// Copyright 2011 The Closure Library Authors. All Rights Reserved.
//
// 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.

/**
 * @fileoverview Provides utility methods to render soy template.
 */

goog.provide('goog.soy');

goog.require('goog.dom');
goog.require('goog.dom.NodeType');
goog.require('goog.dom.TagName');



/**
 * Renders a Soy template and then set the output string as
 * the innerHTML of an element. It is recommended to use this helper function
 * instead of directly setting innerHTML in your hand-written code, so that it
 * will be easier to audit the code for cross-site scripting vulnerabilities.
 *
 * @param {Element} element The element whose content we are rendering into.
 * @param {Function} template The Soy template defining the element's content.
 * @param {Object=} opt_templateData The data for the template.
 * @param {Object=} opt_injectedData The injected data for the template.
 */
goog.soy.renderElement = function(element, template, opt_templateData,
                                  opt_injectedData) {
  element.innerHTML = template(
      opt_templateData || goog.soy.defaultTemplateData_, undefined,
      opt_injectedData);
};


/**
 * Renders a Soy template into a single node or a document
 * fragment. If the rendered HTML string represents a single node, then that
 * node is returned (note that this is *not* a fragment, despite them name of
 * the method). Otherwise a document fragment is returned containing the
 * rendered nodes.
 *
 * @param {Function} template The Soy template defining the element's content.
 * @param {Object=} opt_templateData The data for the template.
 * @param {Object=} opt_injectedData The injected data for the template.
 * @param {goog.dom.DomHelper=} opt_domHelper The DOM helper used to
 *     create DOM nodes; defaults to {@code goog.dom.getDomHelper}.
 * @return {!Node} The resulting node or document fragment.
 */
goog.soy.renderAsFragment = function(template, opt_templateData,
                                     opt_injectedData, opt_domHelper) {
  var dom = opt_domHelper || goog.dom.getDomHelper();
  return dom.htmlToDocumentFragment(
      template(opt_templateData || goog.soy.defaultTemplateData_,
               undefined, opt_injectedData));
};


/**
 * Renders a Soy template into a single node. If the rendered
 * HTML string represents a single node, then that node is returned. Otherwise,
 * a DIV element is returned containing the rendered nodes.
 *
 * @param {Function} template The Soy template defining the element's content.
 * @param {Object=} opt_templateData The data for the template.
 * @param {Object=} opt_injectedData The injected data for the template.
 * @param {goog.dom.DomHelper=} opt_domHelper The DOM helper used to
 *     create DOM nodes; defaults to {@code goog.dom.getDomHelper}.
 * @return {!Element} Rendered template contents, wrapped in a parent DIV
 *     element if necessary.
 */
goog.soy.renderAsElement = function(template, opt_templateData,
                                    opt_injectedData, opt_domHelper) {
  var dom = opt_domHelper || goog.dom.getDomHelper();
  var wrapper = dom.createElement(goog.dom.TagName.DIV);
  wrapper.innerHTML = template(
      opt_templateData || goog.soy.defaultTemplateData_,
      undefined, opt_injectedData);

  // If the template renders as a single element, return it.
  if (wrapper.childNodes.length == 1) {
    var firstChild = wrapper.firstChild;
    if (firstChild.nodeType == goog.dom.NodeType.ELEMENT) {
      return /** @type {!Element} */ (firstChild);
    }
  }

  // Otherwise, return the wrapper DIV.
  return wrapper;
};


/**
 * Immutable object that is passed into templates that are rendered
 * without any data.
 * @type {Object}
 * @private
 */
goog.soy.defaultTemplateData_ = {};