const { Pool } = require('pg');
const { execSync } = require('child_process');
const fs = require('fs');
const readline = require('readline');
require('dotenv').config();

const DATA_URL = 'https://download.geonames.org/export/dump/cities5000.zip';
const ZIP_FILE = '/tmp/cities.zip';
const TXT_FILE = '/tmp/cities5000.txt';

async function importGeoNames() {
  const pool = new Pool({
    connectionString: process.env.DATABASE_URL || 'postgresql://line_of_sight:line_of_sight_pass@postgres:5432/line_of_sight'
  });

  try {
    console.log('Downloading GeoNames cities5000 (Pop > 5000)...');
    execSync(`wget -q ${DATA_URL} -O ${ZIP_FILE}`);
    
    console.log('Extracting data...');
    execSync(`unzip -o ${ZIP_FILE} -d /tmp`);

    console.log('Connecting to database...');
    const client = await pool.connect();

    // Ensure table is clean
    await client.query('TRUNCATE TABLE cities');

    console.log('Starting stream import...');
    
    const fileStream = fs.createReadStream(TXT_FILE);
    const rl = readline.createInterface({
      input: fileStream,
      crlfDelay: Infinity
    });

    let batch = [];
    const batchSize = 500;
    let count = 0;

    for await (const line of rl) {
      const parts = line.split('\t');
      if (parts.length < 15) continue;

      const name = parts[1]; // name
      const lat = parseFloat(parts[4]);
      const lon = parseFloat(parts[5]);
      const country = parts[8]; // country code
      const population = parseInt(parts[14]) || 0;

      batch.push({ name, lat, lon, country, population });

      if (batch.length >= batchSize) {
        await insertBatch(client, batch);
        count += batch.length;
        if (count % 5000 === 0) console.log(`Imported ${count} cities...`);
        batch = [];
      }
    }

    if (batch.length > 0) {
      await insertBatch(client, batch);
      count += batch.length;
    }

    console.log(`SUCCESS: Imported ${count} cities and towns.`);
    client.release();

  } catch (err) {
    console.error('ERROR during import:', err);
  } finally {
    // Cleanup
    if (fs.existsSync(ZIP_FILE)) fs.unlinkSync(ZIP_FILE);
    if (fs.existsSync(TXT_FILE)) fs.unlinkSync(TXT_FILE);
    await pool.end();
  }
}

async function insertBatch(client, batch) {
  const queryParts = [];
  const values = [];
  
  batch.forEach((city, index) => {
    const base = index * 5;
    queryParts.push(`($${base + 1}, $${base + 2}, $${base + 3}, ST_SetSRID(ST_MakePoint($${base + 4}, $${base + 5}), 4326)::geography)`);
    values.push(city.name, city.population, city.country, city.lon, city.lat);
  });

  await client.query(
    `INSERT INTO cities (name, population, country, geom) VALUES ${queryParts.join(',')}`,
    values
  );
}

importGeoNames();