// Copyright 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.

/**
 * @fileoverview
 * Script to be injected into SAML provider pages that do not support the
 * auth service provider postMessage API. It serves two main purposes:
 * 1. Signal hosting extension that an external page is loaded so that the
 *    UI around it could be changed accordingly;
 * 2. Scrape password and send it back to be used for encrypt user data and
 *    use for offline login;
 */

(function() {
  /**
   * A class to scrape password from type=password input elements under a given
   * docRoot and send them back via a Channel.
   */
  function PasswordInputScraper() {
  }

  PasswordInputScraper.prototype = {
    // URL of the page.
    pageURL_: null,

    // Channel to send back changed password.
    channel_: null,

    // An array to hold password fields.
    passwordFields_: null,

    // An array to hold cached password values.
    passwordValues_: null,

    /**
     * Initialize the scraper with given channel and docRoot. Note that the
     * scanning for password fields happens inside the function and does not
     * handle DOM tree changes after the call returns.
     * @param {!Object} channel The channel to send back password.
     * @param {!string} pageURL URL of the page.
     * @param {!HTMLElement} docRoot The root element of the DOM tree that
     *     contains the password fields of interest.
     */
    init: function(channel, pageURL, docRoot) {
      this.pageURL_ = pageURL;
      this.channel_ = channel;

      this.passwordFields_ = docRoot.querySelectorAll('input[type=password]');
      this.passwordValues_ = [];

      for (var i = 0; i < this.passwordFields_.length; ++i) {
        this.passwordFields_[i].addEventListener(
            'change', this.onPasswordChanged_.bind(this, i));
        // 'keydown' event is needed for the case that the form is submitted
        // on enter key, in which case no 'change' event is dispatched.
        this.passwordFields_[i].addEventListener(
            'keydown', this.onPasswordKeyDown_.bind(this, i));

        this.passwordValues_[i] = this.passwordFields_[i].value;
      }
    },

    /**
     * Check if the password field at |index| has changed. If so, sends back
     * the updated value.
     */
    maybeSendUpdatedPassword: function(index) {
      var newValue = this.passwordFields_[index].value;
      if (newValue == this.passwordValues_[index])
        return;

      this.passwordValues_[index] = newValue;

      // Use an invalid char for URL as delimiter to concatenate page url and
      // password field index to construct a unique ID for the password field.
      var passwordId = this.pageURL_ + '|' + index;
      this.channel_.send({
        name: 'updatePassword',
        id: passwordId,
        password: newValue
      });
    },

    /**
     * Handles 'change' event in the scraped password fields.
     * @param {number} index The index of the password fields in
     *     |passwordFields_|.
     */
    onPasswordChanged_: function(index) {
      this.maybeSendUpdatedPassword(index);
    },

    /**
     * Handles 'keydown' event to trigger password change detection and
     * updates on enter key.
     * @param {number} index The index of the password fields in
     *     |passwordFields_|.
     * @param {Event} e The keydown event.
     */
    onPasswordKeyDown_: function(index, e) {
      if (e.keyIdentifier == 'Enter')
        this.maybeSendUpdatedPassword(index);
    }
  };

  /**
   * Returns true if the script is injected into auth main page.
   */
  function isAuthMainPage() {
    return window.location.href.indexOf(
        'chrome-extension://mfffpogegjflfpflabcdkioaeobkgjik/main.html') == 0;
  }

  /**
   * Heuristic test whether the current page is a relevant SAML page.
   * Current implementation checks if it is a http or https page and has
   * some content in it.
   * @return {boolean} Whether the current page looks like a SAML page.
   */
  function isSAMLPage() {
    var url = window.location.href;
    if (!url.match(/^(http|https):\/\//))
      return false;

    return document.body.scrollWidth > 50 && document.body.scrollHeight > 50;
  }

  if (isAuthMainPage()) {
    // Use an event to signal the auth main to enable SAML support.
    var e = document.createEvent('Event');
    e.initEvent('enableSAML', false, false);
    document.dispatchEvent(e);
  } else {
    var channel;
    var passwordScraper;
    if (isSAMLPage()) {
      var pageURL = window.location.href;

      channel = new Channel();
      channel.connect('injected');
      channel.send({name: 'pageLoaded', url: pageURL});

      passwordScraper = new PasswordInputScraper();
      passwordScraper.init(channel, pageURL, document.documentElement);
    }
  }
})();