feat: introduce PageService (#2111)

* feat: introduce PageService

* chore: fix typo

Author: edusperoni

Diff for: e2e/modal-navigation-ng/app/home/home.component.ts

@@ -10,6 +10,7 @@ import { ModalViewComponent } from "../modal-shared/modal-view.component";
 import { confirm } from "tns-core-modules/ui/dialogs";
 
 import { AppModule } from "../app.module";
+import { PageService } from "nativescript-angular";
 
 @Component({
   moduleId: module.id,
@@ -21,7 +22,10 @@ export class HomeComponent {
     private modal: ModalDialogService,
     private vcRef: ViewContainerRef,
     private viewContainerRefService: ViewContainerRefService,
-    private routerExtension: RouterExtensions) { }
+    private pageService: PageService,
+    private routerExtension: RouterExtensions) {
+      this.pageService.inPage$.subscribe((inPage) => console.log("HomeComponent - inPage", inPage));
+    }
 
   onNavigateSecond() {
       this.routerExtension.navigate(["second"]);

Diff for: nativescript-angular/nativescript.module.ts

@@ -27,7 +27,7 @@ import { NativeScriptCommonModule } from "./common";
 import { NativeScriptRendererFactory } from "./renderer";
 import { DetachedLoader } from "./common/detached-loader";
 import { throwIfAlreadyLoaded } from "./common/utils";
-import { FrameService } from "./platform-providers";
+import { FrameService, PageService } from "./platform-providers";
 
 export function errorHandlerFactory() {
     return new ErrorHandler();
@@ -41,6 +41,7 @@ export { DetachedLoader };
     ],
     providers: [
         FrameService,
+        PageService,
         NativeScriptRendererFactory,
         SystemJsNgModuleLoader,
         { provide: APP_ROOT, useValue: true },

Diff for: nativescript-angular/platform-providers.ts

@@ -1,9 +1,11 @@
-import { InjectionToken, Injectable } from "@angular/core";
+import { InjectionToken, Injectable, OnDestroy } from "@angular/core";
 
-import { Frame } from "tns-core-modules/ui/frame";
+import { Frame, NavigatedData } from "tns-core-modules/ui/frame";
 import { View } from "tns-core-modules/ui/core/view";
 import { Page } from "tns-core-modules/ui/page";
 import { device, Device } from "tns-core-modules/platform";
+import { BehaviorSubject, Subject, Observable } from "rxjs";
+import { distinctUntilChanged } from "rxjs/operators";
 
 export const APP_ROOT_VIEW = new InjectionToken<View>("App Root View");
 export const DEVICE = new InjectionToken<Device>("platform device");
@@ -71,3 +73,45 @@ export class FrameService {
         return topmostFrame;
     }
 }
+
+@Injectable()
+export class PageService implements OnDestroy {
+    private _inPage$ = new BehaviorSubject<boolean>(false);
+    private _pageEvents$ = new Subject<NavigatedData>();
+
+    get inPage(): boolean { return this._inPage$.value; }
+    get inPage$(): Observable<boolean> { return this._inPage$.pipe(distinctUntilChanged()); }
+    get pageEvents$(): Observable<NavigatedData> { return this._pageEvents$.asObservable(); }
+    constructor(public page: Page) {
+        if (this.page) {
+            this.page.on("navigatedFrom", this.pageEvent, this);
+            this.page.on("navigatedTo", this.pageEvent, this);
+            this.page.on("navigatingFrom", this.pageEvent, this);
+            this.page.on("navigatingTo", this.pageEvent, this);
+        }
+    }
+
+    ngOnDestroy() {
+        if (this.page) {
+            this.page.off("navigatedFrom", this.pageEvent, this);
+            this.page.off("navigatedTo", this.pageEvent, this);
+            this.page.off("navigatingFrom", this.pageEvent, this);
+            this.page.off("navigatingTo", this.pageEvent, this);
+        }
+        this._inPage$.complete();
+        this._pageEvents$.complete();
+    }
+
+    private pageEvent(evt: NavigatedData) {
+        this._pageEvents$.next(evt);
+        switch (evt.eventName) {
+            case "navigatedTo":
+                this._inPage$.next(true);
+                break;
+            case "navigatedFrom":
+                this._inPage$.next(false);
+                break;
+            default:
+        }
+    }
+}

