import { Injectable } from '@angular/core';
import { BROWSE_DEFINITION } from '../shared/browse-definition.resource-type';
import { BrowseDefinition } from '../shared/browse-definition.model';
import { RequestService } from '../data/request.service';
import { RemoteDataBuildService } from '../cache/builders/remote-data-build.service';
import { ObjectCacheService } from '../cache/object-cache.service';
import { HALEndpointService } from '../shared/hal-endpoint.service';
import { FollowLinkConfig } from '../../shared/utils/follow-link-config.model';
import { Observable } from 'rxjs';
import { RemoteData } from '../data/remote-data';
import { PaginatedList } from '../data/paginated-list.model';
import { FindListOptions } from '../data/find-list-options.model';
import { IdentifiableDataService } from '../data/base/identifiable-data.service';
import { FindAllData, FindAllDataImpl } from '../data/base/find-all-data';
import { dataService } from '../data/base/data-service.decorator';
import { getPaginatedListPayload, getRemoteDataPayload } from '../shared/operators';
import { RequestParam } from '../cache/models/request-param.model';
import { SearchData, SearchDataImpl } from '../data/base/search-data';
import { distinctUntilChanged, map, startWith } from 'rxjs/operators';
import { isEmpty, isNotEmpty } from '../../shared/empty.util';

/**
 * Data service responsible for retrieving browse definitions from the REST server
 */
@Injectable({
  providedIn: 'root',
})
@dataService(BROWSE_DEFINITION)
export class BrowseDefinitionDataService extends IdentifiableDataService<BrowseDefinition> implements FindAllData<BrowseDefinition>, SearchData<BrowseDefinition> {
  private findAllData: FindAllDataImpl<BrowseDefinition>;
  private searchData: SearchDataImpl<BrowseDefinition>;

  public static toSearchKeyArray(metadataKey: string): string[] {
    const keyParts = metadataKey.split('.');
    const searchFor = [];
    searchFor.push('*');
    for (let i = 0; i < keyParts.length - 1; i++) {
      const prevParts = keyParts.slice(0, i + 1);
      const nextPart = [...prevParts, '*'].join('.');
      searchFor.push(nextPart);
    }
    searchFor.push(metadataKey);
    return searchFor;
  }

  constructor(
    protected requestService: RequestService,
    protected rdbService: RemoteDataBuildService,
    protected objectCache: ObjectCacheService,
    protected halService: HALEndpointService,
  ) {
    super('browses', requestService, rdbService, objectCache, halService);
    this.searchData = new SearchDataImpl(this.linkPath, requestService, rdbService, objectCache, halService, this.responseMsToLive);
    this.findAllData = new FindAllDataImpl(this.linkPath, requestService, rdbService, objectCache, halService, this.responseMsToLive);
  }

  /**
   * Returns {@link RemoteData} of all object with a list of {@link FollowLinkConfig}, to indicate which embedded
   * info should be added to the objects
   *
   * @param options                     Find list options object
   * @param useCachedVersionIfAvailable If this is true, the request will only be sent if there's
   *                                    no valid cached version. Defaults to true
   * @param reRequestOnStale            Whether or not the request should automatically be re-
   *                                    requested after the response becomes stale
   * @param linksToFollow               List of {@link FollowLinkConfig} that indicate which
   *                                    {@link HALLink}s should be automatically resolved
   * @return {Observable<RemoteData<PaginatedList<T>>>}
   *    Return an observable that emits object list
   */
  findAll(options: FindListOptions = {}, useCachedVersionIfAvailable = true, reRequestOnStale = true, ...linksToFollow: FollowLinkConfig<BrowseDefinition>[]): Observable<RemoteData<PaginatedList<BrowseDefinition>>> {
    return this.findAllData.findAll(options, useCachedVersionIfAvailable, reRequestOnStale, ...linksToFollow);
  }

  /**
   * Make a new FindListRequest with given search method
   *
   * @param searchMethod                The search method for the object
   * @param options                     The [[FindListOptions]] object
   * @param useCachedVersionIfAvailable If this is true, the request will only be sent if there's
   *                                    no valid cached version. Defaults to true
   * @param reRequestOnStale            Whether or not the request should automatically be re-
   *                                    requested after the response becomes stale
   * @param linksToFollow               List of {@link FollowLinkConfig} that indicate which
   *                                    {@link HALLink}s should be automatically resolved
   * @return {Observable<RemoteData<PaginatedList<T>>}
   *    Return an observable that emits response from the server
   */
  public searchBy(searchMethod: string, options?: FindListOptions, useCachedVersionIfAvailable?: boolean, reRequestOnStale?: boolean, ...linksToFollow: FollowLinkConfig<BrowseDefinition>[]): Observable<RemoteData<PaginatedList<BrowseDefinition>>> {
    return this.searchData.searchBy(searchMethod, options, useCachedVersionIfAvailable, reRequestOnStale, ...linksToFollow);
  }

  /**
   * Create the HREF for a specific object's search method with given options object
   *
   * @param searchMethod The search method for the object
   * @param options The [[FindListOptions]] object
   * @return {Observable<string>}
   *    Return an observable that emits created HREF
   * @param linksToFollow   List of {@link FollowLinkConfig} that indicate which {@link HALLink}s should be automatically resolved
   */
  public getSearchByHref(searchMethod: string, options?: FindListOptions, ...linksToFollow: FollowLinkConfig<BrowseDefinition>[]): Observable<string> {
    return this.searchData.getSearchByHref(searchMethod, options, ...linksToFollow);
  }

  findByField(
    field: string,
    useCachedVersionIfAvailable = true,
    reRequestOnStale = true,
    ...linksToFollow: FollowLinkConfig<BrowseDefinition>[]
  ): Observable<RemoteData<BrowseDefinition>> {
    const searchParams = [];
    searchParams.push(new RequestParam('field', field));

    const hrefObs = this.getSearchByHref(
      'byField',
      { searchParams },
      ...linksToFollow
    );

    return this.findByHref(
      hrefObs,
      useCachedVersionIfAvailable,
      reRequestOnStale,
      ...linksToFollow,
    );
  }

  findAllLinked(
    useCachedVersionIfAvailable = true,
    reRequestOnStale = true,
    ...linksToFollow: FollowLinkConfig<BrowseDefinition>[]
  ): Observable<RemoteData<BrowseDefinition>> {
    const searchParams = [];

    const hrefObs = this.getSearchByHref(
      'allLinked',
      { searchParams },
      ...linksToFollow
    );

    return this.findByHref(
      hrefObs,
      useCachedVersionIfAvailable,
      reRequestOnStale,
      ...linksToFollow,
    );
  }

  /**
   * Get the browse URL by providing a list of metadata keys
   * @param metadatumKey
   * @param linkPath
   */
  findByFields(
    fields: string[],
    useCachedVersionIfAvailable = true,
    reRequestOnStale = true,
    ...linksToFollow: FollowLinkConfig<BrowseDefinition>[]
  ): Observable<RemoteData<BrowseDefinition>> {
    const searchParams = [];
    searchParams.push(new RequestParam('fields', fields));

    const hrefObs = this.getSearchByHref(
      'byFields',
      { searchParams },
      ...linksToFollow
    );

    return this.findByHref(
      hrefObs,
      useCachedVersionIfAvailable,
      reRequestOnStale,
      ...linksToFollow,
    );
  }

}