argos/dmp-frontend/src/app/services/help-content/help-content.service.ts

/**
 * Created by stefania on 7/17/17.
 */
import { Injectable } from '@angular/core';
import { Http, Response } from '@angular/http';
import { Observable } from 'rxjs/Rx';
import { PageHelpContent } from '../../models/help-content/page-help-content';
import { CachedContentItem } from './CachedContentItem';
import { HostConfiguration } from '../../app.constants';
@Injectable()
export class HelpContentService {
  private _helpServiceUrl = HostConfiguration.HelpServiceUrl;
  cache = new Map<String, CachedContentItem>();

  constructor(private http: Http) {
  }

  getActivePageContent(route: string) {
    if (!this.cache.get(route) || !this.isValidCachedItem(route)) {
      return this.http.get(this._helpServiceUrl + "/page/route?q=" + route)
        .map(res => {
          this.cache.set(route, { timestamp: Date.now(), content: <PageHelpContent>res.json() })
          return res.json();
        })
        .catch(this.handleError)
    }
    return Observable.create(observer => observer.next(this.cache.get(route).content));
  }
  private extractData(res: Response) {
    let body = res.json();
    return body.data || {};
  }
  private handleError(error: Response | any) {
    // In a real world app, we might use a remote logging infrastructure
    // We'd also dig deeper into the error to get a better message
    let errMsg = "";
    if (error instanceof Response) {
      const body = error.text() || '';
      //const err = body.error || JSON.stringify(body);
      errMsg = `${error.status} - ${error.statusText || ''} ${body}`;
    } else {
      errMsg = (error.message) ? error.message :
        error.status ? `${error.status} - ${error.statusText}` : 'Server error';
      console.error(errMsg); // log to console instead
    }
    return Observable.throw(errMsg);
  }

  isValidCachedItem(route) {
    let cachedTimestamp = this.cache.get(route).timestamp;
    let currentTimestamp = Date.now();
    if (currentTimestamp - cachedTimestamp > HostConfiguration.CacheLifeTimeMillis) return false;
    else return true;
  }
}