/**
 *@namespace
 **/
var Util = {
    /**Return the bounds for a given set of points, useful as every class uses a
    *  similar implementation.
    *@param {Array<Point>} points  - the points collected around the outside of
    *  the shape.
    *@return {Array<Number>} - returns [minX, minY, maxX, maxY] - bounds, where
    *  all points are in the bounds.
    *@author Maxim Georgievskiy <max.kharkov.ua@gmail.com>
    **/
    getBounds: function (points) {
        if (!points.length)
            return null;
        var minX = points[0].x;
        var maxX = minX;
        var minY = points[0].y;
        var maxY = minY;
        for (var i = 1; i < points.length; i++) {
            minX = Math.min(minX, points[i].x);
            minY = Math.min(minY, points[i].y);
            maxX = Math.max(maxX, points[i].x);
            maxY = Math.max(maxY, points[i].y);
        }
        return [minX, minY, maxX, maxY];
    },


    /**
    * Converts an RGB color value to HSL. Conversion formula
    * adapted from http://en.wikipedia.org/wiki/HSL_color_space.
    * Assumes r, g, and b are contained in the set [0, 255] and
    * returns h, s, and l in the set [0, 1].
    *
    * @param {Number} r - The red color value
    * @param {Number} g - The green color value
    * @param {Number} b - The blue color value
    * @return {Array<Number>} - the HSL representation
    *
    * Taken from: http://stackoverflow.com/a/9493060
    */
    rgbToHsl: function (r, g, b) {
        r /= 255;
        g /= 255;
        b /= 255;

        var max = Math.max(r, g, b);
        var min = Math.min(r, g, b);
        var h, s, l = (max + min) / 2;

        if (max === min) {
            h = s = 0; // achromatic
        } else {
            var d = max - min;
            s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
            switch (max) {
                case r: h = (g - b) / d + (g < b ? 6 : 0); break;
                case g: h = (b - r) / d + 2; break;
                case b: h = (r - g) / d + 4; break;
            }
            h /= 6;
        }

        return [h, s, l];
    },


    /**
    * Converts hex representation of RGB color (#33ffee) to object [r, g, b],
    * where r, g, b values are contained in the set [0, 255].
    *
    * @param {String} hex - Hex representation of rgb color
    * @return {Object} - in a form of
    *  {
    *  r - red color value,
    *  g - green color value,
    *  b - blue color value
    *  }
    *
    * Taken from: http://stackoverflow.com/a/5624139
    */
    hexToRgb: function (hex) {
        // Expand shorthand form (e.g. "03F") to full form (e.g. "0033FF")
        var shorthandRegex = /^#?([a-f\d])([a-f\d])([a-f\d])$/i;
        hex = hex.replace(shorthandRegex, function (m, r, g, b) {
            return r + r + g + g + b + b;
        });

        var result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
        return result ? {
            r: parseInt(result[1], 16),
            g: parseInt(result[2], 16),
            b: parseInt(result[3], 16)
        } : null;
    },


    /**
    * Converts hsl representation array [h,s,l] contained in the set [0,1]
    * to css-applicable string, like '(14%,80%,75%)'
    *
    * @param {Array<Number>} hsl - Hsl representation array [h,s,l]
    * @return {String} - css-applicable string of hsl
    * @author Arty
    */
    hslToString: function (hsl) {
        return 'hsl(' + hsl[0] * 360 + ', ' + hsl[1] * 100 + '%, ' + hsl[2] * 100 + '%)';
    },


    /***/
    getUnionBounds: function (shapes) {
        //tODo
    },

    /**
    * See if some bounds are inside other bounds.
    * Bounds are in form [minX, minY, maxX, maxY]
    * @param {Array<Number>} innerBounds the inner bounds
    * @param {Array<Number>} outerBounds the outer bounds
    * @return {Boolean} true if innerBounds are inside outerBounds
    * */
    areBoundsInBounds: function (innerBounds, outerBounds) {
        return (outerBounds[0] <= innerBounds[0] && (innerBounds[0] <= outerBounds[2]))
        && (outerBounds[1] <= innerBounds[1] && (innerBounds[1] <= outerBounds[3]))
        && (outerBounds[0] <= innerBounds[2] && (innerBounds[2] <= outerBounds[2]))
        && (outerBounds[1] <= innerBounds[3] && (innerBounds[3] <= outerBounds[3]));
    },


    /**Returns a Polygon out of an Array of points 
    *@param {Array} data -  [minX, minY, maxX, maxY]
    **/
    boundsToPolygon: function (data) {
        var poly = new Polygon();
        poly.addPoint(new Point(data[0], data[1]));
        poly.addPoint(new Point(data[2], data[1]));
        poly.addPoint(new Point(data[2], data[3]));
        poly.addPoint(new Point(data[0], data[3]));

        return poly;
    },

    /**Updates first letter of a string
    *@param {String} string -  the actual string
    *@return {String} the string with first letter capitalized
    *@see <a href="http://STACKoverflow.com/questions/1026069/capitalize-first-letter-of-string-in-javascript">http://STACKoverflow.com/questions/1026069/capitalize-first-letter-of-string-in-javascript</a>
    **/
    capitaliseFirstLetter: function (string) {
        return string.charAt(0).toUpperCase() + string.slice(1);
    },


    /**Increase the area of a rectangle by size in any direction
    *@param {Array} rectangle - the [topX, topY, bottomX, bottomY]
    *@param {Number} size - the size to increase the rectangle in any direction
    *@return {Array} - the new reactangle increased :)
    *@author Alex Gheorghiu <alex@scriptoid.com>
    **/
    feather: function (rectangle, size) {
        return [rectangle[0] + size, rectangle[1] + size, rectangle[2] + size, rectangle[3] + size];
    },


