First commit

Repository/JsonRepository.cs

@@ -0,0 +1,61 @@
+using System.Text.Json;
+using Models;
+
+namespace Repository;
+
+public class JsonRepository : IRepository
+{
+    private const string _fileName = "data.json";
+
+    public User? Read()
+    {
+        if (File.Exists(_fileName))
+        {
+            try
+            {
+                string json = File.ReadAllText(_fileName);
+                return JsonSerializer.Deserialize<User>(json) ?? new User("fallback", "fallback", "fallback");
+            }
+            catch (JsonException e)
+            {
+                WriteToStdErr($"JSON error: {e.Message}");
+            }
+            catch (IOException e)
+            {
+                WriteToStdErr($"File I/O error: {e.Message}");
+            }
+            catch (Exception e)
+            {
+                WriteToStdErr($"Unexpected error: {e.Message}");
+            }
+        }
+        return null;
+    }
+
+    public void Write(User item)
+    {
+        try
+        {
+            string json = JsonSerializer.Serialize(item);
+            File.WriteAllText(_fileName, json);
+        }
+        catch (JsonException e)
+        {
+            WriteToStdErr($"JSON error: {e.Message}");
+        }
+        catch (IOException e)
+        {
+            WriteToStdErr($"File I/O error: {e.Message}");
+        }
+        catch (Exception e)
+        {
+            WriteToStdErr($"Unexpected error: {e.Message}");
+        }
+    }
+
+    private void WriteToStdErr(string message)
+    {
+        using var sw = new StreamWriter(Console.OpenStandardError());
+        sw.WriteLine(message);
+    }
+}