import { Injectable } from '@angular/core';
import {ApiService} from './api.service';
import {ActivatedRouteSnapshot, CanActivate, Router, RouterStateSnapshot} from '@angular/router';
import {LocalStorageService} from 'angular-2-local-storage';
import {Observable} from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class LoginService implements CanActivate {

  private pathPermissions = [
    {path: 'templates', permission: 'maintain'},
    {path: 'users', permission: 'admin'}
  ];
  readonly levels = [
    'read',
    'write',
    'maintain',
    'dev',
    'admin'
  ];

  private loggedIn;
  private level;

  constructor(
    private api: ApiService,
    private storage: LocalStorageService,
    private router: Router
  ) {

  }

  login(username = '', password = '') {
    return new Promise(resolve => {
      if (username !== '' || password !== '') {  // some credentials given
        let credentials: string[];
        const credentialString: string = this.storage.get('basicAuth');
        if (credentialString) {  // found stored credentials
          credentials = atob(credentialString).split(':');
        }
        else {
          credentials = ['', ''];
        }
        if (username !== '' && password !== '') {  // all credentials given
          this.storage.set('basicAuth', btoa(username + ':' + password));
        }
        else if (username !== '') {  // username given
          this.storage.set('basicAuth', btoa(username + ':' + credentials[1]));
        }
        else if (password !== '') {  // password given
          this.storage.set('basicAuth', btoa(credentials[0] + ':' + password));
        }
      }
      this.api.get('/authorized', (data: any, error) => {
        if (!error) {
          if (data.status === 'Authorization successful') {
            this.loggedIn = true;
            this.level = data.level;
            resolve(true);
          } else {
            this.loggedIn = false;
            this.storage.remove('basicAuth');
            resolve(false);
          }
        } else {
          this.loggedIn = false;
          this.storage.remove('basicAuth');
          resolve(false);
        }
      });
    });
  }

  logout() {
    this.storage.remove('basicAuth');
    this.loggedIn = false;
  }

  canActivate(route: ActivatedRouteSnapshot = null, state: RouterStateSnapshot = null): Observable<boolean> {
    return new Observable<boolean>(observer => {
      new Promise(resolve => {
        if (this.loggedIn === undefined) {
          this.login().then(res => {
            resolve(res);
          });
        }
        else {
          resolve(this.loggedIn);
        }
      }).then(res => {
        const pathPermission = this.pathPermissions.find(e => e.path.indexOf(route.url[0].path) >= 0);
        const ok = res && !pathPermission || this.is(pathPermission.permission); // check if level is permitted for path
        observer.next(ok);
        observer.complete();
        if (!ok) {
          this.router.navigate(['/']);
        }
      });
    });
  }

  get isLoggedIn() {
    return this.loggedIn;
  }

  is(level) {
    return this.levels.indexOf(this.level) >= this.levels.indexOf(level);
  }

  get username() {
    return atob(this.storage.get('basicAuth')).split(':')[0];
  }
}