ko.utils = (function () {
    function objectForEach(obj, action) {
        for (var prop in obj) {
            if (obj.hasOwnProperty(prop)) {
                action(prop, obj[prop]);
            }
        }
    }

    function extend(target, source) {
        if (source) {
            for(var prop in source) {
                if(source.hasOwnProperty(prop)) {
                    target[prop] = source[prop];
                }
            }
        }
        return target;
    }

    function setPrototypeOf(obj, proto) {
        obj.__proto__ = proto;
        return obj;
    }

    var canSetPrototype = ({ __proto__: [] } instanceof Array);

    // Represent the known event types in a compact way, then at runtime transform it into a hash with event name as key (for fast lookup)
    var knownEvents = {}, knownEventTypesByEventName = {};
    var keyEventTypeName = (navigator && /Firefox\/2/i.test(navigator.userAgent)) ? 'KeyboardEvent' : 'UIEvents';
    knownEvents[keyEventTypeName] = ['keyup', 'keydown', 'keypress'];
    knownEvents['MouseEvents'] = ['click', 'dblclick', 'mousedown', 'mouseup', 'mousemove', 'mouseover', 'mouseout', 'mouseenter', 'mouseleave'];
    objectForEach(knownEvents, function(eventType, knownEventsForType) {
        if (knownEventsForType.length) {
            for (var i = 0, j = knownEventsForType.length; i < j; i++)
                knownEventTypesByEventName[knownEventsForType[i]] = eventType;
        }
    });
    var eventsThatMustBeRegisteredUsingAttachEvent = { 'propertychange': true }; // Workaround for an IE9 issue - https://github.com/SteveSanderson/knockout/issues/406

    // Detect IE versions for bug workarounds (uses IE conditionals, not UA string, for robustness)
    // Note that, since IE 10 does not support conditional comments, the following logic only detects IE < 10.
    // Currently this is by design, since IE 10+ behaves correctly when treated as a standard browser.
    // If there is a future need to detect specific versions of IE10+, we will amend this.
    var ieVersion = document && (function() {
        var version = 3, div = document.createElement('div'), iElems = div.getElementsByTagName('i');

        // Keep constructing conditional HTML blocks until we hit one that resolves to an empty fragment
        while (
            div.innerHTML = '<!--[if gt IE ' + (++version) + ']><i></i><![endif]-->',
            iElems[0]
        ) {}
        return version > 4 ? version : undefined;
    }());
    var isIe6 = ieVersion === 6,
        isIe7 = ieVersion === 7;

    function isClickOnCheckableElement(element, eventType) {
        if ((ko.utils.tagNameLower(element) !== "input") || !element.type) return false;
        if (eventType.toLowerCase() != "click") return false;
        var inputType = element.type;
        return (inputType == "checkbox") || (inputType == "radio");
    }

    return {
        fieldsIncludedWithJsonPost: ['authenticity_token', /^__RequestVerificationToken(_.*)?$/],

        arrayForEach: function (array, action) {
            for (var i = 0, j = array.length; i < j; i++)
                action(array[i], i);
        },

        arrayIndexOf: function (array, item) {
            if (typeof Array.prototype.indexOf == "function")
                return Array.prototype.indexOf.call(array, item);
            for (var i = 0, j = array.length; i < j; i++)
                if (array[i] === item)
                    return i;
            return -1;
        },

        arrayFirst: function (array, predicate, predicateOwner) {
            for (var i = 0, j = array.length; i < j; i++)
                if (predicate.call(predicateOwner, array[i], i))
                    return array[i];
            return null;
        },

        arrayRemoveItem: function (array, itemToRemove) {
            var index = ko.utils.arrayIndexOf(array, itemToRemove);
            if (index > 0) {
                array.splice(index, 1);
            }
            else if (index === 0) {
                array.shift();
            }
        },

        arrayGetDistinctValues: function (array) {
            array = array || [];
            var result = [];
            for (var i = 0, j = array.length; i < j; i++) {
                if (ko.utils.arrayIndexOf(result, array[i]) < 0)
                    result.push(array[i]);
            }
            return result;
        },

        arrayMap: function (array, mapping) {
            array = array || [];
            var result = [];
            for (var i = 0, j = array.length; i < j; i++)
                result.push(mapping(array[i], i));
            return result;
        },

        arrayFilter: function (array, predicate) {
            array = array || [];
            var result = [];
            for (var i = 0, j = array.length; i < j; i++)
                if (predicate(array[i], i))
                    result.push(array[i]);
            return result;
        },

