soma-frontend/src/app/services/token.interceptor.ts

import { Injectable } from '@angular/core';
import { HttpRequest, HttpHandler, HttpEvent, HttpInterceptor, HttpErrorResponse } from '@angular/common/http';
import { AuthService } from '@app/services/auth2.service';
import { Observable, throwError, BehaviorSubject } from 'rxjs';
import { catchError, filter, take, switchMap } from 'rxjs/operators';

@Injectable()
export class TokenInterceptor implements HttpInterceptor {

  private isRefreshing = false;
  private refreshTokenSubject: BehaviorSubject<any> = new BehaviorSubject<any>(null);

  constructor(public authService: AuthService) { }

  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    if (request.url.indexOf("auth/refresh")!= -1){
      request = this.addToken(request, this.authService.getRefreshToken());
    }
    else if (request.url.indexOf("openweather")!= -1){
      request;
    }
    else {
      if (this.authService.getJwtToken()) {
        request = this.addToken(request, this.authService.getJwtToken());
      }
    }
    
    return next.handle(request).pipe(catchError(error => {
      if (error instanceof HttpErrorResponse && error.status === 401) {
        return this.handle401Error(request, next);
      } else {
        return throwError(error);
      }
    }));      

  }

  private addToken(request: HttpRequest<any>, token: string) {
    return request.clone({
      setHeaders: {
        'Authorization': `Bearer ${token}`
      }
    });
  }

  private handle401Error(request: HttpRequest<any>, next: HttpHandler) {
    if (!this.isRefreshing) {
      this.isRefreshing = true;
      this.refreshTokenSubject.next(null);

      return this.authService.refreshToken().pipe(
        switchMap((token: any) => {
          this.isRefreshing = false;
          this.refreshTokenSubject.next(token["data"]["access_token"]);
          return next.handle(this.addToken(request, token["data"]["access_token"]));
        }));

    } else {
      return this.refreshTokenSubject.pipe(
        filter(token => token != null),
        take(1),
        switchMap(jwt => {
          return next.handle(this.addToken(request, jwt));
        }));
    }
  }
}