/**
* The `Matter.Common` module contains utility functions that are common to all modules.
*
* @class Common
*/

var Common = {};

module.exports = Common;

(function() {

    Common._nextId = 0;
    Common._seed = 0;
    Common._nowStartTime = +(new Date());

    /**
     * Extends the object in the first argument using the object in the second argument.
     * @method extend
     * @param {} obj
     * @param {boolean} deep
     * @return {} obj extended
     */
    Common.extend = function(obj, deep) {
        var argsStart,
            args,
            deepClone;

        if (typeof deep === 'boolean') {
            argsStart = 2;
            deepClone = deep;
        } else {
            argsStart = 1;
            deepClone = true;
        }

        for (var i = argsStart; i < arguments.length; i++) {
            var source = arguments[i];

            if (source) {
                for (var prop in source) {
                    if (deepClone && source[prop] && source[prop].constructor === Object) {
                        if (!obj[prop] || obj[prop].constructor === Object) {
                            obj[prop] = obj[prop] || {};
                            Common.extend(obj[prop], deepClone, source[prop]);
                        } else {
                            obj[prop] = source[prop];
                        }
                    } else {
                        obj[prop] = source[prop];
                    }
                }
            }
        }
        
        return obj;
    };

    /**
     * Creates a new clone of the object, if deep is true references will also be cloned.
     * @method clone
     * @param {} obj
     * @param {bool} deep
     * @return {} obj cloned
     */
    Common.clone = function(obj, deep) {
        return Common.extend({}, deep, obj);
    };

    /**
     * Returns the list of keys for the given object.
     * @method keys
     * @param {} obj
     * @return {string[]} keys
     */
    Common.keys = function(obj) {
        if (Object.keys)
            return Object.keys(obj);

        // avoid hasOwnProperty for performance
        var keys = [];
        for (var key in obj)
            keys.push(key);
        return keys;
    };

    /**
     * Returns the list of values for the given object.
     * @method values
     * @param {} obj
     * @return {array} Array of the objects property values
     */
    Common.values = function(obj) {
        var values = [];
        
        if (Object.keys) {
            var keys = Object.keys(obj);
            for (var i = 0; i < keys.length; i++) {
                values.push(obj[keys[i]]);
            }
            return values;
        }
        
        // avoid hasOwnProperty for performance
        for (var key in obj)
            values.push(obj[key]);
        return values;
    };

    /**
     * Gets a value from `base` relative to the `path` string.
     * @method get
     * @param {} obj The base object
     * @param {string} path The path relative to `base`, e.g. 'Foo.Bar.baz'
     * @param {number} [begin] Path slice begin
     * @param {number} [end] Path slice end
     * @return {} The object at the given path
     */
    Common.get = function(obj, path, begin, end) {
        path = path.split('.').slice(begin, end);

        for (var i = 0; i < path.length; i += 1) {
            obj = obj[path[i]];
        }

        return obj;
    };

    /**
     * Sets a value on `base` relative to the given `path` string.
     * @method set
     * @param {} obj The base object
     * @param {string} path The path relative to `base`, e.g. 'Foo.Bar.baz'
     * @param {} val The value to set
     * @param {number} [begin] Path slice begin
     * @param {number} [end] Path slice end
     * @return {} Pass through `val` for chaining
     */
    Common.set = function(obj, path, val, begin, end) {
        var parts = path.split('.').slice(begin, end);
        Common.get(obj, path, 0, -1)[parts[parts.length - 1]] = val;
        return val;
    };

    /**
     * Shuffles the given array in-place.
     * The function uses a seeded random generator.
     * @method shuffle
     * @param {array} array
     * @return {array} array shuffled randomly
     */
    Common.shuffle = function(array) {
        for (var i = array.length - 1; i > 0; i--) {
            var j = Math.floor(Common.random() * (i + 1));
            var temp = array[i];
            array[i] = array[j];
            array[j] = temp;
        }
        return array;
    };

    /**
     * Randomly chooses a value from a list with equal probability.
     * The function uses a seeded random generator.
     * @method choose
     * @param {array} choices
     * @return {object} A random choice object from the array
     */
    Common.choose = function(choices) {
        return choices[Math.floor(Common.random() * choices.length)];
    };

    /**
     * Returns true if the object is a HTMLElement, otherwise false.
     * @method isElement
     * @param {object} obj
     * @return {boolean} True if the object is a HTMLElement, otherwise false
     */
    Common.isElement = function(obj) {
        return obj instanceof HTMLElement;
    };

    /**
     * Returns true if the object is an array.
     * @method isArray
     * @param {object} obj
     * @return {boolean} True if the object is an array, otherwise false
     */
    Common.isArray = function(obj) {
        return Object.prototype.toString.call(obj) === '[object Array]';
    };

