// vim: set tw=80 ts=2 sw=2 sts=2 :

import { Injectable, Injector } from '@angular/core';
import {
  HttpEvent, HttpInterceptor, HttpHandler, HttpRequest, HttpErrorResponse
} from '@angular/common/http';

import { Observable} from 'rxjs/Rx';
import 'rxjs/add/operator/catch';

import { Logger } from '@nsalaun/ng-logger';

import { LoginService } from './login.service';
import { Token } from './token';

@Injectable()
export class AuthInterceptor implements HttpInterceptor {
  private observable: Observable<Token>;

  constructor(
    private logger: Logger,
    private injector: Injector,
  ) {}

  injectAuthorizationHeader(request: HttpRequest<any>, accessToken: string) {
    this.logger.log('Injecting Authorization header');

    return request;
  }

  intercept(
    request: HttpRequest<any>,
    next: HttpHandler,
    pass?: number
  ): Observable<HttpEvent<any>> {
    if(!pass) {
      pass = 1;
    }

    let loginService = this.injector.get(LoginService);

    if(request.url == loginService.url) {
      this.logger.log("Login URL, do not handle.");

      return next.handle(request);
    }

    this.logger.log(`Intercepted request, pass #${pass}`, request, next);

    let accessToken = loginService.accessToken;

    if(accessToken){
      request = request.clone({
        headers: request.headers.set('Authorization', `Bearer ${accessToken}`)
      });
    }

    this.logger.log('Request', request);

    let observable: Observable<any> = next.handle(request);

    return observable.catch(
      (error, caught): Observable<any> => {
        this.logger.error("Error", error, caught);

        if(!(error instanceof HttpErrorResponse) || error.status != 401) {
          return Observable.throw(error);
        }

        this.logger.log('Unauthorized', error);

        if(pass === 3) {
          return Observable.throw(error);
        }

        if(!this.observable) {
          this.logger.log("No current login observable.")
          this.observable = loginService.login();
        }

        return this.observable.flatMap((token: Token): Observable<HttpEvent<any>> => {
          this.logger.log("Logged in, access_token:", token.access_token);
          this.observable = null;
          return this.intercept(request, next, ++pass);
        }).catch((error) => {
          this.observable = null;
          return Observable.throw(error);
        });
      }
    );
  }
}