import {Injectable} from '@angular/core';
import {HttpClient, HttpErrorResponse} from '@angular/common/http';
import {BehaviorSubject, from, Observable, of, Subscriber, throwError, zip} from 'rxjs';
import {AutoCompleteValue} from '../../searchPages/searchUtils/searchHelperClasses.class';

import {EnvProperties} from '../properties/env-properties';
import {catchError, map} from 'rxjs/operators';

@Injectable({  providedIn: 'root' })
export class ISVocabulariesService {
  private vocabularies: Map<string, BehaviorSubject<AutoCompleteValue[]>> = new Map<string, BehaviorSubject<AutoCompleteValue[]>>();
  private provenanceActionVocabulary: BehaviorSubject<{}> = new BehaviorSubject(null);
  private subscriptions = [];

  constructor(private http: HttpClient) {}

  ngOnDestroy() {
    this.clearSubscriptions();
  }

  clearSubscriptions() {
    this.subscriptions.forEach(subscription => {
      if (subscription instanceof Subscriber) {
        subscription.unsubscribe();
      }
    });
  }
  getVocabularyByType(field: string, entity: string, properties: EnvProperties): Observable<any> {
    //console.log("getVocabulary field: "+ field + " for entity: "+ entity);
    var file = "";
    var vocabulary = "";
    if (field == "lang") {
      // file="languages.json";
      // return this.getVocabularyFromFile(file);
      vocabulary = "dnet:languages.json";
      //return this.getVocabularyFromService(vocabulary, properties);
      return from(this.getVocabularyFromServiceAsync(vocabulary, properties));
    } else if (field == "type" && (entity == "publication")) {
      // file = "publicationTypes.json";
      // return this.getVocabularyFromFile(file);
      vocabulary = "dnet:publication_resource.json";
      //return this.getVocabularyFromService(vocabulary, properties);
      return from(this.getVocabularyFromServiceAsync(vocabulary, properties));
    } else if (field == "type" && (entity == "dataset")) {
      // file = "dnet:dataCite_resource.json";
      // return this.getVocabularyFromFile(file);
      vocabulary = "dnet:dataCite_resource.json";
      //return this.getVocabularyFromService(vocabulary, properties);
      return from(this.getVocabularyFromServiceAsync(vocabulary, properties));
    } else if (field == "type" && (entity == "software" || entity == "other")) {
      return of([]);
    } else if (field == "type" && entity == "result" ) {
      //return Observable.zip(this.getVocabularyFromService("dnet:publication_resource.json", properties),this.getVocabularyFromService("dnet:dataCite_resource.json", properties));
      return zip(from(this.getVocabularyFromServiceAsync("dnet:publication_resource.json", properties)),from(this.getVocabularyFromServiceAsync("dnet:dataCite_resource.json", properties)));
    } else if (field == "access" && (entity == "publication" || entity == "dataset" || entity == "software" || entity == "other" || entity == "result")) {
      // file= "accessMode.json";
      // return this.getVocabularyFromFile(file);
      vocabulary = "dnet:access_modes.json";
      //return this.getVocabularyFromService(vocabulary, properties);
      return from(this.getVocabularyFromServiceAsync(vocabulary, properties));
    } else if ((field == "type") && (entity == "dataprovider")) {
      // file = "dataProviderType.json";
      //   return this.getVocabularyFromFile(file);
      vocabulary = "dnet:datasource_typologies.json";
      //return this.getVocabularyFromService(vocabulary, properties);
      return from(this.getVocabularyFromServiceAsync(vocabulary, properties));
      
    } else if (field == "compatibility" && (entity == "dataprovider")) {
      // file = "dataProviderCompatibility.json";
      //   return this.getVocabularyFromFile(file);
      vocabulary = "dnet:datasourceCompatibilityLevel.json";
      //return this.getVocabularyFromService(vocabulary, properties);
      return from(this.getVocabularyFromServiceAsync(vocabulary, properties));
      
