ice/src/i18n/index.ts

import fs from 'fs';
import path from 'path';

export interface TranslationData {
  [key: string]: any;
}

export class I18nService {
  private translations: Map<string, TranslationData> = new Map();
  private defaultLocale = 'en';
  private availableLocales = ['en', 'es-MX'];

  constructor() {
    this.loadTranslations();
  }

  /**
   * Load all translation files from the locales directory
   */
  private loadTranslations(): void {
    const localesDir = path.join(__dirname, 'locales');
    
    for (const locale of this.availableLocales) {
      try {
        const filePath = path.join(localesDir, `${locale}.json`);
        const translationData = JSON.parse(fs.readFileSync(filePath, 'utf8'));
        this.translations.set(locale, translationData);
        console.log(`Loaded translations for locale: ${locale}`);
      } catch (error) {
        console.error(`Failed to load translations for locale ${locale}:`, error);
      }
    }
  }

  /**
   * Get a translated string by key path (e.g., 'common.appName')
   */
  public t(keyPath: string, locale: string = this.defaultLocale, params?: Record<string, string>): string {
    const translations = this.translations.get(locale) || this.translations.get(this.defaultLocale);
    
    if (!translations) {
      console.warn(`No translations found for locale: ${locale}`);
      return keyPath;
    }

    const keys = keyPath.split('.');
    let value: any = translations;

    for (const key of keys) {
      value = value?.[key];
      if (value === undefined) {
        // Fallback to default locale if key not found
        if (locale !== this.defaultLocale) {
          return this.t(keyPath, this.defaultLocale, params);
        }
        console.warn(`Translation key not found: ${keyPath} for locale: ${locale}`);
        return keyPath;
      }
    }

    if (typeof value !== 'string') {
      console.warn(`Translation value is not a string for key: ${keyPath}`);
      return keyPath;
    }

    // Replace parameters if provided
    if (params) {
      return this.replaceParams(value, params);
    }

    return value;
  }

  /**
   * Replace parameters in translation strings (e.g., "Hello {{name}}" with {name: "John"})
   */
  private replaceParams(text: string, params: Record<string, string>): string {
    return text.replace(/\{\{(\w+)\}\}/g, (match, key) => {
      return params[key] || match;
    });
  }

  /**
   * Get all translations for a specific locale
   */
  public getTranslations(locale: string): TranslationData | null {
    return this.translations.get(locale) || null;
  }

  /**
   * Get list of available locales
   */
  public getAvailableLocales(): string[] {
    return [...this.availableLocales];
  }

  /**
   * Check if a locale is supported
   */
  public isLocaleSupported(locale: string): boolean {
    return this.availableLocales.includes(locale);
  }

  /**
   * Get the default locale
   */
  public getDefaultLocale(): string {
    return this.defaultLocale;
  }

  /**
   * Detect user's preferred locale from Accept-Language header
   */
  public detectLocale(acceptLanguageHeader?: string): string {
    if (!acceptLanguageHeader) {
      return this.defaultLocale;
    }

    // Parse Accept-Language header (e.g., "es-MX,es;q=0.9,en;q=0.8")
    const languages = acceptLanguageHeader
      .split(',')
      .map(lang => {
        const parts = lang.trim().split(';');
        const code = parts[0];
        const quality = parts[1] ? parseFloat(parts[1].split('=')[1]) : 1;
        return { code, quality };
      })
      .sort((a, b) => b.quality - a.quality);

    // Find the first supported locale
    for (const lang of languages) {
      // Check for exact match first (e.g., "es-MX")
      if (this.isLocaleSupported(lang.code)) {
        return lang.code;
      }
      
      // Check for language match (e.g., "es" matches "es-MX")
      const languageCode = lang.code.split('-')[0];
      const matchingLocale = this.availableLocales.find(locale => 
        locale.startsWith(languageCode)
      );
      if (matchingLocale) {
        return matchingLocale;
      }
    }

    return this.defaultLocale;
  }

  /**
   * Get locale display names
   */
  public getLocaleDisplayName(locale: string): string {
    const displayNames: Record<string, string> = {
      'en': 'English',
      'es-MX': 'Español (México)'
    };
    return displayNames[locale] || locale;
  }
}

// Create singleton instance
export const i18nService = new I18nService();

// Helper function for easier access
export function t(keyPath: string, locale?: string, params?: Record<string, string>): string {
  return i18nService.t(keyPath, locale, params);
}

export default i18nService;