/**
+ * 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.log('The iframe transport for transaction ' + id + 'has been destroyed.', 'info', 'io');
+ }
+
+ 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);
+ Y.log('Transaction timeout started for transaction ' + 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 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);
+ }
+ }
+ }
+ }
+ });
+