import { APP_INITIALIZER, ModuleWithProviders, NgModule } from '@angular/core';
import { IGoogleAnalyticsCommand, NgxGoogleAnalyticsModule } from 'ngx-google-analytics';

import { ConsentService } from './consent.service';
import { GoogleAnalyticsSyncService } from './google-analytics-sync.service';
import { LocalStorageSyncService } from './local-storage-sync.service';

export interface AnalyticsOptions {
  gaToken: string;

  appName?: string;
  projectName?: string;

  developmentMode?: boolean;
}

const EAGERLY_LOADED_SERVICES = [ConsentService, GoogleAnalyticsSyncService, LocalStorageSyncService];

function toAttributes(obj: Record<string, unknown>): Record<string, string> {
  return Object.entries(obj).reduce<Record<string, string>>((attrs, [key, value]) => {
    if (value != null) {
      attrs[key] = `${value}`;
    }

    return attrs;
  }, {});
}

function initCommands(options: AnalyticsOptions): IGoogleAnalyticsCommand[] {
  const { appName, projectName, developmentMode } = options;

  return [
    {
      command: 'set',
      values: [
        toAttributes({
          appName,
          projectName,
          developmentMode,
        }),
      ],
    },
  ];
}

@NgModule({
  imports: [NgxGoogleAnalyticsModule],
  providers: [
    ...EAGERLY_LOADED_SERVICES,

    {
      provide: APP_INITIALIZER,
      multi: true,
      useFactory: () => () => undefined,
      deps: EAGERLY_LOADED_SERVICES,
    },
  ],
})
export class AnalyticsModule {
  static forRoot(options: AnalyticsOptions): ModuleWithProviders<AnalyticsModule> {
    const { providers = [] } = NgxGoogleAnalyticsModule.forRoot(options.gaToken, initCommands(options));

    return { ngModule: AnalyticsModule, providers };
  }
}