goog.provide('webfont.DomHelper');
/**
 * Handles common DOM manipulation tasks. The aim of this library is to cover
 * the needs of typical font loading. Not more, not less.
 * @param {Window} mainWindow The main window webfontloader.js is loaded in.
 * @param {Window=} opt_loadWindow The window we'll load the font into. By
 *   default, the main window is used.
 * @constructor
 */
webfont.DomHelper = function(mainWindow, opt_loadWindow) {
  this.mainWindow_ = mainWindow;
  this.loadWindow_ = opt_loadWindow || mainWindow;
  /** @type {string} */
  this.protocol_;
  /** @type {Document} */
  this.document_ = this.loadWindow_.document;
};
goog.scope(function () {
  var DomHelper = webfont.DomHelper;
  /**
   * The NativeFontWatchRunnner depends on the correct and reliable
   * |onload| event, and browsers with the native font loading API
   * have reliable @onload support as far as we know. So we use the
   * event for such a case and unconditionally invokes the callback
   * otherwise.
   *
   * @const
   * @type {boolean}
   */
  DomHelper.CAN_WAIT_STYLESHEET = !!window['FontFace'];
  /**
   * Creates an element.
   * @param {string} elem The element type.
   * @param {Object=} opt_attr A hash of attribute key/value pairs.
   * @param {string=} opt_innerHtml Contents of the element.
   * @return {Element} the new element.
   */
  DomHelper.prototype.createElement = function(elem, opt_attr,
	  opt_innerHtml) {
	var domElement = this.document_.createElement(elem);
	if (opt_attr) {
	  for (var attr in opt_attr) {
		// protect against native prototype augmentations
		if (opt_attr.hasOwnProperty(attr)) {
		  if (attr == "style") {
			this.setStyle(domElement, opt_attr[attr]);
		  } else {
			domElement.setAttribute(attr, opt_attr[attr]);
		  }
		}
	  }
	}
	if (opt_innerHtml) {
	  domElement.appendChild(this.document_.createTextNode(opt_innerHtml));
	}
	return domElement;
  };
  /**
   * Inserts an element into the document. This is intended for unambiguous
   * elements such as html, body, head.
   * @param {string} tagName The element name.
   * @param {Element} e The element to append.
   * @return {boolean} True if the element was inserted.
   */
  DomHelper.prototype.insertInto = function(tagName, e) {
	var t = this.document_.getElementsByTagName(tagName)[0];
	if (!t) { // opera allows documents without a head
	  t = document.documentElement;
	}
	// This is safer than appendChild in IE. appendChild causes random
	// JS errors in IE. Sometimes errors in other JS exectution, sometimes
	// complete 'This page cannot be displayed' errors. For our purposes,
	// it's equivalent because we don't need to insert at any specific
	// location.
	t.insertBefore(e, t.lastChild);
	return true;
  };
  /**
   * Calls a function when the body tag exists.
   * @param {function()} callback The function to call.
   */
  DomHelper.prototype.whenBodyExists = function(callback) {
	var that = this;
	if (that.document_.body) {
	  callback();
	} else {
	  if (that.document_.addEventListener) {
		that.document_.addEventListener('DOMContentLoaded', callback);
	  } else {
		that.document_.attachEvent('onreadystatechange', function () {
		  if (that.document_.readyState == 'interactive' || that.document_.readyState == 'complete') {
			callback();
		  }
		});
	  }
	}
  };
  /**
   * Removes an element from the DOM.
   * @param {Element} node The element to remove.
   * @return {boolean} True if the element was removed.
   */
  DomHelper.prototype.removeElement = function(node) {
	if (node.parentNode) {
	  node.parentNode.removeChild(node);
	  return true;
	}
	return false;
  };
  /**
   * @deprecated Use updateClassName().
   *
   * Appends a name to an element's class attribute.
   * @param {Element} e The element.
   * @param {string} name The class name to add.
   */
  DomHelper.prototype.appendClassName = function(e, name) {
	this.updateClassName(e, [name]);
  };
  /**
   * @deprecated Use updateClassName().
   *
   * Removes a name to an element's class attribute.
   * @param {Element} e The element.
   * @param {string} name The class name to remove.
   */
  DomHelper.prototype.removeClassName = function(e, name) {
	this.updateClassName(e, null, [name]);
  };
  /**
   * Updates an element's class attribute in a single change. This
   * allows multiple updates in a single class name change so there
   * is no chance for a browser to relayout in between changes.
   *
   * @param {Element} e The element.
   * @param {Array.<string>=} opt_add List of class names to add.
   * @param {Array.<string>=} opt_remove List of class names to remove.
   */
  DomHelper.prototype.updateClassName = function (e, opt_add, opt_remove) {
	var add = opt_add || [],
		remove = opt_remove || [];
	var classes = e.className.split(/\s+/);
	for (var i = 0; i < add.length; i += 1) {
	  var found = false;
	  for (var j = 0; j < classes.length; j += 1) {
		if (add[i] === classes[j]) {
		  found = true;
		  break;
		}
	  }
	  if (!found) {
		classes.push(add[i]);
	  }
	}
	var remainingClasses = [];
	for (var i = 0; i < classes.length; i += 1) {
	  var found = false;
	  for (var j = 0; j < remove.length; j += 1) {
		if (classes[i] === remove[j]) {
		  found = true;
		  break;
		}
	  }
	  if (!found) {
		remainingClasses.push(classes[i]);
	  }
	}
	e.className = remainingClasses.join(' ')
					.replace(/\s+/g, ' ')
					.replace(/^\s+|\s+$/, '');
  };
  /**
   * Returns true if an element has a given class name and false otherwise.
   * @param {Element} e The element.
   * @param {string} name The class name to check for.
   * @return {boolean} Whether or not the element has this class name.
