Fix - "Browsing by Issue Date" year suppression is confusing as some years are not obviously accessible

src/app/browse-by/browse-by-date/browse-by-date.component.spec.ts

@@ -32,6 +32,9 @@ import { PaginationService } from '../../core/pagination/pagination.service';
 import { BrowseEntry } from '../../core/shared/browse-entry.model';
 import { Community } from '../../core/shared/community.model';
 import { Item } from '../../core/shared/item.model';
+import { SearchService } from '../../core/shared/search/search.service';
+import { SearchConfigurationService } from '../../core/shared/search/search-configuration.service';
+import { SearchConfig } from '../../core/shared/search/search-filters/search-config.model';
 import { ThemedBrowseByComponent } from '../../shared/browse-by/themed-browse-by.component';
 import { ThemedComcolPageBrowseByComponent } from '../../shared/comcol/comcol-page-browse-by/themed-comcol-page-browse-by.component';
 import { ComcolPageContentComponent } from '../../shared/comcol/comcol-page-content/comcol-page-content.component';
@@ -40,7 +43,14 @@ import { ComcolPageHeaderComponent } from '../../shared/comcol/comcol-page-heade
 import { ComcolPageLogoComponent } from '../../shared/comcol/comcol-page-logo/comcol-page-logo.component';
 import { ThemedLoadingComponent } from '../../shared/loading/themed-loading.component';
 import { RouterMock } from '../../shared/mocks/router.mock';
-import { createSuccessfulRemoteDataObject$ } from '../../shared/remote-data.utils';
+import {
+  createSuccessfulRemoteDataObject,
+  createSuccessfulRemoteDataObject$,
+} from '../../shared/remote-data.utils';
+import { FacetValues } from '../../shared/search/models/facet-values.model';
+import { FilterType } from '../../shared/search/models/filter-type.model';
+import { PaginatedSearchOptions } from '../../shared/search/models/paginated-search-options.model';
+import { SearchFilterConfig } from '../../shared/search/models/search-filter-config.model';
 import { ActivatedRouteStub } from '../../shared/testing/active-router.stub';
 import { PaginationServiceStub } from '../../shared/testing/pagination-service.stub';
 import { EnumKeysPipe } from '../../shared/utils/enum-keys-pipe';
@@ -85,12 +95,41 @@ describe('BrowseByDateComponent', () => {
     },
   });
 
+  const mockFilterConfig: SearchFilterConfig = Object.assign(new SearchFilterConfig(), {
+    name: 'dateIssued',
+    filterType: FilterType.range,
+    hasFacets: false,
+    isOpenByDefault: false,
+    pageSize: 1,
+  });
+
+  const mockFacetValue: FacetValues  =
+    Object.assign(new FacetValues(), {
+      authorityKey: null,
+      count: 1,
+      label: '2009 - 2009',
+      value: '2009 - 2009',
+      type: 'discover',
+    });
+
+
+  const filtersConfigRD = createSuccessfulRemoteDataObject([mockFilterConfig]);
+  const filtersConfigRD$ = observableOf(filtersConfigRD);
+
   const mockBrowseService = {
     getBrowseEntriesFor: (options: BrowseEntrySearchOptions) => toRemoteData([]),
     getBrowseItemsFor: (value: string, options: BrowseEntrySearchOptions) => toRemoteData([firstItem]),
     getFirstItemFor: (definition: string, scope?: string, sortDirection?: SortDirection) => null,
   };
 
+  const mockSearchConfigService = {
+    getConfig: () => filtersConfigRD$,
+  };
+
+  const mockSearchService = {
+    getFacetValuesFor: (filterConfig: SearchFilterConfig, valuePage: number, searchOptions?: PaginatedSearchOptions, filterQuery?: string, useCachedVersionIfAvailable = true) => toRemoteData([mockFacetValue]),
+  };
+
   const mockDsoService = {
     findById: () => createSuccessfulRemoteDataObject$(mockCommunity),
   };
@@ -128,6 +167,8 @@ describe('BrowseByDateComponent', () => {
         { provide: Store, useValue: {} },
         { provide: APP_CONFIG, useValue: environment },
         { provide: PLATFORM_ID, useValue: 'browser' },
+        { provide: SearchConfigurationService, useValue: mockSearchConfigService },
+        { provide: SearchService, useValue: mockSearchService },
       ],
       schemas: [NO_ERRORS_SCHEMA],
     })
@@ -149,12 +190,8 @@ describe('BrowseByDateComponent', () => {
 
