Fix issues with meta tags

src/app/+collection-page/collection-page.component.ts

@@ -1,15 +1,18 @@
 import { ChangeDetectionStrategy, Component, OnInit } from '@angular/core';
 import { ActivatedRoute, Router } from '@angular/router';
-import { BehaviorSubject, combineLatest as observableCombineLatest, Observable, Subject } from 'rxjs';
+import {
+  BehaviorSubject,
+  combineLatest as observableCombineLatest,
+  Observable,
+  Subject
+} from 'rxjs';
 import { filter, map, mergeMap, startWith, switchMap, take } from 'rxjs/operators';
 import { PaginatedSearchOptions } from '../shared/search/paginated-search-options.model';
 import { SearchService } from '../core/shared/search/search.service';
 import { SortDirection, SortOptions } from '../core/cache/models/sort-options.model';
 import { CollectionDataService } from '../core/data/collection-data.service';
 import { PaginatedList } from '../core/data/paginated-list.model';
 import { RemoteData } from '../core/data/remote-data';
-
-import { MetadataService } from '../core/metadata/metadata.service';
 import { Bitstream } from '../core/shared/bitstream.model';
 
 import { Collection } from '../core/shared/collection.model';
@@ -65,7 +68,6 @@ export class CollectionPageComponent implements OnInit {
   constructor(
     private collectionDataService: CollectionDataService,
     private searchService: SearchService,
-    private metadata: MetadataService,
     private route: ActivatedRoute,
     private router: Router,
     private authService: AuthService,
@@ -122,10 +124,6 @@ export class CollectionPageComponent implements OnInit {
       getAllSucceededRemoteDataPayload(),
       map((collection) => getCollectionPageRoute(collection.id))
     );
-
-    this.route.queryParams.pipe(take(1)).subscribe((params) => {
-      this.metadata.processRemoteData(this.collectionRD$);
-    });
   }
 
   isNotEmpty(object: any) {

src/app/+item-page/full/full-item-page.component.ts

@@ -1,8 +1,8 @@
-import {filter, map} from 'rxjs/operators';
+import { filter, map } from 'rxjs/operators';
 import { ChangeDetectionStrategy, Component, OnInit } from '@angular/core';
 import { ActivatedRoute, Router } from '@angular/router';
 
-import { Observable ,  BehaviorSubject } from 'rxjs';
+import { Observable, BehaviorSubject } from 'rxjs';
 
 import { ItemPageComponent } from '../simple/item-page.component';
 import { MetadataMap } from '../../core/shared/metadata.models';
@@ -11,8 +11,6 @@ import { ItemDataService } from '../../core/data/item-data.service';
 import { RemoteData } from '../../core/data/remote-data';
 import { Item } from '../../core/shared/item.model';
 
-import { MetadataService } from '../../core/metadata/metadata.service';
-
 import { fadeInOut } from '../../shared/animations/fade';
 import { hasValue } from '../../shared/empty.util';
 import { AuthService } from '../../core/auth/auth.service';
@@ -35,8 +33,8 @@ export class FullItemPageComponent extends ItemPageComponent implements OnInit {
 
   metadata$: Observable<MetadataMap>;
 
-  constructor(route: ActivatedRoute, router: Router, items: ItemDataService, metadataService: MetadataService, authService: AuthService) {
-    super(route, router, items, metadataService, authService);
+  constructor(route: ActivatedRoute, router: Router, items: ItemDataService, authService: AuthService) {
+    super(route, router, items, authService);
   }
 
   /*** AoT inheritance fix, will hopefully be resolved in the near future **/

src/app/+item-page/simple/item-page.component.ts

@@ -8,8 +8,6 @@ import { RemoteData } from '../../core/data/remote-data';
 
 import { Item } from '../../core/shared/item.model';
 
-import { MetadataService } from '../../core/metadata/metadata.service';
-
 import { fadeInOut } from '../../shared/animations/fade';
 import { getAllSucceededRemoteDataPayload, redirectOn4xx } from '../../core/shared/operators';
 import { ViewMode } from '../../core/shared/view-mode.model';
@@ -54,7 +52,6 @@ export class ItemPageComponent implements OnInit {
     private route: ActivatedRoute,
     private router: Router,
     private items: ItemDataService,
-    private metadataService: MetadataService,
     private authService: AuthService,
   ) { }
 
