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

const CACHE_DIR = path.join(__dirname, '..', 'cache');

// Ensure cache directory exists
if (!fs.existsSync(CACHE_DIR)) {
  fs.mkdirSync(CACHE_DIR, { recursive: true });
}

/**
 * Generate a safe filename from a city query
 * @param {string} cityQuery - City name
 * @returns {string} Safe filename
 */
function getCacheFileName(cityQuery) {
  const hash = crypto.createHash('md5').update(cityQuery.toLowerCase().trim()).digest('hex');
  return `geocode_${hash}.json`;
}

/**
 * Get cached geocode data if available
 * @param {string} cityQuery - City name
 * @returns {Object|null} Cached data or null
 */
function getCachedGeocode(cityQuery) {
  try {
    const cacheFile = path.join(CACHE_DIR, getCacheFileName(cityQuery));
    if (fs.existsSync(cacheFile)) {
      const data = fs.readFileSync(cacheFile, 'utf8');
      const cached = JSON.parse(data);
      // Verify the query matches
      if (cached.query && cached.query.toLowerCase().trim() === cityQuery.toLowerCase().trim()) {
        console.log(`Geocode: ${cityQuery} (cached)`);
        return cached;
      }
    }
  } catch (error) {
    // Silent fail
  }
  return null;
}

/**
 * Save geocode data to cache
 * @param {string} cityQuery - City name
 * @param {Object} data - Geocode data to cache
 */
function saveCachedGeocode(cityQuery, data) {
  try {
    const cacheFile = path.join(CACHE_DIR, getCacheFileName(cityQuery));
    fs.writeFileSync(cacheFile, JSON.stringify(data, null, 2), 'utf8');
  } catch (error) {
    // Silent fail
  }
}

/**
 * Geocode city to lat/lon using Nominatim (OpenStreetMap)
 * @param {string} cityQuery - City name to geocode
 * @returns {Promise<{lat: number, lon: number, displayName: string}>}
 */
async function geocodeCity(cityQuery) {
  // Check cache first
  const cached = getCachedGeocode(cityQuery);
  if (cached) {
    return cached;
  }
  return new Promise((resolve, reject) => {
    const encodedQuery = encodeURIComponent(cityQuery);
    const url = `https://nominatim.openstreetmap.org/search?q=${encodedQuery}&format=json&limit=1`;
    
    const options = {
      headers: {
        'User-Agent': 'webpage-to-hls-streaming-app/1.0'
      }
    };

    https.get(url, options, (res) => {
      let data = '';
      
      res.on('data', (chunk) => {
        data += chunk;
      });
      
      res.on('end', () => {
        try {
          const results = JSON.parse(data);
          if (results && results.length > 0) {
            const geocodeResult = {
              query: cityQuery,
              lat: parseFloat(results[0].lat),
              lon: parseFloat(results[0].lon),
              displayName: results[0].display_name
            };
            console.log(`Geocode: ${cityQuery} -> ${geocodeResult.displayName} (API)`);
            // Save to cache
            saveCachedGeocode(cityQuery, geocodeResult);
            resolve(geocodeResult);
          } else {
            reject(new Error('No results found'));
          }
        } catch (error) {
          reject(error);
        }
      });
    }).on('error', (error) => {
      reject(error);
    });
  });
}

module.exports = { geocodeCity };