Saving and loading but still has error(Pls fix)

PolyChat/Controller.cs

@@ -5,8 +5,10 @@ using System.Net;
 using SocketIOSharp.Server;
 using SocketIOSharp.Server.Client;
 using PolyChat.Models;
+using System.IO;
+using System.Threading;
+using System;
 using System.Text.Json;
-using Newtonsoft.Json;
 
 namespace PolyChat
 {
@@ -33,6 +35,8 @@ namespace PolyChat
         {
             UIController = uiController;
             OwnIP = getIP();
+            loadChats();
+            //SaveChats("10", "{das ist ein test}");
             Serve();
         }
 
@@ -86,10 +90,12 @@ namespace PolyChat
             Debug.WriteLine($"{type} -> {ip} content: {content}");
             JObject json = new JObject(
                 new JProperty("type", type),
-                new JProperty("content", content)
+                new JProperty("content", content),
+                new JProperty("timestamp", DateTime.Now.ToString())
             );
             Debug.WriteLine($"json: {json.ToString()}");
             Connections[ip].SendMessage(json.ToString());
+            SaveChats(ip, json.ToString());
         }
 
         private void OnMessage(string ip, JToken[] data)
@@ -99,6 +105,7 @@ namespace PolyChat
             {
                 Debug.WriteLine("RAW: " + data[0]);
                 UIController.OnIncomingMessage(ip, data[0].ToString());
+                SaveChats(ip, data[0].ToString());
             }
             else Debug.WriteLine("Undefined: " + data);
         }
@@ -111,7 +118,7 @@ namespace PolyChat
                 Connections[IP].Close();
                 Connections.Remove(IP);
             }
-            CloseChatUI(IP,wasConnected);
+            CloseChatUI(IP, wasConnected);
         }
 
         private void CloseChatUI(string IP, bool wasConnected = true)
@@ -123,7 +130,7 @@ namespace PolyChat
 
         private bool isInConnections(string IP)
         {
-            if(Connections.ContainsKey(IP))
+            if (Connections.ContainsKey(IP))
                 return true;
             return false;
         }
@@ -141,5 +148,89 @@ namespace PolyChat
             }
             return null;
         }
+
+        /// <summary>
+        /// sends chatlogs as json array to uiController wit corrosponding ip
+        /// </summary>
+        /// <param name="ip"></param>
+        public void loadChats()
+        {
+            //load dir and create if non existant
+            if (Directory.Exists("U:\\PolyChat\\Saves"))
+            {
+                Debug.WriteLine("--Path exists.--");
+            }
+            else
+            {
+                Directory.CreateDirectory("U:\\PolyChat\\Saves");
+                Debug.WriteLine("--Path Created--.");
+            }
+
+            //go through all files and send ip and json array to ui
+            String[] filepaths = Directory.GetFiles("U:\\PolyChat\\Saves");
+            if (filepaths.Length > 0)
+            {
+                foreach (String path in filepaths)
+                {
+                    Debug.WriteLine("---Loading Saves---");
+                    Debug.WriteLine("--" + path + "--");
+                    String jsonArr = File.ReadAllText(path);
+                    String ip = Path.GetFileName(path);
+                    ip = ip.Substring(0, ip.Length - 4);
+                    Debug.WriteLine("-" + ip + "-");
+                    Debug.WriteLine(jsonArr);
+                    UIController.OnIncomingMessages(ip, jsonArr);
+                }
+            }
+
+        }
+
+        /// <summary>
+        /// Saves incoming chat message to 
+        /// </summary>
+        /// <param name="ip"></param>
+        /// <param name="json"></param>
+        public void SaveChats(String ip, String json)
+        {
+            //Vielleicht noch so machen dass die mit gleicher ip nacheinander gemacht
+            //werden damit es ncith zu überschreibungen kommt vielleicth auch ganz oben oder am ende ne
+            //writing flag setzen oder auch in der datei selbst ne flag setzen
+            //also save fils from myself
+            new Thread(() =>
+            {
+                if (File.Exists($"U:\\PolyChat\\Saves\\{ip}.txt"))
+                {
+                    Debug.WriteLine("--File allready exists--");
+                    //check for integraty of file
+                    string output = File.ReadAllText($"U:\\PolyChat\\Saves\\{ip}.txt");
+                    Debug.WriteLine($"---{output}---");
+                    if (output.Substring(0, 1).Equals("[") && output.Substring(output.Length - 1, 1).Equals("]"))
+                    {
+                        Debug.WriteLine("--adding new chatmessage--");
+                        //structure intact
+                        //save new chat
+                        String saved = output.Substring(0, output.Length - 1);
+                        output = saved + ", " + json + " ]";
+                        File.Delete($"U:\\PolyChat\\Saves\\{ip}.txt");
+                        File.WriteAllText($"U:\\PolyChat\\Saves\\{ip}.txt", output);
+                    }
+                    else
+                    {
+                        Debug.WriteLine("--Structure not intact--");
+                        Debug.WriteLine("--redoing file--");
+                        //structure not intact
+                        //redo file
+                        File.Delete($"U:\\PolyChat\\Saves\\{ip}.txt");
+                        File.WriteAllText($"U:\\PolyChat\\Saves\\{ip}.txt", $"[ {json} ]");
+                    }
+                }
+                else
+                {
+                    Debug.WriteLine("--Creating new File--");
+                    //setup file
+                    File.WriteAllText($"U:\\PolyChat\\Saves\\{ip}.txt", $"[ {json} ]");
+                }
+            }).Start();
+        }
     }
 }

PolyChat/MainPage.xaml.cs

@@ -152,6 +152,7 @@ namespace PolyChat
             });
         }
 
+
         private void OnDeleteChat(object sender = null, RoutedEventArgs e = null)
         {
             Controller.CloseChat(selectedPartner.Code);