Choose button remains disabled unless files are chosen

from filepicker

This is will help user to understand that you can only
click choose button once the files are selected from the
file picker. This addresses the solution for issue 16106

Signed-off-by: Sujith Haridasan <Sujith_Haridasan@mentor.com>

core/js/oc-dialogs.js

@@ -218,6 +218,13 @@ var OCdialogs = {
 					self.$filePicker = null;
 				}
 			});
+
+			// We can access primary class only from oc-dialog.
+			// Hence this is one of the approach to get the choose button.
+			var getOcDialog = self.$filePicker.closest('.oc-dialog');
+			var buttonEnableDisable = getOcDialog.find('.primary');
+			buttonEnableDisable.prop("disabled", "true");
+
 			if (!OC.Util.hasSVGSupport()) {
 				OC.Util.replaceSVG(self.$filePicker.parent());
 			}
@@ -812,18 +819,25 @@ var OCdialogs = {
 		var self = event.data;
 		var dir = $(event.target).data('dir');
 		self._fillFilePicker(dir);
+		var getOcDialog = this.closest('.oc-dialog');
+		var buttonEnableDisable = $('.primary', getOcDialog);
+		buttonEnableDisable.prop("disabled", true);
 	},
 	/**
 	 * handle clicks made in the filepicker
 	*/
 	_handlePickerClick:function(event, $element) {
+		var getOcDialog = this.$filePicker.closest('.oc-dialog');
+		var buttonEnableDisable = getOcDialog.find('.primary');
 		if ($element.data('type') === 'file') {
 			if (this.$filePicker.data('multiselect') !== true || !event.ctrlKey) {
 				this.$filelist.find('.filepicker_element_selected').removeClass('filepicker_element_selected');
 			}
 			$element.toggleClass('filepicker_element_selected');
+			buttonEnableDisable.prop("disabled", false);
 		} else if ( $element.data('type') === 'dir' ) {
 			this._fillFilePicker(this.$filePicker.data('path') + '/' + $element.data('entryname'));
+			buttonEnableDisable.prop("disabled", true);
 		}
 	}
 };