    /**Returns the distance between 2 points
    *@param {Point} p1 - first {Point}
    *@param {Point} p2 - second {Point}
    *@return {Number} - the distance between those 2 points. It is always positive.
    *@author Alex Gheorghiu <alex@scriptoid.com>
    **/
    distance: function (p1, p2) {
        return Math.sqrt(Math.pow(p1.x - p2.x, 2) + Math.pow(p1.y - p2.y, 2));
    },


    /**Find the location of a point located on segment [p1,p2] at a certain distance from p1
    *@param {Point} p1 - first {Point}
    *@param {Point} p2 - second {Point}
    *@param {Number} distance_from_p1 - the distance from P1 toward P2 where searched point should be
    *@return {Point} - the distance between those 2 points. It is always positive.
    *@author Alex Gheorghiu <alex@scriptoid.com>
    **/
    point_on_segment: function (p1, p2, distance_from_p1) {
        var d = Util.distance(p1, p2);
        var Xm = p1.x + distance_from_p1 / d * (p2.x - p1.x);
        var Ym = p1.y + distance_from_p1 / d * (p2.y - p1.y);

        return new Point(Xm, Ym);
    },


    /*
    * Creates a set of dashes/dots/etc along a set of points
    * points = [p1, p2,p3]
    * pt = [10,2,2 4,7] /*the pattern 10 dotts, 2 spaces, 2 dots, 7 spaces, etc
    * 
    * @param {Context} ctx - Canvas' 2D context
    * @param {Array} points - an {Array} of {Point}s
    * @param {Array} pattern - an {Array} of {Integer}s that define the pattern. 
    * Pattern is increased/decreased to accomodate the lineWidth
    * Ex: Scale whole pattern by line width (ex: if lineWidth = 2 then all variables in patter got multiplied by 2)
    * 
    * @author Alex Gheorghiu <alex@scriptoid.com>
    */
    decorate: function (ctx, points, pattern) {

        /*Algorithm:
        *We begin with first segment and start applying the pattern as many time
        *as we can on it.  If we complete the segment then we move to next segment
        *but we have to keep the rest of the pattern (that were not painted yet) and
        *apply on the next segment (or segments). And so on.
        **/

        function info(msg) {
            //			console.info(msg);
        }

        function group(name) {
            //			console.group(name);
        }

        function groupEnd() {
            //			console.groupEnd();
        }

        var t0 = (new Date).getMilliseconds();

        /**Scale the pattern up/down to fit the lineWidth*/
        var pt = [];

        for (var i = 0; i < pattern.length; i++) {
            pt[i] = pattern[i] * ctx.lineWidth;
        }


        /**
        *@param {Point} p - the {Point}
        **/
        function lineTo(p) {
            ctx.lineTo(p.x, p.y);
        }

        /**
        *@param {Point} p - the {Point}
        **/
        function moveTo(p) {
            ctx.moveTo(p.x, p.y);
        }

        var current_point = points[0];
        //path = 0
        i = 0; //current point/segment
        var pt_i = 0; //index position in pattern
        var pt_left = pt[0]; // spaces or dotts left to paint from current index position in pattern

        info("current_point" + current_point);

        //position at the begining
        moveTo(current_point);



        while (i < points.length - 1) {
            //inside [Pi, Pi+1] segment
            var segment_path = 0; //how much of current segment was painted

            group("Paint segment " + i);
            info("i = " + i + " current_point = " + current_point + " pt_i = " + pt_i + " pt_left = " + pt_left + " segment_path = " + segment_path);

            if (pt_left < 0) {
                break;
            }


            //paint previous/left part of pattern
            if (pt_left > 0) {
                group("Paint rest of pattern");
                info("Pattern left,  pt_left : " + pt_left + " pt_i : " + pt_i);

                //are we about to cross to another segment?
                if (pt_left > Util.distance(current_point, points[i + 1])) { //we exceed current segment
                    info("We exceed current segment");

                    //paint what is left and move to next segment
                    if (pt_i % 2 == 0) { //dots
                        lineTo(points[i + 1])
                    }
                    else { //spaces
                        moveTo(points[i + 1])
                    }

                    //store what was left unpainted
                    segment_path += Util.distance(current_point, points[i + 1]);
                    pt_left = pt_left - Util.distance(current_point, points[i + 1]);
                    current_point = points[i + 1];
                    i++; //move to next segment
                    groupEnd(); //end inner group
                    groupEnd(); //end outer group
                    continue;
                }
                else { //still inside segment
                    info("Painting from rest path pt_i = " + pt_i + " current_segment = " + segment_path);
                    var newP = Util.point_on_segment(current_point, points[i + 1], pt_left); //translate on current_point with pt_left from Pi to Pi+1
                    info("\t newP = " + newP);
                    if (pt_i % 2 == 0) { //dots
                        lineTo(newP)
                    }
                    else { //spaces
                        moveTo(newP)
                    }

                    segment_path += Util.distance(current_point, newP);
                    current_point = newP;
                    pt_left = 0;
                    pt_i = (pt_i + 1) % pt.length;
                }
                groupEnd();
            }



            /*We should have:
            pt_i >= 0
            pt_left = 0;
            */
            group('No rest left, normal paint');
            info("We should have (pt_i >= 0) and (pt_left = 0) AND WE HAVE " + "pt_i = " + pt_i + " pt_left = " + pt_left);