   beforeEach(() => {
     fixture = TestBed.createComponent(BrowseByDateComponent);
-    const browseService = fixture.debugElement.injector.get(BrowseService);
-    spyOn(browseService, 'getFirstItemFor')
-      // ok to expect the default browse as first param since we just need the mock items obtained via sort direction.
-      .withArgs('author', undefined, SortDirection.ASC).and.returnValue(createSuccessfulRemoteDataObject$(firstItem))
-      .withArgs('author', undefined, SortDirection.DESC).and.returnValue(createSuccessfulRemoteDataObject$(lastItem));
     comp = fixture.componentInstance;
+    comp.browseId = 'dateissued';
     route = (comp as any).route;
     fixture.detectChanges();
   });
@@ -170,12 +207,12 @@ describe('BrowseByDateComponent', () => {
   });
 
   it('should create a list of startsWith options with the earliest year at the end (rounded down by 10)', () => {
-    expect(comp.startsWithOptions[comp.startsWithOptions.length - 1]).toEqual(1950);
+    expect(comp.startsWithOptions[comp.startsWithOptions.length - 1]).toEqual(2009);
   });
 
   it('should create a list of startsWith options with the current year first', () => {
     //expect(comp.startsWithOptions[0]).toEqual(new Date().getUTCFullYear());
-    expect(comp.startsWithOptions[0]).toEqual(1960);
+    expect(comp.startsWithOptions[0]).toEqual(2009);
   });
 
   describe('when rendered in SSR', () => {
@@ -198,12 +235,16 @@ describe('BrowseByDateComponent', () => {
     beforeEach(() => {
       comp.platformId = 'browser';
       spyOn((comp as any).browseService, 'getBrowseItemsFor').and.returnValue(createSuccessfulRemoteDataObject$(new BrowseEntry()));
+      spyOn((comp as any).searchConfigService, 'getConfig').and.returnValue(createSuccessfulRemoteDataObject$([new SearchConfig()]));
+      spyOn((comp as any).searchService, 'getFacetValuesFor').and.returnValue(createSuccessfulRemoteDataObject$([new FacetValues()]));
     });
 
     it('should call getBrowseItemsFor on init', fakeAsync(() => {
       comp.ngOnInit();
       tick(100);
       expect((comp as any).browseService.getBrowseItemsFor).toHaveBeenCalled();
+      expect((comp as any).searchConfigService.getConfig).toHaveBeenCalled();
+      expect((comp as any).searchService.getFacetValuesFor).toHaveBeenCalled();
     }));
   });
 });

src/app/browse-by/browse-by-date/browse-by-date.component.ts

@@ -23,7 +23,9 @@ import {
 } from 'rxjs';
 import {
   distinctUntilChanged,
+  filter,
   map,
+  switchMap,
 } from 'rxjs/operators';
 import { ThemedBrowseByComponent } from 'src/app/shared/browse-by/themed-browse-by.component';
 
@@ -42,6 +44,12 @@ import { DSpaceObjectDataService } from '../../core/data/dspace-object-data.serv
 import { RemoteData } from '../../core/data/remote-data';
 import { PaginationService } from '../../core/pagination/pagination.service';
 import { Item } from '../../core/shared/item.model';
+import {
+  getAllSucceededRemoteDataPayload,
+  getFirstSucceededRemoteDataPayload,
+} from '../../core/shared/operators';
+import { SearchService } from '../../core/shared/search/search.service';
+import { SearchConfigurationService } from '../../core/shared/search/search-configuration.service';
 import { isValidDate } from '../../shared/date.util';
 import {
   hasValue,
@@ -55,6 +63,7 @@ import {
   browseParamsToOptions,
 } from '../browse-by-metadata/browse-by-metadata.component';
 
