/*
Copyright (c) 2009, Yahoo! Inc. All rights reserved.
Code licensed under the BSD License:
http://developer.yahoo.net/yui/license.txt
version: 3.0.0
build: 1549
*/
YUI.add('io-upload-iframe', function(Y) {

   /**
   	* Extends the IO base class to enable file uploads, with HTML forms,
   	* using an iframe as the transport medium.
	* @module io
	* @submodule io-upload-iframe
	*/

	var w = Y.config.win;
   /**
	* @description Parses the POST data object and creates hidden form elements
	* for each key-value, and appends them to the HTML form object.
	* @method appendData
	* @private
	* @static
	* @param {object} f HTML form object.
	* @param {string} s The key-value POST data.
	* @return {array} e Array of created fields.
	*/
	function _addData(f, s) {
		var o = [],
			m = s.split('='),
			i, l;

		for (i = 0, l = m.length - 1; i < l; i++) {
			o[i] = document.createElement('input');
			o[i].type = 'hidden';
			o[i].name = m[i].substring(m[i].lastIndexOf('&') + 1);
			o[i].value = (i + 1 === l) ? m[i + 1] : m[i + 1].substring(0, (m[i + 1].lastIndexOf('&')));
			f.appendChild(o[i]);
		}

		return o;
	}

   /**
	* @description Removes the custom fields created to pass additional POST
	* data, along with the HTML form fields.
	* @method f
	* @private
	* @static
	* @param {object} f HTML form object.
	* @param {object} o HTML form fields created from configuration.data.
	* @return {void}
	*/
	function _removeData(f, o) {
		var i, l;

		for(i = 0, l = o.length; i < l; i++){
			f.removeChild(o[i]);
		}
	}

   /**
	* @description Sets the appropriate attributes and values to the HTML
	* form, in preparation of a file upload transaction.
	* @method _setAttrs
	* @private
	* @static
	* @param {object} f HTML form object.
	* @param {object} id The Transaction ID.
	* @param {object} uri Qualified path to transaction resource.
	* @return {void}
	*/
	function _setAttrs(f, id, uri) {
		var ie8 = (document.documentMode && document.documentMode === 8) ? true : false;

		f.setAttribute('action', uri);
		f.setAttribute('method', 'POST');
		f.setAttribute('target', 'ioupload' + id );
		f.setAttribute(Y.UA.ie && !ie8 ? 'encoding' : 'enctype', 'multipart/form-data');
	}

   /**
	* @description Sets the appropriate attributes and values to the HTML
	* form, in preparation of a file upload transaction.
	* @method _resetAttrs
	* @private
	* @static
	* @param {object} f HTML form object.
	* @param {object} a Object of original attributes.
	* @return {void}
	*/
	function _resetAttrs(f, a){
		var p;

		for (p in a) {
			if (a.hasOwnProperty(a, p)) {
				if (a[p]) {
					f.setAttribute(p, f[p]);
				}
				else {
					f.removeAttribute(p);
				}
			}
		}
	}

   /**
	* @description Creates the iframe transported used in file upload
	* transactions, and binds the response event handler.
	*
	* @method _create
	* @private
	* @static
    * @param {object} o Transaction object generated by _create().
    * @param {object} c Configuration object passed to YUI.io().
    * @return {void}
	*/
	function _create(o, c) {
		var i = Y.Node.create('<iframe id="ioupload' + o.id + '" name="ioupload' + o.id + '" />');
			i._node.style.position = 'absolute';
			i._node.style.top = '-1000px';
			i._node.style.left = '-1000px';

		Y.one('body').appendChild(i);
		// Bind the onload handler to the iframe to detect the file upload response.
		Y.on("load", function() { _handle(o, c) }, '#ioupload' + o.id);
	}

