// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * Namespace for keyboard utility functions.
 */
var keyboard = {};

/**
 * keyboard_utils may be injected as content script. This variable gets and
 * saves the host window.
 * @private
 */
var keyboardHostWindow_;

/**
 * keyboard_utils may be injected as content script. This variable gets and
 * saves the host origin.
 * @private
 */
var keyboardHostOrigin_;

/**
 * Handles the initial messaging posted from webview, where this script is
 * injected.
 * @param {Event} event Message event posted from webview.
 * @private
 */
keyboard.onInitMessage_ = function(event) {
  if (event.data == 'initialMessage' &&
      event.origin == 'chrome://oobe') {
    keyboardHostWindow_ = event.source;
    keyboardHostOrigin_ = event.origin;
  }
};

/**
 * Handles the actual focus advancing by raising tab/shift-tab key events
 * on C++ side.
 * @param {boolean} reverse true if focus is moving backward, otherwise forward.
 */
keyboard.onAdvanceFocus = function(reverse) {
  chrome.send('raiseTabKeyEvent', [reverse]);
};

/**
 * Swallows keypress and keyup events of arrow keys.
 * @param {Event} event Raised event.
 * @private
 */
keyboard.onKeyIgnore_ = function(event) {
  event = /** @type {KeyboardEvent} */(event);

  if (event.ctrlKey || event.shiftKey || event.altKey || event.metaKey)
    return;

  if (event.key == 'ArrowLeft' ||
      event.key == 'ArrowRight' ||
      event.key == 'ArrowUp' ||
      event.key == 'ArrowDown') {
    event.stopPropagation();
    event.preventDefault();
  }
};

/**
 * Handles arrow key events, depending on if self is a content script.
 * @param {Event} event Raised event.
 * @private
 */
keyboard.onKeyDown_ = function(event) {
  event = /** @type {KeyboardEvent} */(event);

  if (event.ctrlKey || event.shiftKey || event.altKey || event.metaKey)
    return;

  // This file also gets embedded inside of the CfM/hotrod enrollment webview.
  // Events will bubble down into the webview, which means that the event
  // handler from the webui will steal the events meant for the webview. So we
  // have to disable the webui handler if the active element is the webview.
  //
  // $ is defined differently depending on how this file gets executed; we have
  // to use document.getElementById to get consistent behavior.
  //
  // See crbug.com/543865.
  if (document.activeElement ===
      document.getElementById('oauth-enroll-auth-view'))
    return;

  // If we are in networks list dropdown container, let network_dropdown.js
  // handle keyboard events.
  if (document.activeElement.classList.contains('dropdown-container'))
    return;

  // Do not map arrow key events to tab events if the user is currently
  // focusing an input element and hits the left or right.
  var needsLeftRightKey =
      (event.key == 'ArrowLeft' || event.key == 'ArrowRight') &&
      document.activeElement.tagName == 'INPUT';

  if (!needsLeftRightKey) {
    // Inside of a content script, instead of callling chrome.send directly
    // (since it is not available) we send an event to the host script
    // which will make the chrome.send call on our behalf.
    if (event.key == 'ArrowLeft' || event.key == 'ArrowUp') {
      if (!keyboardHostWindow_)
        keyboard.onAdvanceFocus(true);
      else
        keyboardHostWindow_.postMessage('backwardFocus', keyboardHostOrigin_);
      event.preventDefault();
    } else if (event.key == 'ArrowRight' || event.key == 'ArrowDown') {
      if (!keyboardHostWindow_)
        keyboard.onAdvanceFocus(false);
      else
        keyboardHostWindow_.postMessage('forwardFocus', keyboardHostOrigin_);
      event.preventDefault();
    }
  }

  if (event.key == 'ArrowLeft' || event.key == 'ArrowUp' ||
      event.key == 'ArrowRight' || event.key == 'ArrowDown')
    event.stopPropagation();
};

/**
 * Initializes event handling for arrow keys driven focus flow.
 * @param {boolean} injected true if script runs as an injected content script.
 */
keyboard.initializeKeyboardFlow = function(injected) {
  document.addEventListener('keydown',
      keyboard.onKeyDown_, true);
  document.addEventListener('keypress',
      keyboard.onKeyIgnore_, true);
  document.addEventListener('keyup',
      keyboard.onKeyIgnore_, true);
  if (injected)
    window.addEventListener('message', keyboard.onInitMessage_);
};