            //nothing left from previous segment
            while (segment_path < Util.distance(points[i], points[i + 1])) {
                info("Distance between " + i + " and " + (i + 1) + " = " + Util.distance(points[i], points[i + 1]));


                info("...painting path pt_i = " + pt_i + " dot/space length = " + pt[pt_i] + " current_segment = " + segment_path);
                if (segment_path + pt[pt_i] <= Util.distance(points[i], points[i + 1])) { //still inside segment
                    group("Still inside segment");
                    var newP = Util.point_on_segment(current_point, points[i + 1], pt[pt_i]); //translate on current segment with pt[pt_i] from Pi to Pi+1
                    info("\t newP = " + newP);
                    if (pt_i % 2 == 0) {
                        lineTo(newP);
                    }
                    else {
                        moveTo(newP);
                    }
                    pt_left = 0;
                    segment_path += pt[pt_i];
                    current_point = newP;
                    pt_i = (pt_i + 1) % pt.length;
                    groupEnd();
                }
                else { //segment exceeded
                    group("Exceed segment");
                    if (pt_i % 2 == 0) {
                        lineTo(points[i + 1]);
                    }
                    else {
                        moveTo(points[i + 1]);
                    }
                    pt_left = pt[pt_i] - Util.distance(current_point, points[i + 1]);
                    segment_path += Util.distance(current_point, points[i + 1]);
                    current_point = points[i + 1];
                    info("...pt_left = " + pt_left + " current_segment = " + segment_path + " current_point = " + current_point);
                    //move to next segment							
                    groupEnd(); //end inner group							
                    break;
                }


            }
            groupEnd();


            ++i;

            groupEnd();
        }

        var t1 = (new Date).getMilliseconds();
        console.info("Took " + (t1 - t0) + " ms");
    },


    /**Trim a number to a fixed number or decimals
    *@param {Numeric} number - the number to be trimmed
    *@param {Integer} decimals - the number of decimals to keep
    *@author Zack
    **/
    round: function (number, decimals) {
        return Math.round(number * Math.pow(10, decimals)) / Math.pow(10, decimals);
    },


    /**Returns the lenght between 2 points
    *@param {Point} startPoint - one point
    *@param {Point} endPoint - the other point
    *@return {Number} - the distance
    **/
    getLength: function (startPoint, endPoint) {
        return Math.sqrt(Math.pow(startPoint.x - endPoint.x, 2) + Math.pow(startPoint.y - endPoint.y, 2));
    },


    /**Returns the middle point between 2 points
    *@param {Point} startPoint - one point
    *@param {Point} endPoint - the other point
    *@return {Point} the middle point
    **/
    getMiddle: function (startPoint, endPoint) {
        return new Point((startPoint.x + endPoint.x) / 2, (startPoint.y + endPoint.y) / 2);
    },


    /**Returns the length of a Polyline that would be created with a set of points
    *@param {Array} v - an {Array} of {Points}
    *@return {Number} - a positive number equal with total length*/
    getPolylineLength: function (v) {
        var l = 0;
        for (var i = 0; i < v.length - 1; i++) {
            l += Util.getLength(v[i], v[i + 1]);
        }

        return l;
    },


    /**
    *Tests if a a line defined by 2 points intersects a rectangle
    *@param {Point} startPoint - the starting point
    *@param {Point} endPoint - the ending point
    *@param {Array} bounds - the bounds of the rectangle defined by (x1, y1, x2, y2)
    *@return true - if line intersects the rectangle, false - if not
    *@author Alex Gheorghiu <alex@scriptoid.com>
    **/
    lineIntersectsRectangle: function (startPoint, endPoint, bounds) {
        //create the initial line/segment
        var l = new Line(startPoint, endPoint);

        //get the 4 lines/segments represented by the bounds
        var lines = [];
        lines.push(new Line(new Point(bounds[0], bounds[1]), new Point(bounds[2], bounds[1])));
        lines.push(new Line(new Point(bounds[2], bounds[1]), new Point(bounds[2], bounds[3])));
        lines.push(new Line(new Point(bounds[2], bounds[3]), new Point(bounds[0], bounds[3])));
        lines.push(new Line(new Point(bounds[0], bounds[3]), new Point(bounds[0], bounds[1])));

        //check if our line intersects any of the 4 lines
        for (var i = 0; i < lines.length; i++) {
            if (this.lineIntersectsLine(l, lines[i])) {
                return true;
            }
        }

        return false;
    },

    /**
    *Tests if a a polyline defined by a set of points intersects a rectangle
    *@param {Array} points - and {Array} of {Point}s
    *@param {Array} bounds - the bounds of the rectangle defined by (x1, y1, x2, y2)
    *@param {Boolean} closedPolyline - incase polyline is closed figure then true, else false
    * 
    *@return true - if line intersects the rectangle, false - if not
    *@author Alex Gheorghiu <alex@scriptoid.com>
    *@author Janis Sejans <janis.sejans@towntech.lv>
    **/
    polylineIntersectsRectangle: function (points, bounds, closedPolyline) {


        //get the 4 lines/segments represented by the bounds
        var lines = [];
        lines.push(new Line(new Point(bounds[0], bounds[1]), new Point(bounds[2], bounds[1])));
        lines.push(new Line(new Point(bounds[2], bounds[1]), new Point(bounds[2], bounds[3])));
        lines.push(new Line(new Point(bounds[2], bounds[3]), new Point(bounds[0], bounds[3])));
        lines.push(new Line(new Point(bounds[0], bounds[3]), new Point(bounds[0], bounds[1])));

        for (var k = 0; k < points.length - 1; k++) {
            //create a line out of each 2 consecutive points            
            var tempLine = new Line(points[k], points[k + 1]);

            //see if that line intersect any of the line on bounds border
            for (var i = 0; i < lines.length; i++) {
                if (this.lineIntersectsLine(tempLine, lines[i])) {
                    return true;
                }
            }
        }

        //check the closed figure - that is last point connected to the first
        if (closedPolyline) {
            //create a line out of each 2 consecutive points            
            var tempLine = new Line(points[points.length - 1], points[0]);