   */
  DomHelper.prototype.hasClassName = function(e, name) {
	var classes = e.className.split(/\s+/);
	for (var i = 0, len = classes.length; i < len; i++) {
	  if (classes[i] == name) {
		return true;
	  }
	}
	return false;
  };
  /**
   * Sets the style attribute on an element.
   * @param {Element} e The element.
   * @param {string} styleString The style string.
   */
  DomHelper.prototype.setStyle = function(e, styleString) {
	e.style.cssText = styleString;
  };
  /**
   * @return {Window} The main window webfontloader.js is loaded in (for config).
   */
  DomHelper.prototype.getMainWindow = function() {
	return this.mainWindow_;
  };
  /**
   * @return {Window} The window that we're loading the font(s) into.
   */
  DomHelper.prototype.getLoadWindow = function() {
	return this.loadWindow_;
  };
  /**
   * Returns the hostname of the current document.
   * @return {string} hostname.
   */
  DomHelper.prototype.getHostName = function() {
	return this.getLoadWindow().location.hostname || this.getMainWindow().location.hostname;
  };
  /**
   * Creates a style element.
   * @param {string} css Contents of the style element.
   * @return {Element} a DOM element.
   */
  DomHelper.prototype.createStyle = function(css) {
	var e = this.createElement('style');
	e.setAttribute('type', 'text/css');
	if (e.styleSheet) { // IE
	  e.styleSheet.cssText = css;
	} else {
	  e.appendChild(document.createTextNode(css));
	}
	return e;
  };
  /**
   * Loads an external stylesheet.
   *
   * @param {string} href the URL of the stylesheet
   * @param {function(Error)=} opt_callback Called when the stylesheet has loaded or failed to
   * load. Note that the callback is *NOT* guaranteed to be called in all browsers. The first
   * argument to the callback is an error object that is falsy when there are no errors and
   * truthy when there are.
   * @param {boolean=} opt_async True if the stylesheet should be loaded asynchronously. Defaults to false.
   * @return {Element} The link element
   */
  DomHelper.prototype.loadStylesheet = function (href, opt_callback, opt_async) {
	var link = this.createElement('link', {
	  'rel': 'stylesheet',
	  'href': href,
	  'media': (opt_async ? 'only x' : 'all')
	});
	var sheets = this.document_.styleSheets,
		eventFired = false,
		asyncResolved = !opt_async,
		callbackArg = null,
		callback = opt_callback || null;
	function mayInvokeCallback() {
	  if (callback && eventFired && asyncResolved) {
		callback(callbackArg);
		callback = null;
	  }
	}
	if (DomHelper.CAN_WAIT_STYLESHEET) {
	  link.onload = function () {
		eventFired = true;
		mayInvokeCallback();
	  };
	  link.onerror = function () {
		eventFired = true;
		callbackArg = new Error('Stylesheet failed to load');
		mayInvokeCallback();
	  };
	} else {
	  // Some callers expect opt_callback being called asynchronously.
	  setTimeout(function () {
		eventFired = true;
		mayInvokeCallback();
	  }, 0);
	}
	function onStylesheetAvailable(callback) {
	  for (var i = 0; i < sheets.length; i++) {
		if (sheets[i].href && sheets[i].href.indexOf(href) !== -1) {
		  return callback();
		}
	  }
	  setTimeout(function () {
		onStylesheetAvailable(callback);
	  }, 0);
	}
	function onMediaAvailable(callback) {
	  for (var i = 0; i < sheets.length; i++) {
		if (sheets[i].href && sheets[i].href.indexOf(href) !== -1 && sheets[i].media) {
		  /**
		   * @type {string|MediaList|null}
		   */
		  var media = sheets[i].media;
		  if (media === "all" || (media.mediaText && media.mediaText === "all")) {
			return callback();
		  }
		}
	  }
	  setTimeout(function () {
		onMediaAvailable(callback);
	  }, 0);
	}
	this.insertInto('head', link);
	if (opt_async) {
	  onStylesheetAvailable(function () {
		link.media = "all";
		// The media type change doesn't take effect immediately on Chrome, so
		// we'll query the media attribute on the stylesheet until it changes
		// to "all".
		onMediaAvailable(function () {
		  asyncResolved = true;
		  mayInvokeCallback();
		});
	  });
	}
	return link;
  };
  /**
   * Loads an external script file.
   * @param {string} src URL of the script.
   * @param {function(Error)=} opt_callback callback when the script has loaded. The first argument to
   * the callback is an error object that is falsy when there are no errors and truthy when there are.
   * @param {number=} opt_timeout The number of milliseconds after which the callback will be called
   * with a timeout error. Defaults to 5 seconds.
   * @return {Element} The script element
   */
  DomHelper.prototype.loadScript = function(src, opt_callback, opt_timeout) {
	var head = this.document_.getElementsByTagName('head')[0];
	if (head) {
	  var script = this.createElement('script', {
		'src': src
	  });
	  var done = false;
	  script.onload = script.onreadystatechange = function() {
		if (!done && (!this.readyState || this.readyState == 'loaded' || this.readyState == 'complete')) {
		  done = true;
		  if (opt_callback) {
			opt_callback(null);
		  }
		  script.onload = script.onreadystatechange = null;
		  // Avoid a bizarre issue with unclosed <base> tag in IE6 - http://blog.dotsmart.net/2008/04/
		  if (script.parentNode.tagName == 'HEAD') head.removeChild(script);
		}
	  };
	  head.appendChild(script);
	  setTimeout(function () {
		if (!done) {
		  done = true;
		  if (opt_callback) {
			opt_callback(new Error('Script load timeout'));
		  }
		}
	  }, opt_timeout || 5000);
	  return script;
	}
	return null;
  };
});
