import { SpotLight, Vector3, type Object3D } from 'three';
import { FLASHLIGHT } from '../constants/flashlight.ts';

/** Convert nominal lumens into candela over the beam cone. Distance is a render cutoff. */
export function createFlashlight(player: Object3D) {
  const grip = player.getObjectByName('HeldFlashlight')!;
  const light = new SpotLight(FLASHLIGHT.color, 0, FLASHLIGHT.distance, FLASHLIGHT.halfAngle, FLASHLIGHT.penumbra, 2);
  const solidAngle = 2 * Math.PI * (1 - Math.cos(FLASHLIGHT.halfAngle));
  light.intensity = FLASHLIGHT.lumens / solidAngle;
  light.visible = false;
  const tip = new Vector3(), aim = new Vector3();
  return {
    light,
    update(on: boolean) {
      light.visible = on;
      if (!on) return;
      grip.updateWorldMatrix(true, false);
      light.position.copy(tip.set(0, -.27, 0).applyMatrix4(grip.matrixWorld));
      light.target.position.copy(aim.set(0, -1.27, 0).applyMatrix4(grip.matrixWorld));
    },
    dispose() { light.removeFromParent(); light.target.removeFromParent(); light.dispose(); },
  };
}