            //see if that line intersect any of the line on bounds border
            for (var i = 0; i < lines.length; i++) {
                if (this.lineIntersectsLine(tempLine, lines[i])) {
                    return true;
                }
            }
        }

        return false;
    },


    /**
    *Test to see if 2 {Line}s intersects. They are considered finite segments
    *and not the infinite lines from geometry
    *@param {Line} l1 - fist line/segment
    *@param {Line} l2 - last line/segment
    *@return {Boolean} true - if the lines intersect or false if not
    *@author Alex Gheorghiu <alex@scriptoid.com>
    *@author Maxim Georgievskiy <max.kharkov.ua@gmail.com>
    **/
    lineIntersectsLine: function (l1, l2) {
        // check for two vertical lines
        if (l1.startPoint.x == l1.endPoint.x && l2.startPoint.x == l2.endPoint.x) {
            return l1.startPoint.x == l2.startPoint.x ? // if 'infinite 'lines do coincide,
            // then check segment bounds for overlapping
			l1.contains(l2.startPoint.x, l2.startPoint.y) ||
                l1.contains(l2.endPoint.x, l2.endPoint.y) :
            // lines are paralel
			false;
        }
        // if one line is vertical, and another line is not vertical
        else if (l1.startPoint.x == l1.endPoint.x || l2.startPoint.x == l2.endPoint.x) {
            // let assume l2 is vertical, otherwise exchange them
            if (l1.startPoint.x == l1.endPoint.x) {
                var l = l1;
                l1 = l2;
                l2 = l;
            }
            // finding intersection of 'infinite' lines
            // equation of the first line is y = ax + b, second: x = c
            var a = (l1.endPoint.y - l1.startPoint.y) / (l1.endPoint.x - l1.startPoint.x);
            var b = l1.startPoint.y - a * l1.startPoint.x;
            var x0 = l2.startPoint.x;
            var y0 = a * x0 + b;
            return l1.contains(x0, y0) && l2.contains(x0, y0);
        }

        // check normal case - both lines are not vertical
        else {
            //line equation is : y = a*x + b, b = y - a * x
            var a1 = (l1.endPoint.y - l1.startPoint.y) / (l1.endPoint.x - l1.startPoint.x);
            var b1 = l1.startPoint.y - a1 * l1.startPoint.x;

            var a2 = (l2.endPoint.y - l2.startPoint.y) / (l2.endPoint.x - l2.startPoint.x);
            var b2 = l2.startPoint.y - a2 * l2.startPoint.x;

            if (a1 == a2) { //paralel lines
                return b1 == b2 ?
                // for coincide lines, check for segment bounds overlapping
				l1.contains(l2.startPoint.x, l2.startPoint.y) || l1.contains(l2.endPoint.x, l2.endPoint.y)
				:
                // not coincide paralel lines have no chance to intersect
				false;
            } else { //usual case - non paralel, the 'infinite' lines intersects...we only need to know if inside the segment

                /*
                * if one of the lines are vertical, then x0 is equal to their x,
                * otherwise:
                * y1 = a1 * x + b1
                * y2 = a2 * x + b2
                * => x0 = (b2 - b1) / (a1 - a2)
                * => y0 = a1 * x0 + b1
                **/
                x0 = (b2 - b1) / (a1 - a2);
                y0 = a1 * x0 + b1;
                return l1.contains(x0, y0) && l2.contains(x0, y0);
            }
        }
    },


    /**Tests if 3 points are coliniar (similar to geometry ...with infinite lines)
    *@param {Point} p1 - first point
    *@param {Point} p2 - second point
    *@param {Point} p3 - third point
    *@return {Boolean} - true if coliniar and false if not
    *@author Alex
    *@deprecated
    **/
    deprecated_collinearity: function (p1, p2, p3) {
        //Check if 2 points coincide. If they do we automatically have collinearity
        if (p1.x === p2.x && p1.y === p2.y) {
            return true;
        }

        if (p1.x === p3.x && p1.y === p3.y) {
            return true;
        }

        if (p2.x === p3.x && p2.y === p3.y) {
            return true;
        }

        // check for vertical line
        if (p1.x === p2.x) {
            return p3.x === p1.x;
        } else { // usual (not vertical) line can be represented as y = a * x + b
            var a = (p2.y - p1.y) / (p2.x - p1.x);
            var b = p1.y - a * p1.x;
            return p3.y === a * p3.x + b;
        }
    },


    /**Tests if 3 points are coliniar with matrix determinants.
    * If the determinat of matrix 
    * /         \
    * | x1 y1 1 |
    * | x2 y2 1 |
    * | x3 y3 1 |
    * \         /
    * is zero it means that the points are colinear
    *@param {Point} p1 - first point
    *@param {Point} p2 - second point
    *@param {Point} p3 - third point
    *@return {Boolean} - true if coliniar and false if not
    *@author Alex
    *@see http://en.wikipedia.org/wiki/Determinant
    *@see https://people.richland.edu/james/lecture/m116/matrices/applications.html
    **/
    collinearity: function (p1, p2, p3, precission) {
        var determinant = (p1.x * p2.y + p1.y * p3.x + p2.x * p3.y)
                - (p2.y * p3.x + p1.y * p2.x + p1.x * p3.y);

        if (precission) {
            return Math.abs(determinant) <= precission;
        }
        else {
            return determinant === 0;
        }


    },


    /** It will return the end point of a line on a given angle (clockwise).
    * @param {Point} startPoint - the start of the line
    * @param {Number} length - the length of the line
    * @param {Number} angle - the angle of the line in radians
    * @return {Point} - the endPoint of the line
    * @author Zack
    */
    getEndPoint: function (startPoint, length, angle) {
        var endPoint = startPoint.clone();
        endPoint.transform(Matrix.translationMatrix(-startPoint.x, -startPoint.y));
        endPoint.y -= length;
        endPoint.transform(Matrix.rotationMatrix(angle));
        endPoint.transform(Matrix.translationMatrix(startPoint.x, startPoint.y));
        return endPoint;
    },


