Added a DeepL facade

I18N Commander/Processor/DeepL.cs

@@ -0,0 +1,66 @@
+using DataModel.Database;
+using DeepL;
+
+namespace Processor;
+
+public static class DeepL
+{
+    private static bool DEEPL_NOT_AVAILABLE = false;
+    
+    public readonly record struct DeepLUsage(bool Enabled, long CharacterCount, long CharacterLimit, bool AuthIssue = false);
+    
+    public static async Task<DeepLUsage> GetUsage()
+    {
+        if(DEEPL_NOT_AVAILABLE)
+            return new DeepLUsage(false, 0, 1);
+        
+        if (await AppSettings.GetDeepLMode() == SettingDeepLMode.DISABLED)
+            return new DeepLUsage(false, 0, 1);
+
+        var deepLAPIKey = await AppSettings.GetDeepLAPIKey();
+        if(string.IsNullOrWhiteSpace(deepLAPIKey))
+            return new DeepLUsage(false, 0, 1);
+
+        try
+        {
+            using var deepl = new Translator(deepLAPIKey);
+            var usage = await deepl.GetUsageAsync();
+        
+            return new DeepLUsage(true, usage.Character!.Count, usage.Character.Limit);
+        }
+        catch (AuthorizationException e)
+        {
+            DEEPL_NOT_AVAILABLE = true;
+            return new DeepLUsage(false, 0, 1, true);
+        }
+    }
+    
+    public static async Task<string> Translate(string text, string targetCulture)
+    {
+        if (DEEPL_NOT_AVAILABLE)
+            return string.Empty;
+        
+        if (await AppSettings.GetDeepLMode() == SettingDeepLMode.DISABLED)
+            return string.Empty;
+
+        var deepLAPIKey = await AppSettings.GetDeepLAPIKey();
+        if(string.IsNullOrWhiteSpace(deepLAPIKey))
+            return string.Empty;
+
+        try
+        {
+            var sourceCultureIndex = await AppSettings.GetDeepLSourceCultureIndex();
+            var sourceCulture = await AppSettings.GetCultureCode(sourceCultureIndex);
+            
+            using var deepl = new Translator(deepLAPIKey);
+            var translation = await deepl.TranslateTextAsync(text, sourceCulture, targetCulture);
+            
+            return translation.Text;
+        }
+        catch (AuthorizationException e)
+        {
+            DEEPL_NOT_AVAILABLE = true;
+            return string.Empty;
+        }
+    }
+}

I18N Commander/Processor/Processor.csproj

@@ -11,4 +11,8 @@
       <ProjectReference Include="..\DataModel\DataModel.csproj" />
     </ItemGroup>
 
+    <ItemGroup>
+      <PackageReference Include="DeepL.net" Version="1.4.0" />
+    </ItemGroup>
+
 </Project>