/**
 * Wrapper to add functionality to Web Storage API
 */
class Storage {
  // We can use localStorage or sessionStorage with the same API
  constructor(name = "localStorage") {
    this.store = window[name];
    // Constant name of the entity array where we store all entity keys
    this.KEY_LIST_NAME = "KEYS";
  }

  // Save on storage the item with the setItem API
  _saveItem(key, data) {
    const transformed = JSON.stringify(data);
    this.store.setItem(key, transformed);
  }

  // Add key to the entity KEYS
  _addKeyToList(key) {
    const keyList = this.get(this.KEY_LIST_NAME) || [];

    if (keyList.includes(key)) {
      return;
    }

    this._saveItem(this.KEY_LIST_NAME, [...keyList, key]);
  }

  // Remove key from the entity KEY_LIST_NAME
  _removeKeyToList(keyToRemove) {
    const keyList = this.get(this.KEY_LIST_NAME);
    const newList = keyList.filter(key => key !== keyToRemove);
    this._saveItem(this.KEY_LIST_NAME, newList);
  }

  // Set data into entity with name key
  set(key, data) {
    this._saveItem(key, data);
    this._addKeyToList(key);
  }

  // Get data from entity with name key
  get(key) {
    const data = this.store.getItem(key);
    return data ? JSON.parse(data) : undefined;
  }

  // Remove entire entity from the store with name key
  remove(key) {
    this.store.removeItem(key);
    this._removeKeyToList(key);
  }

  // Return the list of keys present in the store
  list() {
    return this.get(this.KEY_LIST_NAME);
  }

  // Clean all the storage
  clear() {
    this.list().forEach(key => {
      if (this.exist(key)) {
        return this.remove(key);
      }

      return this._removeKeyToList(key);
    });
  }

  // Return boolean if exist the key in the storage
  exist(key) {
    const keyList = this.get(this.KEY_LIST_NAME);
    return keyList.includes(key);
  }
}