    /** Will return the angle of rotation between 2 points, with 0 being north.
    * Actually the angle with N on a compass
    * @param {@link Point} centerPoint - the point that is to be considered the center of the shape
    * @param {@link Point} outsidePoint - the point that we need to find the rotation about the center.
    * @param {Number} round - amount to round to nearest angle (optional). Think of it as precision
    * @return {Number} - the angle in radians
    * @see /documentation/specs/getAngle.png
    * @author Alex Gheorghiu <alex@scriptoid.com>
    * */
    getAngle: function (centerPoint, outsidePoint, round) {
        centerPoint.x = Util.round(centerPoint.x, 5);
        centerPoint.y = Util.round(centerPoint.y, 5);
        outsidePoint.x = Util.round(outsidePoint.x, 5);
        outsidePoint.y = Util.round(outsidePoint.y, 5);
        var angle = Math.atan((outsidePoint.x - centerPoint.x) / (outsidePoint.y - centerPoint.y));
        angle = -angle;

        //endAngle+=90;
        if (outsidePoint.x >= centerPoint.x && outsidePoint.y >= centerPoint.y) {
            angle += Math.PI;
        }
        else if (outsidePoint.x <= centerPoint.x && outsidePoint.y >= centerPoint.y) {
            angle += Math.PI;
        }
        else if (outsidePoint.x <= centerPoint.x && outsidePoint.y <= centerPoint.y) {
            angle += Math.PI * 2;
        }
        while (angle >= Math.PI * 2) {
            angle -= Math.PI * 2;
        }
        if (isNaN(angle)) {//Nan
            angle = 0; //we are at center point;
        }
        if (round) {
            angle = Math.round(angle / round) * round
        }
        return angle;
    },


    /**
    *Computes the angle formed by 3 {Point}s
    *@param {@link Point} startPoint - the start point
    *@param {@link Point} centerPoint - the center/tid of the angle point
    *@param {@link Point} endPoint - the end/angle point
    *@param {Number} round - amount to round to nearest angle (optional)
    *@author Alex Gheorghiu <alex@scriptoid.com>
    */
    getAngle3Points: function (startPoint, centerPoint, endPoint, round) {
        var a1 = Util.getAngle(centerPoint, startPoint);
        var a2 = Util.getAngle(centerPoint, endPoint);

        var angle = a2 - a1;

        if (round) {
            angle = Math.round(angle / round) * round
        }

        return angle;
    },


    /**
    /* Tests whether a point is inside the area (excluding border) determined by a set of other points.
    * If the points is on the border of the area it will not be counted
    *
    * @param point {Point} the point we want to chek
    * @param points {Array<Point>} a set of points ordered clockwise.
    * @see  <a href="http://local.wasp.uwa.edu.au/~pbourke/geometry/insidepoly/">http://local.wasp.uwa.edu.au/~pbourke/geometry/insidepoly/</a> solution 1
    * */
    isPointInside: function (point, points) {
        if (points.length < 3) {
            return false;
        }
        var counter = 0;
        var p1 = points[0];

        //calulates horizontal intersects
        for (var i = 1; i <= points.length; i++) {
            var p2 = points[i % points.length];
            if (point.y > Math.min(p1.y, p2.y)) { //our point is between start(Y) and end(Y) points
                if (point.y <= Math.max(p1.y, p2.y)) {
                    if (point.x <= Math.max(p1.x, p2.x)) { //to the left of any point
                        if (p1.y != p2.y) { //no horizontal line
                            var xinters = (point.y - p1.y) * (p2.x - p1.x) / (p2.y - p1.y) + p1.x; //get slope of line and make it start from the same place as p1
                            if (p1.x == p2.x || point.x <= xinters) { //if vertical line or our x is before the end x of the actual line.
                                counter++; //we have an intersection
                            }
                        }
                    }
                }
            }
            p1 = p2;
        }

        if (counter % 2 == 0) {
            return false;
        }
        else {
            return true;
        }
    },


    /**
    /* Tests whether a point is inside the area (including border) determined by a set of other points.
    * If the points is on the border of the area it will be counted
    *
    * Algorithm: just get border (min/max) values for x and y
    * and then check if target point inside and on a borer or outside of points
    *
    * @param point {Point} the point we want to check
    * @param points {Array<Point>} a set of points ordered clockwise.
    * */
    isPointInsideOrOnBorder: function (point, points) {
        if (points.length < 3) {
            return false;
        }

        // set min & max values to coordinates of first point
        var minX = points[0].x;
        var maxX = points[0].x;
        var minY = points[0].y;
        var maxY = points[0].y;

        // go through points and get min and max x, y values
        for (var i = 1; i < points.length; i++) {
            var p = points[i];

            minX = Math.min(p.x, minX);
            maxX = Math.max(p.x, maxX);
            minY = Math.min(p.y, minY);
            maxY = Math.max(p.y, maxY);
        }

        // check if point is inside and on a border of points or outside
        if (point.x >= minX && point.x <= maxX && point.y >= minY && point.y <= maxY) {
            return true;
        } else {
            return false;
        }
    },


    /**
    * Calculates the number of times the vector from P0(x0,y0) to P1(x1,y1)
    * crosses the ray extending to the right from P(px,py).
    * @return {Number} 
    *  0 - if the point lies on the line or no intersection
    * +1 - if intersection happened and the Y coordinate is increasing (y0 < y1)
    * -1 - if intersection happened and the Y coordinate is decreasing (y0 >= y1)
    * @param {Number} px coordinates x for point P
    * @param {Number} py coordinates y for point P
    * @param {Number} x0 coordinates x for point P0
    * @param {Number} y0 coordinates y for point P0
    * @param {Number} x1 coordinates x for point P1
    * @param {Number} y1 coordinates y for point P1
    * Note: This is pretty much similar to what we have in isPointInside(...) method
    * but this was inspired from JDK thus older and not used
    */
    pointCrossingsForLine: function (px, py, x0, y0, x1, y1) {
        if (py < y0 && py < y1) return 0;
        if (py >= y0 && py >= y1) return 0;
        if (px >= x0 && px >= x1) return 0;
        // assert(y0 != y1);        
        if (y0 == y1) throw Exception('Asserted: ' + y0 + ' == ' + y1);
        if (px < x0 && px < x1) return (y0 < y1) ? 1 : -1;
        var xintercept = x0 + (py - y0) * (x1 - x0) / (y1 - y0);
        if (px >= xintercept) return 0;
        return (y0 < y1) ? 1 : -1;
    },


