D-Net

import {Injectable} from '@angular/core';

import {Http, Response} from '@angular/http';

import {Observable}     from 'rxjs/Observable';

import {OpenaireProperties} from '../../../utils/properties/openaireProperties';

import 'rxjs/add/observable/of';

import 'rxjs/add/operator/do';

import 'rxjs/add/operator/share';

import { CacheService  } from '../../../shared/cache.service';

@Injectable()

export class SearchCrossrefService {

  constructor( private http: Http, public _cache: CacheService) {}

  searchCrossrefResults (term: string, size : number, page : number):any {

     let url = OpenaireProperties.getSearchCrossrefAPIURL()+'?query='+term+'&rows='+size+'&offset='+(size*(page-1));

     let key = url;

     if (this._cache.has(key)) {

       return Observable.of(this._cache.get(key));

     }

     return this.http.get( url)

                     .map(request => <any> request.json().message)

                     .do(items => console.log("Crossref Results: total results = "+items['total-results']+" keyword = "+term))

                     .do(res => {

                       this._cache.set(key, res);

                     });

                     //.catch(this.handleError);

    }

    searchCrossrefByDOIs(DOIs: string[]):any {

      /*

      $request ="http://api.crossref.org/works"."?filter=";

                      foreach($dois as $doi){

                          $request.="doi:".urlencode( trim($doi)).",";

                      }

      */

      var doisParams = "";

      for(var i =0 ;i < DOIs.length; i++){

        doisParams+=(doisParams.length > 0?",":"")+'doi:'+DOIs[i];

      }

       let url = OpenaireProperties.getSearchCrossrefAPIURL()+'?filter='+doisParams;

       let key = url;

       if (this._cache.has(key)) {

         return Observable.of(this._cache.get(key));

       }

       return this.http.get( url)

                       .map(request => <any> request.json().message)

                       .do(items => console.log("Crossref Results: total results = "+items['total-results']+" for doi = "+doisParams))

                       .do(res => {

                         this._cache.set(key, res);

                       });

                       //.catch(this.handleError);

      }

      searchCrossrefByMultipleDOIs(dois: string[]):any {

        let url = OpenaireProperties.getSearchCrossrefAPIURL()+'?filter=doi:';

        for(var i=0; i<dois.length; i++){

          url=url+(url.length==0?'':',')+'doi:'+dois[i];

        }

        url = OpenaireProperties.getSearchCrossrefAPIURL()+'?filter='+url;

        let key = url;

        if (this._cache.has(key)) {

          return Observable.of(this._cache.get(key));

        }

         return this.http.get( url)

                         .map(request => <any> request.json().message)

                         .do(items => console.log("Crossref Results: total results = "+items['total-results'])).

                         do(res => {

                           this._cache.set(key, res);

                         });

                         //.catch(this.handleError);

        }

  private handleError (error: Response) {

    // in a real world app, we may send the error to some remote logging infrastructure

    // instead of just logging it to the console

    console.log(error);

    return Observable.throw(error  || 'Server error');

  }

}