GODSIGH/js/layers/ais.js

// Live AIS shipping (Wave 7) — every real vessel aisstream.io can hear,
// worldwide. ais_bridge.py (a tiny daemon next to the web root) holds the
// websocket and drops ais_snapshot.json every ~20 s; this layer just polls
// that static file. Live-only: hidden when the clock is scrubbed off now
// (there's no ship history recorder).

const POLL_MS = 30000;
const NAV = {
  0: 'under way', 1: 'at anchor', 2: 'not under command', 3: 'restricted manoeuvre',
  4: 'constrained by draught', 5: 'moored', 6: 'aground', 7: 'fishing', 8: 'under sail',
};
function typeLabel(t) {
  if (t == null) return null;
  if (t === 30) return 'fishing';
  if (t === 35) return 'military';
  if (t === 36 || t === 37) return 'sailing / pleasure';
  if (t === 52) return 'tug';
  if (t >= 60 && t <= 69) return 'passenger';
  if (t >= 70 && t <= 79) return 'cargo';
  if (t >= 80 && t <= 89) return 'tanker';
  return `type ${t}`;
}

export default function create(ctx) {
  const { viewer, Cesium, ui } = ctx;
  const pts = viewer.scene.primitives.add(new Cesium.PointPrimitiveCollection());
  pts.show = false;

  const C_CARGO = Cesium.Color.fromCssColorString('#39d98a');
  const C_TANKER = Cesium.Color.fromCssColorString('#ff9f43');
  const C_PASS = Cesium.Color.fromCssColorString('#54a0ff');
  const C_FISH = Cesium.Color.fromCssColorString('#c58fff');
  const C_OTHER = Cesium.Color.fromCssColorString('#9fd8cb');
  const C_STILL = Cesium.Color.fromCssColorString('#7c8b97');
  const OUTLINE = Cesium.Color.BLACK;
  const colorFor = (s) => {
    if ((s.sog ?? 0) < 0.5 || s.nav === 1 || s.nav === 5) return C_STILL;
    const t = s.type;
    if (t >= 70 && t <= 79) return C_CARGO;
    if (t >= 80 && t <= 89) return C_TANKER;
    if (t >= 60 && t <= 69) return C_PASS;
    if (t === 30) return C_FISH;
    return C_OTHER;
  };

  let enabled = false;
  let live = true;
  let timer = null;
  let lastCount = 0;
  let lastTs = null;

  ui.addLayer('ais', 'Ships (live AIS)', true, (on) => {
    enabled = on;
    pts.show = on && live;
    if (on && !timer) { poll(); timer = setInterval(poll, POLL_MS); }
    if (!on && timer) { clearInterval(timer); timer = null; }
    if (!on) { ui.hidePickOverlay(); ui.setStatus('ais', '', 'ok'); }
    else status();
  }, 'Sea');
  enabled = true;
  pts.show = true; // defaultOn — addLayer doesn't fire onToggle for the initial state
  poll();
  timer = setInterval(poll, POLL_MS);

  function status() {
    if (!enabled) return;
    if (!live) { ui.setStatus('ais', 'live only — return clock to now', 'warn'); return; }
    const age = lastTs ? Math.round(Date.now() / 1000 - lastTs) : null;
    ui.setStatus('ais', lastCount ? `${lastCount} live vessels · ${age}s ago · aisstream.io` : 'waiting for bridge…', lastCount ? 'ok' : 'warn');
  }

  async function poll() {
    if (!enabled || document.hidden) return;
    let res;
    try {
      // rolling bucket busts any CDN cache; no-store busts the browser's
      res = await fetch(`ais_snapshot.json?t=${Math.floor(Date.now() / POLL_MS)}`, { cache: 'no-store' });
    } catch { ui.setStatus('ais', 'network error', 'warn'); return; }
    if (res.status === 404) { ui.setStatus('ais', 'bridge offline (no snapshot)', 'err'); return; }
    if (!res.ok) { ui.setStatus('ais', `HTTP ${res.status}`, 'warn'); return; }
    let snap;
    try { snap = await res.json(); } catch { ui.setStatus('ais', 'bad snapshot', 'err'); return; }
    const ships = snap.ships || [];
    pts.removeAll();
    for (const s of ships) {
      if (!isFinite(s.lat) || !isFinite(s.lon)) continue;
      pts.add({
        position: Cesium.Cartesian3.fromDegrees(s.lon, s.lat),
        pixelSize: (s.sog ?? 0) > 0.5 ? 4 : 3,
        color: colorFor(s),
        outlineColor: OUTLINE,
        outlineWidth: 1,
        disableDepthTestDistance: 50000,
        id: { layer: 'ais', ...s },
      });
    }
    lastCount = ships.length;
    lastTs = snap.ts;
    status();
  }

  function onClockTick(_t, isLive) {
    if (live === isLive) return;
    live = isLive;
    pts.show = enabled && live;
    status();
  }

  function handlePick(picked) {
    if (!enabled || picked?.id?.layer !== 'ais') return false;
    const d = picked.id;
    ui.showPickOverlay('🚢 ' + (d.name || `MMSI ${d.mmsi}`), [
      ['MMSI', String(d.mmsi)],
      ['Type', typeLabel(d.type) || '—'],
      ['Speed', d.sog != null ? `${d.sog.toFixed(1)} kn` : '—'],
      ['Course', d.cog != null ? `${Math.round(d.cog)}°` : '—'],
      ['Status', NAV[d.nav] || '—'],
      ['Destination', d.dest || '—'],
    ]);
    return true;
  }
  function clearPick() { ui.hidePickOverlay(); }

  return { id: 'ais', handlePick, clearPick, onClockTick };
}