/**
 * UndoStack.js
 *
 * Released under LGPL License.
 * Copyright (c) 1999-2016 Ephox Corp. All rights reserved
 *
 * License: http://www.tinymce.com/license
 * Contributing: http://www.tinymce.com/contributing
 */

define("tinymce/imagetoolsplugin/UndoStack", [
], function() {
	return function() {
		var data = [], index = -1;

		function add(state) {
			var removed;

			removed = data.splice(++index);
			data.push(state);

			return {
				state: state,
				removed: removed
			};
		}

		function undo() {
			if (canUndo()) {
				return data[--index];
			}
		}

		function redo() {
			if (canRedo()) {
				return data[++index];
			}
		}

		function canUndo() {
			return index > 0;
		}

		function canRedo() {
			return index != -1 && index < data.length - 1;
		}

		return {
			data: data,
			add: add,
			undo: undo,
			redo: redo,
			canUndo: canUndo,
			canRedo: canRedo
		};
	};
});