const fs = require('fs');
const path = require('path');

// Load translation files
const loadTranslations = () => {
  const translations = {};
  const localesDir = path.join(__dirname, '..', 'locales');
  
  try {
    const localeFiles = fs.readdirSync(localesDir);
    
    for (const file of localeFiles) {
      if (file.endsWith('.json')) {
        const locale = path.basename(file, '.json');
        const filePath = path.join(localesDir, file);
        translations[locale] = JSON.parse(fs.readFileSync(filePath, 'utf8'));
      }
    }
  } catch (error) {
    console.warn('Could not load translations:', error.message);
  }
  
  return translations;
};

let translations = loadTranslations();

// Internationalization middleware
const i18n = (req, res, next) => {
  // Get language from query parameter, session, or default to English
  let lang = req.query.lang || req.session.lang || 'en';
  
  // Validate language (only allow en or id)
  if (!['en', 'id'].includes(lang)) {
    lang = 'en';
  }
  
  // Store language in session
  req.session.lang = lang;
  
  // Translation function
  req.__ = (key, params = {}) => {
    const translation = translations[lang] && translations[lang][key];
    
    if (!translation) {
      // Fallback to English if key not found in current language
      const fallback = translations['en'] && translations['en'][key];
      if (!fallback) {
        console.warn(`Translation key not found: ${key}`);
        return key; // Return the key itself if no translation found
      }
      return interpolate(fallback, params);
    }
    
    return interpolate(translation, params);
  };
  
  // Make translation function available in templates
  res.locals.__ = req.__;
  res.locals.currentLang = lang;
  res.locals.otherLang = lang === 'en' ? 'id' : 'en';
  
  next();
};

// Simple string interpolation
const interpolate = (template, params) => {
  return template.replace(/\{\{(\w+)\}\}/g, (match, key) => {
    return params[key] || match;
  });
};

// Get bilingual content based on current language
const getBilingualContent = (req, contentEn, contentId) => {
  const lang = req.session.lang || 'en';
  return lang === 'id' ? (contentId || contentEn) : contentEn;
};

// Format bilingual content for database queries
const formatBilingualQuery = (fields, lang = 'en') => {
  return fields.map(field => {
    if (field.includes('_en') || field.includes('_id')) {
      const baseField = field.replace('_en', '').replace('_id', '');
      const suffix = lang === 'id' ? '_id' : '_en';
      return `${baseField}${suffix} as ${baseField}`;
    }
    return field;
  }).join(', ');
};

// Reload translations (useful for development)
const reloadTranslations = () => {
  translations = loadTranslations();
  console.log('Translations reloaded');
};

module.exports = {
  i18n,
  getBilingualContent,
  formatBilingualQuery,
  reloadTranslations
};