import Handsontable from './../../browser';
import {registerPlugin} from './../../plugins';

export {HandsontablePersistentState};

function Storage(prefix) {
  var savedKeys;

  var saveSavedKeys = function() {
    window.localStorage[prefix + '__' + 'persistentStateKeys'] = JSON.stringify(savedKeys);
  };

  var loadSavedKeys = function() {
    var keysJSON = window.localStorage[prefix + '__' + 'persistentStateKeys'];
    var keys = typeof keysJSON == 'string' ? JSON.parse(keysJSON) : void 0;
    savedKeys = keys ? keys : [];
  };

  var clearSavedKeys = function() {
    savedKeys = [];
    saveSavedKeys();
  };

  loadSavedKeys();

  this.saveValue = function(key, value) {
    window.localStorage[prefix + '_' + key] = JSON.stringify(value);
    if (savedKeys.indexOf(key) == -1) {
      savedKeys.push(key);
      saveSavedKeys();
    }

  };

  this.loadValue = function(key, defaultValue) {

    key = typeof key === 'undefined' ? defaultValue : key;

    var value = window.localStorage[prefix + '_' + key];

    return typeof value == 'undefined' ? void 0 : JSON.parse(value);
  };

  this.reset = function(key) {
    window.localStorage.removeItem(prefix + '_' + key);
  };

  this.resetAll = function() {
    for (var index = 0; index < savedKeys.length; index++) {
      window.localStorage.removeItem(prefix + '_' + savedKeys[index]);
    }

    clearSavedKeys();
  };
}

/**
 * @private
 * @class PersistentState
 * @plugin PersistentState
 */
function HandsontablePersistentState() {
  var plugin = this;

  this.init = function() {
    var instance = this,
      pluginSettings = instance.getSettings().persistentState;

    plugin.enabled = !!(pluginSettings);

    if (!plugin.enabled) {
      removeHooks.call(instance);
      return;
    }

    if (!instance.storage) {
      instance.storage = new Storage(instance.rootElement.id);
    }

    instance.resetState = plugin.resetValue;

    addHooks.call(instance);

  };

  this.saveValue = function(key, value) {
    var instance = this;

    instance.storage.saveValue(key, value);
  };

  this.loadValue = function(key, saveTo) {
    var instance = this;

    saveTo.value = instance.storage.loadValue(key);
  };

  this.resetValue = function(key) {
    var instance = this;

    if (typeof key === 'undefined') {
      instance.storage.resetAll();
    } else {
      instance.storage.reset(key);
    }

  };

  var hooks = {
    persistentStateSave: plugin.saveValue,
    persistentStateLoad: plugin.loadValue,
    persistentStateReset: plugin.resetValue
  };

  for (var hookName in hooks) {
    if (hooks.hasOwnProperty(hookName)) {
      Handsontable.hooks.register(hookName);
    }
  }

  function addHooks() {
    var instance = this;

    for (var hookName in hooks) {
      if (hooks.hasOwnProperty(hookName)) {
        instance.addHook(hookName, hooks[hookName]);
      }
    }
  }

  function removeHooks() {
    var instance = this;

    for (var hookName in hooks) {
      if (hooks.hasOwnProperty(hookName)) {
        instance.removeHook(hookName, hooks[hookName]);
      }
    }
  }
}

var htPersistentState = new HandsontablePersistentState();
Handsontable.hooks.add('beforeInit', htPersistentState.init);
Handsontable.hooks.add('afterUpdateSettings', htPersistentState.init);