    /**
     * Returns true if the object is a function.
     * @method isFunction
     * @param {object} obj
     * @return {boolean} True if the object is a function, otherwise false
     */
    Common.isFunction = function(obj) {
        return typeof obj === "function";
    };

    /**
     * Returns true if the object is a plain object.
     * @method isPlainObject
     * @param {object} obj
     * @return {boolean} True if the object is a plain object, otherwise false
     */
    Common.isPlainObject = function(obj) {
        return typeof obj === 'object' && obj.constructor === Object;
    };

    /**
     * Returns true if the object is a string.
     * @method isString
     * @param {object} obj
     * @return {boolean} True if the object is a string, otherwise false
     */
    Common.isString = function(obj) {
        return Object.prototype.toString.call(obj) === '[object String]';
    };
    
    /**
     * Returns the given value clamped between a minimum and maximum value.
     * @method clamp
     * @param {number} value
     * @param {number} min
     * @param {number} max
     * @return {number} The value clamped between min and max inclusive
     */
    Common.clamp = function(value, min, max) {
        if (value < min)
            return min;
        if (value > max)
            return max;
        return value;
    };
    
    /**
     * Returns the sign of the given value.
     * @method sign
     * @param {number} value
     * @return {number} -1 if negative, +1 if 0 or positive
     */
    Common.sign = function(value) {
        return value < 0 ? -1 : 1;
    };
    
    /**
     * Returns the current timestamp since the time origin (e.g. from page load).
     * The result will be high-resolution including decimal places if available.
     * @method now
     * @return {number} the current timestamp
     */
    Common.now = function() {
        if (window.performance) {
            if (window.performance.now) {
                return window.performance.now();
            } else if (window.performance.webkitNow) {
                return window.performance.webkitNow();
            }
        }

        return (new Date()) - Common._nowStartTime;
    };
    
    /**
     * Returns a random value between a minimum and a maximum value inclusive.
     * The function uses a seeded random generator.
     * @method random
     * @param {number} min
     * @param {number} max
     * @return {number} A random number between min and max inclusive
     */
    Common.random = function(min, max) {
        min = (typeof min !== "undefined") ? min : 0;
        max = (typeof max !== "undefined") ? max : 1;
        return min + _seededRandom() * (max - min);
    };

    var _seededRandom = function() {
        // https://en.wikipedia.org/wiki/Linear_congruential_generator
        Common._seed = (Common._seed * 9301 + 49297) % 233280;
        return Common._seed / 233280;
    };

    /**
     * Converts a CSS hex colour string into an integer.
     * @method colorToNumber
     * @param {string} colorString
     * @return {number} An integer representing the CSS hex string
     */
    Common.colorToNumber = function(colorString) {
        colorString = colorString.replace('#','');

        if (colorString.length == 3) {
            colorString = colorString.charAt(0) + colorString.charAt(0)
                        + colorString.charAt(1) + colorString.charAt(1)
                        + colorString.charAt(2) + colorString.charAt(2);
        }

        return parseInt(colorString, 16);
    };

    /**
     * The console logging level to use, where each level includes all levels above and excludes the levels below.
     * The default level is 'debug' which shows all console messages.  
     *
     * Possible level values are:
     * - 0 = None
     * - 1 = Debug
     * - 2 = Info
     * - 3 = Warn
     * - 4 = Error
     * @property Common.logLevel
     * @type {Number}
     * @default 1
     */
    Common.logLevel = 1;

    /**
     * Shows a `console.log` message only if the current `Common.logLevel` allows it.
     * The message will be prefixed with 'matter-js' to make it easily identifiable.
     * @method log
     * @param ...objs {} The objects to log.
     */
    Common.log = function() {
        if (console && Common.logLevel > 0 && Common.logLevel <= 3) {
            console.log.apply(console, ['matter-js:'].concat(Array.prototype.slice.call(arguments)));
        }
    };

    /**
     * Shows a `console.info` message only if the current `Common.logLevel` allows it.
     * The message will be prefixed with 'matter-js' to make it easily identifiable.
     * @method info
     * @param ...objs {} The objects to log.
     */
    Common.info = function() {
        if (console && Common.logLevel > 0 && Common.logLevel <= 2) {
            console.info.apply(console, ['matter-js:'].concat(Array.prototype.slice.call(arguments)));
        }
    };

    /**
     * Shows a `console.warn` message only if the current `Common.logLevel` allows it.
     * The message will be prefixed with 'matter-js' to make it easily identifiable.
     * @method warn
     * @param ...objs {} The objects to log.
     */
    Common.warn = function() {
        if (console && Common.logLevel > 0 && Common.logLevel <= 3) {
            console.warn.apply(console, ['matter-js:'].concat(Array.prototype.slice.call(arguments)));
        }
    };

