import { Injectable } from '@angular/core';
import { HttpErrorResponse } from '@angular/common/http';
import { Observable, of } from 'rxjs';
import { MessageService } from 'node_modules/primeng/api';

/** Type of the handleError function returned by HttpErrorHandler.createHandleError */
export type HandleError =
  <T> (operation?: string, result?: T) => (error: HttpErrorResponse) => Observable<T>;

/** Handles HttpClient errors */
@Injectable()
export class HttpErrorHandler {
  constructor(public messageService: MessageService) { }

  /** Create curried handleError function that already knows the service name */
  createHandleError = (serviceName = '') => <T>
    (operation = 'operation', result = {} as T) => this.handleError(serviceName, operation, result);

  /**
   * Returns a function that handles Http operation failures.
   * This error handler lets the app continue to run as if no error occurred.
   * @param serviceName = name of the data service that attempted the operation
   * @param operation - name of the operation that failed
   * @param result - optional value to return as the observable result
   */
  handleError<T> (serviceName = '', operation = 'operation', result = {} as T) {

    return (error: HttpErrorResponse): Observable<T> => {
      // TODO: send the error to remote logging infrastructure
      console.error(error); // log to console instead

      // const message =
      //   (error.error instanceof ErrorEvent) ? error.error.message :
      //   (error.error instanceof ProgressEvent) ? error.message :
      //   error.error;

      let message = '';
      try {
        if (error.error instanceof ErrorEvent) {
          message = error.error.message;
        } else if (error.error instanceof ProgressEvent) {
          message = error.message;
        } else if (typeof(error.error) === 'object') {
          message = error.message;
        } else {
          message = error.error;
        }
      } catch (error) {}
      //  `server returned code ${error.status} with body "${error.error}"`;

      //  console.log(error.error);
    //    this.MessageServiceP.add({severity:'error', summary:'Error',
    //    detail:`failed: ${message}`});
    //    this.MessageServiceP.add({severity:'error', summary:'Error',
    //    detail:`failed: ${message}`, key: 'fixtop'});
    //    alert(message);

       this.messageService.clear();
       this.messageService.add({ key: 'errorDialog', sticky: true, severity: 'error',
       summary: 'Error',
       detail: message });

      // TODO: better job of transforming error for user consumption
      // this.messageService.add(`${serviceName}: ${operation} failed: ${message}`);

      // Let the app keep running by returning a safe result.
      return of( result );
    };

  }
}