UI for key update

EpsonPrintService/ConfigurationLoader.cs

@@ -0,0 +1,55 @@
+using Inspectron.Epson.PrintServer.ConfigurationSources;
+
+namespace EpsonPrintService;
+
+public record ConfigLoadResult(bool Success, EpsonPrintServiceConfiguration? Config, string? Error);
+
+public static class ConfigurationLoader
+{
+    public static ConfigLoadResult TryLoadFromBase64(string base64Content)
+    {
+        try
+        {
+            var decoded = System.Text.Encoding.UTF8.GetString(Convert.FromBase64String(base64Content.Trim()));
+            var parts = decoded.Split(';');
+            if (parts.Length != 3)
+                return new ConfigLoadResult(false, null, $"Invalid configuration format. Expected 'apiUrl;restaurantId;apiKey', got {parts.Length} parts.");
+
+            var config = new EpsonPrintServiceConfiguration
+            {
+                ApiUrl = parts[0],
+                RestaurantId = parts[1],
+                ApiKey = parts[2]
+            };
+
+            if (string.IsNullOrWhiteSpace(config.ApiUrl) || string.IsNullOrWhiteSpace(config.RestaurantId) || string.IsNullOrWhiteSpace(config.ApiKey))
+                return new ConfigLoadResult(false, null, "Configuration contains empty values.");
+
+            return new ConfigLoadResult(true, config, null);
+        }
+        catch (FormatException)
+        {
+            return new ConfigLoadResult(false, null, "Invalid base64 content.");
+        }
+    }
+
+    public static ConfigLoadResult TryLoadFromFile()
+    {
+        try
+        {
+            var configPath = ConfigurationPaths.GetConfigPath();
+            if (!File.Exists(configPath))
+                return new ConfigLoadResult(false, null, $"Configuration file not found: {configPath}");
+
+            var base64Line = File.ReadAllText(configPath).Trim();
+            if (string.IsNullOrWhiteSpace(base64Line))
+                return new ConfigLoadResult(false, null, "Configuration file is empty.");
+
+            return TryLoadFromBase64(base64Line);
+        }
+        catch (Exception ex)
+        {
+            return new ConfigLoadResult(false, null, $"Failed to read configuration: {ex.Message}");
+        }
+    }
+}