((typeof define === "function" && define.amd && function (m) { define("samsam", m); }) ||
 (typeof module === "object" &&
      function (m) { module.exports = m(); }) || // Node
 function (m) { this.samsam = m(); } // Browser globals
)(function () {
    var o = Object.prototype;
    var div = typeof document !== "undefined" && document.createElement("div");

    function isNaN(value) {
        // Unlike global isNaN, this avoids type coercion
        // typeof check avoids IE host object issues, hat tip to
        // lodash
        var val = value; // JsLint thinks value !== value is "weird"
        return typeof value === "number" && value !== val;
    }

    function getClass(value) {
        // Returns the internal [[Class]] by calling Object.prototype.toString
        // with the provided value as this. Return value is a string, naming the
        // internal class, e.g. "Array"
        return o.toString.call(value).split(/[ \]]/)[1];
    }

    /**
     * @name samsam.isArguments
     * @param Object object
     *
     * Returns ``true`` if ``object`` is an ``arguments`` object,
     * ``false`` otherwise.
     */
    function isArguments(object) {
        if (getClass(object) === 'Arguments') { return true; }
        if (typeof object !== "object" || typeof object.length !== "number" ||
                getClass(object) === "Array") {
            return false;
        }
        if (typeof object.callee == "function") { return true; }
        try {
            object[object.length] = 6;
            delete object[object.length];
        } catch (e) {
            return true;
        }
        return false;
    }

    /**
     * @name samsam.isElement
     * @param Object object
     *
     * Returns ``true`` if ``object`` is a DOM element node. Unlike
     * Underscore.js/lodash, this function will return ``false`` if ``object``
     * is an *element-like* object, i.e. a regular object with a ``nodeType``
     * property that holds the value ``1``.
     */
    function isElement(object) {
        if (!object || object.nodeType !== 1 || !div) { return false; }
        try {
            object.appendChild(div);
            object.removeChild(div);
        } catch (e) {
            return false;
        }
        return true;
    }

    /**
     * @name samsam.keys
     * @param Object object
     *
     * Return an array of own property names.
     */
    function keys(object) {
        var ks = [], prop;
        for (prop in object) {
            if (o.hasOwnProperty.call(object, prop)) { ks.push(prop); }
        }
        return ks;
    }

    /**
     * @name samsam.isDate
     * @param Object value
     *
     * Returns true if the object is a ``Date``, or *date-like*. Duck typing
     * of date objects work by checking that the object has a ``getTime``
     * function whose return value equals the return value from the object's
     * ``valueOf``.
     */
    function isDate(value) {
        return typeof value.getTime == "function" &&
            value.getTime() == value.valueOf();
    }

    /**
     * @name samsam.isNegZero
     * @param Object value
     *
     * Returns ``true`` if ``value`` is ``-0``.
     */
    function isNegZero(value) {
        return value === 0 && 1 / value === -Infinity;
    }

    /**
     * @name samsam.equal
     * @param Object obj1
     * @param Object obj2
     *
     * Returns ``true`` if two objects are strictly equal. Compared to
     * ``===`` there are two exceptions:
     *
     *   - NaN is considered equal to NaN
     *   - -0 and +0 are not considered equal
     */
    function identical(obj1, obj2) {
        if (obj1 === obj2 || (isNaN(obj1) && isNaN(obj2))) {
            return obj1 !== 0 || isNegZero(obj1) === isNegZero(obj2);
        }
    }


    /**
     * @name samsam.deepEqual
     * @param Object obj1
     * @param Object obj2
     *
     * Deep equal comparison. Two values are "deep equal" if:
     *
     *   - They are equal, according to samsam.identical
     *   - They are both date objects representing the same time
     *   - They are both arrays containing elements that are all deepEqual
     *   - They are objects with the same set of properties, and each property
     *     in ``obj1`` is deepEqual to the corresponding property in ``obj2``
     *
     * Supports cyclic objects.
     */
    function deepEqualCyclic(obj1, obj2) {

        // used for cyclic comparison
        // contain already visited objects
        var objects1 = [],
            objects2 = [],
        // contain pathes (position in the object structure)
        // of the already visited objects
        // indexes same as in objects arrays
            paths1 = [],
            paths2 = [],
        // contains combinations of already compared objects
        // in the manner: { "$1['ref']$2['ref']": true }
            compared = {};

        /**
         * used to check, if the value of a property is an object
         * (cyclic logic is only needed for objects)
         * only needed for cyclic logic
         */
        function isObject(value) {

            if (typeof value === 'object' && value !== null &&
                    !(value instanceof Boolean) &&
                    !(value instanceof Date)    &&
                    !(value instanceof Number)  &&
                    !(value instanceof RegExp)  &&
                    !(value instanceof String)) {

                return true;
            }

            return false;
        }

        /**
         * returns the index of the given object in the
         * given objects array, -1 if not contained
         * only needed for cyclic logic
         */
        function getIndex(objects, obj) {

            var i;
            for (i = 0; i < objects.length; i++) {
                if (objects[i] === obj) {
                    return i;
                }
            }

            return -1;
        }

        // does the recursion for the deep equal check
        return (function deepEqual(obj1, obj2, path1, path2) {
            var type1 = typeof obj1;
            var type2 = typeof obj2;

