package A2;

public class PolygonImpl implements Polygon {

	private Point points[];
	
	PolygonImpl(Point[] points){
		this.points=points.clone();
	}
	
	@Override
	public Point[] getPoints() {
		// TODO Auto-generated method stub
		return points.clone();
	}


	
	public int getNumSides() {
		// TODO Auto-generated method stub
		return points.length;
	}

	
	public Point getVertexAverage() {
		// TODO Auto-generated method stub
		double sumOfX =0;
		double sumOfY= 0;
		for (Point p: this.getPoints()){
			sumOfX+=p.getX();
			sumOfY+=p.getY();
		}
		double xCoord = (double) sumOfX/getPoints().length;
		double yCoord = (double) sumOfY/getPoints().length;
		Point vertexAverage= new Point(xCoord,yCoord);
		return vertexAverage;
		
	}

	
	public RectangleImpl getBoundingBox() {
		// TODO Auto-generated method stub
		double maxEx = 0;
		double maxY = 0;
		double minEx = 0;
		double minY = 0;

		for(int i=0; i<points.length; i++){
			double xCoord = points[i].getX();
			double yCoord = points[i].getY();
			
			if(i==0){
				//initializing
				maxEx = xCoord;
				 maxY = yCoord;
				 minEx = xCoord;
				 minY = yCoord;
			}
			if(xCoord> maxEx){
				maxEx = xCoord;
			}
			if(xCoord< minEx){
				minEx = xCoord;
			}
			if(yCoord> maxY){
				maxY = yCoord;
			}
			if(yCoord< minY){
				minY = yCoord;
			}
			
		}
		
		
		Point bottomLeft = new Point(minEx,minY);
		Point topRight = new Point(maxEx,maxY);
		RectangleImpl boundingBox = new RectangleImpl(bottomLeft,topRight);
		return boundingBox;
		
	}

	@Override
	public Point getCentroid() {
		// TODO Auto-generated method stub
		double C_x=0; 
		double C_y=0; 
		
		for(int i=0;i<points.length;i++){
			double currentX= points[i].getX();
			double currentY = points[i].getY();
			
			
			if(i==points.length-1){
				//we've looped around
				C_x += (currentX+points[0].getX())*(currentX*points[0].getY()-currentY*points[0].getX());
				C_y += (currentY+points[0].getY())*(currentX*points[0].getY()-currentY*points[0].getX());
			}else{
				double nextX = points[i+1].getX();
				double nextY = points[i+1].getY();
				C_x += (currentX+nextX)*(currentX*nextY-currentY*nextX);
				C_y += (currentY+nextY)*(currentX*nextY-currentY*nextX);
			}
	
		}
	
		double Area = 1/(6*getSignedArea());
		Point centroid = new Point(Area*C_x,Area*C_y);
		return centroid;

	}

	@Override
	public double getArea() {
		// TODO Auto-generated method stub
		return Math.abs(getSignedArea());
	
	}

	public double getSignedArea() {
		// TODO Auto-generated method stub
		double sum = 0;
		
		
		for(int i=0;i<getPoints().length;i++){
			double x = points[i].getX();
			double y= points[i].getY();
			
			if(i==(points.length-1)){
				sum += (x*points[0].getY())-(y*points[0].getX());
			}else{
			double nextX = points[i+1].getX();
			double nextY = points[i+1].getY();
			sum+=(x*nextY-nextX*y);
			}
			
		}
		
		return sum/2;
	}
	
	@Override
	
	public void move(double dx, double dy) {
		// TODO Auto-generated method stub
	
		for(int i=0;i<points.length;i++){
			points[i]=points[i].translate(dx, dy);
		}
		
		
	}

	@Override
	public void move(Point c) {
		// TODO Auto-generated method stub
	move(c.getX()-getCentroid().getX(),c.getY()-getCentroid().getY());
	}

	@Override
	public void scale(double factor) {
		// TODO Auto-generated method stub
		
		
		
		double currentX = getCentroid().getX();
		double currentY = getCentroid().getY();
		move(new Point(0,0));
		
	
		for(int i=0;i<points.length;i++){
			points[i] = new Point(points[i].getX()*factor,points[i].getY()*factor);
		}
		move(new Point(currentX,currentY));
		
	}

}