Custom ngIf directive

<!DOCTYPE html>
<html>

  <head>
    <base href="." />
    <script type="text/javascript" charset="utf-8">
      window.AngularVersionForThisPlunker = '4.3.3'
    </script>
    <title>angular playground</title>
    <link rel="stylesheet" href="style.css" />
    <script src="https://unpkg.com/core-js@2.4.1/client/shim.min.js"></script>
    <script src="https://unpkg.com/zone.js/dist/zone.js"></script>
    <script src="https://unpkg.com/zone.js/dist/long-stack-trace-zone.js"></script>
    <script src="https://unpkg.com/reflect-metadata@0.1.3/Reflect.js"></script>
    <script src="https://unpkg.com/systemjs@0.19.31/dist/system.js"></script>
    <script src="config.js"></script>
    <script>
    System.import('app')
      .catch(console.error.bind(console));
  </script>
  </head>

  <body>
    <my-app>
    loading...
  </my-app>
  </body>

</html>

/* Styles go here */

### Angular Starter Plunker - Typescript

var angularVersion;
if(window.AngularVersionForThisPlunker === 'latest'){
  angularVersion = ''; //picks up latest
}
else {
  angularVersion = '@' + window.AngularVersionForThisPlunker;
}

System.config({
  //use typescript for compilation
  transpiler: 'typescript',
  //typescript compiler options
  typescriptOptions: {
    emitDecoratorMetadata: true
  },
  paths: {
    'npm:': 'https://unpkg.com/'
  },
  //map tells the System loader where to look for things
  map: {
    
    'app': './src',
    '@angular/core': 'npm:@angular/core'+ angularVersion + '/bundles/core.umd.js',
    '@angular/common': 'npm:@angular/common' + angularVersion + '/bundles/common.umd.js',
    '@angular/compiler': 'npm:@angular/compiler' + angularVersion  + '/bundles/compiler.umd.js',
    '@angular/platform-browser': 'npm:@angular/platform-browser' + angularVersion + '/bundles/platform-browser.umd.js',
    '@angular/platform-browser-dynamic': 'npm:@angular/platform-browser-dynamic' + angularVersion + '/bundles/platform-browser-dynamic.umd.js',
    '@angular/http': 'npm:@angular/http' + angularVersion + '/bundles/http.umd.js',
    '@angular/router': 'npm:@angular/router' + angularVersion +'/bundles/router.umd.js',
    '@angular/forms': 'npm:@angular/forms' + angularVersion + '/bundles/forms.umd.js',
    '@angular/animations': 'npm:@angular/animations' + angularVersion + '/bundles/animations.umd.js',
    '@angular/platform-browser/animations': 'npm:@angular/platform-browser' + angularVersion + '/bundles/platform-browser-animations.umd.js',
    '@angular/animations/browser': 'npm:@angular/animations' + angularVersion + '/bundles/animations-browser.umd.js',
    
    '@angular/core/testing': 'npm:@angular/core' + angularVersion + '/bundles/core-testing.umd.js',
    '@angular/common/testing': 'npm:@angular/common' + angularVersion + '/bundles/common-testing.umd.js',
    '@angular/compiler/testing': 'npm:@angular/compiler' + angularVersion + '/bundles/compiler-testing.umd.js',
    '@angular/platform-browser/testing': 'npm:@angular/platform-browser' + angularVersion + '/bundles/platform-browser-testing.umd.js',
    '@angular/platform-browser-dynamic/testing': 'npm:@angular/platform-browser-dynamic' + angularVersion + '/bundles/platform-browser-dynamic-testing.umd.js',
    '@angular/http/testing': 'npm:@angular/http' + angularVersion + '/bundles/http-testing.umd.js',
    '@angular/router/testing': 'npm:@angular/router' + angularVersion + '/bundles/router-testing.umd.js',
    'tslib': 'npm:tslib@1.6.1',
    'rxjs': 'npm:rxjs@5.4.2',
    'rxjs-compat': 'npm:rxjs-compat',
    'rxjs/operators': 'npm:rxjs/operators',
    'typescript': 'npm:typescript@2.2.1/lib/typescript.js'
  },
  //packages defines our app package
  packages: {
    app: {
      main: './main.ts',
      defaultExtension: 'ts'
    },
    'rxjs': { main: 'index.js', defaultExtension: 'js' },
    'rxjs/operators': {main: 'index.js', defaultExtension: 'js' }
  }
});

//main entry point
import {platformBrowserDynamic} from '@angular/platform-browser-dynamic';
import {AppModule} from './app';

platformBrowserDynamic().bootstrapModule(AppModule)

//our root app component
import {Component, NgModule, VERSION} from '@angular/core'
import {BrowserModule} from '@angular/platform-browser'
import { AllowedDirective } from './allowed.directive';
import { AuthService } from './auth.service';

@Component({
  selector: 'my-app',
  template: `
    <div>
      <button (click)="authService.switchLoggedIn()">Switch logged</button>
    </div>
    <div *allowed="true">
      <h2>Logged In</h2>
    </div>
    <div *allowed="false">
      <h2>Not Logged</h2>
    </div>
  `,
})
export class App {
  constructor(private authService: AuthService) {
  }
}

@NgModule({
  imports: [ BrowserModule ],
  declarations: [ App, AllowedDirective],
  providers:[ AuthService ]
  bootstrap: [ App ]
})
export class AppModule {}

import {Directive, Input, TemplateRef, ViewContainerRef, OnInit} from '@angular/core';
import { NgIf } from '@angular/common';
import { AuthService } from './auth.service'
import { AuthModel } from './auth-model.ts'
import { Subscriber } from "rxjs/Subject";

@Directive({ selector: '[allowed]' })
export class AllowedDirective {
  
  private _allowed: boolean;
  private ngIfDirective: NgIf;
  private isLoggedInSubs: Subscription;
  
  @Input()
    public set allowed(val: boolean) {
        this._allowed = val;
        this.setNgIf();
    };
  
  constructor(private templateRef: TemplateRef<any>, private viewContainer: ViewContainerRef, 
  private authService: AuthService) {
    if(!this.ngIfDirective) {
          this.ngIfDirective = new NgIf(this.viewContainer,this.templateRef);
    }
        
    this.isLoggedInSubs = this.authService.isLoggedInChanged.subscribe((value) => { 
      this.setNgIf();
    });
  }
  
  setNgIf() {
    this.ngIfDirective.ngIf = this.authService.authModel.isLoggedIn == this._allowed;
  }
  
   ngOnDestroy() {
    this.isLoggedInSubs.unsubscribe();
  }
  
}

import { Injectable } from '@angular/core';
import { AuthModel } from './auth-model.ts';
import { Subject } from "rxjs/Subject";

@Injectable()
export class AuthService {
  private authModel: AuthModel;
  public isLoggedInChanged: Subject<string> = new Subject<string>();
  
  constructor() {
    this.authModel = new AuthModel();
  }
  
  set isLoggedIn(val: boolean) {
    this.authModel.isLoggedIn = val;
    this.isLoggedInChanged.next(val);
  }
  
  get isLoggedIn(): boolean {
    return this.authModel.isLoggedIn;
  }
  
  public switchLoggedIn() {
    this.isLoggedIn = !this.isLoggedIn;
  }
}

export class AuthModel {
  public isLoggedIn : boolean = true;
}