Add discord oauth endpoint

ChaosBot/WebServer/App/DiscordController.cs

@@ -0,0 +1,58 @@
+using System.Collections.Generic;
+using System.Net.Http;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.Configuration;
+using Newtonsoft.Json;
+using NLog;
+
+namespace ChaosBot.WebServer.App
+{
+    [ApiController]
+    [Route("/discord")]
+    public class DiscordController : Controller
+    {
+        private static readonly HttpClient client = new HttpClient();
+        private static readonly ILogger Logger = Program.Logger;
+        
+        [HttpGet]
+        public async Task<IActionResult> Index(string code = null)
+        {
+            string redirectUri = $"{Request.Scheme}://{Request.Host}/discord";
+            string clientId = Program.AppSettingsHandler.GetValue<string>("Discord:ClientId");
+            string clientSecret = Program.AppSettingsHandler.GetValue<string>("Discord:ClientSecret");
+            
+            if (code == null)
+                return Redirect($"https://discord.com/api/oauth2/authorize?client_id={clientId}&redirect_uri={redirectUri}&response_type=code&scope=identify%20guilds");
+
+            Dictionary<string, string> values = new Dictionary<string, string>
+            {
+                { "client_id", clientId },
+                { "client_secret", clientSecret },
+                { "grant_type", "authorization_code" },
+                { "code", code },
+                { "redirect_uri", redirectUri },
+                { "scope", "identify guild" }
+            };
+
+            FormUrlEncodedContent content = new FormUrlEncodedContent(values);
+            HttpResponseMessage response = await client.PostAsync("https://discord.com/api/oauth2/token", content);
+            string responseString = await response.Content.ReadAsStringAsync();
+            DiscordOauthResponse responseObject = JsonConvert.DeserializeObject<DiscordOauthResponse>(responseString);
+
+            return LocalRedirect($"/#/?access_token={responseObject.access_token}");
+        }
+    }
+
+    internal class DiscordOauthResponse
+    {
+        public string error = null;
+        public string error_description = null;
+        
+        public string access_token = null;
+        public int expires_in = 0;
+        public string refresh_token = null;
+        public string scope = null;
+        public string token_type = null;
+    }
+}