSlugGroup.MapGroup("openid-connect");
        openidConnect.MapPost("auth", OpenIdConnectAuth);
        openidConnect.MapPost("token", OpenIdConnectToken);
        openidConnect.MapGet("jwks", OpenIdConnectJwks);
    }
    
    private static async Task<JsonHttpResult<OpenIdConfiguration>> GetOpenIdConfiguration(
        string realmSlug,
        [FromServices]IRealmService realmService,
        HttpContext context)
    {
        Realm realm = context.GetValidatedRealm();
        
        var s = $"{context.Request.Scheme}://{context.Request.Host}{context.Request.Path}";
        var searchString = $"realms/{realmSlug}";
        int index = s.IndexOf(searchString, StringComparison.OrdinalIgnoreCase);
        string baseUri = s.Substring(0, index + searchString.Length);

        return TypedResults.Json(new OpenIdConfiguration()
        {
            AuthorizationEndpoint = baseUri + "/openid-connect/auth",
            TokenEndpoint = baseUri + "/openid-connect/token",
            Issuer =  baseUri,
            JwksUri =  baseUri + "/openid-connect/jwks",
        }, AppJsonSerializerContext.Default.OpenIdConfiguration);
    }

    private static async Task<Results<Ok<JsonWebKeySet>, BadRequest>> OpenIdConnectJwks(
        string realmSlug,
        [FromServices]IRealmService realmService,
        [FromServices]KeyMapper keyMapper,
        HttpContext context)
    {
        Realm realm = context.GetValidatedRealm();
        await realmService.LoadActiveKeys(realm);
        return TypedResults.Ok(keyMapper.KeyListToJsonWebKeySet(realm.TokenSigningKeys));
    }

    private static async  Task<Results<
            Ok<TokenResponse>,
            BadRequest<ErrorDto>,
            ISUnauthorizedHttpResult
    >> OpenIdConnectToken(
        string realmSlug,
        [FromServices] IClientService clientService,
        HttpContext context,
        CancellationToken ct)
    {
        IFormCollection form = await context.Request.ReadFormAsync();
        
        string grantType = form["grant_type"].ToString();
        string clientId = form["client_id"].ToString();
        string scope = form["scope"].ToString();

        if (grantType == "client_credentials")
        {
            string? clientSecret = null;
            bool withAuthHeader = false;
            if (HeaderHelpers.TryGetBasicAuth(context, out string? user, out string? password))
            {
                withAuthHeader = true;
                clientId = user;
                clientSecret = password;
            }
            clientSecret ??= form["client_secret"].ToString();

            if (string.IsNullOrEmpty(clientId) ||
                string.IsNullOrEmpty(clientSecret))
            {
                return CreateBadRequest("invalid_request");
            }
            
            Realm realm = context.GetValidatedRealm();
            Client? client = await clientService.GetByClientId(realm.Id, clientId, ct);
            if (client is null)
            {
                if (withAuthHeader)
                {
                    return new ISUnauthorizedHttpResult([$"Basic realm=\"{realm.Slug}\""]);
                }
                return CreateBadRequest("invalid_client");
            }
            
            if (!client.AllowClientCredentialsFlow)
                return CreateBadRequest("unauthorized_client");

        }
        else
            return CreateBadRequest("unsupported_grant_type");

        context.Response.Headers.CacheControl = "no-store";
        context.Response.Headers.Pragma = "no-cache";

        return TypedResults.Ok(new TokenResponse()
        {
            AccessToken = "token",
            TokenType = "bearer",
            ExpiresIn = 3600,
        });
    }

    private static BadRequest<ErrorDto> CreateBadRequest(string error) =>
        TypedResults.BadRequest(new ErrorDto(error));

        
    
    private static Task OpenIdConnectAuth(HttpContext context)
    {
        throw new NotImplementedException();
    }
}