/**
 * Copyright (c) 2015-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @format
 * @flow
 */

'use strict';

const LayoutAnimation = require('LayoutAnimation');
const invariant = require('fbjs/lib/invariant');
const NativeEventEmitter = require('NativeEventEmitter');
const KeyboardObserver = require('NativeModules').KeyboardObserver;
const dismissKeyboard = require('dismissKeyboard');
const KeyboardEventEmitter = new NativeEventEmitter(KeyboardObserver);

type KeyboardEventName =
  | 'keyboardWillShow'
  | 'keyboardDidShow'
  | 'keyboardWillHide'
  | 'keyboardDidHide'
  | 'keyboardWillChangeFrame'
  | 'keyboardDidChangeFrame';

type ScreenRect = $ReadOnly<{|
  screenX: number,
  screenY: number,
  width: number,
  height: number,
|}>;

export type KeyboardEvent = $ReadOnly<{|
  duration?: number,
  easing?: string,
  endCoordinates: ScreenRect,
  startCoordinates?: ScreenRect,
|}>;

type KeyboardEventListener = (e: KeyboardEvent) => void;

// The following object exists for documentation purposes
// Actual work happens in
// https://github.com/facebook/react-native/blob/master/Libraries/EventEmitter/NativeEventEmitter.js

/**
 * `Keyboard` module to control keyboard events.
 *
 * ### Usage
 *
 * The Keyboard module 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 () {
 *     alert('Keyboard Shown');
 *   }
 *
 *   _keyboardDidHide () {
 *     alert('Keyboard Hidden');
 *   }
 *
 *   render() {
 *     return (
 *       <TextInput
 *         onSubmitEditing={Keyboard.dismiss}
 *       />
 *     );
 *   }
 * }
 *```
 */

let Keyboard = {
  /**
   * 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} eventName 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`
   *
   * Note that if you set `android:windowSoftInputMode` to `adjustResize`  or `adjustNothing`,
   * only `keyboardDidShow` and `keyboardDidHide` events will be available on Android.
   * `keyboardWillShow` as well as `keyboardWillHide` are generally not available on Android
   * since there is no native corresponding event.
   *
   * @param {function} callback function to be called when the event fires.
   */
  addListener(eventName: KeyboardEventName, callback: KeyboardEventListener) {
    invariant(false, 'Dummy method used for documentation');
  },

  /**
   * Removes a specific listener.
   *
   * @param {string} eventName The `nativeEvent` is the string that identifies the event you're listening for.
   * @param {function} callback function to be called when the event fires.
   */
  removeListener(eventName: KeyboardEventName, callback: Function) {
    invariant(false, 'Dummy method used for documentation');
  },

  /**
   * Removes all listeners for a specific event type.
   *
   * @param {string} eventType The native event string listeners are watching which will be removed.
   */
  removeAllListeners(eventName: KeyboardEventName) {
    invariant(false, 'Dummy method used for documentation');
  },

  /**
   * Dismisses the active keyboard and removes focus.
   */
  dismiss() {
    invariant(false, 'Dummy method used for documentation');
  },

  /**
   * Useful for syncing TextInput (or other keyboard accessory view) size of
   * position changes with keyboard movements.
   */
  scheduleLayoutAnimation(event: KeyboardEvent) {
    invariant(false, 'Dummy method used for documentation');
  },
};

// Throw away the dummy object and reassign it to original module
Keyboard = KeyboardEventEmitter;
Keyboard.dismiss = dismissKeyboard;
Keyboard.scheduleLayoutAnimation = function(event: KeyboardEvent) {
  const {duration, easing} = event;
  if (duration) {
    LayoutAnimation.configureNext({
      duration: duration,
      update: {
        duration: duration,
        type: (easing && LayoutAnimation.Types[easing]) || 'keyboard',
      },
    });
  }
};

module.exports = Keyboard;