silphius/app/ecs-components/wielder.js

import Component from '@/ecs/component.js';

export default class Wielder extends Component {
  instanceFromSchema() {
    const {ecs} = this;
    return class WielderInstance extends super.instanceFromSchema() {
      activeItem() {
        const {Inventory, Wielder} = ecs.get(this.entity);
        return Inventory.item(Wielder.activeSlot + 1);
      }
      useActiveItem(state) {
        const entity = ecs.get(this.entity);
        const {Ticking} = entity;
        const activeItem = this.activeItem();
        if (activeItem) {
          const {startInstance, stopInstance} = activeItem.scripts;
          let script = state ? startInstance : stopInstance;
          if (script) {
            script = script.clone();
            script.context.ecs = ecs;
            script.context.item = activeItem;
            script.context.wielder = entity;
            Ticking.addTickingPromise(script.tickingPromise());
          }
        }
      }
    }
  }
  static properties = {
    activeSlot: {type: 'uint16'},
  };
}