import { Injectable } from '@angular/core';
import { Http, Headers, Response } from '@angular/http';
import { PageResponse } from './pageresponse'

import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/toPromise';

@Injectable()
export class PagingService {
  pageNumber: number;
  pageSize: number;
  pageIsLoading: boolean;
  pageResponse: PageResponse;
  allItems: any[] = [];

  constructor(private http: Http) {
    this.pageNumber = 0;
    this.pageSize = 10;
    this.pageIsLoading = false;
    this.pageResponse = new PageResponse();
  }

  callNextPage(httpUrl: string){
    this.pageIsLoading = true;

    if(httpUrl.indexOf("?") >= 0) //url already contains a '?'
    {
      httpUrl += "&";
    }
    else{
      httpUrl += "?";
    }
    httpUrl += "pageNumber="+this.pageNumber+"&pageSize="+this.pageSize;

    var pageResponse = this.http.get(httpUrl)
                              .toPromise()
                              .then(response => response.json() as PageResponse);
    pageResponse.then(response =>{
      this.pageResponse = response;
      this.pageResponse.items.forEach(element => {
        this.allItems.push(element);
      });
      if(this.pageResponse.items.length > 0)
      {
        this.pageNumber++;
      }
      this.pageIsLoading = false;
    });
  }
}