import {Injectable} from '@angular/core';

@Injectable({
  providedIn: 'root'
})
export class StorageService {

  /**
   * This is so we can detect if they have local or session storage available, which we report on
   * From MDN - https://developer.mozilla.org/en-US/docs/Web/API/Web_Storage_API/Using_the_Web_Storage_API
   * @param type  the type of storage (localStorage, or sessionStorage)
   */
  static storageAvailable(type): boolean {
    let storage;
    try {
      storage = window[type];
      var x = '__storage_test__';
      storage.setItem(x, x);
      storage.removeItem(x);
      return true;
    } catch (e) {
      return e instanceof DOMException && (
          // everything except Firefox
        e.code === 22 ||
        // Firefox
        e.code === 1014 ||
        // test name field too, because code might not be present
        // everything except Firefox
        e.name === 'QuotaExceededError' ||
        // Firefox
        e.name === 'NS_ERROR_DOM_QUOTA_REACHED') &&
        // acknowledge QuotaExceededError only if there's something already stored
        (storage && storage.length !== 0);
    }
  }

  /**
   * save to localStorage (forever storage)
   * @param key  the key to store the data under
   * @param payload  the data
   */
  saveLocal(key: string, payload: string): boolean {
    if (StorageService.storageAvailable('localStorage')) { // if we have localstorage, we will us that
      localStorage.setItem(key, payload);
      return true;
    } else if (navigator.cookieEnabled) { // we have no localstorage, so we'll try cookies
      this.saveCookie(key, payload, false);
      return true;
    }
    return false;
  }

  /**
   * retrieve data from localStorage (forever storage)
   * @param key  the key to the stored data get
   */
  getLocal(key: string): any {
    if (StorageService.storageAvailable('localStorage')) {
      return localStorage.getItem(key);
    } else {
      return this.getCookie(key);
    }
  }

  /**
   * delete data from localStorage (forever storage) identified by key (not delete all)
   * @param key  the key to the stored data we want to delete
   */
  deleteLocal(key: string): any {
    if (StorageService.storageAvailable('localStorage')) {
      localStorage.removeItem(key);
    } else {
      this.deleteCookie(key);
    }
  }

  /**
   * save data to sessionStorage (until browsers closes storage)
   * @param key  the key to save the data under
   * @param payload  the data
   */
  saveSession(key: string, payload: string): boolean {
    if (StorageService.storageAvailable('sessionStorage')) { // if we have localstorage, we will us that
      sessionStorage.setItem(key, payload);
      return true;
    } else if (navigator.cookieEnabled) { // we have no localstorage, so we'll try cookies
      this.saveCookie(key, payload, true);
      return true;
    }
    return false;
  }

  /**
   * retrieve data from session storage (until browser closes storage)
   * @param key  the key to the data we want to get
   */
  getSession(key: string): any {
    if (StorageService.storageAvailable('sessionStorage')) {
      return sessionStorage.getItem(key);
    } else {
      return this.getCookie(key);
    }
  }

  /**
   * delete data from session storage (until browsers closes storage) by key (not delete all)
   * @param key  the key to the data we want to delete
   */
  deleteSession(key: string): any {
    if (StorageService.storageAvailable('sessionStorage')) {
      sessionStorage.removeItem(key);
    } else {
      this.deleteCookie(key);
    }
  }

  /**
   * if local or session storage isn't available (browser doesn't support, or its full) we fall back to using cookies.
   * This is the save fallback
   * @param key  the key to the data we want to save
   * @param payload  the data
   * @param session  whether this is session storage (temporary - short term cookie), otherwise its local (long term)
   */
  private saveCookie(key: string, payload: string, session: boolean = false) {
    let expires = session ? 'expires=Fri, 31 Dec 9999 23:59:59 GMT;' : '';
    document.cookie = key + "=" + encodeURIComponent(payload) + "; " + expires + " domain=" + window.location.hostname + "; path=/";
  }

  /**
   * the cookie fallback to getting a value
   * @param key  the key of the data we want to get
   */
  private getCookie(key: string) {
    return decodeURIComponent(document.cookie.replace(new RegExp("(?:(?:^|.*;)\\s*" + key + "\\s*\\=\\s*([^;]*).*$)|^.*$"), "$1")) || null;
  }

  /**
   * the cookie fallback to delete a value by key (not delete all)
   * @param key  the key fo the data we want to delete
   */
  private deleteCookie(key: string) {
    document.cookie = key + "= ;expires=Thu, 01 Jan 1970 00:00:00 GMT;";
  }


}