#!/usr/bin/env node
// Build server/data/airports.json from OurAirports (davidmegginson.github.io/ourairports-data).
// License: Public Domain. Keeps large/medium airports with an IATA code; timezone derived from coords via tz-lookup.

import fs from 'node:fs'
import path from 'node:path'
import https from 'node:https'
import { fileURLToPath } from 'node:url'
import tzLookup from 'tz-lookup'

const __dirname = path.dirname(fileURLToPath(import.meta.url))
const OUT = path.join(__dirname, '..', 'data', 'airports.json')
const SRC = 'https://davidmegginson.github.io/ourairports-data/airports.csv'

function fetchText(url) {
  return new Promise((resolve, reject) => {
    https.get(url, (res) => {
      if (res.statusCode !== 200) return reject(new Error(`HTTP ${res.statusCode}`))
      let data = ''
      res.setEncoding('utf8')
      res.on('data', chunk => { data += chunk })
      res.on('end', () => resolve(data))
    }).on('error', reject)
  })
}

function parseCsv(text) {
  const rows = []
  let row = []
  let cur = ''
  let inQuotes = false
  for (let i = 0; i < text.length; i++) {
    const ch = text[i]
    if (inQuotes) {
      if (ch === '"') {
        if (text[i + 1] === '"') { cur += '"'; i++ } else { inQuotes = false }
      } else {
        cur += ch
      }
    } else {
      if (ch === '"') inQuotes = true
      else if (ch === ',') { row.push(cur); cur = '' }
      else if (ch === '\n') { row.push(cur); rows.push(row); row = []; cur = '' }
      else if (ch === '\r') { /* skip */ }
      else cur += ch
    }
  }
  if (cur.length > 0 || row.length > 0) { row.push(cur); rows.push(row) }
  return rows
}

const raw = await fetchText(SRC)
const rows = parseCsv(raw)
const header = rows[0]
const idx = (name) => header.indexOf(name)
const TYPE = idx('type')
const NAME = idx('name')
const LAT = idx('latitude_deg')
const LNG = idx('longitude_deg')
const COUNTRY = idx('iso_country')
const MUNICIPALITY = idx('municipality')
const SERVICE = idx('scheduled_service')
const ICAO = idx('icao_code')
const IATA = idx('iata_code')

const KEEP = new Set(['large_airport', 'medium_airport'])
const airports = []
let skippedNoTz = 0

for (let i = 1; i < rows.length; i++) {
  const r = rows[i]
  if (!r || r.length < header.length) continue
  if (!KEEP.has(r[TYPE])) continue
  const iata = r[IATA]?.trim().toUpperCase()
  if (!iata || iata.length !== 3) continue
  if (r[SERVICE] !== 'yes') continue
  const lat = Number(r[LAT])
  const lng = Number(r[LNG])
  if (!Number.isFinite(lat) || !Number.isFinite(lng)) continue

  let tz = null
  try { tz = tzLookup(lat, lng) } catch { skippedNoTz++; continue }
  if (!tz) { skippedNoTz++; continue }

  airports.push({
    iata,
    icao: r[ICAO]?.trim().toUpperCase() || null,
    name: r[NAME],
    city: r[MUNICIPALITY] || '',
    country: r[COUNTRY] || '',
    lat: Math.round(lat * 1e6) / 1e6,
    lng: Math.round(lng * 1e6) / 1e6,
    tz,
  })
}

const seen = new Map()
for (const a of airports) {
  const existing = seen.get(a.iata)
  if (!existing) { seen.set(a.iata, a); continue }
  if (existing.icao && !a.icao) continue
  if (!existing.icao && a.icao) seen.set(a.iata, a)
}
const unique = Array.from(seen.values()).sort((a, b) => a.iata.localeCompare(b.iata))

fs.writeFileSync(OUT, JSON.stringify(unique))
const size = fs.statSync(OUT).size
console.log(`Wrote ${unique.length} airports to ${OUT} (${(size / 1024).toFixed(1)} KB); skipped ${skippedNoTz} without timezone`)