import { Injectable } from '@angular/core';
import { Observable, Subject } from 'rxjs';
import { CultureInfo } from './models/culture-info';
import { registerLocaleData } from '@angular/common';
import { AuthService } from '../../services/auth/auth.service';

const availableCultures: CultureInfo[] = require('../../../assets/resources/available-cultures.json');

@Injectable()
export class CultureService {

  private cultureValues = new Map<string, CultureInfo>(); // cultures by name
  private cultureChangeSubject = new Subject<CultureInfo>();
  private currentCulture: CultureInfo;

  constructor(
    private authService: AuthService
  ) {
    if (availableCultures) {
      this.cultureValues = new Map<string, CultureInfo>();
      availableCultures.forEach(culture => {
        this.cultureValues.set(culture.name, culture);
      });
    }
  }

  getCultureValues(): CultureInfo[] {
    const values: CultureInfo[] = [];
    this.cultureValues.forEach((value) => values.push(value));
    return values;
  }

  getCultureValue(culture: string): CultureInfo | undefined {
    return this.cultureValues.get(culture);
  }

  cultureSelected(culture: string | CultureInfo) {
    let newCultureName: string;
    if (typeof culture == 'string') {
      if (this.currentCulture && this.currentCulture.name === culture) { return; }
      newCultureName = culture;
    } else {
      if (this.currentCulture && this.currentCulture.name === culture.name) { return; }
      newCultureName = culture.name;
    }

    const newCulture = this.cultureValues.get(newCultureName);
    if (!newCulture) {
      console.error(`unsupported culture given: ${newCultureName}`); //TODO: throw error?
      return;
    }
    this.currentCulture = newCulture;
    this.cultureChangeSubject.next(newCulture);

    // Set angular locale based on user selection.
    const locale = newCulture.name.split('-')[0];
    import(`@angular/common/locales/${locale}.js`).catch(reason => {
      console.error('Could not load locale: ' + locale);
    }).then(selectedLocale => {
      registerLocaleData(selectedLocale.default);
    });
  }

  getCultureChangeObservable(): Observable<CultureInfo> {
    return this.cultureChangeSubject.asObservable();
  }

  getCurrentCulture(): String {
    return this.authService.current() && this.authService.current().culture ? this.authService.current().culture : this.currentCulture.name;
  }
}