#!/usr/bin/env node
/**
 * OSM Data Build Script
 * ---------------------
 * Queries the OpenStreetMap Overpass API for one or more configurable areas,
 * fetches the requested feature types, and converts the results into static
 * GeoJSON files under static/data/. These are bundled into the SvelteKit
 * build and served as plain static files by the frontend.
 *
 * Usage:
 *   node scripts/osm-data.mjs                # build all areas
 *   node scripts/osm-data.mjs --area=tulsa   # build a single area
 *   node scripts/osm-data.mjs --queries      # list available queries
 *
 * Output layout:
 *   static/data/<area>.geojson               # merged FeatureCollection per area
 *   static/data/_index.json                  # manifest of all built areas
 */

import { mkdir, writeFile } from 'node:fs/promises';
import { dirname, resolve } from 'node:path';
import { fileURLToPath } from 'node:url';

const __dirname = dirname(fileURLToPath(import.meta.url));
const ROOT = resolve(__dirname, '..');
const OUT_DIR = resolve(ROOT, 'static', 'data');

const OVERPASS_ENDPOINTS = [
  'https://overpass-api.de/api/interpreter',
  'https://overpass.kumi.systems/api/interpreter',
  'https://maps.mail.ru/osm/tools/overpass/api/interpreter'
];

// ---------------------------------------------------------------------------
// Configuration: edit this to describe the areas and features you want.
// Each query is an Overpass QL snippet; the request is wrapped with the
// [out:json] output format. Use {{bbox}} as a placeholder for the area bbox.
// ---------------------------------------------------------------------------
const AREAS = {
  tulsa: {
    label: 'Tulsa, Oklahoma',
    bbox: [35.9, -96.1, 36.3, -95.7], // [south, west, north, east]
    queries: {
      schools: `
        (
          node["amenity"="school"]({{bbox}});
          way["amenity"="school"]({{bbox}});
          relation["amenity"="school"]({{bbox}});
        );
        out center tags;
      `,
      firestations: `
        (
          node["amenity"="fire_station"]({{bbox}});
          way["amenity"="fire_station"]({{bbox}});
        );
        out center tags;
      `,
      parks: `
        way["leisure"="park"]({{bbox}});
        out center tags geom;
      `
    }
  }
};

// ---------------------------------------------------------------------------
// Overpass API client with retry/fallback across endpoints.
// ---------------------------------------------------------------------------
async function overpassFetch(query, signal) {
  const body = new URLSearchParams({ data: query });
  let lastErr;
  for (const endpoint of OVERPASS_ENDPOINTS) {
    if (signal.aborted) throw new DOMException('Aborted', 'AbortError');
    try {
      const res = await fetch(endpoint, {
        method: 'POST',
        headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
        body: body.toString(),
        signal
      });
      if (!res.ok) throw new Error(`HTTP ${res.status} from ${endpoint}`);
      return await res.json();
    } catch (err) {
      lastErr = err;
      console.warn(`  [warn] endpoint failed: ${endpoint} -> ${err.message}`);
    }
  }
  throw new Error(`All Overpass endpoints failed. Last error: ${lastErr?.message}`);
}

function wait(ms, signal) {
  return new Promise((resolve) => {
    setTimeout(resolve, ms);
  });
}

// ---------------------------------------------------------------------------
// Overpass JSON -> GeoJSON conversion helpers.
// ---------------------------------------------------------------------------
function coordsFor(el) {
  if (el.type === 'node') return [el.lon, el.lat];
  if (el.center) return [el.center.lon, el.center.lat];       // out center
  if (el.geometry && el.geometry.length) {                       // way geom outline
    return el.geometry.map((p) => [p.lon, p.lat]);
  }
  return null;
}

function geometryFor(el) {
  const coords = coordsFor(el);
  if (!coords) return null;
  // Preserve polygons for closed ways when we have full geometry.
  if (el.type === 'way' && el.geometry && el.geometry.length > 2 &&
      coords[0][0] === coords[coords.length - 1][0] &&
      coords[0][1] === coords[coords.length - 1][1]) {
    return { type: 'Polygon', coordinates: [coords] };
  }
  if (coords.length === 1) return { type: 'Point', coordinates: coords[0] };
  return { type: 'LineString', coordinates: coords };
}

function toFeature(el) {
  const geom = geometryFor(el);
  if (!geom) return null;
  return {
    type: 'Feature',
    id: `${el.type}/${el.id}`,
    properties: { ...(el.tags || {}), _type: el.type, _id: el.id },
    geometry: geom
  };
}

// ---------------------------------------------------------------------------
// Build a single area.
// ---------------------------------------------------------------------------
async function buildArea(name, cfg, signal) {
  console.log(`\n==> Building area "${name}" (${cfg.label})`);
  const [south, west, north, east] = cfg.bbox;
  const bboxStr = `${south},${west},${north},${east}`;
  const features = [];

  for (const [qname, qbody] of Object.entries(cfg.queries)) {
    if (signal.aborted) throw new DOMException('Aborted', 'AbortError');
    const ql = `[out:json][timeout:180];\n${qbody.replaceAll('{{bbox}}', bboxStr)}`;
    console.log(`  - query: ${qname} (${bboxStr})`);
    try {
      const json = await overpassFetch(ql, signal);
      const els = json.elements || [];
      let count = 0;
      for (const el of els) {
        const f = toFeature(el);
        if (f) { features.push(f); count++; }
      }
      console.log(`    fetched ${els.length} elements, converted ${count} features`);
    } catch (err) {
      console.error(`    [error] query ${qname} failed: ${err.message}`);
    }
    await wait(1500, signal); // be polite to the Overpass API
  }

  const fc = { type: 'FeatureCollection', crs: { type: 'name', properties: { name: 'urn:ogc:def:crs:OGC:1.3:CRS84' } }, features };
  const outPath = resolve(OUT_DIR, `${name}.geojson`);
  await writeFile(outPath, JSON.stringify(fc));
  console.log(`  wrote ${features.length} features -> ${outPath}`);
  return { name, label: cfg.label, bbox: cfg.bbox, featureCount: features.length, path: `/data/${name}.geojson` };
}

// ---------------------------------------------------------------------------
// Main.
// ---------------------------------------------------------------------------
async function main() {
  const args = process.argv.slice(2);
  if (args.includes('--queries')) {
    console.log('Configured areas and queries:\n');
    for (const [name, cfg] of Object.entries(AREAS)) {
      console.log(`  ${name} (${cfg.label})`);
      for (const q of Object.keys(cfg.queries)) console.log(`    - ${q}`);
    }
    return;
  }

  const onlyArg = args.find((a) => a.startsWith('--area='));
  const only = onlyArg ? onlyArg.split('=')[1] : null;

  const signal = new AbortController().signal;
  await mkdir(OUT_DIR, { recursive: true });

  const manifest = [];
  for (const [name, cfg] of Object.entries(AREAS)) {
    if (only && name !== only) continue;
    manifest.push(await buildArea(name, cfg, signal));
  }

  await writeFile(resolve(OUT_DIR, '_index.json'), JSON.stringify(manifest, null, 2));
  console.log(`\nWrote manifest -> ${resolve(OUT_DIR, '_index.json')}`);
  console.log('Done.');
}

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