        arrayPushAll: function (array, valuesToPush) {
            if (valuesToPush instanceof Array)
                array.push.apply(array, valuesToPush);
            else
                for (var i = 0, j = valuesToPush.length; i < j; i++)
                    array.push(valuesToPush[i]);
            return array;
        },

        addOrRemoveItem: function(array, value, included) {
            var existingEntryIndex = ko.utils.arrayIndexOf(ko.utils.peekObservable(array), value);
            if (existingEntryIndex < 0) {
                if (included)
                    array.push(value);
            } else {
                if (!included)
                    array.splice(existingEntryIndex, 1);
            }
        },

        canSetPrototype: canSetPrototype,

        extend: extend,

        setPrototypeOf: setPrototypeOf,

        setPrototypeOfOrExtend: canSetPrototype ? setPrototypeOf : extend,

        objectForEach: objectForEach,

        objectMap: function(source, mapping) {
            if (!source)
                return source;
            var target = {};
            for (var prop in source) {
                if (source.hasOwnProperty(prop)) {
                    target[prop] = mapping(source[prop], prop, source);
                }
            }
            return target;
        },

        emptyDomNode: function (domNode) {
            while (domNode.firstChild) {
                ko.removeNode(domNode.firstChild);
            }
        },

        moveCleanedNodesToContainerElement: function(nodes) {
            // Ensure it's a real array, as we're about to reparent the nodes and
            // we don't want the underlying collection to change while we're doing that.
            var nodesArray = ko.utils.makeArray(nodes);

            var container = document.createElement('div');
            for (var i = 0, j = nodesArray.length; i < j; i++) {
                container.appendChild(ko.cleanNode(nodesArray[i]));
            }
            return container;
        },

        cloneNodes: function (nodesArray, shouldCleanNodes) {
            for (var i = 0, j = nodesArray.length, newNodesArray = []; i < j; i++) {
                var clonedNode = nodesArray[i].cloneNode(true);
                newNodesArray.push(shouldCleanNodes ? ko.cleanNode(clonedNode) : clonedNode);
            }
            return newNodesArray;
        },

        setDomNodeChildren: function (domNode, childNodes) {
            ko.utils.emptyDomNode(domNode);
            if (childNodes) {
                for (var i = 0, j = childNodes.length; i < j; i++)
                    domNode.appendChild(childNodes[i]);
            }
        },

        replaceDomNodes: function (nodeToReplaceOrNodeArray, newNodesArray) {
            var nodesToReplaceArray = nodeToReplaceOrNodeArray.nodeType ? [nodeToReplaceOrNodeArray] : nodeToReplaceOrNodeArray;
            if (nodesToReplaceArray.length > 0) {
                var insertionPoint = nodesToReplaceArray[0];
                var parent = insertionPoint.parentNode;
                for (var i = 0, j = newNodesArray.length; i < j; i++)
                    parent.insertBefore(newNodesArray[i], insertionPoint);
                for (var i = 0, j = nodesToReplaceArray.length; i < j; i++) {
                    ko.removeNode(nodesToReplaceArray[i]);
                }
            }
        },

        fixUpContinuousNodeArray: function(continuousNodeArray, parentNode) {
            // Before acting on a set of nodes that were previously outputted by a template function, we have to reconcile
            // them against what is in the DOM right now. It may be that some of the nodes have already been removed, or that
            // new nodes might have been inserted in the middle, for example by a binding. Also, there may previously have been
            // leading comment nodes (created by rewritten string-based templates) that have since been removed during binding.
            // So, this function translates the old "map" output array into its best guess of the set of current DOM nodes.
            //
            // Rules:
            //   [A] Any leading nodes that have been removed should be ignored
            //       These most likely correspond to memoization nodes that were already removed during binding
            //       See https://github.com/SteveSanderson/knockout/pull/440
            //   [B] We want to output a continuous series of nodes. So, ignore any nodes that have already been removed,
            //       and include any nodes that have been inserted among the previous collection

            if (continuousNodeArray.length) {
                // The parent node can be a virtual element; so get the real parent node
                parentNode = (parentNode.nodeType === 8 && parentNode.parentNode) || parentNode;

                // Rule [A]
                while (continuousNodeArray.length && continuousNodeArray[0].parentNode !== parentNode)
                    continuousNodeArray.shift();

