/**
+ * 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]);
+ Y.log('key: ' + o[i].name + ' and value: ' + o[i].value + ' added as form data.', 'info', 'io');
+ }
+
+ 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');
+ Y.log('The responseText value for transaction ' + o.id + ' is: ' + o.c.responseText + '.', 'info', 'io');
+ }
+ else if (xml) {
+ o.c.responseXML = d._node;
+ Y.log('The response for transaction ' + o.id + ' is an XML document.', 'info', 'io');
+ }
+
+ 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);
+ Y.log('Transaction ' + o.id + ' timeout.', 'info', 'io');
+ }, 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.log('The iframe transport for transaction ' + id + ' has been destroyed.', 'info', 'io');
+ }
+
+ 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);
+ Y.log('Transaction timeout started for transaction ' + o.id + '.', 'info', 'io');
+ }
+
+ // 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);
+ Y.log('Transaction ' + o.id + ' aborted.', 'info', 'io');
+ }
+ else {
+ Y.log('Attempted to abort transaction ' + o.id + ' but transaction has completed.', 'info', 'io');
+ return false;
+ }
+ },
+ isInProgress: function() {
+ return Y.one('#ioupload' + o.id) ? true : false;
+ }
+ }
+ }
+ });
+