    /**
    * Calculates the number of times the cubic from point P0(x0,y0) to point P1(x1,y1)
    * crosses the ray extending to the right from point P(px,py).
    * @return {Number}
    *  0 - If the point lies on a part of the curve or no intersetion
    * +1 - is added for each crossing where the Y coordinate is increasing
    * -1 - is added for each crossing where the Y coordinate is decreasing
    * 
    * @param {Number} px coordinates x for point P
    * @param {Number} py coordinates y for point P
    * @param {Number} x0 coordinates x for point P0 (start point)
    * @param {Number} y0 coordinates y for point P0 (start point)
    * @param {Number} xc0 coordinates x for point C0 (first controll point)
    * @param {Number} yc0 coordinates y for point C0 (first controll point)
    * @param {Number} xc1 coordinates x for point C1 (second controll point)
    * @param {Number} yc1 coordinates y for point C1 (second controll point)
    * @param {Number} x1 coordinates x for point P1 (end point)
    * @param {Number} y1 coordinates y for point P1 (end point)
    * @param {Number} level The level parameter should be 0 at the top-level 
    * call and will count up for each recursion level to prevent infinite recursion
    * @see http://www.atalasoft.com/blogs/stevehawley/may-2013/how-to-split-a-cubic-bezier-curve
    */
    pointCrossingsForCubic: function (px, py, x0, y0, xc0, yc0, xc1, yc1, x1, y1, level) {
        if (py < y0 && py < yc0 && py < yc1 && py < y1) return 0;
        if (py >= y0 && py >= yc0 && py >= yc1 && py >= y1) return 0;
        // Note y0 could equal yc0...
        if (px >= x0 && px >= xc0 && px >= xc1 && px >= x1) return 0;
        if (px < x0 && px < xc0 && px < xc1 && px < x1) {
            if (py >= y0) {
                if (py < y1) return 1;
            } else {
                // py < y0
                if (py >= y1) return -1;
            }
            // py outside of y01 range, and/or y0==yc0
            return 0;
        }
        // double precision only has 52 bits of mantissa (Give up and fall back to line intersection)
        if (level > 52) return pointCrossingsForLine(px, py, x0, y0, x1, y1);

        //"split" current cubic into 2 new cubic curves
        var xmid = (xc0 + xc1) / 2;
        var ymid = (yc0 + yc1) / 2;
        xc0 = (x0 + xc0) / 2;
        yc0 = (y0 + yc0) / 2;
        xc1 = (xc1 + x1) / 2;
        yc1 = (yc1 + y1) / 2;
        var xc0m = (xc0 + xmid) / 2;
        var yc0m = (yc0 + ymid) / 2;
        var xmc1 = (xmid + xc1) / 2;
        var ymc1 = (ymid + yc1) / 2;
        xmid = (xc0m + xmc1) / 2;
        ymid = (yc0m + ymc1) / 2;
        if (isNaN(xmid) || isNaN(ymid)) {
            // [xy]mid are NaN if any of [xy]c0m or [xy]mc1 are NaN
            // [xy]c0m or [xy]mc1 are NaN if any of [xy][c][01] are NaN
            // These values are also NaN if opposing infinities are added
            return 0;
        }
        return (Util.pointCrossingsForCubic(px, py, x0, y0, xc0, yc0, xc0m, yc0m, xmid, ymid, level + 1)
                + Util.pointCrossingsForCubic(px, py, xmid, ymid, xmc1, ymc1, xc1, yc1, x1, y1, level + 1));
    },


    /**Returns the min of a vector
    *@param {Array} v - vector of {Number}s
    *@return {Number} - the minimum number from the vector or NaN if vector is empty
    *@author alex@scriptoid.com
    **/
    min: function (v) {
        if (v.lenght == 0) {
            return NaN;
        }
        else {
            var m = v[0];
            for (var i = 0; i < v.length; i++) {
                if (m > v[i]) {
                    m = v[i];
                }
            }

            return m;
        }
    },


    /**Returns the max of a vector
    *@param {Array} v - vector of {Number}s
    *@return {Number} - the maximum number from the vector or NaN if vector is empty
    *@author alex@scriptoid.com
    **/
    max: function (v) {
        if (v.lenght == 0) {
            return NaN;
        }
        else {
            var m = v[0];
            for (var i = 0; i < v.length; i++) {
                if (m < v[i]) {
                    m = v[i];
                }
            }

            return m;
        }
    },

    /**
    *Tests if a vector of points is a valid path (not going back)
    *There are a few problems here. If you have p1, p2, p3 and p4 and p2 = p3 you need to ignore that
    *@param {Array} v - an {Array} of {Point}s
    *@return {Boolean} - true if path is valid, false otherwise
    *@author Alex <alex@scriptoid.com>
    **/
    forwardPath: function (v) {
        if (v.length <= 2) {
            return true;
        }

