import { TranslateLoader } from '@ngx-translate/core';
import { Observable } from 'rxjs';
import { NativeService, UCAP_NATIVE_SERVICE } from '@ucap-webmessenger/native';
import { take, map } from 'rxjs/operators';
import { FileUtil } from '@ucap-webmessenger/core';
import { Injectable, Inject } from '@angular/core';

@Injectable({
  providedIn: 'root'
})
export class TranslateBrowserLoader implements TranslateLoader {
  constructor(
    @Inject(UCAP_NATIVE_SERVICE) private nativeService: NativeService,
    private prefix: string = '/assets/i18n/',
    private suffix: string = '.json'
  ) {}

  /**
   * Gets the translations from the server
   */
  public getTranslation(lang: string): Observable<any> {
    return this.nativeService
      .readFile(`${this.prefix}${lang}.${this.suffix}`)
      .pipe(
        take(1),
        map(buffer => {
          return JSON.parse(buffer.toString('utf-8'));
        })
      );
  }
}