/**
 * @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 {Location, LocationStrategy} from '@angular/common';
import {MockLocationStrategy, SpyLocation} from '@angular/common/testing';
import {Compiler, Injectable, Injector, ModuleWithProviders, NgModule, NgModuleFactory, NgModuleFactoryLoader} from '@angular/core';
import {NoPreloading, PreloadingStrategy, Route, Router, RouterModule, RouterOutletMap, Routes, UrlSerializer, provideRoutes} from '@angular/router';

import {ROUTER_PROVIDERS, ROUTES, flatten} from './private_import_router';


/**
 * @whatItDoes Allows to simulate the loading of ng modules in tests.
 *
 * @howToUse
 *
 * ```
 * const loader = TestBed.get(NgModuleFactoryLoader);
 *
 * @Component({template: 'lazy-loaded'})
 * class LazyLoadedComponent {}
 * @NgModule({
 *   declarations: [LazyLoadedComponent],
 *   imports: [RouterModule.forChild([{path: 'loaded', component: LazyLoadedComponent}])]
 * })
 *
 * class LoadedModule {}
 *
 * // sets up stubbedModules
 * loader.stubbedModules = {lazyModule: LoadedModule};
 *
 * router.resetConfig([
 *   {path: 'lazy', loadChildren: 'lazyModule'},
 * ]);
 *
 * router.navigateByUrl('/lazy/loaded');
 * ```
 *
 * @stable
 */
@Injectable()
export class SpyNgModuleFactoryLoader implements NgModuleFactoryLoader {
  /**
   * @docsNotRequired
   */
  public stubbedModules: {[path: string]: any} = {};

  constructor(private compiler: Compiler) {}

  load(path: string): Promise<NgModuleFactory<any>> {
    if (this.stubbedModules[path]) {
      return this.compiler.compileModuleAsync(this.stubbedModules[path]);
    } else {
      return <any>Promise.reject(new Error(`Cannot find module ${path}`));
    }
  }
}

/**
 * Router setup factory function used for testing.
 *
 * @stable
 */
export function setupTestingRouter(
    urlSerializer: UrlSerializer, outletMap: RouterOutletMap, location: Location,
    loader: NgModuleFactoryLoader, compiler: Compiler, injector: Injector, routes: Route[][]) {
  return new Router(
      null, urlSerializer, outletMap, location, injector, loader, compiler, flatten(routes));
}

/**
 * @whatItDoes Sets up the router to be used for testing.
 *
 * @howToUse
 *
 * ```
 * beforeEach(() => {
 *   TestBed.configureTestModule({
 *     modules: [
 *       RouterTestingModule.withRoutes(
 *         [{path: '', component: BlankCmp}, {path: 'simple', component: SimpleCmp}])]
 *       )
 *     ]
 *   });
 * });
 * ```
 *
 * @description
 *
 * The modules sets up the router to be used for testing.
 * It provides spy implementations of {@link Location}, {@link LocationStrategy}, and {@link
 * NgModuleFactoryLoader}.
 *
 * @stable
 */
@NgModule({
  exports: [RouterModule],
  providers: [
    ROUTER_PROVIDERS, {provide: Location, useClass: SpyLocation},
    {provide: LocationStrategy, useClass: MockLocationStrategy},
    {provide: NgModuleFactoryLoader, useClass: SpyNgModuleFactoryLoader}, {
      provide: Router,
      useFactory: setupTestingRouter,
      deps: [
        UrlSerializer, RouterOutletMap, Location, NgModuleFactoryLoader, Compiler, Injector, ROUTES
      ]
    },
    {provide: PreloadingStrategy, useExisting: NoPreloading}, provideRoutes([])
  ]
})
export class RouterTestingModule {
  static withRoutes(routes: Routes): ModuleWithProviders {
    return {ngModule: RouterTestingModule, providers: [provideRoutes(routes)]};
  }
}