import * as _ from "lodash";

export class AnalyticsService {
  private dataLayer: AnalyticsEvent[];

  constructor($window: DataLayerWindow) {
    // Depends if the GTM script has run yet
    if (!$window.dataLayer)
      $window.dataLayer = [];
    this.dataLayer = $window.dataLayer;
  }


  push(...events: AnalyticsEvent[]) {
    this.dataLayer.push(...events)
  }

  /** Sends undefined values for all the fields that currently exist in the data layer */
  clear() {
    let keys = _.uniq(_.flatMap(this.dataLayer, e => Object.keys(e))).filter(e => e !== 'event' && !e.startsWith('gtm.'));
    if (keys.length > 0) {
      let cleanVariables = Object.assign({}, ...keys.map(k => ({ [k]: undefined })));
      this.dataLayer.push(cleanVariables);
    }
  }
}

export interface DataLayerWindow extends angular.IWindowService {
  dataLayer: AnalyticsEvent[];
}

export interface AnalyticsEvent {
  event?: EventName;

  // Remember that if these properties are not provided, GTM will use the previous value
  [p: string]: any;
}

type EventName = 'GetQuickQuote' | 'ViewQuoteForm'  | 'ViewSwitchForm' | 'ViewPlan' | 'SubmitAcquisition' | 'ViewConfirmation' | 'ViewPropertyQuestions';