        for (var i = 0; i < v.length - 2; i++) {
            if (v[i].x == v[i + 1].x && v[i + 1].x == v[i + 2].x) { //on the same vertical
                if (signum(v[i + 1].y - v[i].y) != 0) { //test only we have a progressing path
                    if (signum(v[i + 1].y - v[i].y) == -1 * signum(v[i + 2].y - v[i + 1].y)) { //going back (ignore zero)
                        return false;
                    }
                }
            }
            else if (v[i].y == v[i + 1].y && v[i + 1].y == v[i + 2].y) { //on the same horizontal
                if (signum(v[i + 1].x - v[i].x) != 0) { //test only we have a progressing path
                    if (signum(v[i + 1].x - v[i].x) == -1 * signum(v[i + 2].x - v[i + 1].x)) { //going back (ignore zero)
                        return false;
                    }
                }
            }
        }

        return true;
    },

    /**
    *Tests if a vector of points is an orthogonal path (moving in multiples of 90 degrees)
    *@param {Array} v - an {Array} of {Point}s
    *@return {Boolean} - true if path is valid, false otherwise
    *@author Alex <alex@scriptoid.com>
    **/
    orthogonalPath: function (v) {
        if (v.length <= 1) {
            return true;
        }

        for (var i = 0; i < v.length - 1; i++) {
            if (v[i].x != v[i + 1].x && v[i].y != v[i + 1].y) {
                return false;
            }
        }

        return true;
    },


    /**Tries to cut the unecessary poins.
    *Ex: If you have 3 points A,B and C and they are collinear then B will be cut
    *@param {Array} v - an {Array} of {Point}s
    *@return {Array} - the "reduced" vector of {Point}s
    *@author Alex <alex@scriptoid.com>
    **/
    collinearReduction: function (v) {
        var r = [];

        if (v.length < 3) {
            return Point.cloneArray(v);
        }

        r.push(v[0].clone());
        for (var i = 1; i < v.length - 1; i++) {
            if ((v[i - 1].x == v[i].x && v[i].x == v[i + 1].x) || (v[i - 1].y == v[i].y && v[i].y == v[i + 1].y)) {
                continue;
            }
            else {
                r.push(v[i].clone());
            }
        }
        r.push(v[v.length - 1].clone());

        return r;
    },




    /**Score a ortogonal path made out of Points
    *Iterates over a set of points (minimum 3)
    *For each 3 points (i, i+1, i+2) :
    *  - if the 3rd one is after the 2nd on the same line we add +1 
    *  - if the 3rd is up or down related to the 2nd we do not do anything +0
    *  - if the 3rd goes back we imediatelly return -1
    *@param {Array} v - an array of {Point}s
    *@return {Number} - -1 if the path is wrong (goes back) or something >= 0 if is fine
    *  The bigger the number the smooth the path is
    *@author Alex Gheorghiu <alex@scriptoid.com>
    **/
    scorePath: function (v) {
        if (v.length <= 2) {
            return -1;
        }

        var score = 0;
        for (var i = 1; i < v.length - 1; i++) {
            if (v[i - 1].x == v[i].x && v[i].x == v[i + 1].x) { //on the same vertical
                if (signum(v[i + 1].y - v[i].y) == signum(v[i].y - v[i - 1].y)) { //same direction
                    score++;
                }
                else { //going back - no good
                    return -1;
                }
            }
            else if (v[i - 1].y == v[i].y && v[i].y == v[i + 1].y) { //on the same horizontal
                if (signum(v[i + 1].x - v[i].x) == signum(v[i].x - v[i - 1].x)) { //same direction
                    score++;
                }
                else { //going back - no good
                    return -1;
                }
            }
            else { //not on same vertical nor horizontal
                score--;
            }
        }

        return score;
    },


    /**
    * Function to be used as a replacer in JSON's stringify process.
    * We need this as Opera does some rounding (@see https://bitbucket.org/scriptoid/diagramo/issue/35/serialization-fails-on-opera-1115)
    * @param {String} key the property of an object
    * @param  val the value of the key
    * @see https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/JSON/stringify
    * @see https://developer.mozilla.org/en-US/docs/Using_native_JSON#The_replacer_parameter
    * @see https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Number/toFixed
    * @author Artyom, Alex
    * @deprecated Since Opera 19.0.1326.47 problem dissapeared. So 0.8999999999999999.toString() no longer returns "0.9"
    * */
    operaReplacer: function (key, val) {
        if (typeof (val) !== 'undefined' && val !== null) {
            // As toFixed(...) method is specific only for Number type we will use it to test if val is actually a Number
            if (val.toFixed) {
                val = val.toFixed(20); //this will ensure that ANY string representation will have a . (dot) and some 0 (zero)s at the end

                // check if val has decimals and it ends with zero(s)
                if (/\.\d*0+$/.test(val)) {
                    // remove last decimal zero(s) from the end of val (and with dot if it is actually)
                    val = val.replace(/(\.)?0+$/, '');
                }
            }
        }
        return val;

        /*by default the return will be undefined which means the 'key' will not be stringified
        * "If you return undefined, the property is not included in the output JSON string."
        */
    },

    /**Creates a new primitive out of JSON parsed object
    *@param {JSONObject} o - the JSON parsed object of primitive
    *@return {primitive} a newly constructed primitive
    *@author Alex Gheorghiu <alex@scriptoid.com>
    *@author Artyom Pokatilov <artyom.pokatilov@gmail.com>
    **/
    loadPrimitive: function (o) {
        var result = null;

