/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {Injector, NgModule, NgZone, Testability} from '@angular/core';

import * as angular from '../common/angular1';
import {$$TESTABILITY, $DELEGATE, $INJECTOR, $INTERVAL, $PROVIDE, INJECTOR_KEY, LAZY_MODULE_REF, UPGRADE_APP_TYPE_KEY, UPGRADE_MODULE_NAME} from '../common/constants';
import {LazyModuleRef, UpgradeAppType, controllerKey} from '../common/util';

import {angular1Providers, setTempInjectorRef} from './angular1_providers';
import {NgAdapterInjector} from './util';


/**
 * @description
 *
 * An `NgModule`, which you import to provide AngularJS core services,
 * and has an instance method used to bootstrap the hybrid upgrade application.
 *
 * *Part of the [upgrade/static](api?query=upgrade/static)
 * library for hybrid upgrade apps that support AoT compilation*
 *
 * The `upgrade/static` package contains helpers that allow AngularJS and Angular components
 * to be used together inside a hybrid upgrade application, which supports AoT compilation.
 *
 * Specifically, the classes and functions in the `upgrade/static` module allow the following:
 *
 * 1. Creation of an Angular directive that wraps and exposes an AngularJS component so
 *    that it can be used in an Angular template. See `UpgradeComponent`.
 * 2. Creation of an AngularJS directive that wraps and exposes an Angular component so
 *    that it can be used in an AngularJS template. See `downgradeComponent`.
 * 3. Creation of an Angular root injector provider that wraps and exposes an AngularJS
 *    service so that it can be injected into an Angular context. See
 *    {@link UpgradeModule#upgrading-an-angular-1-service Upgrading an AngularJS service} below.
 * 4. Creation of an AngularJS service that wraps and exposes an Angular injectable
 *    so that it can be injected into an AngularJS context. See `downgradeInjectable`.
 * 3. Bootstrapping of a hybrid Angular application which contains both of the frameworks
 *    coexisting in a single application.
 *
 * @usageNotes
 *
 * ```ts
 * import {UpgradeModule} from '@angular/upgrade/static';
 * ```
 *
 * See also the {@link UpgradeModule#examples examples} below.
 *
 * ### Mental Model
 *
 * When reasoning about how a hybrid application works it is useful to have a mental model which
 * describes what is happening and explains what is happening at the lowest level.
 *
 * 1. There are two independent frameworks running in a single application, each framework treats
 *    the other as a black box.
 * 2. Each DOM element on the page is owned exactly by one framework. Whichever framework
 *    instantiated the element is the owner. Each framework only updates/interacts with its own
 *    DOM elements and ignores others.
 * 3. AngularJS directives always execute inside the AngularJS framework codebase regardless of
 *    where they are instantiated.
 * 4. Angular components always execute inside the Angular framework codebase regardless of
 *    where they are instantiated.
 * 5. An AngularJS component can be "upgraded"" to an Angular component. This is achieved by
 *    defining an Angular directive, which bootstraps the AngularJS component at its location
 *    in the DOM. See `UpgradeComponent`.
 * 6. An Angular component can be "downgraded" to an AngularJS component. This is achieved by
 *    defining an AngularJS directive, which bootstraps the Angular component at its location
 *    in the DOM. See `downgradeComponent`.
