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

@Injectable({
  providedIn: 'root'
})
export class AuthInterceptorService implements HttpInterceptor {

  constructor(private authService: AuthService) { }

  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {

    console.log("Interceptor - interceptor request.");
    const accessToken = this.authService.getAccessToken();

    if (accessToken) {
      request = this.addToken(request, accessToken);
    }

    return next.handle(request).pipe(
      catchError((error) => {
        console.error("Interception Error: ", error);
        if (error.status === 401 && accessToken) {
          console.log('Interceptor - handling 401 error');
          return this.handle401Error(request, next, accessToken);
        }
        return throwError(error);
      })
    )
  }
  addToken(request: HttpRequest<any>, accessToken: string): HttpRequest<any> {
    return request.clone({
      setHeaders: {
        Authorization: `Bearer ${accessToken}`
      }
    });
  }
  handle401Error(request: HttpRequest<any>, next: HttpHandler, accessToken: string): Observable<HttpEvent<any>> {
    const refreshToken = this.authService.getRefreshToken();

    if (!refreshToken) {
      this.authService.logout();
      return throwError("No refresh token available.");
    }

    return this.authService.refreshTokens(accessToken, refreshToken).pipe(
      switchMap((response) => {
        if (response.accessToken) {
          request = this.addToken(request, response.accessToken);
          return next.handle(request);
        } else {
          this.authService.logout();
          return throwError("token refresh failed");
        }

      }),
      catchError((error) => {
        this.authService.logout();
        return throwError(error);
      }));

  }


}