    } else if (field == "country") {
      // file = "countries.json";
      //   return this.getVocabularyFromFile(file);
      vocabulary = "dnet:countries.json";
      //return this.getVocabularyFromService(vocabulary, properties);
      return from(this.getVocabularyFromServiceAsync(vocabulary, properties));
      
    }
    return null;
    
  }

  async getVocabularyFromServiceAsync(vocabularyName: string, properties: EnvProperties): Promise<AutoCompleteValue[]> {
    if(!this.vocabularies.has(vocabularyName)) {
      await  new Promise<any>(resolve => {
        this.vocabularies.set(vocabularyName, new BehaviorSubject<any>(null));

        this.subscriptions.push(this.getVocabularyFromService(vocabularyName, properties).subscribe(
          vocabularyRes => {
            this.vocabularies.get(vocabularyName).next(vocabularyRes);
            resolve();
          }, error => {
            this.vocabularies.get(vocabularyName).next(null);
            resolve();
          }
        ));
      });
      this.clearSubscriptions();
    }

    return this.vocabularies.get(vocabularyName).getValue();
  }

  getVocabularyFromService(vocabularyName: string, properties: EnvProperties): Observable<AutoCompleteValue[]> {
    let url = properties.vocabulariesAPI + vocabularyName;
    return this.http.get((properties.useLongCache) ? (properties.cacheUrl + encodeURIComponent(url)) : url)
      //.map(res => <any> res.json())
      .pipe(map(res => res['terms']))
      .pipe(map(res => this.parse(res, vocabularyName)))
      .pipe(catchError(this.handleError));
    
  }
  
  parse(data: any, vocabularyName: string): AutoCompleteValue[] {
    var array: AutoCompleteValue[] = []
    for (var i = 0; i < data.length; i++) {
      var value: AutoCompleteValue = new AutoCompleteValue();
      value.id = data[i].englishName;//data[i].code;
      if (vocabularyName == 'dnet:countries.json') { //use Country code instead of country name
        value.id = data[i].code;
      }
      value.label = data[i].englishName;
      array.push(value);
    }
    
    return array;
    
  }

  getProvenanceActionVocabulary(properties: EnvProperties): Observable<any> {
      let vocabulary = "dnet:provenanceActions.json";
      return from(this.getProvenanceActionVocabularyFromServiceAsync(vocabulary, properties));
    }

  async getProvenanceActionVocabularyFromServiceAsync (vocabularyName: string, properties: EnvProperties): Promise<{}> {
    if(!this.provenanceActionVocabulary || !this.provenanceActionVocabulary.getValue()) {
      await  new Promise<any>(resolve => {
        this.subscriptions.push(this.getProvenanceActionVocabularyFromService(vocabularyName, properties).subscribe(
          vocabularyRes => {
            this.provenanceActionVocabulary.next(vocabularyRes);
            resolve();
          },
          error => {
            this.provenanceActionVocabulary.next(null);
            resolve();
          }
        ));
      });
      this.clearSubscriptions();
    }
    return this.provenanceActionVocabulary.getValue();
  }

  getProvenanceActionVocabularyFromService (vocabularyName: string, properties: EnvProperties): any {
    let url = properties.vocabulariesAPI+vocabularyName;

    return this.http.get((properties.useLongCache) ? (properties.cacheUrl + encodeURIComponent(url)) : url)
      .pipe(map(res => res['terms']))
      .pipe(map(res => this.parseProvenanceActionVocabulary(res)));
  }

  parseProvenanceActionVocabulary(terms: any) {
    var provenanceActionVocabulary: {} = {};
    for(let term of terms) {
      provenanceActionVocabulary[term.code] = term.englishName;
    }
    return provenanceActionVocabulary;
  }


  private handleError(error: HttpErrorResponse) {
    // 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 throwError(error || 'Server error');
  }
}