security.service.ts

import { Injectable } from '@angular/core';
import { JwtHelperService } from '@auth0/angular-jwt';
import { interval } from 'rxjs/internal/observable/interval';
import { of } from 'rxjs/internal/observable/of';
import { map, startWith, switchMap } from 'rxjs/operators';
import { Observable } from 'rxjs/Rx';
import { LoginResponseVm, LoginVm, SecurityClient } from '../app.api';
import { LocalStorageService } from './local-storage.service';

@Injectable({
    providedIn: 'root',
})
export class SecurityService {
    jwtHelper: JwtHelperService;
    token: string;
    loginResult: LoginResponseVm;

    private bufferMinuteMilli = 1000 * 60;
    private bufferMinute = 5;

    constructor(
        private _securityApiClient: SecurityClient,
        private _localStorageService: LocalStorageService,
    ) {
        this.jwtHelper = new JwtHelperService();
    }

    login(loginVm: LoginVm): Observable<LoginResponseVm> {
        return this._securityApiClient.login(loginVm);
    }

    isTokenExpired(token: string): boolean {
        return this.jwtHelper.isTokenExpired(token);
    }

    saveLocalLogin(data: LoginResponseVm) {
        this._localStorageService.setObject('loginResult', data);
        this._localStorageService.set('token', data.token);
    }

    checkLocalLogin(): boolean {
        const result: LoginResponseVm = this._localStorageService.getObject('loginResult');

        if (result && result.user) {
            this.token = result.token;
            if (this.isTokenExpired(this.token)) {
                this.clearLocalLogin();
                return false;
            }

            this.loginResult = result;
            return true;
        }

        return false;
    }

    startRefreshCheck(): Observable<LoginResponseVm> {
        const result: LoginResponseVm = this._localStorageService.getObject('loginResult');
        this.token = this._localStorageService.get('token');

        if (!result || !result.user || !this.token || this.isTokenExpired(this.token)) {
            return of();
        }

        let refreshInterval = interval(this.bufferMinuteMilli * this.bufferMinute);

        if (this.tokenShouldRefresh(this.token)) {
            refreshInterval = refreshInterval.pipe(startWith(0));
        }

        return refreshInterval.pipe(
            switchMap((i: number) => {
                if (!this.tokenShouldRefresh(this.token)) {
                    return of();
                }

                return this._securityApiClient.refreshToken().pipe(
                    map((data: LoginResponseVm) => {
                        this.saveLocalLogin(data);
                        return data;
                    }),
                );
            }),
        );
    }

    private tokenShouldRefresh(token: string): boolean {
        return this.jwtHelper.isTokenExpired(token, 300);
    }

    clearLocalLogin() {
        this._localStorageService.remove('loginResult');
        this._localStorageService.remove('token');
        this._localStorageService.setObject('loginResult', null);
        this._localStorageService.set('token', null);
        this.loginResult = null;
        this.token = null;
        this._localStorageService.clear();
    }
}