/*****
*
*   Polygon.js
*
*   copyright 2002, Kevin Lindsey
*
*****/

/*****
*
*   Setup inheritance
*
*****/
Polygon.prototype             = new Shape();
Polygon.prototype.constructor = Polygon;
Polygon.superclass            = Shape.prototype;


/*****
*
*   constructor
*
*****/
function Polygon(svgNode) {
    if ( arguments.length > 0 ) {
        this.init(svgNode);
    }
}


/*****
*
*   init
*
*****/
Polygon.prototype.init = function(svgNode) {
    if ( svgNode.localName == "polygon" ) {
        // Call superclass method
        Polygon.superclass.init.call(this, svgNode);

        // Init properties
        var points = svgNode.getAttributeNS(null, "points").split(/[\s,]+/);

        this.handles = new Array();
        for ( var i = 0; i < points.length; i += 2) {
            var x = parseFloat( points[i]   );
            var y = parseFloat( points[i+1] );
            
            this.handles.push( new Handle(x, y, this) );
        }
    } else {
        throw new Error("Polygon.init: Invalid SVG Node: " + svgNode.localName);
    }
};


/*****
*
*   realize
*
*****/
Polygon.prototype.realize = function() {
    if ( this.svgNode != null ) {
        for ( var i = 0; i < this.handles.length; i++ ) {
            this.handles[i].realize();
            this.handles[i].show(false);
        }

        this.svgNode.addEventListener("mousedown", this, false);
    }
};


/*****
*
*   refresh
*
*****/
Polygon.prototype.refresh = function() {
    var points = new Array();
    
    for ( var i = 0; i < this.handles.length; i++ ) {
        points.push( this.handles[i].point.toString() );
    }
    this.svgNode.setAttributeNS(null, "points", points.join(" "));
};


/*****
*
*   registerHandles
*
*****/
Polygon.prototype.registerHandles = function() {
    for ( var i = 0; i < this.handles.length; i++ )
        mouser.register( this.handles[i] );
};


/*****
*
*   unregisterHandles
*
*****/
Polygon.prototype.unregisterHandles = function() {
    for ( var i = 0; i < this.handles.length; i++ )
        mouser.unregister( this.handles[i] );
};


/*****
*
*   selectHandles
*
*****/
Polygon.prototype.selectHandles = function(select) {
    for ( var i = 0; i < this.handles.length; i++ )
        this.handles[i].select(select);
};


/*****
*
*   showHandles
*
*****/
Polygon.prototype.showHandles = function(state) {
    for ( var i = 0; i < this.handles.length; i++ )
        this.handles[i].show(state);
};


/*****
*
*   pointInPolygon
*
*****/
Polygon.prototype.pointInPolygon = function(point) {
    var length  = this.handles.length;
    var counter = 0;
    var x_inter;

    var p1 = this.handles[0].point;
    for ( var i = 1; i <= length; i++ ) {
        var p2 = this.handles[i%length].point;

        if ( point.y > Math.min(p1.y, p2.y)) {
            if ( point.y <= Math.max(p1.y, p2.y)) {
                if ( point.x <= Math.max(p1.x, p2.x)) {
                    if ( p1.y != p2.y ) {
                        x_inter = (point.y - p1.y) * (p2.x - p1.x) / (p2.y - p1.y) + p1.x;
                        if ( p1.x == p2.x || point.x <= x_inter) {
                            counter++;
                        }
                    }
                }
            }
        }
        p1 = p2;
    }

    return ( counter % 2 == 1 );
};


/*****
*
*   get/set/info methods
*
*****/

/*****
*
*   getIntersectionParams
*
*****/
Polygon.prototype.getIntersectionParams = function() {
    var points = new Array();
    for ( var i = 0; i < this.handles.length; i++ ) {
        points.push( this.handles[i].point );
    }
    
    return new IntersectionParams(
        "Polygon",
        [ points ]
    );
};


/*****
*
*   getArea
*
*****/
Polygon.prototype.getArea = function() {
    var area   = 0;
    var length = this.handles.length;
    var neg    = 0;
    var pos    = 0;

    for ( var i = 0; i < length; i++ ) {
        var h1 = this.handles[i].point;
        var h2 = this.handles[(i+1) % length].point;

        area += (h1.x * h2.y - h2.x * h1.y);
    }

    return area / 2;
};


/*****
*
*   getCentroid
*
*****/
Polygon.prototype.getCentroid = function() {
    var length = this.handles.length;
    var area6x = 6*this.getArea();
    var x_sum  = 0;
    var y_sum  = 0;

    for ( var i = 0; i < length; i++ ) {
        var p1    = this.handles[i].point;
        var p2    = this.handles[(i+1) % length].point;
        var cross = (p1.x*p2.y - p2.x*p1.y);

        x_sum += (p1.x + p2.x) * cross;
        y_sum += (p1.y + p2.y) * cross;
    }
    
    return new Point2D(x_sum / area6x, y_sum / area6x);
};


/*****
*
*   isClockwise
*
*****/
Polygon.prototype.isClockwise = function() {
    return this.getArea() < 0;
};


/*****
*
*   isCounterClockwise
*
*****/
Polygon.prototype.isCounterClockwise = function() {
    return this.getArea() > 0;
};


/*****
*
*   isConcave
*
*****/
Polygon.prototype.isConcave = function() {
    var positive = 0;
    var negative = 0;
    var length = this.handles.length;

    for ( var i = 0; i < length; i++) {
        var p0 = this.handles[i].point;
        var p1 = this.handles[(i+1) % length].point;
        var p2 = this.handles[(i+2) % length].point;
        var v0 = Vector2D.fromPoints(p0, p1);
        var v1 = Vector2D.fromPoints(p1, p2);
        var cross = v0.cross(v1);
        
        if ( cross < 0 ) {
            negative++;
        } else {
            positive++;
        }
    }

    return ( negative != 0 && positive != 0 );
};


/*****
*
*   isConvex
*
*****/
Polygon.prototype.isConvex = function() {
    return !this.isConcave();
};