import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';
import {
  find,
  map,
} from 'rxjs/operators';

import { hasValue } from '../../shared/empty.util';
import { NotificationsService } from '../../shared/notifications/notifications.service';
import { FollowLinkConfig } from '../../shared/utils/follow-link-config.model';
import { RemoteDataBuildService } from '../cache/builders/remote-data-build.service';
import { RequestParam } from '../cache/models/request-param.model';
import { ObjectCacheService } from '../cache/object-cache.service';
import {
  DeleteData,
  DeleteDataImpl,
} from '../data/base/delete-data';
import { IdentifiableDataService } from '../data/base/identifiable-data.service';
import {
  SearchData,
  SearchDataImpl,
} from '../data/base/search-data';
import { FindListOptions } from '../data/find-list-options.model';
import { PaginatedList } from '../data/paginated-list.model';
import { RemoteData } from '../data/remote-data';
import { DeleteByIDRequest } from '../data/request.models';
import { RequestService } from '../data/request.service';
import { HALEndpointService } from '../shared/hal-endpoint.service';
import { NoContent } from '../shared/NoContent.model';
import { getFirstCompletedRemoteData } from '../shared/operators';
import { WorkflowItem } from './models/workflowitem.model';
import { WorkspaceItem } from './models/workspaceitem.model';

/**
 * A service that provides methods to make REST requests with workflow items endpoint.
 */
@Injectable({ providedIn: 'root' })
export class WorkflowItemDataService extends IdentifiableDataService<WorkflowItem> implements SearchData<WorkflowItem>, DeleteData<WorkflowItem> {
  protected linkPath = 'workflowitems';
  protected searchByItemLinkPath = 'item';
  protected responseMsToLive = 10 * 1000;

  private searchData: SearchDataImpl<WorkflowItem>;
  private deleteData: DeleteDataImpl<WorkflowItem>;

  constructor(
    protected requestService: RequestService,
    protected rdbService: RemoteDataBuildService,
    protected objectCache: ObjectCacheService,
    protected halService: HALEndpointService,
    protected notificationsService: NotificationsService,
  ) {
    super('workspaceitems', requestService, rdbService, objectCache, halService);

    this.searchData = new SearchDataImpl(this.linkPath, requestService, rdbService, objectCache, halService, this.responseMsToLive);
    this.deleteData = new DeleteDataImpl(this.linkPath, requestService, rdbService, objectCache, halService, notificationsService, this.responseMsToLive, this.constructIdEndpoint);
  }

  /**
   * Delete an existing Workflow Item on the server
   * @param id The Workflow Item's id to be removed
   * @return an observable that emits true when the deletion was successful, false when it failed
   */
  delete(id: string): Observable<RemoteData<NoContent>> {
    return this.deleteWFI(id, true);
  }

  /**
   * Send an existing Workflow Item back to the workflow on the server
   * @param id The Workspace Item's id to be sent back
   * @return an observable that emits true when sending back the item was successful, false when it failed
   */
  sendBack(id: string): Observable<boolean> {
    return this.deleteWFI(id, false).pipe(
      getFirstCompletedRemoteData(),
      map((response: RemoteData<NoContent>) => response.hasSucceeded),
    );
  }

  /**
   * Method to delete a workflow item from the server
   * @param id The identifier of the server
   * @param expunge Whether or not to expunge:
   * When true, the workflow item and its item will be permanently expunged on the server
   * When false, the workflow item will be removed, but the item will still be available as a workspace item
   */
  private deleteWFI(id: string, expunge: boolean): Observable<RemoteData<NoContent>> {
    const requestId = this.requestService.generateRequestId();

    const hrefObs = this.halService.getEndpoint(this.linkPath).pipe(
      map((endpoint: string) => this.deleteData.getIDHref(endpoint, id)),
      map((endpoint: string) => endpoint + '?expunge=' + expunge),
    );

    hrefObs.pipe(
      find((href: string) => hasValue(href)),
    ).subscribe((href: string) => {
      const request = new DeleteByIDRequest(requestId, href, id);
      this.requestService.send(request);
    });

    return this.rdbService.buildFromRequestUUID(requestId);
  }

  /**
   * Return the WorkflowItem object found through the UUID of an item
   *
   * @param uuid           The uuid of the item
   * @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 options        The {@link FindListOptions} object
   * @param linksToFollow  List of {@link FollowLinkConfig} that indicate which {@link HALLink}s should be automatically resolved
   */
  public findByItem(uuid: string, useCachedVersionIfAvailable = false, reRequestOnStale = true, options: FindListOptions = {}, ...linksToFollow: FollowLinkConfig<WorkspaceItem>[]): Observable<RemoteData<WorkspaceItem>> {
    const findListOptions = new FindListOptions();
    findListOptions.searchParams = [new RequestParam('uuid', uuid)];
    const href$ = this.searchData.getSearchByHref(this.searchByItemLinkPath, findListOptions, ...linksToFollow);
    return this.findByHref(href$, 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<WorkspaceItem>[]): Observable<RemoteData<PaginatedList<WorkspaceItem>>> {
    return this.searchData.searchBy(searchMethod, options, useCachedVersionIfAvailable, reRequestOnStale, ...linksToFollow);
  }

  /**
   * Delete an existing object on the server
   * @param   href The self link of the object to be removed
   * @param   copyVirtualMetadata (optional parameter) the identifiers of the relationship types for which the virtual
   *                            metadata should be saved as real metadata
   * @return  A RemoteData observable with an empty payload, but still representing the state of the request: statusCode,
   *          errorMessage, timeCompleted, etc
   *          Only emits once all request related to the DSO has been invalidated.
   */
  public deleteByHref(href: string, copyVirtualMetadata?: string[]): Observable<RemoteData<NoContent>> {
    return this.deleteData.deleteByHref(href, copyVirtualMetadata);
  }
}