/**
 * Write a description of class Polygon here.
 *
 * @author (your name)
 * @version (a version number or a date)
 */
public class Polygon
{
    private PointNode _head;

    public Polygon()
    {
        _head = null;
    }

    public boolean addVertex ( Point p , int pos)
    {
        PointNode p1= new PointNode(p);
        if(pos <=0 )
            return false;
        if(_head==null){
            _head = new PointNode(p,null);
            return true;
        }
        if(_head.getNext()==null){
            _head.setNext(p1);
            return true;
        }
        else
        {
            PointNode t,prev;
            t=_head;
            prev=null;
            for (int i = 0;i!= pos-1;i++){
                prev=t;
                t=t.getNext();
            }
            if(prev != null){
                p1.setNext(t);
                prev.setNext(p1);
            }
            return true;
        }
    }

    public Point highestVertex()
    {
        if ( _head == null)
            return null;
        Point Higest= _head.getPoint();
        for(PointNode p= _head ; p != null; p=p.getNext()){
            if ((p.getPoint()).isAbove(Higest))
                Higest = p.getPoint();
        }
        return new Point(Higest);
    }

    public String toString()
    {
        if(_head!=null)
        {
            int count = 0;
            String toReturn = " " ;
            toReturn = "(" +(_head.getPoint()).toString();
            for (PointNode p= _head.getNext() ; p != null; p=p.getNext())
            {
                toReturn+= ","+ p.getPoint() ;
                count++;
            }
            return  "The polygon has " + count + " vertices:\n" +  toReturn + ")"  ;
        }
        else
            return "The polygon has 0 vertices.";

    }

    public double calcPerimeter ()
    {
        if(_head==null || _head.getNext()== null)
            return 0;
        if((_head.getNext()).getNext()== null)
            return (_head.getPoint()).distance((_head.getNext()).getPoint());
        else
        {
            double Perimeter =0;
            PointNode p= _head;
            while (  p.getNext()!= null)
            {
                Perimeter += (p.getPoint()).distance((p.getNext()).getPoint());
                p=p.getNext();
            }
            Perimeter+=p.getPoint().distance(_head.getPoint());
            return Perimeter;
        }
    }

    public double calcArea()
    {
        if(_head==null || _head.getNext()== null)
            return 0;
        else
        {
            double area = 0;
            PointNode p= _head;
            while ((p.getNext()).getNext()!= null){
                //Parameters for Heron's Formula
                //********************
                double a =  (_head.getPoint()).distance (((p.getNext()).getPoint())) ; // Side of the triangle
                double b =  (p.getNext().getPoint()).distance ((p.getNext()).getNext().getPoint()) ; // Side of the triangle
                double c = (p.getNext()).getNext().getPoint().distance (_head.getPoint());// Side of the triangle
                double s = (a+b+c)/2; //  Half of perimeter
                //********************
                area+=Math.sqrt(s * (s - a) * (s - b) * (s - c)); // Calculates area using Heron's Formula
                p=p.getNext();
            } // end of for loop
            return area;
        } // end of if

    }
    public boolean isBigger(Polygon other)
    {
        if (this.calcArea() > other.calcArea())
            return true;
        else
            return false;
    }

    public int findVertex(Point p)
    {
        PointNode t= _head;
        int count =0;
        while (t!= null){
              count++;
            {
                if((t.getPoint()).equals(p))
                    return count;
            }
            t=t.getNext();
        }
        return -1;
        }


        public Point getNextVertex(Point p)
        {
        if(this.findVertex (p)== -1)
            return null;
          else{
            PointNode t= _head;
            while (t.getNext()!= null){
            if((t.getPoint()).equals(p)){
             return new Point( t.getNext().getPoint());
            }
            t=t.getNext();
            }
        }
        return new Point(_head.getPoint());
    }

    public Polygon getBoundingBox()
    {
        if (_head.getNext().getNext() == null|| _head== null)
            return  null;
        Point Down = _head.getPoint();
        Point Up = this.highestVertex();
        Point Right = _head.getPoint();
        Point Left = _head.getPoint();
        PointNode t= _head.getNext();
        while (t.getNext() != null){
            if( t.getPoint().isUnder(Down))
                Down= t.getPoint();
            if( t.getPoint().isRight(Right))
                Right= t.getPoint();
            if( t.getPoint().isLeft(Left))
                Left= t.getPoint();
            t = t.getNext();
        }
        Polygon BoundingBox = new Polygon();
        BoundingBox.addVertex(new Point(Left.getX(),Down.getY()), 1);
        BoundingBox.addVertex(new Point(Right.getX(),Down.getY()), 2);
        BoundingBox.addVertex(new Point(Right.getX(),Up.getY()), 3);
        BoundingBox.addVertex(new Point(Left.getX(),Up.getY()),4);
        return BoundingBox;
    } // end of method getBoundingBox
}