import { Meteor } from 'meteor/meteor';
import { ReactiveVar } from 'meteor/reactive-var';
import { Tracker } from 'meteor/tracker';
import GoogleMapsLoader from 'google-maps';

class GkeysC {
  constructor() {
    this.gmapkey = new ReactiveVar(null);
    // Separate from the key itself: a deployment with no gmaps key configured
    // still loads the script and still has to render. Waiting on the key value
    // meant that with an empty key every component mounted after the script had
    // loaded (i.e. any client-side navigation) sat forever on "Waiting for the
    // gkey" and rendered an empty <div> — /subscriptions/new was blank, with no
    // error anywhere.
    this.loaded = new ReactiveVar(false);
    const self = this;
    this.callbacks = [];
    Meteor.startup(() => {
      Meteor.call('getMapKey', (error, key) => {
        // console.log(google.maps);
        GoogleMapsLoader.KEY = key;
        GoogleMapsLoader.LIBRARIES = ['places'];
        // The google-maps npm package (v3.2.1) builds the script URL without
        // `loading=async`, which Google now warns about. It exposes no hook for
        // extra params, so wrap createUrl to append it (no node_modules edit).
        const origCreateUrl = GoogleMapsLoader.createUrl;
        GoogleMapsLoader.createUrl = () => `${origCreateUrl()}&loading=async`;
        GoogleMapsLoader.load(() => {
          self.gmapkey.set(key);
          self.loaded.set(true);
          console.log('GMaps script just loaded');
          self.doCallbacks(key);
        });
      });
    });
  }

  doCallbacks(key) {
    for (let i = 0; i < this.callbacks.length; i += 1) {
      this.callbacks[i](null, key);
    }
    this.callbacks = [];
  }

  load(callback) {
    this.callbacks.push(callback);
    Tracker.autorun((computation) => {
      if (this.loaded.get()) {
        // already loaded; the key may legitimately be empty
        this.doCallbacks(this.gmapkey.get());
        computation.stop();
      } else {
        console.log('Waiting for the gmaps script');
      }
    });
  }
}

const Gkeys = new GkeysC();

export default Gkeys;