// Generate the About page's dot-grid world map (public/images/about/worldmap-dots.svg)
// from world-atlas land-110m (Natural Earth, public domain). Equirectangular
// projection, Antarctica cropped. Also prints the team-city pin positions as
// percentages of the SVG box, to be baked into src/site/pages/about.html.
//
//   node scripts/build-worldmap.mjs
//
// Deps (devDependencies): world-atlas, topojson-client.
import fs from "node:fs";
import { createRequire } from "node:module";
import { feature } from "topojson-client";

const require = createRequire(import.meta.url);
const topo = require("world-atlas/land-110m.json");
const land = feature(topo, topo.objects.land); // FeatureCollection of MultiPolygon

// Projection window: full longitudes, latitudes 84N..56S (arctic coastlines
// intact, Antarctica cut).
const LON0 = -180, LON1 = 180, LAT0 = 84, LAT1 = -56;
const W = 1000;
const H = Math.round(((LAT0 - LAT1) / (LON1 - LON0)) * W); // 361
const px = (lon) => ((lon - LON0) / (LON1 - LON0)) * W;
const py = (lat) => ((LAT0 - lat) / (LAT0 - LAT1)) * H;

// Unwrap ring longitudes so antimeridian-crossing polygons (Fiji) don't create
// a phantom edge across the whole map: keep each vertex within 180deg of the
// previous one, letting the ring run past +/-180 instead of jumping.
function unwrap(ring) {
  const out = [ring[0].slice()];
  for (let i = 1; i < ring.length; i++) {
    let x = ring[i][0];
    const prev = out[i - 1][0];
    while (x - prev > 180) x -= 360;
    while (x - prev < -180) x += 360;
    out.push([x, ring[i][1]]);
  }
  return out;
}
const POLYS = [];
for (const f of land.features) {
  const polys = f.geometry.type === "Polygon" ? [f.geometry.coordinates] : f.geometry.coordinates;
  for (const poly of polys) POLYS.push(poly.map(unwrap));
}

// Ray-cast point-in-ring (lon/lat space). Tests lon and lon+/-360 so points
// still hit rings that were unwrapped past the antimeridian.
function inRing(lon, lat, ring) {
  let inside = false;
  for (let i = 0, j = ring.length - 1; i < ring.length; j = i++) {
    const [xi, yi] = ring[i], [xj, yj] = ring[j];
    if (yi > lat !== yj > lat && lon < ((xj - xi) * (lat - yi)) / (yj - yi) + xi)
      inside = !inside;
  }
  return inside;
}
function inRingWrapped(lon, lat, ring) {
  return inRing(lon, lat, ring) || inRing(lon + 360, lat, ring) || inRing(lon - 360, lat, ring);
}
function inLand(lon, lat) {
  for (const poly of POLYS) {
    if (!inRingWrapped(lon, lat, poly[0])) continue;
    let inHole = false;
    for (let h = 1; h < poly.length; h++) if (inRingWrapped(lon, lat, poly[h])) { inHole = true; break; }
    if (!inHole) return true;
  }
  return false;
}

// Dot grid: ~1.5 deg step -> ~4.2px spacing in the 1000px box (fine pitch;
// the map renders at full container width).
const STEP = 1.5, R = 1.05;
// The 0.07deg jitter keeps sample rows off exact polygon-vertex latitudes,
// where the ray cast can mis-count and paint a solid row across the ocean.
const EPS = 0.07;
let dots = [];
for (let lat = LAT1 + STEP / 2 + EPS; lat < LAT0; lat += STEP) {
  for (let lon = LON0 + STEP / 2 + EPS; lon < LON1; lon += STEP) {
    if (inLand(lon, lat)) dots.push(`<circle cx="${px(lon).toFixed(1)}" cy="${py(lat).toFixed(1)}" r="${R}"/>`);
  }
}

// Full-alpha dots: the page dims the <img> via CSS opacity, so the same file
// doubles as a fully-opaque mask for the signal-wave overlay.
const svg =
  `<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 ${W} ${H}" fill="#0B0B0C" aria-hidden="true">` +
  `<g>${dots.join("")}</g></svg>`;
fs.writeFileSync("public/images/about/worldmap-dots.svg", svg);
console.log(`worldmap-dots.svg  ${dots.length} dots  ${(svg.length / 1024).toFixed(0)}KB  viewBox 0 0 ${W} ${H}`);

// Team cities. Prints the pin position (x/y % of the SVG box) and the viewBox
// px,py (for authoring arc paths) to bake into src/site/pages/about.html.
const CITIES = [
  ["Los Angeles",    34.05, -118.24, "America/Los_Angeles"],
  ["San Francisco",  37.77, -122.42, "America/Los_Angeles"],
  ["Vancouver",      49.28, -123.12, "America/Vancouver"],
  ["Vermont",        44.26,  -72.58, "America/New_York"],
  ["South Carolina", 34.00,  -81.03, "America/New_York"],
  ["Toronto",        43.65,  -79.38, "America/Toronto"],
  ["Buenos Aires",  -34.60,  -58.38, "America/Argentina/Buenos_Aires"],
  ["Scotland",       55.95,   -3.19, "Europe/London"],
  ["London",         51.51,   -0.13, "Europe/London"],
  ["Amsterdam",      52.37,    4.90, "Europe/Amsterdam"],
  ["Helsinki",       60.17,   24.94, "Europe/Helsinki"],
  ["Hong Kong",      22.32,  114.17, "Asia/Hong_Kong"],
  ["Tokyo",          35.68,  139.65, "Asia/Tokyo"],
  ["Auckland",      -36.85,  174.76, "Pacific/Auckland"],
];
for (const [name, lat, lon, tz] of CITIES) {
  const x = ((px(lon) / W) * 100).toFixed(1), y = ((py(lat) / H) * 100).toFixed(1);
  console.log(`${name.padEnd(15)} --x:${x}%  --y:${y}%   px ${px(lon).toFixed(0)},${py(lat).toFixed(0)}   ${tz}`);
}