import {of,  Observable } from 'rxjs';
import { filter, take, switchMap } from 'rxjs/operators';
import { Injectable } from '@angular/core';
import { SDK } from '../../../../../shared/sdk/sdk.interface';
import { TranslateService, LangChangeEvent } from '@ngx-translate/core';
import { SdkService } from '../../../../../shared/sdk/sdk.service';
import { SdkError } from '../../../../../shared/errors/sdkError';
import { Locale } from '../interfaces/locale.interface';

@Injectable()
export class LocalesApiService {

  _defaultLang = 'en_US';
  lang: string         = this._defaultLang;

  get sdk (): Observable<SDK> {
    return this.fbService.sdk
               .pipe(
                 filter((FB: SDK) => Boolean(FB)),
                 take(1)
               );
  }

  _locales: Array<Locale>;
  locales$ = this.sdk
                 .pipe(
                   switchMap((FB: SDK) => {
                       if (this._locales) {
                         return of(this._locales);
                       }
                       return Observable.create((observer) => {
                         FB.api(`/search`, {
                           type:   'adlocale',
                           limit:  500,
                           locale: this.lang
                         }, (response) => {
                           if (response.error) {
                             observer.error(new SdkError(response.error));
                           } else {
                             observer.next(response.data);
                             observer.complete();
                           }
                         });
                       });
                     })
                 );

  constructor (private fbService: SdkService,
               private translateService: TranslateService) {
    this.translateService.onLangChange.subscribe((event: LangChangeEvent) => {
      this.lang = event.lang;
    });

    this.locales$
        .pipe(
          take(1)
        )
        .subscribe((locales: Array<Locale>) => this._locales = locales);
  }

}