import { Injectable } from '@angular/core';
import { HttpRequest, HttpHandler, HttpEvent, HttpInterceptor } from '@angular/common/http';
import { AuthService } from './auth.service';
import { Observable } from 'rxjs';
import { filter, mergeMap } from 'rxjs/operators';

@Injectable()
export class InterceptorService implements HttpInterceptor {

  constructor(private auth: AuthService) { }

  intercept(
    req: HttpRequest<any>,
    next: HttpHandler
  ): Observable<HttpEvent<any>> {
    // @NOTE: If you have some endpoints that are public
    // and do not need Authorization header, implement logic
    // here to accommodate that and conditionally let public
    // requests pass through based on your requirements
    return this.auth.token$
      .pipe(
        filter(token => typeof token === 'string'),
        mergeMap(token => {
          const tokenReq = req.clone({
            setHeaders: { Authorization: `Bearer ${token}` }
          });
          return next.handle(tokenReq);
        })
      );
  }
}