I18NCommander/I18N Commander/Processor/DeepL.cs

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)
        {
            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 (string.IsNullOrWhiteSpace(text))
            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, TransformSourceCulture(sourceCulture), TransformTargetCulture(targetCulture));

            return translation.Text;
        }
        catch (AuthorizationException e)
        {
            Console.WriteLine($"DeepL authorization failed: {e.Message}");
            DEEPL_NOT_AVAILABLE = true;
            return string.Empty;
        }
        catch (DeepLException e)
        {
            Console.WriteLine($"DeepL issue: {e.Message}");
            DEEPL_NOT_AVAILABLE = true;
            return string.Empty;
        }
    }
    
    public static void ResetState() => DEEPL_NOT_AVAILABLE = false;

    private static string TransformSourceCulture(string sourceCulture) => sourceCulture switch
    {
        ['b', 'g', ..] => "BG", // Bulgarian
        ['c', 's', ..] => "CS", // Czech
        ['d', 'a', ..] => "DA", // Danish
        ['d', 'e', ..] => "DE", // German
        ['e', 'l', ..] => "EL", // Greek
        ['e', 'n', ..] => "EN", // English
        ['e', 's', ..] => "ES", // Spanish
        ['e', 't', ..] => "ET", // Estonian
        ['f', 'i', ..] => "FI", // Finnish
        ['f', 'r', ..] => "FR", // French
        ['h', 'u', ..] => "HU", // Hungarian
        ['i', 'd', ..] => "ID", // Indonesian
        ['i', 't', ..] => "IT", // Italian
        ['j', 'a', ..] => "JA", // Japanese
        ['k', 'o', ..] => "KO", // Korean
        ['l', 't', ..] => "LT", // Lithuanian
        ['l', 'v', ..] => "LV", // Latvian
        ['n', 'b', ..] => "NB", // Norwegian
        ['n', 'l', ..] => "NL", // Dutch
        ['p', 'l', ..] => "PL", // Polish
        ['p', 't', ..] => "PT", // Portuguese
        ['r', 'o', ..] => "RO", // Romanian
        ['r', 'u', ..] => "RU", // Russian
        ['s', 'k', ..] => "SK", // Slovak
        ['s', 'l', ..] => "SL", // Slovenian
        ['s', 'v', ..] => "SV", // Swedish
        ['t', 'r', ..] => "TR", // Turkish
        ['u', 'k', ..] => "UK", // Ukrainian
        ['z', 'h', ..] => "ZH", // Chinese

        _ => sourceCulture,
    };

    private static string TransformTargetCulture(string targetCulture) => targetCulture switch
    {
        ['b', 'g', ..] => "BG", // Bulgarian
        ['c', 's', ..] => "CS", // Czech
        ['d', 'a', ..] => "DA", // Danish
        ['d', 'e', ..] => "DE", // German
        ['e', 'l', ..] => "EL", // Greek
        ['e', 'n', '-', 'G', 'B', ..] => "EN-GB", // English (British)
        ['e', 'n', '-', 'U', 'S', ..] => "EN-US", // English (American)
        ['e', 'n', ..] => "EN-US", // English (American)
        ['e', 's', ..] => "ES", // Spanish
        ['e', 't', ..] => "ET", // Estonian
        ['f', 'i', ..] => "FI", // Finnish
        ['f', 'r', ..] => "FR", // French
        ['h', 'u', ..] => "HU", // Hungarian
        ['i', 'd', ..] => "ID", // Indonesian
        ['i', 't', ..] => "IT", // Italian
        ['j', 'a', ..] => "JA", // Japanese
        ['k', 'o', ..] => "KO", // Korean
        ['l', 't', ..] => "LT", // Lithuanian
        ['l', 'v', ..] => "LV", // Latvian
        ['n', 'b', ..] => "NB", // Norwegian
        ['n', 'l', ..] => "NL", // Dutch
        ['p', 'l', ..] => "PL", // Polish
        ['p', 't', '-', 'B', 'R', ..] => "PT-BR", // Portuguese (Brazilian)
        ['p', 't', '-', 'P', 'T', ..] => "PT-PT", // Portuguese (European)
        ['p', 't', ..] => "PT-PT", // Portuguese (European)
        ['r', 'o', ..] => "RO", // Romanian
        ['r', 'u', ..] => "RU", // Russian
        ['s', 'k', ..] => "SK", // Slovak
        ['s', 'l', ..] => "SL", // Slovenian
        ['s', 'v', ..] => "SV", // Swedish
        ['t', 'r', ..] => "TR", // Turkish
        ['u', 'k', ..] => "UK", // Ukrainian
        ['z', 'h', ..] => "ZH", // Chinese
        
        _ => targetCulture,
    };
}