/*

Copyright (c) 2009, Yahoo! Inc. All rights reserved.

Code licensed under the BSD License:

http://developer.yahoo.net/yui/license.txt

version: 3.0.0b1

build: 1163

*/

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} d The key-value hash map.

	* @return {array} e Array of created fields.

	*/

	function _addData(f, d) {

		var e = [],

			p, i;

		for (p in d) {

			if (d.hasOwnProperty(d, p)) {

				e[i] = document.createElement('input');

				e[i].type = 'hidden';

				e[i].name = p;

				e[i].value = d[p].

				f.appendChild(e[i]);

			}

		}

		return e;

	}

	function _removeData(f, e) {

		var i, l;

		if (e && e.length > 0) {

			for(i = 0, l = e.length; i < l; i++){

				f.removeChild(e[i]);

			}

		}

	}

	function _create(o, c) {

		var i = Y.Node.create('<iframe id="ioupload' + o.id + '" name="ioupload' + o.id + '" />'),

			cfg = {

				position: 'absolute',

				top: '-1000px',

				left: '-1000px'

			};

		i.setStyles(cfg);

		Y.get('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);

	}

	// Create the upload callback handler that fires when the iframe

	// receives the load event.  Subsequently, the event handler is detached

	// and the iframe removed from the document.

	function _handle(o, c) {

		var p,

		    b = Y.get('#ioupload' + o.id).get('contentWindow.document.body');

		if (c.timeout) {

			_clearTimeout(o.id);

		}

		// 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');

		Y.io.complete(o, c);

		// The transaction is complete, so call _destroy to remove

		// the event listener bound to the iframe transport, and then

		// destroy the iframe.

		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() { Y.io.abort(o, 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];

	}

	function _destroy(id) {

		Y.Event.purgeElement('#ioupload' + id, false);

		Y.get('body').removeChild(Y.get('#ioupload' + id));

	}

	Y.mix(Y.io, {

	   /**

		* @description Uploads HTML form, inclusive of files/attachments, using the

		* iframe created in createFrame 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') ? document.getElementById(c.form.id) : c.form.id,

				e, fields, i, p, attr;

			_create(o, c);

			// Track original HTML form attribute values.

			attr = {

				action: f.getAttribute('action'),

				target: f.getAttribute('target')

			};

			// Initialize the HTML form properties in case they are

			// not defined in the HTML form.

			f.setAttribute('action', uri);

			f.setAttribute('method', 'POST');

			f.setAttribute('target', 'ioupload' + o.id );

			f.setAttribute((Y.UA.ie && !document.documentMode) ? 'encoding' : 'enctype', 'multipart/form-data');

			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 prior to file upload.

			for (p in attr) {

				if (attr.hasOwnProperty(attr, p)) {

					if (attr[p]) {

				  		f.setAttribute(p, f[prop]);

					}

					else {

				  		f.removeAttribute(p);

					}

			  	}

			}

		}

	});

}, '3.0.0b1' ,{requires:['io-base']});