import {System} from '@/ecs/index.js';
import {normalizeVector} from '@/util/math.js';

export default class Attract extends System {

  static queries() {
    return {
      default: ['Magnet'],
    };
  }

  tick() {
    for (const entity of this.select('default')) {
      const {Magnet, Position} = entity;
      const aabb = {
        x0: Position.x - Magnet.strength / 2,
        x1: Position.x + (Magnet.strength / 2) - 1,
        y0: Position.y - Magnet.strength / 2,
        y1: Position.y + (Magnet.strength / 2) - 1,
      };
      for (const other of this.ecs.system('Colliders').within(aabb)) {
        if (other === entity || !other.Magnetic) {
          continue;
        }
        const difference = {
          x: entity.Position.x - other.Position.x,
          y: entity.Position.y - other.Position.y,
        };
        const toward = normalizeVector(difference);
        other.Forces.applyImpulse({
          x: Math.abs(toward.x) * 8 * Magnet.strength / difference.x,
          y: Math.abs(toward.y) * 8 * Magnet.strength / difference.y,
        });
      }
    }
  }

}