    /**
     * Returns the next unique sequential ID.
     * @method nextId
     * @return {Number} Unique sequential ID
     */
    Common.nextId = function() {
        return Common._nextId++;
    };

    /**
     * A cross browser compatible indexOf implementation.
     * @method indexOf
     * @param {array} haystack
     * @param {object} needle
     * @return {number} The position of needle in haystack, otherwise -1.
    Common.indexOf = function(haystack, needle) {
        if (haystack.indexOf)
            return haystack.indexOf(needle);

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

        return -1;
    };
     */

    /**
     * A cross browser compatible array map implementation.
     * @method map
     * @param {array} list
     * @param {function} func
     * @return {array} Values from list transformed by func.
     */
    Common.map = function(list, func) {
        if (list.map) {
            return list.map(func);
        }

        var mapped = [];

        for (var i = 0; i < list.length; i += 1) {
            mapped.push(func(list[i]));
        }

        return mapped;
    };

    /**
     * Takes a directed graph and returns the partially ordered set of vertices in topological order.
     * Circular dependencies are allowed.
     * @method topologicalSort
     * @param {object} graph
     * @return {array} Partially ordered set of vertices in topological order.
     */
    Common.topologicalSort = function(graph) {
        // https://github.com/mgechev/javascript-algorithms
        // Copyright (c) Minko Gechev (MIT license)
        // Modifications: tidy formatting and naming
        var result = [],
            visited = [],
            temp = [];

        for (var node in graph) {
            if (!visited[node] && !temp[node]) {
                _topologicalSort(node, visited, temp, graph, result);
            }
        }

        return result;
    };

    var _topologicalSort = function(node, visited, temp, graph, result) {
        var neighbors = graph[node] || [];
        temp[node] = true;

        for (var i = 0; i < neighbors.length; i += 1) {
            var neighbor = neighbors[i];

            if (temp[neighbor]) {
                // skip circular dependencies
                continue;
            }

            if (!visited[neighbor]) {
                _topologicalSort(neighbor, visited, temp, graph, result);
            }
        }

        temp[node] = false;
        visited[node] = true;

        result.push(node);
    };

    /**
     * Takes _n_ functions as arguments and returns a new function that calls them in order.
     * The arguments applied when calling the new function will also be applied to every function passed.
     * The value of `this` refers to the last value returned in the chain that was not `undefined`.
     * Therefore if a passed function does not return a value, the previously returned value is maintained.
     * After all passed functions have been called the new function returns the last returned value (if any).
     * If any of the passed functions are a chain, then the chain will be flattened.
     * @method chain
     * @param ...funcs {function} The functions to chain.
     * @return {function} A new function that calls the passed functions in order.
     */
    Common.chain = function() {
        var funcs = [];

        for (var i = 0; i < arguments.length; i += 1) {
            var func = arguments[i];

            if (func._chained) {
                // flatten already chained functions
                funcs.push.apply(funcs, func._chained);
            } else {
                funcs.push(func);
            }
        }

        var chain = function() {
            // https://github.com/GoogleChrome/devtools-docs/issues/53#issuecomment-51941358
            var lastResult,
                args = new Array(arguments.length);

            for (var i = 0, l = arguments.length; i < l; i++) {
                args[i] = arguments[i];
            }

            for (i = 0; i < funcs.length; i += 1) {
                var result = funcs[i].apply(lastResult, args);

                if (typeof result !== 'undefined') {
                    lastResult = result;
                }
            }

            return lastResult;
        };

        chain._chained = funcs;

        return chain;
    };

    /**
     * Chains a function to excute before the original function on the given `path` relative to `base`.
     * See also docs for `Common.chain`.
     * @method chainPathBefore
     * @param {} base The base object
     * @param {string} path The path relative to `base`
     * @param {function} func The function to chain before the original
     * @return {function} The chained function that replaced the original
     */
    Common.chainPathBefore = function(base, path, func) {
        return Common.set(base, path, Common.chain(
            func,
            Common.get(base, path)
        ));
    };

    /**
     * Chains a function to excute after the original function on the given `path` relative to `base`.
     * See also docs for `Common.chain`.
     * @method chainPathAfter
     * @param {} base The base object
     * @param {string} path The path relative to `base`
     * @param {function} func The function to chain after the original
     * @return {function} The chained function that replaced the original
     */
    Common.chainPathAfter = function(base, path, func) {
        return Common.set(base, path, Common.chain(
            Common.get(base, path),
            func
        ));
    };

})();
