/**
 * Copyright (c) 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule Keyboard
 * @flow
 */
'use strict';

const NativeEventEmitter = require('NativeEventEmitter');
const KeyboardObserver = require('NativeModules').KeyboardObserver;
const dismissKeyboard = require('dismissKeyboard');
const KeyboardEventEmitter = new NativeEventEmitter(KeyboardObserver);

// The following object exists for documentation purposes
// Actual work happens in
// https://github.com/facebook/react-native/blob/master/Libraries/EventEmitter/NativeEventEmitter.js
/**
 * `Keyboard` component to control keyboard events.
 *
 * ### Usage
 *
 * The Keyboard component allows you to listen for native events and react to them, as
 * well as make changes to the keyboard, like dismissing it.
 *
 *```
 * import React, { Component } from 'react';
 * import { Keyboard, TextInput } from 'react-native';
 *
 * class Example extends Component {
 *   componentWillMount () {
 *     this.keyboardDidShowListener = Keyboard.addListener('keyboardDidShow', this._keyboardDidShow);
 *     this.keyboardDidHideListener = Keyboard.addListener('keyboardDidHide', this._keyboardDidHide);
 *   }
 *
 *   componentWillUnmount () {
 *      this.keyboardDidShowListener.remove();
 *      this.keyboardDidHideListener.remove();
 *   }
 *
 *   _keyboardDidShow () {
 *    window.alert('Keyboard Shown');
 *   }
 *
 *   _keyboardDidHide () {
 *    window.alert('Keyboard Hidden');
 *   }
 *
 *   render() {
 *     return (
 *       <TextInput
 *         onSubmitEditing={Keyboard.dismiss}
 *       />
 *     );
 *   }
 * }
 *```
 */
module.exports = {

  /**
   * The `addListener` function connects a JavaScript function to an identified native
   * keyboard notification event.
   *
   * This function then returns the reference to the listener.
   *
   * @param {string} nativeEvent The `nativeEvent` is the string that identifies the event you're listening for.  This
   *can be any of the following:
   * - `keyboardWillShow`
   * - `keyboardDidShow`
   * - `keyboardWillHide`
   * - `keyboardDidHide`
   * - `keyboardWillChangeFrame`
   * - `keyboardDidChangeFrame`
   *
   * @param {function} jsFunction function to be called when the event fires.
   */
  addListener (nativeEvent: string, jsFunction: Function) {
    return KeyboardEventEmitter.addListener(nativeEvent, jsFunction);
  },

  /**
   * Removes all listeners for a specific event type.
   *
   * @param {string} eventType The native event string listeners are watching which will be removed.
   */
  removeAllListeners (eventType: string) {
    KeyboardEventEmitter.removeAllListeners(eventType);
  },

  /**
   * Removes a specific subscription.
   *
   * @param {EmitterSubscription} subscription The subscription emitter to be removed.
   */
  removeSubscription (subscription: Object) {
    KeyboardEventEmitter.removeSubscription(subscription);
  },

  /**
   * Dismisses the active keyboard and removes focus.
   */
  dismiss () {
    dismissKeyboard();
  }

};