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

@Injectable()
export class NaTranslateService {
  private change$ = new BehaviorSubject<any>(new Object());

  constructor(private translate: TranslateService) {
    if (translate.getLangs() == null || translate.getLangs().length <= 0) {
      // translate.addLangs(['zh', 'en']);
      translate.addLangs([this.translate.getBrowserLang()]);
    }
    // if (this.translate.currentLang == null) {
    //   this.translate.use(this.translate.getBrowserLang());
    // }
    if (this.translate.getDefaultLang() == null) {
      // this.translate.setDefaultLang(this.translate.getBrowserCultureLang()); // zh_CN
      this.translate.setDefaultLang(this.translate.getBrowserLang()); // zh
    }
  }

  get change(): Observable<string> {
    return this.change$.asObservable().pipe(filter(w => w != null));
  }

  get currentLang() {
    return this.translate.currentLang;
  }

  /**
   * Gets the translated value of a key (or an array of keys)
   */
  get(key: string | Array<string>, interpolateParams?: Object): Observable<string | any> {
    return this.translate.get(key, interpolateParams);
  }

  /**
   * Returns a stream of translated values of a key (or an array of keys) which updates
   * whenever the language changes.
   */
  public stream(key: string | Array<string>, interpolateParams?: Object): Observable<string | any> {
    return this.translate.stream(key, interpolateParams);
  }

  /**
   * Returns a translation instantly from the internal state of loaded translation.
   * All rules regarding the current language, the preferred language of even fallback languages will be used except any promise handling.
   */
  public instant(key: string | Array<string>, interpolateParams?: Object): string | any {
    return this.translate.instant(key, interpolateParams);
  }

  /**
   * Changes the lang currently used
   */
  use(lang: string): Observable<any> {
    this.change$.next(lang);
    return this.translate.use(lang);
  }

  /**
   * Sets the default language to use as a fallback
   */
  public setDefaultLang(lang: string): void {
    this.translate.setDefaultLang(lang);
  }

  /**
   * Gets the default language used
   * @returns string
   */
  public getDefaultLang(): string {
    return this.translate.defaultLang;
  }

  /**
   * Returns an array of currently available langs
   * @returns any
   */
  public getLangs(): Array<string> {
    return this.translate.langs;
  }

  /**
   * @param langs
   * Add available langs
   */
  public addLangs(langs: Array<string>): void {
    this.translate.addLangs(langs);
  }

  /**
   * Sets the translated value of a key
   */
  public set(key: string, value: string, lang: string = this.translate.currentLang): void {
    this.translate.set(key, value, lang);
  }

  /**
   * Allows to reload the lang file from the file
   */
  public reloadLang(lang: string): Observable<any> {
    return this.translate.reloadLang(lang);
  }

  /**
   * Deletes inner translation
   */
  public resetLang(lang: string): void {
    this.translate.resetLang(lang);
  }

  /**
   * Returns the language code name from the browser, e.g. "de"
   *
   * @returns string
   */
  public getBrowserLang(): string {
    return this.translate.getBrowserLang();
  }

  /**
   * Returns the culture language code name from the browser, e.g. "de-DE"
   *
   * @returns string
   */
  public getBrowserCultureLang(): string {
    return this.translate.getBrowserCultureLang();
  }

}