Added upper limit to browse by date

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

@@ -22,6 +22,7 @@ import { PaginationService } from '../../core/pagination/pagination.service';
 import { PaginationServiceStub } from '../../shared/testing/pagination-service.stub';
 import { APP_CONFIG } from '../../../config/app-config.interface';
 import { environment } from '../../../environments/environment';
+import { SortDirection } from '../../core/cache/models/sort-options.model';
 
 describe('BrowseByDatePageComponent', () => {
   let comp: BrowseByDatePageComponent;
@@ -49,11 +50,21 @@ describe('BrowseByDatePageComponent', () => {
       ]
     }
   });
+  const lastItem = Object.assign(new Item(), {
+    id: 'last-item-id',
+    metadata: {
+      'dc.date.issued': [
+        {
+          value: '1960-01-01'
+        }
+      ]
+    }
+  });
 
    const mockBrowseService = {
      getBrowseEntriesFor: (options: BrowseEntrySearchOptions) => toRemoteData([]),
      getBrowseItemsFor: (value: string, options: BrowseEntrySearchOptions) => toRemoteData([firstItem]),
-    getFirstItemFor: () => createSuccessfulRemoteDataObject$(firstItem)
+     getFirstItemFor: (definition: string, scope?: string, sortDirection?: SortDirection) => null
    };
 
   const mockDsoService = {
@@ -91,9 +102,14 @@ describe('BrowseByDatePageComponent', () => {
 
   beforeEach(() => {
     fixture = TestBed.createComponent(BrowseByDatePageComponent);
+    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;
-    fixture.detectChanges();
     route = (comp as any).route;
+    fixture.detectChanges();
   });
 
   it('should initialize the list of items', () => {
@@ -107,6 +123,7 @@ describe('BrowseByDatePageComponent', () => {
   });
 
   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(new Date().getUTCFullYear());
+    expect(comp.startsWithOptions[0]).toEqual(1960);
   });
 });

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

@@ -1,11 +1,10 @@
 import { ChangeDetectorRef, Component, Inject } from '@angular/core';
 import {
   BrowseByMetadataPageComponent,
-  browseParamsToOptions, getBrowseSearchOptions
+  browseParamsToOptions,
+  getBrowseSearchOptions
 } from '../browse-by-metadata-page/browse-by-metadata-page.component';
 import { combineLatest as observableCombineLatest } from 'rxjs';
-import { RemoteData } from '../../core/data/remote-data';
-import { Item } from '../../core/shared/item.model';
 import { hasValue, isNotEmpty } from '../../shared/empty.util';
 import { ActivatedRoute, Params, Router } from '@angular/router';
 import { BrowseService } from '../../core/browse/browse.service';
@@ -16,7 +15,9 @@ import { map } from 'rxjs/operators';
 import { PaginationComponentOptions } from '../../shared/pagination/pagination-component-options.model';
 import { SortDirection, SortOptions } from '../../core/cache/models/sort-options.model';
 import { isValidDate } from '../../shared/date.util';
-import { AppConfig, APP_CONFIG } from '../../../config/app-config.interface';
+import { APP_CONFIG, AppConfig } from '../../../config/app-config.interface';
+import { RemoteData } from '../../core/data/remote-data';
+import { Item } from '../../core/shared/item.model';
 
 @Component({
   selector: 'ds-browse-by-date-page',
@@ -72,30 +73,24 @@ export class BrowseByDatePageComponent extends BrowseByMetadataPageComponent {
 