        /**We can not use instanceof Point construction as
        *the JSON objects are typeless... so JSONObject are simply objects */
        if (o.oType == 'Point') {
            result = Point.load(o);
        }
        else if (o.oType == 'Line') {
            result = Line.load(o);
        }
        else if (o.oType == 'Polyline') {
            result = Polyline.load(o);
        }
        else if (o.oType == 'Polygon') {
            result = Polygon.load(o);
        }
        else if (o.oType == 'DottedPolygon') {
            result = DottedPolygon.load(o);
        }
        else if (o.oType == 'QuadCurve') {
            result = QuadCurve.load(o);
        }
        else if (o.oType == 'CubicCurve') {
            result = CubicCurve.load(o);
        }
        else if (o.oType == 'Arc') {
            result = Arc.load(o);
        }
        else if (o.oType == 'Ellipse') {
            result = Ellipse.load(o);
        }
        else if (o.oType == 'DashedArc') {
            result = DashedArc.load(o);
        }
        else if (o.oType == 'Text') {
            result = Text.load(o);
        }
        else if (o.oType == 'Path') {
            result = Path.load(o);
        }
        else if (o.oType == 'Figure') {
            result = Figure.load(o); //kinda recursevly
        }
        else if (o.oType == 'ImageFrame') {
            result = ImageFrame.load(o); //kinda recursevly
        }

        return result;
    },


    /** Selects an object using x and y coordinates:
    * it can be one of: Figure, Group, Connector, Container or none.
    * 
    * Note: Connectors are more important than Figures and Figures more important 
    * than Container so Connectors > Figures > Container
    * @param {Number} x - the x coordinate
    * @param {Number} y - the y coordinate
    * @return {Object}- in a form of
    *  {
    *  id - id of object or -1 if none,
    *  type - type of object, the same as oType or '' if none
    *  }
    * @author Arty
    */
    getObjectByXY: function (x, y) {
        //find Connector at (x,y)
        var cId = CONNECTOR_MANAGER.connectorGetByXY(x, y);
        if (cId != -1) { // found a Connector
            return {
                id: cId,
                type: 'Connector'
            };
        }

        //find Figure at (x,y)
        var fId = STACK.figureGetByXY(x, y);
        if (fId != -1) { // found a Figure
            var gId = STACK.figureGetById(fId).groupId;
            if (gId != -1) { // if the Figure belongs to a Group then return that Group
                return {
                    id: gId,
                    type: 'Group'
                }
            }
            else { // lonely Figure
                return {
                    id: fId,
                    type: 'Figure'
                };
            }
        }

        //find Container at (x,y)
        var contId = STACK.containerGetByXY(x, y);
        if (contId !== -1) { // found a Container
            return {
                id: contId,
                type: 'Container'
            };
        }

        // none of above
        return {
            id: -1,
            type: ''
        };
    },
    NewGUID: function () {
        function S4() {
            return (((1 + Math.random()) * 0x10000) | 0).toString(16).substring(1);
        }
        var newGuid = (S4() + S4() + "-" + S4() + "-" + S4() + "-" + S4() + "-" + S4() + S4() + S4());
        return newGuid.toUpperCase();
    }
};

/**Returns the sign of a number
 *@param {Number} x - the number
 *@returns {Number}
 *@see <a href="http://en.wikipedia.org/wiki/Sign_function">http://en.wikipedia.org/wiki/Sign_function</a>
 *@author alex@scriptoid.com
 **/
function signum(x){
    if(x > 0)
        return 1;
    else if(x < 0)
        return -1;
    else
        return 0;
}

/** Check if a value is numeric
 * @param {String} input - a numeric value
 * @see <a href="http://STACKoverflow.com/questions/18082/validate-numbers-in-javascript-isnumeric">http://STACKoverflow.com/questions/18082/validate-numbers-in-javascript-isnumeric</a>
 * @author Zack Newsham <zack_newsham@yahoo.co.uk>
 * */
function isNumeric(input){
	return (input - 0) == input && (input.length > 0 || input != "");
}

/**Repeats a string for several time and return the concatenated result
 *@param {String} str - the string
 *@param  {Integer} count - the number of time the string should be repeated
 *@return {String}
 **/
function repeat(str, count){
    var res = '';
    for(var i=0;i<count;i++){
        res += str;
    }
    
    return res;
}

/**
 * Set selection on target interval inside text DOM element
 * @param {HTMLElement} input - DOM element to set selection
 * @param {Number} selectionStart - start position of selection
 * @param {Number} selectionEnd - end position of selection
 * @author Artyom
 **/
function setSelectionRange(input, selectionStart, selectionEnd) {
    if (input.setSelectionRange) {
        input.focus();
        input.setSelectionRange(selectionStart, selectionEnd);
    }
}

/**A simple class to detect browser and it's version using navigator properties.
 * Computing logic can be found here: http://stackoverflow.com/a/2401861/2097494
 *
 * @this {Browser}
 * @constructor
 *
 * @author Artyom Pokatilov <artyom.pokatilov@gmail.com>
 **/
function Browser() {
    var N = navigator.appName.toLowerCase();
    var ua = navigator.userAgent.toLowerCase();
    var M = ua.match(/(opera|chrome|safari|firefox|msie)\/?\s*(\.?\d+(\.\d+)*)/i);
    var temp = ua.match(/version\/([\.\d]+)/i);
    if(M && temp != null) {
        M[2]= temp[1];
    }
    M= M? [M[1], M[2]]: [N, navigator.appVersion,'-?'];

    this.webkit = M[0].indexOf("chrome") > -1 || M[0].indexOf("safari") > -1;
    this.opera = M[0].indexOf("opera") > -1;
    this.msie = M[0].indexOf("msie") > -1;
    this.mozilla = M[0].indexOf("firefox") > -1;
    this.version = M[1];
}


/**
 * Removes DOM element
 * @param {HTMLElement} element - DOM element to remove
 *
 * @author Artyom Pokatilov <artyom.pokatilov@gmail.com>
 *
 * Note:  <br/>
 * Cross-browser solution for native JS.
 */
function removeElement(element) {
    element && element.parentNode && element.parentNode.removeChild(element);
}

/**
 * Removes NodeList
 * @param {NodeList} list - NodeList to remove
 *
 * @author Artyom Pokatilov <artyom.pokatilov@gmail.com>
 *
 * Note:  <br/>
 * Cross-browser solution for native JS.
 */
function removeNodeList(list) {
    var i;
    var length = list.length;

    for (i = 0; i < length; i++) {
        removeElement(list[i]);
    }
}