/**
 * This code is mostly from the old Etherpad. Please help us to comment this code. 
 * This helps other people to understand this code better and helps them to improve it.
 * TL;DR COMMENTS ON THIS FILE ARE HIGHLY APPRECIATED
 */

/**
 * Copyright 2009 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS-IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

var Security = require('./security');

function isNodeText(node)
{
  return (node.nodeType == 3);
}

function object(o)
{
  var f = function(){};
  f.prototype = o;
  return new f();
}
var userAgent = (((function () {return this;})().navigator || {}).userAgent || 'node-js').toLowerCase();

// Figure out what browser is being used (stolen from jquery 1.2.1)
var browser = {
  version: (userAgent.match(/.+(?:rv|it|ra|ie)[\/: ]([\d.]+)/) || [])[1],
  safari: /webkit/.test(userAgent),
  opera: /opera/.test(userAgent),
  msie: /msie/.test(userAgent) && !/opera/.test(userAgent),
  mozilla: /mozilla/.test(userAgent) && !/(compatible|webkit)/.test(userAgent),
  windows: /windows/.test(userAgent),
  mobile: /mobile/.test(userAgent) || /android/.test(userAgent)
};


function getAssoc(obj, name)
{
  return obj["_magicdom_" + name];
}

function setAssoc(obj, name, value)
{
  // note that in IE designMode, properties of a node can get
  // copied to new nodes that are spawned during editing; also,
  // properties representable in HTML text can survive copy-and-paste
  obj["_magicdom_" + name] = value;
}

// "func" is a function over 0..(numItems-1) that is monotonically
// "increasing" with index (false, then true).  Finds the boundary
// between false and true, a number between 0 and numItems inclusive.


function binarySearch(numItems, func)
{
  if (numItems < 1) return 0;
  if (func(0)) return 0;
  if (!func(numItems - 1)) return numItems;
  var low = 0; // func(low) is always false
  var high = numItems - 1; // func(high) is always true
  while ((high - low) > 1)
  {
    var x = Math.floor((low + high) / 2); // x != low, x != high
    if (func(x)) high = x;
    else low = x;
  }
  return high;
}

function binarySearchInfinite(expectedLength, func)
{
  var i = 0;
  while (!func(i)) i += expectedLength;
  return binarySearch(i, func);
}

function htmlPrettyEscape(str)
{
  return Security.escapeHTML(str).replace(/\r?\n/g, '\\n');
}

var noop = function(){};

exports.isNodeText = isNodeText;
exports.object = object;
exports.browser = browser;
exports.getAssoc = getAssoc;
exports.setAssoc = setAssoc;
exports.binarySearch = binarySearch;
exports.binarySearchInfinite = binarySearchInfinite;
exports.htmlPrettyEscape = htmlPrettyEscape;
exports.noop = noop;