refactor(angular): removes Events service (#19600)

BREAKING CHANGES

The Events Service in @ionic/angular has been removed. 

- Use "Observables" for a similar pub/sub architecture: https://angular.io/guide/observables
- Use "Redux" for advanced state management: https://ngrx.io

angular/src/index.ts

@@ -20,7 +20,6 @@ export * from './directives/proxies';
 export { AngularDelegate } from './providers/angular-delegate';
 export { ActionSheetController } from './providers/action-sheet-controller';
 export { AlertController } from './providers/alert-controller';
-export { Events } from './providers/events';
 export { LoadingController } from './providers/loading-controller';
 export { MenuController } from './providers/menu-controller';
 export { PickerController } from './providers/picker-controller';

angular/src/providers/events.ts

@@ -1,81 +0,0 @@
-import { Injectable } from '@angular/core';
-
-export type EventHandler = (...args: any[]) => any;
-@Injectable({
-  providedIn: 'root',
-})
-export class Events {
-  private c = new Map<string, EventHandler[]>();
-
-  constructor() {
-    console.warn(`[DEPRECATION][Events]: The Events provider is deprecated and it will be removed in the next major release.
-  - Use "Observables" for a similar pub/sub architecture: https://angular.io/guide/observables
-  - Use "Redux" for advanced state management: https://ngrx.io`);
-  }
-  /**
-   * Subscribe to an event topic. Events that get posted to that topic will trigger the provided handler.
-   *
-   * @param topic the topic to subscribe to
-   * @param handler the event handler
-   */
-  subscribe(topic: string, ...handlers: EventHandler[]) {
-    let topics = this.c.get(topic);
-    if (!topics) {
-      this.c.set(topic, topics = []);
-    }
-    topics.push(...handlers);
-  }
-
-  /**
-   * Unsubscribe from the given topic. Your handler will no longer receive events published to this topic.
-   *
-   * @param topic the topic to unsubscribe from
-   * @param handler the event handler
-   *
-   * @return true if a handler was removed
-   */
-  unsubscribe(topic: string, handler?: EventHandler): boolean {
-    if (!handler) {
-      return this.c.delete(topic);
-    }
-
-    const topics = this.c.get(topic);
-    if (!topics) {
-      return false;
-    }
-
-    // We need to find and remove a specific handler
-    const index = topics.indexOf(handler);
-
-    if (index < 0) {
-      // Wasn't found, wasn't removed
-      return false;
-    }
-    topics.splice(index, 1);
-    if (topics.length === 0) {
-      this.c.delete(topic);
-    }
-    return true;
-  }
-
-  /**
-   * Publish an event to the given topic.
-   *
-   * @param topic the topic to publish to
-   * @param eventData the data to send as the event
-   */
-  publish(topic: string, ...args: any[]): any[] | null {
-    const topics = this.c.get(topic);
-    if (!topics) {
-      return null;
-    }
-    return topics.map(handler => {
-      try {
-        return handler(...args);
-      } catch (e) {
-        console.error(e);
-        return null;
-      }
-    });
-  }
-}

angular/test/test-app/src/app/providers/providers.component.ts

@@ -1,7 +1,7 @@
 import { Component, NgZone } from '@angular/core';
 import {
   Platform, ModalController, AlertController, ActionSheetController,
-  PopoverController, ToastController, Events, PickerController, MenuController,
+  PopoverController, ToastController, PickerController, MenuController,
   LoadingController, NavController, DomController, Config
 } from '@ionic/angular';
 
@@ -13,7 +13,6 @@ export class ProvidersComponent {
 
   isLoaded = false;
   isReady = false;
-  isEvent = false;
   isResumed = false;
   isPaused = false;
   isResized = false;
@@ -25,7 +24,6 @@ export class ProvidersComponent {
   constructor(
     actionSheetCtrl: ActionSheetController,
     alertCtrl: AlertController,
-    events: Events,
     loadingCtrl: LoadingController,
     menuCtrl: MenuController,
     pickerCtrl: PickerController,
@@ -40,7 +38,7 @@ export class ProvidersComponent {
   ) {
     // test all providers load
     if (
-      actionSheetCtrl && alertCtrl && events && loadingCtrl && menuCtrl && pickerCtrl &&
+      actionSheetCtrl && alertCtrl && loadingCtrl && menuCtrl && pickerCtrl &&
       modalCtrl && platform && popoverCtrl && toastCtrl && navCtrl && domCtrl && config
       ) {
         this.isLoaded = true;
@@ -69,13 +67,6 @@ export class ProvidersComponent {
     this.isDesktop = platform.is('desktop');
     this.isMobile = platform.is('mobile');
 
-    // test events
-    events.subscribe('topic', () => {
-      this.isEvent = true;
-      NgZone.assertInAngularZone();
-    });
-    events.publish('topic');
-
     // test config
     this.isTesting = config.getBoolean('_testing');
     config.set('keyboardHeight', 12345);