                // Rule [B]
                if (continuousNodeArray.length > 1) {
                    var current = continuousNodeArray[0], last = continuousNodeArray[continuousNodeArray.length - 1];
                    // Replace with the actual new continuous node set
                    continuousNodeArray.length = 0;
                    while (current !== last) {
                        continuousNodeArray.push(current);
                        current = current.nextSibling;
                        if (!current) // Won't happen, except if the developer has manually removed some DOM elements (then we're in an undefined scenario)
                            return;
                    }
                    continuousNodeArray.push(last);
                }
            }
            return continuousNodeArray;
        },

        setOptionNodeSelectionState: function (optionNode, isSelected) {
            // IE6 sometimes throws "unknown error" if you try to write to .selected directly, whereas Firefox struggles with setAttribute. Pick one based on browser.
            if (ieVersion < 7)
                optionNode.setAttribute("selected", isSelected);
            else
                optionNode.selected = isSelected;
        },

        stringTrim: function (string) {
            return string === null || string === undefined ? '' :
                string.trim ?
                    string.trim() :
                    string.toString().replace(/^[\s\xa0]+|[\s\xa0]+$/g, '');
        },

        stringStartsWith: function (string, startsWith) {
            string = string || "";
            if (startsWith.length > string.length)
                return false;
            return string.substring(0, startsWith.length) === startsWith;
        },

        domNodeIsContainedBy: function (node, containedByNode) {
            if (node === containedByNode)
                return true;
            if (node.nodeType === 11)
                return false; // Fixes issue #1162 - can't use node.contains for document fragments on IE8
            if (containedByNode.contains)
                return containedByNode.contains(node.nodeType === 3 ? node.parentNode : node);
            if (containedByNode.compareDocumentPosition)
                return (containedByNode.compareDocumentPosition(node) & 16) == 16;
            while (node && node != containedByNode) {
                node = node.parentNode;
            }
            return !!node;
        },

        domNodeIsAttachedToDocument: function (node) {
            return ko.utils.domNodeIsContainedBy(node, node.ownerDocument.documentElement);
        },

        anyDomNodeIsAttachedToDocument: function(nodes) {
            return !!ko.utils.arrayFirst(nodes, ko.utils.domNodeIsAttachedToDocument);
        },

        tagNameLower: function(element) {
            // For HTML elements, tagName will always be upper case; for XHTML elements, it'll be lower case.
            // Possible future optimization: If we know it's an element from an XHTML document (not HTML),
            // we don't need to do the .toLowerCase() as it will always be lower case anyway.
            return element && element.tagName && element.tagName.toLowerCase();
        },

        registerEventHandler: function (element, eventType, handler) {
            var mustUseAttachEvent = ieVersion && eventsThatMustBeRegisteredUsingAttachEvent[eventType];
            if (!mustUseAttachEvent && jQueryInstance) {
                jQueryInstance(element)['bind'](eventType, handler);
            } else if (!mustUseAttachEvent && typeof element.addEventListener == "function")
                element.addEventListener(eventType, handler, false);
            else if (typeof element.attachEvent != "undefined") {
                var attachEventHandler = function (event) { handler.call(element, event); },
                    attachEventName = "on" + eventType;
                element.attachEvent(attachEventName, attachEventHandler);

                // IE does not dispose attachEvent handlers automatically (unlike with addEventListener)
                // so to avoid leaks, we have to remove them manually. See bug #856
                ko.utils.domNodeDisposal.addDisposeCallback(element, function() {
                    element.detachEvent(attachEventName, attachEventHandler);
                });
            } else
                throw new Error("Browser doesn't support addEventListener or attachEvent");
        },

        triggerEvent: function (element, eventType) {
            if (!(element && element.nodeType))
                throw new Error("element must be a DOM node when calling triggerEvent");

            // For click events on checkboxes and radio buttons, jQuery toggles the element checked state *after* the
            // event handler runs instead of *before*. (This was fixed in 1.9 for checkboxes but not for radio buttons.)
            // IE doesn't change the checked state when you trigger the click event using "fireEvent".
            // In both cases, we'll use the click method instead.
            var useClickWorkaround = isClickOnCheckableElement(element, eventType);

            if (jQueryInstance && !useClickWorkaround) {
                jQueryInstance(element)['trigger'](eventType);
            } else if (typeof document.createEvent == "function") {
                if (typeof element.dispatchEvent == "function") {
                    var eventCategory = knownEventTypesByEventName[eventType] || "HTMLEvents";
                    var event = document.createEvent(eventCategory);
                    event.initEvent(eventType, true, true, window, 0, 0, 0, 0, 0, false, false, false, false, 0, element);
                    element.dispatchEvent(event);
                }
                else
                    throw new Error("The supplied element doesn't support dispatchEvent");
            } else if (useClickWorkaround && element.click) {
                element.click();
            } else if (typeof element.fireEvent != "undefined") {
                element.fireEvent("on" + eventType);
            } else {
                throw new Error("Browser doesn't support triggering events");
            }
        },

