Start der Backend Implementierung

Projekt für die Implementierung des Backends hinzugefügt. Klasse Logger --> Dient zum Loggen in die Datenbank. Klasse Ticket_System --> Hauptklasse für das die Backendanwendung. Auth Client hinzugefügt. Token stuff hinzugefügt.

Ticket_System/AuthClient.cs

@@ -0,0 +1,59 @@
+using System;
+using System.Collections.Generic;
+using System.Net.Http.Headers;
+using System.Text;
+using System.Text.Json;
+
+namespace Ticket_System
+{
+
+
+    public sealed class AuthApiClient
+    {
+        private readonly HttpClient _http;
+        private readonly JsonSerializerOptions _json = new() { PropertyNameCaseInsensitive = true };
+
+        public AuthApiClient(string baseUrl)
+        {
+            _http = new HttpClient { BaseAddress = new Uri(baseUrl.TrimEnd('/') + "/") };
+        }
+
+        public async Task<ResponseToken?> SignInAsync(string name, string password)
+        {
+            var req = new SignInRequest { name = name, password = password };
+
+            var content = new StringContent(
+                JsonSerializer.Serialize(req),
+                Encoding.UTF8,
+                "application/json"
+            );
+
+            using var resp = await _http.PostAsync("signin", content);
+            var body = await resp.Content.ReadAsStringAsync();
+
+            if (resp.IsSuccessStatusCode)
+            {
+                return JsonSerializer.Deserialize<ResponseToken>(body, _json);
+            }
+
+            // optional: Fehler-Body auswerten
+            // var err = JsonSerializer.Deserialize<SignInErrorResponse>(body, _json);
+            return null;
+        }
+
+        public async Task<bool> ValidateTokenAsync(string token)
+        {
+            using var req = new HttpRequestMessage(HttpMethod.Get, "token/validate");
+            req.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token);
+
+            using var resp = await _http.SendAsync(req);
+            var body = await resp.Content.ReadAsStringAsync();
+
+            if (!resp.IsSuccessStatusCode) return false;
+
+            var result = JsonSerializer.Deserialize<TokenIsValid>(body, _json);
+            return result?.is_valid == true;
+        }
+    }
+
+}