@@ -66,7 +63,6 @@ export class ItemPageComponent implements OnInit {
       map((data) => data.dso as RemoteData<Item>),
       redirectOn4xx(this.router, this.authService)
     );
-    this.metadataService.processRemoteData(this.itemRD$);
     this.itemPageRoute$ = this.itemRD$.pipe(
       getAllSucceededRemoteDataPayload(),
       map((item) => getItemPageRoute(item))

src/app/core/core.reducers.ts

@@ -13,6 +13,7 @@ import {
   BitstreamFormatRegistryState
 } from '../+admin/admin-registries/bitstream-formats/bitstream-format.reducers';
 import { historyReducer, HistoryState } from './history/history.reducer';
+import { metaTagReducer, MetaTagState } from './metadata/meta-tag.reducer';
 
 export interface CoreState {
   'bitstreamFormats': BitstreamFormatRegistryState;
@@ -24,6 +25,7 @@ export interface CoreState {
   'index': MetaIndexState;
   'auth': AuthState;
   'json/patch': JsonPatchOperationsState;
+  'metaTag': MetaTagState;
   'route': RouteState;
 }
 
@@ -37,5 +39,6 @@ export const coreReducers: ActionReducerMap<CoreState> = {
   'index': indexReducer,
   'auth': authReducer,
   'json/patch': jsonPatchOperationsReducer,
+  'metaTag': metaTagReducer,
   'route': routeReducer
 };

src/app/core/metadata/meta-tag.actions.ts

@@ -0,0 +1,23 @@
+import { type } from '../../shared/ngrx/type';
+import { Action } from '@ngrx/store';
+
+// tslint:disable:max-classes-per-file
+export const MetaTagTypes = {
+  ADD: type('dspace/meta-tag/ADD'),
+  CLEAR: type('dspace/meta-tag/CLEAR')
+};
+
+export class AddMetaTagAction implements Action {
+  type = MetaTagTypes.ADD;
+  payload: string;
+
+  constructor(property: string) {
+    this.payload = property;
+  }
+}
+
+export class ClearMetaTagAction implements Action {
+  type = MetaTagTypes.CLEAR;
+}
+
+export type MetaTagAction = AddMetaTagAction | ClearMetaTagAction;

src/app/core/metadata/meta-tag.reducer.spec.ts

@@ -0,0 +1,50 @@
+/**
+ * The contents of this file are subject to the license and copyright
+ * detailed in the LICENSE and NOTICE files at the root of the source
+ * tree and available online at
+ *
+ * http://www.dspace.org/license/
+ */
+
+import { metaTagReducer } from './meta-tag.reducer';
+import { AddMetaTagAction, ClearMetaTagAction } from './meta-tag.actions';
+
+const nullAction = { type: null };
+
+describe('metaTagReducer', () => {
+  it('should start with an empty array', () => {
+    const state0 = metaTagReducer(undefined, nullAction);
+    expect(state0.tagsInUse).toEqual([]);
+  });
+
+  it('should return the current state on invalid action', () => {
+    const state0 = {
+      tagsInUse: ['foo', 'bar'],
+    };
+
+    const state1 = metaTagReducer(state0, nullAction);
+    expect(state1).toEqual(state0);
+  });
+
+  it('should add tags on AddMetaTagAction', () => {
+    const state0 = {
+      tagsInUse: ['foo'],
+    };
+
+    const state1 = metaTagReducer(state0, new AddMetaTagAction('bar'));
+    const state2 = metaTagReducer(state1, new AddMetaTagAction('baz'));
+
+    expect(state1.tagsInUse).toEqual(['foo', 'bar']);
+    expect(state2.tagsInUse).toEqual(['foo', 'bar', 'baz']);
+  });
+
+  it('should clear tags on ClearMetaTagAction', () => {
+    const state0 = {
+      tagsInUse: ['foo', 'bar'],
+    };
+
+    const state1 = metaTagReducer(state0, new ClearMetaTagAction());
+
+    expect(state1.tagsInUse).toEqual([]);
+  });
+});

src/app/core/metadata/meta-tag.reducer.ts

@@ -0,0 +1,38 @@
+import {
+  MetaTagAction,
+  MetaTagTypes,
+  AddMetaTagAction,
+  ClearMetaTagAction,
+} from './meta-tag.actions';
+
+export interface MetaTagState {
+  tagsInUse: string[];
+}
+
+const initialstate: MetaTagState = {
+  tagsInUse: []
+};
+
+export const metaTagReducer = (state: MetaTagState = initialstate, action: MetaTagAction): MetaTagState => {
+  switch (action.type) {
+    case MetaTagTypes.ADD: {
+      return addMetaTag(state, action as AddMetaTagAction);
+    }
+    case MetaTagTypes.CLEAR: {
+      return clearMetaTags(state, action as ClearMetaTagAction);
+    }
+    default: {
+      return state;
+    }
+  }
+};
+
+const addMetaTag = (state: MetaTagState, action: AddMetaTagAction): MetaTagState => {
+  return {
+    tagsInUse: [...state.tagsInUse, action.payload]
+  };
+};
+
+const clearMetaTags = (state: MetaTagState, action: ClearMetaTagAction): MetaTagState => {
+  return Object.assign({}, initialstate);
+};