D-Net

import {throwError as observableThrowError, Observable} from 'rxjs';

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

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

import { HttpClient } from '@angular/common/http';

import { ClaimResult} from  '../claimEntities.class';

import {map} from "rxjs/operators";

@Injectable()

export class SearchCrossrefService {

  constructor( private http: HttpClient ) {}

  searchCrossrefResults (term: string, size : number, page : number, apiUrl:string, parse:boolean = false):any {

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

     let key = url;

     return this.http.get(url)

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

                     .pipe(map(request => request['message']))

                     .pipe(map(request => (parse?this.parse(request.items):request)))

                     //.catch(this.handleError);

    }

    searchCrossrefByDOIs(DOIs: string[], apiUrl:string, parse:boolean = false):any {

      var doisParams = "";

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

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

      }

       let url = apiUrl+'?filter='+doisParams;

       let key = url;

       return this.http.get(url)

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

                       .pipe(map(request => request['message']))

                       .pipe(map(request => (parse?this.parse(request.items):request)))

                       //.catch(this.handleError);

      }

      searchCrossrefByMultipleDOIs(dois: string[], apiUrl:string, parse:boolean = false):any {

        let url = apiUrl+'?filter=doi:';

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

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

        }

        url = apiUrl+'?filter='+url;

        let key = url;

         return this.http.get(url)

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

                         .pipe(map(request => request['message']))

                         .pipe(map(request => (parse?this.parse(request.items):request)))

                         //.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 observableThrowError(error  || 'Server error');

  }

  parse(response):ClaimResult[]{

    var results:ClaimResult[] = [];

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

      var item=response[i];

      var result:ClaimResult = new ClaimResult();

      result.publisher =  null;

      result.journal =  null;

      result.DOI = item.DOI;

      result.id = item.DOI;

      result.title = item.title;

      result.url = item.URL;

      result.source = 'crossref';

      result.type = 'publication';

      if(item['published-print']){

        result.date = item['published-print']['date-parts'][0];

      }

      result.accessRights =  "OPEN";

      result.publisher = item.publisher;

      result.journal = null;

      result.result = item;

      if(item.author){

        for(var j=0; j<item.author.length; j++){

            result.authors.push(item.author[j].family+", "+item.author[j].given);

        }

      }

      if(item.editor){

        for(var j=0; j<item.editor.length; j++){

            result.editors.push(item.editor[j].family+", "+item.editor[j].given);

        }

      }

      results.push(result);

    }

    return results;

  }

}