+
 @Component({
   selector: 'ds-browse-by-date',
   styleUrls: ['../browse-by-metadata/browse-by-metadata.component.scss'],
@@ -90,6 +99,8 @@ export class BrowseByDateComponent extends BrowseByMetadataComponent implements
     public dsoNameService: DSONameService,
     protected cdRef: ChangeDetectorRef,
     @Inject(PLATFORM_ID) public platformId: any,
+    public searchConfigService: SearchConfigurationService,
+    public searchService: SearchService,
   ) {
     super(route, browseService, dsoService, paginationService, router, appConfig, dsoNameService, platformId);
   }
@@ -137,50 +148,44 @@ export class BrowseByDateComponent extends BrowseByMetadataComponent implements
    * @param scope           The scope under which to fetch the earliest item for
    */
   updateStartsWithOptions(definition: string, metadataKeys: string[], scope?: string) {
-    const firstItemRD$: Observable<RemoteData<Item>> = this.browseService.getFirstItemFor(definition, scope, SortDirection.ASC);
-    const lastItemRD$: Observable<RemoteData<Item>> = this.browseService.getFirstItemFor(definition, scope, SortDirection.DESC);
-    this.loading$ = observableCombineLatest([
-      firstItemRD$,
-      lastItemRD$,
-    ]).pipe(
-      map(([firstItemRD, lastItemRD]: [RemoteData<Item>, RemoteData<Item>]) => firstItemRD.isLoading || lastItemRD.isLoading),
-    );
-    this.subs.push(
-      observableCombineLatest([
-        firstItemRD$,
-        lastItemRD$,
-      ]).subscribe(([firstItemRD, lastItemRD]: [RemoteData<Item>, RemoteData<Item>]) => {
-        let lowerLimit: number = this.getLimit(firstItemRD, metadataKeys, this.appConfig.browseBy.defaultLowerLimit);
-        const upperLimit: number = this.getLimit(lastItemRD, metadataKeys, new Date().getUTCFullYear());
-        const options: number[] = [];
-        const oneYearBreak: number = Math.floor((upperLimit - this.appConfig.browseBy.oneYearLimit) / 5) * 5;
-        const fiveYearBreak: number = Math.floor((upperLimit - this.appConfig.browseBy.fiveYearLimit) / 10) * 10;
-        if (lowerLimit <= fiveYearBreak) {
-          lowerLimit -= 10;
-        } else if (lowerLimit <= oneYearBreak) {
-          lowerLimit -= 5;
-        } else {
-          lowerLimit -= 1;
-        }
-        let i: number = upperLimit;
-        while (i > lowerLimit) {
-          options.push(i);
-          if (i <= fiveYearBreak) {
-            i -= 10;
-          } else if (i <= oneYearBreak) {
-            i -= 5;
-          } else {
-            i--;
-          }
-        }
+    this.searchConfigService.getConfig(null,definition).pipe(
+      getFirstSucceededRemoteDataPayload(),
+      filter( configs => configs.length > 0 ),
+      map( configs => configs.filter( filterConfig => filterConfig.name?.toUpperCase() === definition.toUpperCase()  ) ),
+      map( findConfig =>  findConfig[0]),
+      switchMap( config => {
+        return this.searchService.getFacetValuesFor(config, 10).pipe(
+          getAllSucceededRemoteDataPayload(),
+        );
+      }),
+      map( facetValue =>  facetValue.page ),
+    ).subscribe(
+      values => {
+        const options = this.generateYearFromFacetValue(values);
         if (isNotEmpty(options)) {
           this.startsWithOptions = options;
           this.cdRef.detectChanges();
         }
-      }),
-    );
+      });
   }
 
+  /**
+   * Prepare  options
+   * @param data   The facets values
+   */
+  generateYearFromFacetValue = (data: any[]) => {
+    const years: number[] = [];
+    if (!hasValue(data)) {return  [];}
+    data.forEach(item => {
+      const [start, end] = item.value.split(' - ').map(Number);
+      for (let year = start; year <= end; year++) {
+        years.push(year);
+      }
+    });
+
+    return years;
+  };
+
   /**
    * Returns the year from the item metadata field or the limit.
    * @param itemRD the item remote data