D-Net

import {throwError as observableThrowError} from 'rxjs';

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

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

import {ClaimEntity, ClaimResult} from '../claimHelper.class';

import {map} from "rxjs/operators";

import {EnvProperties} from "../../../utils/properties/env-properties";

@Injectable()

export class SearchCrossrefService {

  constructor( private http: HttpClient ) {}

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

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

     return this.http.get((properties.useCache) ? (properties.cacheUrl + encodeURIComponent(url)) : url)

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

                     .pipe(map(request => [request["total-results"], parse ? this.parse(request.items) : request]))

                     //.catch(this.handleError);

  }

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

    var doisParams = "";

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

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

    }

    let url = properties.searchCrossrefAPIURL + '?filter=' + doisParams;

           return this.http.get(url)

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

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

                       .pipe(map(request => [request["total-results"], parse ? this.parse(request['items']) : request]))

                       //.catch(this.handleError);

}

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

    let url = properties.searchCrossrefAPIURL + '?filter=doi:';

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

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

    }

    url = properties.searchCrossrefAPIURL + '?filter=' + url;

         return this.http.get(url)

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

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

                         .pipe(map( request => [request["total-results"], parse ? this.parse(request.items) : request]))

                         //.catch(this.handleError);

  }

  private handleError(error: any) {

    // 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): ClaimEntity[] {

    const results: ClaimEntity[] = [];

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

      const item = response[i];

      const entity: ClaimEntity = new ClaimEntity();

      entity.result = new ClaimResult();

      entity.result.publisher = null;

      entity.result.journal = null;

      entity.result.DOI = item.DOI;

      entity.id = item.DOI;

      entity.title = item.title;

      entity.result.url = item.URL;

      entity.result.source = 'crossref';

      entity.type = 'publication';

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

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

      }

      entity.result.accessRights = "OPEN";

      entity.result.publisher = item.publisher;

      entity.result.journal = null;

      entity.result.record = item;

      if (item.author) {

        entity.result.authors = [];

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

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

        }

      }

      if (item.editor) {

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

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

        }

      }

      results.push(entity);

    }

    return results;

  }

}