import type { Ray, Vector, World } from "@dimforge/rapier3d-compat";
import { interactionGroups } from "@react-three/rapier";

interface LabelRapierApi {
  readonly Ray: new (origin: Vector, direction: Vector) => Ray;
  readonly QueryFilterFlags: {
    readonly ONLY_FIXED: number;
    readonly EXCLUDE_SENSORS: number;
  };
}

const LABEL_OCCLUSION_GROUPS = interactionGroups(0, 0);
const LABEL_SURFACE_MARGIN = 0.08;

/** Uses Rapier's spatial index, bounded to the camera-to-label segment. */
export function hasDungeonLabelLineOfSight(
  rapier: LabelRapierApi,
  world: World,
  camera: Vector,
  label: Vector,
): boolean {
  const dx = label.x - camera.x;
  const dy = label.y - camera.y;
  const dz = label.z - camera.z;
  const distance = Math.hypot(dx, dy, dz);
  if (!Number.isFinite(distance)) return false;
  if (distance <= LABEL_SURFACE_MARGIN) return true;
  const ray = new rapier.Ray(camera, { x: dx / distance, y: dy / distance, z: dz / distance });
  return !world.castRay(
    ray,
    distance - LABEL_SURFACE_MARGIN,
    true,
    rapier.QueryFilterFlags.ONLY_FIXED | rapier.QueryFilterFlags.EXCLUDE_SENSORS,
    LABEL_OCCLUSION_GROUPS,
  );
}