   /**
	* @description Bound to the iframe's Load event and processes
	* the response data.
	* @method _handle
	* @private
	* @static
	* @param {o} o The transaction object
	* @param {object} c Configuration object for the transaction.
	* @return {void}
	*/
	function _handle(o, c) {
		var d = Y.one('#ioupload' + o.id).get('contentWindow.document'),
			b = d.one('body'),
			xml = (d._node.nodeType === 9),
			p;

		if (c.timeout) {
			_clearTimeout(o.id);
		}

		if (b) {
			// When a response Content-Type of "text/plain" is used, Firefox and Safari
			// will wrap the response string with <pre></pre>.
			p = b.query('pre:first-child');
			o.c.responseText = p ? p.get('innerHTML') : b.get('innerHTML');
		}
		else if (xml) {
			o.c.responseXML =  d._node;
		}

		Y.io.complete(o, c);
		Y.io.end(o, c);
		// The transaction is complete, so call _destroy to remove
		// the event listener bound to the iframe transport, and then
		// destroy the iframe.
		w.setTimeout( function() { _destroy(o.id); }, 0);
	}

   /**
	* @description Starts timeout count if the configuration object
	* has a defined timeout property.
	*
	* @method _startTimeout
	* @private
	* @static
    * @param {object} o Transaction object generated by _create().
    * @param {object} c Configuration object passed to YUI.io().
    * @return {void}
	*/
	function _startTimeout(o, c) {
		Y.io._timeout[o.id] = w.setTimeout(
			function() {
				var r = { id: o.id, status: 'timeout' };

				Y.io.complete(r, c);
				Y.io.end(r, c);
			}, c.timeout);
	}

   /**
	* @description Clears the timeout interval started by _startTimeout().
	* @method _clearTimeout
	* @private
	* @static
    * @param {number} id - Transaction ID.
    * @return {void}
	*/
	function _clearTimeout(id) {
		w.clearTimeout(Y.io._timeout[id]);
		delete Y.io._timeout[id];
	}

   /**
	* @description
	* @method _destroy
	* @private
	* @static
	* @param {o} o The transaction object
	* @param {object} uri Qualified path to transaction resource.
	* @param {object} c Configuration object for the transaction.
	* @return {void}
	*/
	function _destroy(id) {
		Y.Event.purgeElement('#ioupload' + id, false);
		Y.one('body').removeChild(Y.one('#ioupload' + id));
	}

	Y.mix(Y.io, {
	   /**
		* @description Uploads HTML form data, inclusive of files/attachments,
		* using the iframe created in _create to facilitate the transaction.
		* @method _upload
		* @private
		* @static
		* @param {o} o The transaction object
		* @param {object} uri Qualified path to transaction resource.
		* @param {object} c Configuration object for the transaction.
		* @return {void}
		*/
		_upload: function(o, uri, c) {
			var f = (typeof c.form.id === 'string') ? Y.config.doc.getElementById(c.form.id) : c.form.id,
				fields,
				// Track original HTML form attribute values.
				attr = {
					action: f.getAttribute('action'),
					target: f.getAttribute('target')
				};

			_create(o, c);
			// Initialize the HTML form properties in case they are
			// not defined in the HTML form.
			_setAttrs(f, o.id, uri);
			if (c.data) {
				fields = _addData(f, c.data);
			}

			// Start polling if a callback is present and the timeout
			// property has been defined.
			if (c.timeout) {
				_startTimeout(o, c);
			}

			// Start file upload.
			f.submit();
			Y.io.start(o.id, c);
			if (c.data) {
				_removeData(f, fields);
			}
			// Restore HTML form attributes to their original values.
			_resetAttrs(f, attr);

			return {
				id: o.id,
				abort: function() {
					var r = { id: o.id, status: 'abort' };

					if (Y.one('#ioupload' + o.id)) {
						_destroy(o.id);
						Y.io.complete(r, c);
						Y.io.end(r, c);
					}
					else {
						return false;
					}
				},
				isInProgress: function() {
					return Y.one('#ioupload' + o.id) ? true : false;
				}
			}
		}
	});



}, '3.0.0' ,{requires:['io-base','node-base','event-base']});