Diff for: nativescript-angular/router/page-router-outlet.ts

@@ -3,7 +3,7 @@ import {
     ComponentFactory, ComponentFactoryResolver, ComponentRef,
     Directive, Inject, InjectionToken, Injector,
     OnDestroy, EventEmitter, Output,
-    Type, ViewContainerRef, ElementRef
+    Type, ViewContainerRef, ElementRef, InjectFlags
 } from "@angular/core";
 import {
     ActivatedRoute,
@@ -19,7 +19,7 @@ import { profile } from "tns-core-modules/profiling";
 
 import { BehaviorSubject } from "rxjs";
 
-import { DEVICE, PAGE_FACTORY, PageFactory } from "../platform-providers";
+import { DEVICE, PAGE_FACTORY, PageFactory, PageService } from "../platform-providers";
 import { routerLog as log, routerError as error, isLogEnabled } from "../trace";
 import { DetachedLoader } from "../common/detached-loader";
 import { ViewUtil } from "../view-util";
@@ -48,23 +48,28 @@ export function destroyComponentRef(componentRef: ComponentRef<any>) {
     }
 }
 
-class ChildInjector implements Injector {
-    constructor(
-        private providers: ProviderMap,
-        private parent: Injector
-    ) { }
-
-    get<T>(token: Type<T> | InjectionToken<T>, notFoundValue?: T): T {
-        let localValue = this.providers.get(token);
-        if (localValue) {
-            return localValue;
+class DestructibleInjector implements Injector {
+    private refs = new Set<any>();
+    constructor(private destructableProviders: ProviderSet, private parent: Injector) {
+    }
+    get<T>(token: Type<T> | InjectionToken<T>, notFoundValue?: T, flags?: InjectFlags): T {
+        const ref = this.parent.get(token, notFoundValue, flags);
+        if (this.destructableProviders.has(token)) {
+            this.refs.add(ref);
         }
-
-        return this.parent.get(token, notFoundValue);
+        return ref;
+    }
+    destroy() {
+        this.refs.forEach((ref) => {
+            if (ref.ngOnDestroy instanceof Function) {
+                ref.ngOnDestroy();
+            }
+        });
+        this.refs.clear();
     }
 }
 
-type ProviderMap = Map<Type<any> | InjectionToken<any>, any>;
+type ProviderSet = Set<Type<any> | InjectionToken<any>>;
 
 /**
  * There are cases where multiple activatedRoute nodes should be associated/handled by the same PageRouterOutlet.
@@ -335,16 +340,24 @@ export class PageRouterOutlet implements OnDestroy { // tslint:disable-line:dire
             componentType: factory.componentType,
         });
 
-        const providers = new Map();
-        providers.set(Page, page);
-        providers.set(Frame, this.frame);
-        providers.set(PageRoute, new PageRoute(activatedRoute));
-        providers.set(ActivatedRoute, activatedRoute);
-        providers.set(ChildrenOutletContexts, this.parentContexts.getOrCreateContext(this.name).children);
+        const destructables = new Set([PageService]);
+        const injector = Injector.create({
+            providers: [
+                { provide: PageService, useClass: PageService, deps: [Page] },
+                { provide: Page, useValue: page },
+                { provide: Frame, useValue: this.frame },
+                { provide: PageRoute, useValue: new PageRoute(activatedRoute) },
+                { provide: ActivatedRoute, useValue: activatedRoute },
+                { provide: ChildrenOutletContexts,
+                    useValue: this.parentContexts.getOrCreateContext(this.name).children }
+            ],
+            parent: this.location.injector
+        });
 
-        const childInjector = new ChildInjector(providers, this.location.injector);
+        const childInjector = new DestructibleInjector(destructables, injector);
         const loaderRef = this.location.createComponent(
             this.detachedLoaderFactory, this.location.length, childInjector, []);
+        loaderRef.onDestroy(() => childInjector.destroy());
         this.changeDetector.markForCheck();
 
         this.activated = loaderRef.instance.loadWithFactory(factory);