export function findNearestWithinRange(tower, enemies) {
  let nearest = null;
  let nearestDistSq = Infinity;

  for (const e of enemies) {
    const dSq = e.mesh.position.distanceToSquared(tower.position);
    if (dSq <= tower.range * tower.range && dSq < nearestDistSq) {
      nearest = e;
      nearestDistSq = dSq;
    }
  }

  return nearest;
}

export function findClosestToExitInRange(tower, enemies) {
  const inRange = [];
  const rangeSq = tower.range * tower.range;
  for (const e of enemies) {
    const dSq = e.mesh.position.distanceToSquared(tower.position);
    if (dSq <= rangeSq) {
      inRange.push(e);
    }
  }
  if (inRange.length === 0) return null;

  const towerPos = tower.position;
  inRange.sort((a, b) => {
    const segA = a.currentSeg ?? 0;
    const segB = b.currentSeg ?? 0;
    if (segA !== segB) return segB - segA;

    const remA = a.target
      ? a.target.distanceTo(a.position ?? a.mesh.position)
      : Infinity;
    const remB = b.target
      ? b.target.distanceTo(b.position ?? b.mesh.position)
      : Infinity;
    if (remA !== remB) return remA - remB;

    const da = (a.mesh?.position || a.position).distanceTo(towerPos);
    const db = (b.mesh?.position || b.position).distanceTo(towerPos);
    return da - db;
  });

  return inRange[0] || null;
}

export function findMultipleInRangeOrdered(tower, enemies, priority = "nearest") {
  const rangeSq = tower.range * tower.range;
  const inRange = [];
  for (const e of enemies) {
    const dSq = e.mesh.position.distanceToSquared(tower.position);
    if (dSq <= rangeSq) inRange.push(e);
  }
  if (inRange.length === 0) return [];

  if (priority === "closestToExit") {
    const towerPos = tower.position;
    inRange.sort((a, b) => {
      const segA = a.currentSeg ?? 0;
      const segB = b.currentSeg ?? 0;
      if (segA !== segB) return segB - segA;
      const remA = a.target
        ? a.target.distanceTo(a.position ?? a.mesh.position)
        : Infinity;
      const remB = b.target
        ? b.target.distanceTo(b.position ?? b.mesh.position)
        : Infinity;
      if (remA !== remB) return remA - remB;
      const da = (a.mesh?.position || a.position).distanceTo(towerPos);
      const db = (b.mesh?.position || b.position).distanceTo(towerPos);
      return da - db;
    });
  } else {
    const towerPos = tower.position;
    inRange.sort((a, b) => {
      const da = (a.mesh?.position || a.position).distanceTo(towerPos);
      const db = (b.mesh?.position || b.position).distanceTo(towerPos);
      return da - db;
    });
  }

  return inRange;
}