 * 7. Whenever an "upgraded"/"downgraded" component is instantiated the host element is owned by
 *    the framework doing the instantiation. The other framework then instantiates and owns the
 *    view for that component.
 *    1. This implies that the component bindings will always follow the semantics of the
 *       instantiation framework.
 *    2. The DOM attributes are parsed by the framework that owns the current template. So
 *       attributes in AngularJS templates must use kebab-case, while AngularJS templates must use
 *       camelCase.
 *    3. However the template binding syntax will always use the Angular style, e.g. square
 *       brackets (`[...]`) for property binding.
 * 8. Angular is bootstrapped first; AngularJS is bootstrapped second. AngularJS always owns the
 *    root component of the application.
 * 9. The new application is running in an Angular zone, and therefore it no longer needs calls to
 *    `$apply()`.
 *
 * ### The `UpgradeModule` class
 *
 * This class is an `NgModule`, which you import to provide AngularJS core services,
 * and has an instance method used to bootstrap the hybrid upgrade application.
 *
 * * Core AngularJS services
 *   Importing this `NgModule` will add providers for the core
 *   [AngularJS services](https://docs.angularjs.org/api/ng/service) to the root injector.
 *
 * * Bootstrap
 *   The runtime instance of this class contains a {@link UpgradeModule#bootstrap `bootstrap()`}
 *   method, which you use to bootstrap the top level AngularJS module onto an element in the
 *   DOM for the hybrid upgrade app.
 *
 *   It also contains properties to access the {@link UpgradeModule#injector root injector}, the
 *   bootstrap `NgZone` and the
 *   [AngularJS $injector](https://docs.angularjs.org/api/auto/service/$injector).
 *
 * ### Examples
 *
 * Import the `UpgradeModule` into your top level {@link NgModule Angular `NgModule`}.
 *
 * {@example upgrade/static/ts/full/module.ts region='ng2-module'}
 *
 * Then inject `UpgradeModule` into your Angular `NgModule` and use it to bootstrap the top level
 * [AngularJS module](https://docs.angularjs.org/api/ng/type/angular.Module) in the
 * `ngDoBootstrap()` method.
 *
 * {@example upgrade/static/ts/full/module.ts region='bootstrap-ng1'}
 *
 * Finally, kick off the whole process, by bootstraping your top level Angular `NgModule`.
 *
 * {@example upgrade/static/ts/full/module.ts region='bootstrap-ng2'}
 *
 * {@a upgrading-an-angular-1-service}
 * ### Upgrading an AngularJS service
 *
 * There is no specific API for upgrading an AngularJS service. Instead you should just follow the
 * following recipe:
 *
 * Let's say you have an AngularJS service:
 *
 * {@example upgrade/static/ts/full/module.ts region="ng1-text-formatter-service"}
 *
 * Then you should define an Angular provider to be included in your `NgModule` `providers`
 * property.
 *
 * {@example upgrade/static/ts/full/module.ts region="upgrade-ng1-service"}
 *
 * Then you can use the "upgraded" AngularJS service by injecting it into an Angular component
 * or service.
 *
 * {@example upgrade/static/ts/full/module.ts region="use-ng1-upgraded-service"}
 *
 * @publicApi
 */
@NgModule({providers: [angular1Providers]})
export class UpgradeModule {
  /**
   * The AngularJS `$injector` for the upgrade application.
   */
  public $injector: any /*angular.IInjectorService*/;
  /** The Angular Injector **/
  public injector: Injector;