   /**
    * Update the StartsWith options
-   * In this implementation, it creates a list of years starting from now, going all the way back to the earliest
-   * date found on an item within this scope. The further back in time, the bigger the change in years become to avoid
-   * extremely long lists with a one-year difference.
+   * In this implementation, it creates a list of years starting from the most recent item or the current year, going
+   * all the way back to the earliest date found on an item within this scope. The further back in time, the bigger
+   * the change in years become to avoid extremely long lists with a one-year difference.
    * To determine the change in years, the config found under GlobalConfig.BrowseBy is used for this.
    * @param definition      The metadata definition to fetch the first item for
    * @param metadataKeys    The metadata fields to fetch the earliest date from (expects a date field)
    * @param scope           The scope under which to fetch the earliest item for
    */
   updateStartsWithOptions(definition: string, metadataKeys: string[], scope?: string) {
+    const firstItemRD = this.browseService.getFirstItemFor(definition, scope, SortDirection.ASC);
+    const lastItemRD = this.browseService.getFirstItemFor(definition, scope, SortDirection.DESC);
     this.subs.push(
-      this.browseService.getFirstItemFor(definition, scope).subscribe((firstItemRD: RemoteData<Item>) => {
-        let lowerLimit = this.appConfig.browseBy.defaultLowerLimit;
-        if (hasValue(firstItemRD.payload)) {
-          const date = firstItemRD.payload.firstMetadataValue(metadataKeys);
-          if (isNotEmpty(date) && isValidDate(date)) {
-            const dateObj = new Date(date);
-            // TODO: it appears that getFullYear (based on local time) is sometimes unreliable. Switching to UTC.
-            lowerLimit = isNaN(dateObj.getUTCFullYear()) ? lowerLimit : dateObj.getUTCFullYear();
-          }
-        }
+      observableCombineLatest([firstItemRD, lastItemRD]).subscribe(([firstItem, lastItem]) => {
+        let lowerLimit = this.getLimit(firstItem, metadataKeys, this.appConfig.browseBy.defaultLowerLimit);
+        let upperLimit = this.getLimit(lastItem, metadataKeys, new Date().getUTCFullYear());
         const options = [];
-        const currentYear = new Date().getUTCFullYear();
-        const oneYearBreak = Math.floor((currentYear - this.appConfig.browseBy.oneYearLimit) / 5) * 5;
-        const fiveYearBreak = Math.floor((currentYear - this.appConfig.browseBy.fiveYearLimit) / 10) * 10;
+        const oneYearBreak = Math.floor((upperLimit - this.appConfig.browseBy.oneYearLimit) / 5) * 5;
+        const fiveYearBreak = Math.floor((upperLimit - this.appConfig.browseBy.fiveYearLimit) / 10) * 10;
         if (lowerLimit <= fiveYearBreak) {
           lowerLimit -= 10;
         } else if (lowerLimit <= oneYearBreak) {
@@ -103,7 +98,7 @@ export class BrowseByDatePageComponent extends BrowseByMetadataPageComponent {
         } else {
           lowerLimit -= 1;
         }
-        let i = currentYear;
+        let i = upperLimit;
         while (i > lowerLimit) {
           options.push(i);
           if (i <= fiveYearBreak) {
@@ -121,4 +116,24 @@ export class BrowseByDatePageComponent extends BrowseByMetadataPageComponent {
       })
     );
   }
+
+  /**
+   * Returns the year from the item metadata field or the limit.
+   * @param itemRD the item remote data
+   * @param metadataKeys The metadata fields to fetch the earliest date from (expects a date field)
+   * @param limit the limit to use if the year can't be found in metadata
+   * @private
+   */
+  private getLimit(itemRD: RemoteData<Item>, metadataKeys: string[], limit: number): number {
+    if (hasValue(itemRD.payload)) {
+      const date = itemRD.payload.firstMetadataValue(metadataKeys);
+      if (isNotEmpty(date) && isValidDate(date)) {
+        const dateObj = new Date(date);
+        // TODO: it appears that getFullYear (based on local time) is sometimes unreliable. Switching to UTC.
+        return isNaN(dateObj.getUTCFullYear()) ? limit : dateObj.getUTCFullYear();
+      } else {
+        return new Date().getUTCFullYear();
+      }
+    }
+  }
 }

src/app/core/browse/browse.service.ts

@@ -22,6 +22,7 @@ import { BrowseEntrySearchOptions } from './browse-entry-search-options.model';
 import { HrefOnlyDataService } from '../data/href-only-data.service';
 import { followLink, FollowLinkConfig } from '../../shared/utils/follow-link-config.model';
 import { BrowseDefinitionDataService } from './browse-definition-data.service';
+import { SortDirection } from '../cache/models/sort-options.model';
 
 
 export const BROWSE_LINKS_TO_FOLLOW: FollowLinkConfig<BrowseEntry | Item>[] = [
@@ -160,8 +161,9 @@ export class BrowseService {
    * Get the first item for a metadata definition in an optional scope
    * @param definition
    * @param scope
+   * @param sortDirection optional sort parameter
    */
-  getFirstItemFor(definition: string, scope?: string): Observable<RemoteData<Item>> {
+  getFirstItemFor(definition: string, scope?: string, sortDirection?: SortDirection): Observable<RemoteData<Item>> {
     const href$ = this.getBrowseDefinitions().pipe(
       getBrowseDefinitionLinks(definition),
       hasValueOperator(),
@@ -177,6 +179,9 @@ export class BrowseService {
         }
         args.push('page=0');
         args.push('size=1');
+        if (sortDirection) {
+          args.push('sort=default,' + sortDirection);
+        }
         if (isNotEmpty(args)) {
           href = new URLCombiner(href, `?${args.join('&')}`).toString();
         }