            // == null also matches undefined
            if (obj1 === obj2 ||
                    isNaN(obj1) || isNaN(obj2) ||
                    obj1 == null || obj2 == null ||
                    type1 !== "object" || type2 !== "object") {

                return identical(obj1, obj2);
            }

            // Elements are only equal if identical(expected, actual)
            if (isElement(obj1) || isElement(obj2)) { return false; }

            var isDate1 = isDate(obj1), isDate2 = isDate(obj2);
            if (isDate1 || isDate2) {
                if (!isDate1 || !isDate2 || obj1.getTime() !== obj2.getTime()) {
                    return false;
                }
            }

            if (obj1 instanceof RegExp && obj2 instanceof RegExp) {
                if (obj1.toString() !== obj2.toString()) { return false; }
            }

            var class1 = getClass(obj1);
            var class2 = getClass(obj2);
            var keys1 = keys(obj1);
            var keys2 = keys(obj2);

            if (isArguments(obj1) || isArguments(obj2)) {
                if (obj1.length !== obj2.length) { return false; }
            } else {
                if (type1 !== type2 || class1 !== class2 ||
                        keys1.length !== keys2.length) {
                    return false;
                }
            }

            var key, i, l,
                // following vars are used for the cyclic logic
                value1, value2,
                isObject1, isObject2,
                index1, index2,
                newPath1, newPath2;

            for (i = 0, l = keys1.length; i < l; i++) {
                key = keys1[i];
                if (!o.hasOwnProperty.call(obj2, key)) {
                    return false;
                }

                // Start of the cyclic logic

                value1 = obj1[key];
                value2 = obj2[key];

                isObject1 = isObject(value1);
                isObject2 = isObject(value2);

                // determine, if the objects were already visited
                // (it's faster to check for isObject first, than to
                // get -1 from getIndex for non objects)
                index1 = isObject1 ? getIndex(objects1, value1) : -1;
                index2 = isObject2 ? getIndex(objects2, value2) : -1;

                // determine the new pathes of the objects
                // - for non cyclic objects the current path will be extended
                //   by current property name
                // - for cyclic objects the stored path is taken
                newPath1 = index1 !== -1
                    ? paths1[index1]
                    : path1 + '[' + JSON.stringify(key) + ']';
                newPath2 = index2 !== -1
                    ? paths2[index2]
                    : path2 + '[' + JSON.stringify(key) + ']';

                // stop recursion if current objects are already compared
                if (compared[newPath1 + newPath2]) {
                    return true;
                }

                // remember the current objects and their pathes
                if (index1 === -1 && isObject1) {
                    objects1.push(value1);
                    paths1.push(newPath1);
                }
                if (index2 === -1 && isObject2) {
                    objects2.push(value2);
                    paths2.push(newPath2);
                }

                // remember that the current objects are already compared
                if (isObject1 && isObject2) {
                    compared[newPath1 + newPath2] = true;
                }

                // End of cyclic logic

                // neither value1 nor value2 is a cycle
                // continue with next level
                if (!deepEqual(value1, value2, newPath1, newPath2)) {
                    return false;
                }
            }

            return true;

        }(obj1, obj2, '$1', '$2'));
    }

    var match;

    function arrayContains(array, subset) {
        if (subset.length === 0) { return true; }
        var i, l, j, k;
        for (i = 0, l = array.length; i < l; ++i) {
            if (match(array[i], subset[0])) {
                for (j = 0, k = subset.length; j < k; ++j) {
                    if (!match(array[i + j], subset[j])) { return false; }
                }
                return true;
            }
        }
        return false;
    }

    /**
     * @name samsam.match
     * @param Object object
     * @param Object matcher
     *
     * Compare arbitrary value ``object`` with matcher.
     */
    match = function match(object, matcher) {
        if (matcher && typeof matcher.test === "function") {
            return matcher.test(object);
        }

        if (typeof matcher === "function") {
            return matcher(object) === true;
        }

        if (typeof matcher === "string") {
            matcher = matcher.toLowerCase();
            var notNull = typeof object === "string" || !!object;
            return notNull &&
                (String(object)).toLowerCase().indexOf(matcher) >= 0;
        }

        if (typeof matcher === "number") {
            return matcher === object;
        }

        if (typeof matcher === "boolean") {
            return matcher === object;
        }

        if (getClass(object) === "Array" && getClass(matcher) === "Array") {
            return arrayContains(object, matcher);
        }

        if (matcher && typeof matcher === "object") {
            var prop;
            for (prop in matcher) {
                var value = object[prop];
                if (typeof value === "undefined" &&
                        typeof object.getAttribute === "function") {
                    value = object.getAttribute(prop);
                }
                if (typeof value === "undefined" || !match(value, matcher[prop])) {
                    return false;
                }
            }
            return true;
        }

        throw new Error("Matcher was not a string, a number, a " +
                        "function, a boolean or an object");
    };

    return {
        isArguments: isArguments,
        isElement: isElement,
        isDate: isDate,
        isNegZero: isNegZero,
        identical: identical,
        deepEqual: deepEqualCyclic,
        match: match,
        keys: keys
    };
});
