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 = "";
        console.log(error);
        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;
    }
}