Added DeepL API key setting

I18N Commander/DataModel/Database/SettingNames.cs

@@ -2,5 +2,6 @@
 
 public static class SettingNames
 {
+    public static readonly string DEEPL_API_KEY = "DeepL API Key";
     public static readonly string DEEPL_MODE = "DeepL Mode";
 }

I18N Commander/Processor/AppSettings.cs

@@ -7,6 +7,8 @@ namespace Processor;
 
 public static class AppSettings
 {
+    #region DeepL Mode
+
     public static async Task SetDeepLMode(SettingDeepL mode)
     {
         // Convert the enum to its int value:
@@ -57,4 +59,58 @@ public static class AppSettings
         
         return (SettingDeepL) setting.IntegerValue;
     }
+
+    #endregion
+    
+    #region DeepL API Key
+    
+    public static async Task SetDeepLAPIKey(string apiKey)
+    {
+        // Get the database:
+        await using var db = ProcessorMeta.ServiceProvider.GetRequiredService<DataContext>();
+        
+        // Check, if the setting is already set:
+        if (await db.Settings.FirstOrDefaultAsync(n => n.Code == SettingNames.DEEPL_API_KEY) is {} existingSetting)
+        {
+            existingSetting.TextValue = apiKey;
+            await db.SaveChangesAsync();
+        }
+        
+        // Does not exist, so create it:
+        else
+        {
+            var setting = new Setting
+            {
+                Code = SettingNames.DEEPL_API_KEY,
+                TextValue = apiKey,
+            };
+            
+            await db.Settings.AddAsync(setting);
+            await db.SaveChangesAsync();
+        }
+    }
+    
+    public static async Task<string> GetDeepLAPIKey()
+    {
+        // Get the database:
+        await using var db = ProcessorMeta.ServiceProvider.GetRequiredService<DataContext>();
+        
+        // Check, if the setting is already set:
+        if (await db.Settings.FirstOrDefaultAsync(n => n.Code == SettingNames.DEEPL_API_KEY) is { } existingSetting)
+            return existingSetting.TextValue;
+        
+        // Does not exist, so create it:
+        var setting = new Setting
+        {
+            Code = SettingNames.DEEPL_API_KEY,
+            TextValue = string.Empty,
+        };
+            
+        await db.Settings.AddAsync(setting);
+        await db.SaveChangesAsync();
+        
+        return setting.TextValue;
+    }
+    
+    #endregion
 }

I18N Commander/UI WinForms/Components/Setting.cs

@@ -45,7 +45,7 @@ public partial class Setting : UserControl
         Func<Control> SetupDataControl
     );
 
-    private static async Task<Setting> ShowDeepLSettingAsync()
+    private static async Task<Setting> ShowDeepLModeSettingAsync()
     {
         var currentSetting = await AppSettings.GetDeepLMode();
         var settingData = new SettingUIData(
@@ -91,8 +91,32 @@ public partial class Setting : UserControl
         };
     }
     
+    private static async Task<Setting> ShowDeepLAPIKeySettingAsync()
+    {
+        var currentSetting = await AppSettings.GetDeepLAPIKey();
+        var settingData = new SettingUIData(
+            Icon: Icons.icons8_key_512,
+            SettingName: () => "DeepL API Key",
+            SettingExplanation: () => "The API key is required to use the DeepL translation service. You can find your API key on the DeepL website.",
+            SetupDataControl: () =>
+            {
+                var textbox = new TextBox();
+                textbox.Text = currentSetting;
+                textbox.TextChanged += async (sender, args) => await AppSettings.SetDeepLAPIKey(textbox.Text);
+                textbox.Dock = DockStyle.Fill;
+                return textbox;
+            }
+        );
+
+        return new Setting(settingData)
+        {
+            Dock = DockStyle.Top,
+        };
+    }
+
     public static IEnumerable<Task<Setting>> GetAllSettings()
     {
-        yield return ShowDeepLSettingAsync();
+        yield return ShowDeepLAPIKeySettingAsync();
+        yield return ShowDeepLModeSettingAsync();
     }
 }