140390: DO show replace button for new versions but not for (unversioned) new submission + cleanup code for nested subscriptions

Author: Jens Vannerum

src/app/submission/sections/upload/file/section-upload-file.component.ts

@@ -14,7 +14,13 @@ import { FeatureID } from '@dspace/core/data/feature-authorization/feature-id';
 import { JsonPatchOperationPathCombiner } from '@dspace/core/json-patch/builder/json-patch-operation-path-combiner';
 import { JsonPatchOperationsBuilder } from '@dspace/core/json-patch/builder/json-patch-operations-builder';
 import { Bitstream } from '@dspace/core/shared/bitstream.model';
+import { followLink } from '@dspace/core/shared/follow-link-config.model';
 import { HALEndpointService } from '@dspace/core/shared/hal-endpoint.service';
+import { Item } from '@dspace/core/shared/item.model';
+import {
+  getAllSucceededRemoteData,
+  getRemoteDataPayload,
+} from '@dspace/core/shared/operators';
 import { WorkspaceitemSectionUploadFileObject } from '@dspace/core/submission/models/workspaceitem-section-upload-file.model';
 import { SubmissionJsonPatchOperationsService } from '@dspace/core/submission/submission-json-patch-operations.service';
 import { SubmissionScopeType } from '@dspace/core/submission/submission-scope-type';
@@ -31,6 +37,7 @@ import { TranslateModule } from '@ngx-translate/core';
 import {
   BehaviorSubject,
   Observable,
+  of,
   Subscription,
 } from 'rxjs';
 import {
@@ -39,6 +46,7 @@ import {
   switchMap,
 } from 'rxjs/operators';
 
+import { LinkService } from '../../../../core/cache/builders/link.service';
 import { BtnDisabledDirective } from '../../../../shared/btn-disabled.directive';
 import { ThemedFileDownloadLinkComponent } from '../../../../shared/file-download-link/themed-file-download-link.component';
 import { FormService } from '../../../../shared/form/form.service';
@@ -210,6 +218,7 @@ export class SubmissionSectionUploadFileComponent implements OnChanges, OnInit,
    * @param {SectionUploadService} uploadService
    * @param {AuthorizationDataService} authorizationService
    * @param {HALEndpointService} halService
+   * @param {LinkService} linkService
    */
   constructor(
     private formService: FormService,
@@ -220,6 +229,7 @@ export class SubmissionSectionUploadFileComponent implements OnChanges, OnInit,
     private uploadService: SectionUploadService,
     private authorizationService: AuthorizationDataService,
     private halService: HALEndpointService,
+    private linkService: LinkService,
   ) {
     this.readMode = true;
   }
@@ -253,20 +263,58 @@ export class SubmissionSectionUploadFileComponent implements OnChanges, OnInit,
     this.subscriptions.push(
       this.uploadService.getFileData(this.submissionId, this.sectionId, this.fileId).pipe(
         filter(isNotUndefined),
-        switchMap((fileData) => {
-          // Replace is only meaningful for archived items being edited, not for fresh submissions.
-          if (this.submissionService.getSubmissionScope() !== SubmissionScopeType.EditItem) {
-            return [false];
-          }
-          return this.halService.getEndpoint('bitstreams').pipe(
-            map(endpoint => `${endpoint}/${fileData.uuid}`),
-            switchMap(bitstreamUrl => this.authorizationService.isAuthorized(FeatureID.CanReplaceBitstreamSubmitter, bitstreamUrl)),
-          );
-        }),
+        switchMap((fileData) => this.canShowReplaceButton(fileData.uuid)),
       ).subscribe((canReplace) => this.showReplaceButton$.next(canReplace)),
     );
   }
 
+  /**
+   * Returns an Observable that emits whether the replace button should be shown for the given
+   * bitstream. WorkflowItems never show the button; WorkspaceItems only show it when the
+   * submission is a new version of an existing item; Archived items rely solely on backend
+   * authorization.
+   */
+  private canShowReplaceButton(bitstreamUuid: string): Observable<boolean> {
+    const scope = this.submissionService.getSubmissionScope();
+    if (scope === SubmissionScopeType.WorkflowItem) {
+      return of(false);
+    }
+    return this.isVersionedSubmission(scope).pipe(
+      switchMap((isVersioned) => isVersioned ? this.isAuthorizedToReplace(bitstreamUuid) : of(false)),
+    );
+  }
+
+  /**
+   * Returns `true` when the current submission is a new-version workspace item (i.e. its item
+   * already belongs to a version history), or unconditionally `true` for EditItem scope where
+   * versioning does not apply.
+   */
+  private isVersionedSubmission(scope: SubmissionScopeType): Observable<boolean> {
+    if (scope !== SubmissionScopeType.WorkspaceItem) {
+      return of(true);
+    }
+    return this.submissionService.retrieveSubmission(this.submissionId).pipe(
+      getAllSucceededRemoteData(),
+      getRemoteDataPayload(),
+      map((submissionObject) => Object.assign(new Item(), submissionObject.item)),
+      map((item: Item) => this.linkService.resolveLink(item, followLink('version'))),
+      switchMap((item: Item) => item.version),
+      getAllSucceededRemoteData(),
+      getRemoteDataPayload(),
+      map((version) => hasValue(version)),
+    );
+  }
+
+  /**
+   * Returns whether the current user is authorized to replace the given bitstream.
+   */
+  private isAuthorizedToReplace(bitstreamUuid: string): Observable<boolean> {
+    return this.halService.getEndpoint('bitstreams').pipe(
+      map((endpoint) => `${endpoint}/${bitstreamUuid}`),
+      switchMap((bitstreamUrl) => this.authorizationService.isAuthorized(FeatureID.CanReplaceBitstreamSubmitter, bitstreamUrl)),
+    );
+  }
+
   /**
    * Show confirmation dialog for delete
    */