        unwrapObservable: function (value) {
            return ko.isObservable(value) ? value() : value;
        },

        peekObservable: function (value) {
            return ko.isObservable(value) ? value.peek() : value;
        },

        toggleDomNodeCssClass: function (node, classNames, shouldHaveClass) {
            if (classNames) {
                var cssClassNameRegex = /\S+/g,
                    currentClassNames = node.className.match(cssClassNameRegex) || [];
                ko.utils.arrayForEach(classNames.match(cssClassNameRegex), function(className) {
                    ko.utils.addOrRemoveItem(currentClassNames, className, shouldHaveClass);
                });
                node.className = currentClassNames.join(" ");
            }
        },

        setTextContent: function(element, textContent) {
            var value = ko.utils.unwrapObservable(textContent);
            if ((value === null) || (value === undefined))
                value = "";

            // We need there to be exactly one child: a text node.
            // If there are no children, more than one, or if it's not a text node,
            // we'll clear everything and create a single text node.
            var innerTextNode = ko.virtualElements.firstChild(element);
            if (!innerTextNode || innerTextNode.nodeType != 3 || ko.virtualElements.nextSibling(innerTextNode)) {
                ko.virtualElements.setDomNodeChildren(element, [element.ownerDocument.createTextNode(value)]);
            } else {
                innerTextNode.data = value;
            }

            ko.utils.forceRefresh(element);
        },

        setElementName: function(element, name) {
            element.name = name;

            // Workaround IE 6/7 issue
            // - https://github.com/SteveSanderson/knockout/issues/197
            // - http://www.matts411.com/post/setting_the_name_attribute_in_ie_dom/
            if (ieVersion <= 7) {
                try {
                    element.mergeAttributes(document.createElement("<input name='" + element.name + "'/>"), false);
                }
                catch(e) {} // For IE9 with doc mode "IE9 Standards" and browser mode "IE9 Compatibility View"
            }
        },

        forceRefresh: function(node) {
            // Workaround for an IE9 rendering bug - https://github.com/SteveSanderson/knockout/issues/209
            if (ieVersion >= 9) {
                // For text nodes and comment nodes (most likely virtual elements), we will have to refresh the container
                var elem = node.nodeType == 1 ? node : node.parentNode;
                if (elem.style)
                    elem.style.zoom = elem.style.zoom;
            }
        },

        ensureSelectElementIsRenderedCorrectly: function(selectElement) {
            // Workaround for IE9 rendering bug - it doesn't reliably display all the text in dynamically-added select boxes unless you force it to re-render by updating the width.
            // (See https://github.com/SteveSanderson/knockout/issues/312, http://stackoverflow.com/questions/5908494/select-only-shows-first-char-of-selected-option)
            // Also fixes IE7 and IE8 bug that causes selects to be zero width if enclosed by 'if' or 'with'. (See issue #839)
            if (ieVersion) {
                var originalWidth = selectElement.style.width;
                selectElement.style.width = 0;
                selectElement.style.width = originalWidth;
            }
        },

        range: function (min, max) {
            min = ko.utils.unwrapObservable(min);
            max = ko.utils.unwrapObservable(max);
            var result = [];
            for (var i = min; i <= max; i++)
                result.push(i);
            return result;
        },

        makeArray: function(arrayLikeObject) {
            var result = [];
            for (var i = 0, j = arrayLikeObject.length; i < j; i++) {
                result.push(arrayLikeObject[i]);
            };
            return result;
        },

        isIe6 : isIe6,
        isIe7 : isIe7,
        ieVersion : ieVersion,

        getFormFields: function(form, fieldName) {
            var fields = ko.utils.makeArray(form.getElementsByTagName("input")).concat(ko.utils.makeArray(form.getElementsByTagName("textarea")));
            var isMatchingField = (typeof fieldName == 'string')
                ? function(field) { return field.name === fieldName }
                : function(field) { return fieldName.test(field.name) }; // Treat fieldName as regex or object containing predicate
            var matches = [];
            for (var i = fields.length - 1; i >= 0; i--) {
                if (isMatchingField(fields[i]))
                    matches.push(fields[i]);
            };
            return matches;
        },

        parseJson: function (jsonString) {
            if (typeof jsonString == "string") {
                jsonString = ko.utils.stringTrim(jsonString);
                if (jsonString) {
                    if (JSON && JSON.parse) // Use native parsing where available
                        return JSON.parse(jsonString);
                    return (new Function("return " + jsonString))(); // Fallback on less safe parsing for older browsers
                }
            }
            return null;
        },

        stringifyJson: function (data, replacer, space) {   // replacer and space are optional
            if (!JSON || !JSON.stringify)
                throw new Error("Cannot find JSON.stringify(). Some browsers (e.g., IE < 8) don't support it natively, but you can overcome this by adding a script reference to json2.js, downloadable from http://www.json.org/json2.js");
            return JSON.stringify(ko.utils.unwrapObservable(data), replacer, space);
        },

        postJson: function (urlOrForm, data, options) {
            options = options || {};
            var params = options['params'] || {};
            var includeFields = options['includeFields'] || this.fieldsIncludedWithJsonPost;
            var url = urlOrForm;

