import { Injectable } from '@angular/core';
import { TranslateService } from '@ngx-translate/core';
import { BehaviorSubject } from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class LanguageService {

  selectedLanguage: string;
  supportedLanguages: Array<string> = ['en', 'fr', 'nl'];

  public selectedLanguageEvent = new BehaviorSubject<string>(undefined);

  constructor(private translate: TranslateService) { }

  public determineDefaultLanguage(): string {
    const language = localStorage.getItem('lang');
    if (!language) {
      this.selectedLanguage = this.supportedLanguages[0];
    } else {
      this.selectedLanguage = localStorage.getItem('lang');
    }
    this.setSelectedLanguage(this.selectedLanguage);
    return this.selectedLanguage;
  }

  public setSelectedLanguage(lang: string) {
    if (lang === undefined || lang === null) {
      console.error('Trying to set a bad language ! - rejected !');
    } else {
      localStorage.setItem('lang', lang);
      this.selectedLanguage = lang;
      this.translate.use(lang);
      this.selectedLanguageEvent.next(lang);
    }
  }
  public getSelectedLanguage(): string {
    if (this.selectedLanguage === null) {
      this.selectedLanguageEvent.next(this.selectedLanguage);
      return this.determineDefaultLanguage();
    }
    return this.selectedLanguage;
  }
}