import { Injectable } from '@angular/core';
import { HttpClient, HttpHeaders } from '@angular/common/http';
import { Observable } from 'rxjs/Observable';
import { of } from 'rxjs/observable/of';
import { catchError, map, tap } from 'rxjs/operators';


import { Employee } from '../models/employee';
import { MessageService } from './message.service';

const httpOptions = {
  headers: new HttpHeaders({ 'Content-Type': 'application/json' })
};

@Injectable()
export class EmployeeService {

  private employeesUrl = '/api/employee';

  constructor(private http: HttpClient, private messageService: MessageService) {  }


  getEmployees(): Observable<Employee[]> {
    return this.http.get<Employee[]>(this.employeesUrl)
      .pipe(
      tap(heroes => this.log(`fetched employees`)),
      catchError(this.handleError('getEmployees', []))
      );
  }

  addEmployee(employee: Employee): Observable<Employee> {

    return this.http.post<Employee>(this.employeesUrl, employee, httpOptions)
      .pipe(tap((employee: Employee) => this.log(`added employee with id=${employee.idEmployee}`)),
      catchError(this.handleError<Employee>('addEmployee'))
      );

  }

  private log(message: string) {
    this.messageService.add('EmployeeService ' + message);
  }

  private handleError<T>(operation = 'operation', result?: T) {
    return (error: any): Observable<T> => {
      console.error(error);
      this.log(`${operation} failed: ${error.message}`);

      return of(result as T);
    };
  }
}