paperless-ngx/src-ui/src/app/services/auth.interceptor.ts

import { Injectable } from '@angular/core';
import {
  HttpRequest,
  HttpHandler,
  HttpEvent,
  HttpInterceptor,
  HttpErrorResponse
} from '@angular/common/http';
import { Observable, throwError } from 'rxjs';
import { AuthService } from './auth.service';
import { catchError } from 'rxjs/operators';
import { Toast, ToastService } from './toast.service';

@Injectable()
export class AuthInterceptor implements HttpInterceptor {

  constructor(private authService: AuthService, private toastService: ToastService) {}

  intercept(request: HttpRequest<unknown>, next: HttpHandler): Observable<HttpEvent<unknown>> {
    if (this.authService.isAuthenticated()) {
      request = request.clone({
        setHeaders: {
          Authorization: 'Token ' + this.authService.getToken()
        }
      });
    }
    return next.handle(request).pipe(
      catchError((error: HttpErrorResponse) => {
        if (error.status == 401 && this.authService.isAuthenticated()) {
          this.authService.logout()
          this.toastService.showToast(Toast.makeError("Your session has expired. Please log in again."))
        }
        return throwError(error)
      })
    );
  }
}