class Subscribable {
  constructor() {
    this.events = {
      addSelf: [],
      editSelf: [],
      removeSelf: [],
      changeSelf: [],
    };
    this.eventDeps = {
      addSelf: ["changeSelf"],
      editSelf: ["changeSelf"],
      removeSelf: ["changeSelf"],
      changeSelf: [],
    };
  }

  subscribe(event, callback) {
    if (this.events[event]) {
      this.events[event].push(callback);
    } else {
      throw new Error(
        `Cannot subscribe to non-existent event ${event}, available events are: ${Object.keys(
          this.events
        ).join(", ")}`
      );
    }
  }

  unsubscribe(event, callback) {
    const index = this.events[event].indexOf(callback);
    if (index === -1)
      throw new Error(
        `Tried to remove a nonexisting subscription from event ${event}`
      );
    this.events[event].splice(index, 1);
  }

  broadcast(event, data) {
    this.eventDeps[event].concat(event).forEach((eventName) => {
      this.events[eventName].forEach((f) => f(event, data));
    });
  }
}

export { Subscribable };