            // If we were given a form, use its 'action' URL and pick out any requested field values
            if((typeof urlOrForm == 'object') && (ko.utils.tagNameLower(urlOrForm) === "form")) {
                var originalForm = urlOrForm;
                url = originalForm.action;
                for (var i = includeFields.length - 1; i >= 0; i--) {
                    var fields = ko.utils.getFormFields(originalForm, includeFields[i]);
                    for (var j = fields.length - 1; j >= 0; j--)
                        params[fields[j].name] = fields[j].value;
                }
            }

            data = ko.utils.unwrapObservable(data);
            var form = document.createElement("form");
            form.style.display = "none";
            form.action = url;
            form.method = "post";
            for (var key in data) {
                // Since 'data' this is a model object, we include all properties including those inherited from its prototype
                var input = document.createElement("input");
                input.type = "hidden";
                input.name = key;
                input.value = ko.utils.stringifyJson(ko.utils.unwrapObservable(data[key]));
                form.appendChild(input);
            }
            objectForEach(params, function(key, value) {
                var input = document.createElement("input");
                input.type = "hidden";
                input.name = key;
                input.value = value;
                form.appendChild(input);
            });
            document.body.appendChild(form);
            options['submitter'] ? options['submitter'](form) : form.submit();
            setTimeout(function () { form.parentNode.removeChild(form); }, 0);
        }
    }
}());

ko.exportSymbol('utils', ko.utils);
ko.exportSymbol('utils.arrayForEach', ko.utils.arrayForEach);
ko.exportSymbol('utils.arrayFirst', ko.utils.arrayFirst);
ko.exportSymbol('utils.arrayFilter', ko.utils.arrayFilter);
ko.exportSymbol('utils.arrayGetDistinctValues', ko.utils.arrayGetDistinctValues);
ko.exportSymbol('utils.arrayIndexOf', ko.utils.arrayIndexOf);
ko.exportSymbol('utils.arrayMap', ko.utils.arrayMap);
ko.exportSymbol('utils.arrayPushAll', ko.utils.arrayPushAll);
ko.exportSymbol('utils.arrayRemoveItem', ko.utils.arrayRemoveItem);
ko.exportSymbol('utils.extend', ko.utils.extend);
ko.exportSymbol('utils.fieldsIncludedWithJsonPost', ko.utils.fieldsIncludedWithJsonPost);
ko.exportSymbol('utils.getFormFields', ko.utils.getFormFields);
ko.exportSymbol('utils.peekObservable', ko.utils.peekObservable);
ko.exportSymbol('utils.postJson', ko.utils.postJson);
ko.exportSymbol('utils.parseJson', ko.utils.parseJson);
ko.exportSymbol('utils.registerEventHandler', ko.utils.registerEventHandler);
ko.exportSymbol('utils.stringifyJson', ko.utils.stringifyJson);
ko.exportSymbol('utils.range', ko.utils.range);
ko.exportSymbol('utils.toggleDomNodeCssClass', ko.utils.toggleDomNodeCssClass);
ko.exportSymbol('utils.triggerEvent', ko.utils.triggerEvent);
ko.exportSymbol('utils.unwrapObservable', ko.utils.unwrapObservable);
ko.exportSymbol('utils.objectForEach', ko.utils.objectForEach);
ko.exportSymbol('utils.addOrRemoveItem', ko.utils.addOrRemoveItem);
ko.exportSymbol('unwrap', ko.utils.unwrapObservable); // Convenient shorthand, because this is used so commonly

if (!Function.prototype['bind']) {
    // Function.prototype.bind is a standard part of ECMAScript 5th Edition (December 2009, http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-262.pdf)
    // In case the browser doesn't implement it natively, provide a JavaScript implementation. This implementation is based on the one in prototype.js
    Function.prototype['bind'] = function (object) {
        var originalFunction = this, args = Array.prototype.slice.call(arguments), object = args.shift();
        return function () {
            return originalFunction.apply(object, args.concat(Array.prototype.slice.call(arguments)));
        };
    };
}
