TDAmeritrade SignIn Api DotNetCore / C#

TDClient.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Net;
using System.Net.Http;
using System.Runtime.InteropServices;
using System.Text.Json;
using System.Threading.Tasks;
using System.Web;

namespace TDConsole
{
    [Serializable]
    public class SignInResult
    {
        public string consumer_key { get; set; }
        public string security_code { get; set; }
        public string access_token { get; set; }
        public string refresh_token { get; set; }
        public string scope { get; set; }
        public int expires_in { get; set; }
        public int refresh_token_expires_in { get; set; }
        public string token_type { get; set; }
    }

    /// <summary>
    /// https://www.reddit.com/r/algotrading/comments/c81vzq/td_ameritrade_api_access_2019_guide/
    /// https://www.reddit.com/r/algotrading/comments/914q22/successful_access_to_td_ameritrade_api/
    /// </summary>
    public class TDClient
    {
        private const string RESULTFILE = "SignInResult.json";

        public string ConsumerKey = "";
        public string RedirectUri = "http://localhost";
        //("Paste from code={code} address bar result in step 1")
        public string SecurityCode = "";

        public SignInResult Result;

        public TDClient()
        {
            Load();
        }

        private void Load()
        {
            if (!File.Exists(RESULTFILE))
            {
                using (var s = File.Create(RESULTFILE)) { }
            }
            var json = File.ReadAllText(RESULTFILE);
            if (string.IsNullOrEmpty(json))
            {
                Result = new SignInResult();
            }
            else
            {
                Result = JsonSerializer.Deserialize<SignInResult>(json);
                ConsumerKey = Result.consumer_key;
                SecurityCode = Result.security_code;
            }
        }

        private void Save()
        {
            if (!File.Exists(RESULTFILE))
            {
                using (var s = File.Create(RESULTFILE)) { }
            }
            var json = JsonSerializer.Serialize(Result);
            File.WriteAllText(RESULTFILE, json);
        }

        public void StartSignIn()
        {
            var encodedKey = HttpUtility.UrlEncode(ConsumerKey);
            var encodedUri = HttpUtility.UrlEncode(RedirectUri);
            var path = $"https://auth.tdameritrade.com/auth?response_type=code&redirect_uri={encodedUri}&client_id={encodedKey}%40AMER.OAUTHAP";
            OpenBrowser(path);
        }

        public async Task CompleteSignIn()
        {
            var decoded = HttpUtility.UrlDecode(SecurityCode);
            var path = "https://api.tdameritrade.com/v1/oauth2/token";

            using (var client = new HttpClient())
            {
                var dict = new Dictionary<string, string>
                {
                    { "grant_type", "authorization_code" },
                    { "access_type", "offline" },
                    { "client_id", $"{ConsumerKey}@AMER.OAUTHAP" },
                    { "redirect_uri", RedirectUri },
                    { "code", decoded }
                };

                var req = new HttpRequestMessage(HttpMethod.Post, path) { Content = new FormUrlEncodedContent(dict) };
                var res = await client.SendAsync(req);

                switch (res.StatusCode)
                {
                    case HttpStatusCode.OK:
                        var r = await res.Content.ReadAsStringAsync();
                        Console.WriteLine(r);
                        Result = JsonSerializer.Deserialize<SignInResult>(r);
                        Result.security_code = SecurityCode;
                        Result.consumer_key = ConsumerKey;
                        Save();
                        break;
                    default:
                        Console.WriteLine("Error: " + res.ReasonPhrase);
                        break;
                }
            }
        }

        public async Task RefreshSignIn()
        {
            var decoded = HttpUtility.UrlDecode(Result.security_code);

            var path = "https://api.tdameritrade.com/v1/oauth2/token";

            var dict = new Dictionary<string, string>
                {
                    { "grant_type", "refresh_token" },
                    { "access_type", "" },
                    { "client_id", $"{Result.consumer_key}@AMER.OAUTHAP" },
                    { "redirect_uri", RedirectUri },
                    { "refresh_token", Result.refresh_token },
                    { "code", decoded }
                };

            var req = new HttpRequestMessage(HttpMethod.Post, path) { Content = new FormUrlEncodedContent(dict) };

            using (var client = new HttpClient())
            {
                var res = await client.SendAsync(req);

                switch (res.StatusCode)
                {
                    case HttpStatusCode.OK:
                        var r = await res.Content.ReadAsStringAsync();
                        Console.WriteLine(r);
                        var result = JsonSerializer.Deserialize<SignInResult>(r);
                        Result.access_token = result.access_token;
                        Save();
                        break;
                    default:
                        Console.WriteLine("Error: " + res.ReasonPhrase);
                        break;
                }
            }
        }

        public async Task GetQuote()
        {

            var symbol = "SPY";
            var key = HttpUtility.UrlEncode(ConsumerKey);

            var path = $"https://api.tdameritrade.com/v1/marketdata/{symbol}/quotes?apikey={key}";

            using (var client = new HttpClient())
            {
                var res = await client.GetAsync(path);

                switch (res.StatusCode)
                {
                    case HttpStatusCode.OK:
                        var r = await res.Content.ReadAsStringAsync();
                        Console.WriteLine(r);
                        break;
                    default:
                        Console.WriteLine("Error: " + res.ReasonPhrase);
                        break;
                }
            }
        }

        static void OpenBrowser(string url)
        {
            try
            {
                Process.Start(url);
            }
            catch
            {
                // hack because of this: https://github.com/dotnet/corefx/issues/10361
                if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
                {
                    url = url.Replace("&", "^&");
                    Process.Start(new ProcessStartInfo("cmd", $"/c start {url}") { CreateNoWindow = true });
                }
                else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
                {
                    Process.Start("xdg-open", url);
                }
                else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
                {
                    Process.Start("open", url);
                }
                else
                {
                    throw;
                }
            }
        }
    }


    class Program
    {
        static async Task Main(string[] args)
        {
            Console.WriteLine("Starting Client");
            Console.WriteLine("...");
            var client = new TDClient();


            Console.WriteLine("1 to sign in fresh, 2 to refresh signin");
            var option = Console.ReadKey();
            switch (option.Key)
            {
                case ConsoleKey.D1:
                    Console.WriteLine("Paste consumer key :");
                    client.ConsumerKey = Console.ReadLine();
                    Console.WriteLine("Opening Browser. Please sign in.");
                    client.StartSignIn();

                    Console.WriteLine("Paste the code. This is in the browser url bar 'code={code}'.");
                    client.SecurityCode = Console.ReadLine();
                    await client.CompleteSignIn();
                    break;
                case ConsoleKey.D2:
                    await client.RefreshSignIn();
                    break;
                default:
                    return;
            }

            await client.GetQuote();
            Console.ReadKey();
        }
    }
}