/* detect.js — tuned ArUco 4x4 detection.
 * Phantom-ID fix: reject any marker decoded with hamming distance > 0 (maxHamming: 0).
 */
export function createDetector() {
  return new AR.Detector({ dictionaryName: 'ARUCO_4X4_1000', maxHammingDistance: 0 });
}

/* Returns the markers usable for solving: present in the scene, sane geometry.
 * The returned array also carries diagnostics so the HUD can distinguish
 * "nothing detected" from "detected but not in the scene" — the latter looks
 * identical on screen but means the scene never loaded, or the crest belongs to
 * a different layout. knownIds may be null/empty; then nothing is solvable and
 * rawIds tells you what the camera actually saw.
 */
export function detectMarkers(detector, imageData, knownIds) {
  const raw = detector.detect(imageData).filter(m => quadArea(m.corners) > 100);
  const usable = (knownIds && knownIds.size) ? raw.filter(m => knownIds.has(m.id)) : [];
  usable.rawCount = raw.length;
  usable.rawIds = raw.map(m => m.id);
  return usable;
}

export function quadArea(c) {
  // shoelace
  let a = 0;
  for (let i = 0; i < 4; i++) {
    const p = c[i], q = c[(i + 1) % 4];
    a += p.x * q.y - q.x * p.y;
  }
  return Math.abs(a) / 2;
}