import { HttpInterceptorFn } from '@angular/common/http';
import { inject } from '@angular/core';
import { LocationService } from '../services/location.service';
import { LanguageService } from '../services/language.service';
import { AuthService } from '../services/auth.service';
import { environment } from '../../environments/environment';

/** Map internal language codes to API header values */
const LANG_HEADER_MAP: Record<string, string> = {
  'ru': 'RU',
  'en': 'EN',
  'hy': 'AM',
};

/** Map region IDs to API header values */
const REGION_HEADER_MAP: Record<string, string> = {
  'moscow': 'Moscow',
  'spb': 'ST. Petersburg',
  'yerevan': 'Yerevan',
};

export const apiHeadersInterceptor: HttpInterceptorFn = (req, next) => {
  if (!req.url.startsWith(environment.apiUrl)) {
    return next(req);
  }

  const locationService = inject(LocationService);
  const languageService = inject(LanguageService);
  const authService = inject(AuthService);

  const regionId = locationService.regionId();
  const lang = languageService.currentLanguage();
  const currency = languageService.currentCurrency();
  const session = authService.session();

  let headers = req.headers;

  if (regionId) {
    headers = headers.set('X-Region', REGION_HEADER_MAP[regionId] ?? regionId);
  }
  if (lang) {
    headers = headers.set('X-Language', LANG_HEADER_MAP[lang] ?? lang.toUpperCase());
  }
  headers = headers.set('Currency', currency || 'RUB');
  if (session?.sessionId) {
    headers = headers.set('WebSessionID', session.sessionId);
  }

  return next(req.clone({ headers }));
};