silphius/app/ecs/components/vulnerable.js

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

export const DamageTypes = {
  PAIN: 0,
  HEALING: 1,
  MANA: 2,
};

export default class Vulnerable extends Component {
  mergeDiff(original, update) {
    const merged = {};
    if (update.damage) {
      merged.damage = {
        ...original.damage,
        ...update.damage,
      }
    }
    return merged;
  }
  instanceFromSchema() {
    const Component = this;
    return class VulnerableInstance extends super.instanceFromSchema() {
      id = 0;
      Types = DamageTypes;
      damage(specification) {
        if (this.isInvulnerable) {
          return;
        }
        const {Alive} = Component.ecs.get(this.entity);
        if (Alive) {
          switch (specification.type) {
            case DamageTypes.PAIN: {
              Alive.acceptDamage(specification.amount);
            }
          }
        }
        Component.markChange(
          this.entity,
          'damage',
          {[`${this.entity}-${this.id++}`]: specification},
        );
      }
    };
  }
  static properties = {
    isInvulnerable: {type: 'uint8'},
  };
}