  constructor(
      /** The root `Injector` for the upgrade application. */
      injector: Injector,
      /** The bootstrap zone for the upgrade application */
      public ngZone: NgZone) {
    this.injector = new NgAdapterInjector(injector);
  }

  /**
   * Bootstrap an AngularJS application from this NgModule
   * @param element the element on which to bootstrap the AngularJS application
   * @param [modules] the AngularJS modules to bootstrap for this application
   * @param [config] optional extra AngularJS bootstrap configuration
   */
  bootstrap(
      element: Element, modules: string[] = [], config?: any /*angular.IAngularBootstrapConfig*/) {
    const INIT_MODULE_NAME = UPGRADE_MODULE_NAME + '.init';

    // Create an ng1 module to bootstrap
    const initModule =
        angular
            .module(INIT_MODULE_NAME, [])

            .constant(UPGRADE_APP_TYPE_KEY, UpgradeAppType.Static)

            .value(INJECTOR_KEY, this.injector)

            .factory(
                LAZY_MODULE_REF,
                [INJECTOR_KEY, (injector: Injector) => ({ injector } as LazyModuleRef)])

            .config([
              $PROVIDE, $INJECTOR,
              ($provide: angular.IProvideService, $injector: angular.IInjectorService) => {
                if ($injector.has($$TESTABILITY)) {
                  $provide.decorator($$TESTABILITY, [
                    $DELEGATE,
                    (testabilityDelegate: angular.ITestabilityService) => {
                      const originalWhenStable: Function = testabilityDelegate.whenStable;
                      const injector = this.injector;
                      // Cannot use arrow function below because we need the context
                      const newWhenStable = function(callback: Function) {
                        originalWhenStable.call(testabilityDelegate, function() {
                          const ng2Testability: Testability = injector.get(Testability);
                          if (ng2Testability.isStable()) {
                            callback();
                          } else {
                            ng2Testability.whenStable(
                                newWhenStable.bind(testabilityDelegate, callback));
                          }
                        });
                      };

                      testabilityDelegate.whenStable = newWhenStable;
                      return testabilityDelegate;
                    }
                  ]);
                }

                if ($injector.has($INTERVAL)) {
                  $provide.decorator($INTERVAL, [
                    $DELEGATE,
                    (intervalDelegate: angular.IIntervalService) => {
                      // Wrap the $interval service so that setInterval is called outside NgZone,
                      // but the callback is still invoked within it. This is so that $interval
                      // won't block stability, which preserves the behavior from AngularJS.
                      let wrappedInterval =
                          (fn: Function, delay: number, count?: number, invokeApply?: boolean,
                           ...pass: any[]) => {
                            return this.ngZone.runOutsideAngular(() => {
                              return intervalDelegate((...args: any[]) => {
                                // Run callback in the next VM turn - $interval calls
                                // $rootScope.$apply, and running the callback in NgZone will
                                // cause a '$digest already in progress' error if it's in the
                                // same vm turn.
                                setTimeout(() => { this.ngZone.run(() => fn(...args)); });
                              }, delay, count, invokeApply, ...pass);
                            });
                          };

                      (wrappedInterval as any)['cancel'] = intervalDelegate.cancel;
                      return wrappedInterval;
                    }
                  ]);
                }
              }
            ])

            .run([
              $INJECTOR,
              ($injector: angular.IInjectorService) => {
                this.$injector = $injector;

                // Initialize the ng1 $injector provider
                setTempInjectorRef($injector);
                this.injector.get($INJECTOR);

                // Put the injector on the DOM, so that it can be "required"
                angular.element(element).data !(controllerKey(INJECTOR_KEY), this.injector);

                // Wire up the ng1 rootScope to run a digest cycle whenever the zone settles
                // We need to do this in the next tick so that we don't prevent the bootup
                // stabilizing
                setTimeout(() => {
                  const $rootScope = $injector.get('$rootScope');
                  const subscription =
                      this.ngZone.onMicrotaskEmpty.subscribe(() => $rootScope.$digest());
                  $rootScope.$on('$destroy', () => { subscription.unsubscribe(); });
                }, 0);
              }
            ]);

    const upgradeModule = angular.module(UPGRADE_MODULE_NAME, [INIT_MODULE_NAME].concat(modules));

    // Make sure resumeBootstrap() only exists if the current bootstrap is deferred
    const windowAngular = (window as any)['angular'];
    windowAngular.resumeBootstrap = undefined;

    // Bootstrap the AngularJS application inside our zone
    this.ngZone.run(() => { angular.bootstrap(element, [upgradeModule.name], config); });

    // Patch resumeBootstrap() to run inside the ngZone
    if (windowAngular.resumeBootstrap) {
      const originalResumeBootstrap: () => void = windowAngular.resumeBootstrap;
      const ngZone = this.ngZone;
      windowAngular.resumeBootstrap = function() {
        let args = arguments;
        windowAngular.resumeBootstrap = originalResumeBootstrap;
        return ngZone.run(() => windowAngular.resumeBootstrap.apply(this, args));
      };
    }
  }
}
