// Regenerate src/server/data/airports.json from the public-domain OurAirports
// dataset. Usage: node scripts/generate-airports.mjs
//
// Keeps airports that have an IATA code AND scheduled service, projecting each
// to { code, name, city, country, lat, lng }.

import fs from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const SOURCE_URL = 'https://davidmegginson.github.io/ourairports-data/airports.csv';
const __dirname = path.dirname(fileURLToPath(import.meta.url));
const OUT_PATH = path.join(__dirname, '..', 'src', 'server', 'data', 'airports.json');

// Minimal RFC-4180 CSV parser (handles quotes, escaped quotes, embedded commas/newlines).
function parseCsv(str) {
  const rows = [];
  let row = [];
  let field = '';
  let inQuotes = false;
  for (let i = 0; i < str.length; i++) {
    const c = str[i];
    if (inQuotes) {
      if (c === '"') {
        if (str[i + 1] === '"') { field += '"'; i++; }
        else inQuotes = false;
      } else field += c;
    } else if (c === '"') inQuotes = true;
    else if (c === ',') { row.push(field); field = ''; }
    else if (c === '\n') { row.push(field); rows.push(row); row = []; field = ''; }
    else if (c === '\r') { /* ignore */ }
    else field += c;
  }
  if (field.length || row.length) { row.push(field); rows.push(row); }
  return rows;
}

async function main() {
  console.log(`Downloading ${SOURCE_URL} ...`);
  const res = await fetch(SOURCE_URL, { headers: { 'User-Agent': 'trip-plan-app/0.1 (self-hosted)' } });
  if (!res.ok) throw new Error(`download failed: HTTP ${res.status}`);
  const text = await res.text();

  const rows = parseCsv(text);
  const header = rows[0];
  const col = (name) => header.indexOf(name);
  const iIata = col('iata_code');
  const iSched = col('scheduled_service');
  const iName = col('name');
  const iCity = col('municipality');
  const iCountry = col('iso_country');
  const iLat = col('latitude_deg');
  const iLng = col('longitude_deg');

  const airports = [];
  for (let r = 1; r < rows.length; r++) {
    const row = rows[r];
    if (!row || row.length < header.length) continue;
    const code = (row[iIata] || '').trim();
    if (!code) continue;
    if ((row[iSched] || '').trim() !== 'yes') continue;
    const lat = Number(row[iLat]);
    const lng = Number(row[iLng]);
    airports.push({
      code,
      name: (row[iName] || '').trim(),
      city: (row[iCity] || '').trim(),
      country: (row[iCountry] || '').trim(),
      lat: Number.isFinite(lat) ? lat : null,
      lng: Number.isFinite(lng) ? lng : null,
    });
  }

  fs.mkdirSync(path.dirname(OUT_PATH), { recursive: true });
  fs.writeFileSync(OUT_PATH, JSON.stringify(airports));
  const bytes = fs.statSync(OUT_PATH).size;
  console.log(`Wrote ${airports.length} airports to ${OUT_PATH} (${bytes} bytes)`);
}

main().catch((err) => {
  console.error(err.message);
  process.exit(1);
});