import { Injectable } from '@angular/core';
import { PreloadingStrategy, Route } from '@angular/router';
import { isEqual } from 'lodash';
import { Observable, of } from 'rxjs';
import { routes } from '../../../app.routes';
import { PortalDeterminationService } from './portal-determination.service';

@Injectable({
  providedIn: 'root'
})
export class GCPreloadingStrategy implements PreloadingStrategy {
  constructor (
    private portal: PortalDeterminationService
  ) { }

  private routes = routes; // for testing

  // look for a route (searchRoute) in the route definition (routeDef) and all children recursively
  findIfInChildRecursive (searchRoute: Route, parentRoute: Route): boolean {
    return isEqual(parentRoute, searchRoute) || (parentRoute.children ? parentRoute.children.some(child => this.findIfInChildRecursive(searchRoute, child)) : false);
  }

  getCurrentRouteRoot () {
    return this.routes.find(wrapper => wrapper.path === this.portal.routeBase);
  }

  getShouldLoad (route: Route) {
    return this.routes.find(wrapper => {
      return this.findIfInChildRecursive(route, wrapper);
    });
  }

  preload (route: Route, load: () => any): Observable<any> {
    const desiredRoot = this.getShouldLoad(route);
    const currentRouteRoot = this.getCurrentRouteRoot();
    // if it isn't in the parent routes (from a module loaded off of the parent module) OR it is under the right parent route, we can preload
    if (!desiredRoot || desiredRoot === currentRouteRoot) {
      return load();
    }

    return of(null);
  }
}