import element.*;       // includes Drawable interface
public class Triangle implements Drawable
{
    private final int n = 3;    // n is number of vertices
    private Pt v[];             // vertices of the triangle
    
    public Triangle()
    // post: generate an equilateral triangle with side 200;
    //       "base" along top 
    {
        this(new Pt(0,0), new Pt(200,0), new Pt(100,173));
    }

    public Triangle(Triangle other)
    // pre: other is a non-null triangle
    // post: this becomes a copy of the triangle
    {
        this(other.v[0], other.v[1], other.v[2]);
    }

    public Triangle(Pt p, Pt q, Pt r)
    // pre: p, q, r are non-null
    // post: new triangle with vertices pqr
    {
        v = new Pt[n];
        v[0] = new Pt(p);
        v[1] = new Pt(q);
        v[2] = new Pt(r);
    }

    public int height()
    // post: returns the height of the triangle
    {
        return bottom()-top();
    }

    public int width()
    // post: returns the width of the triangle
    {
        return right()-left();
    }

    public int left()
    // post: returns the left-most coordinate of the bounding
    //       box containing the triangle
    {
        int i;
        int result = v[0].x();
        for (i = 1; i < n; i++)
        {
            result = Math.min(result,v[i].x());
        }
        return result;
    }

    public int right()
    // post: returns the right-most coordinate of the bounding
    //       box containing the triangle
    {   
        int i;
        int result = v[0].x();
        for (i = 1; i < n; i++)
        {
            result = Math.max(result,v[i].x());
        }
        return result;
    }

    public int bottom()
    // post: returns the bottom-most coordinate of the bounding
    //       box containing the triangle
    {
        int i;
        int result = v[0].y();
        for (i = 1; i < n; i++)
        {
            result = Math.max(result,v[i].y());
        }
        return result;
    }
    
    public int top()
    // post: returns the top-most coordinate of the bounding
    //       box containing the triangle
    {
        int i;
        int result = v[0].y();
        for (i = 1; i < n; i++)
        {
            result = Math.min(result,v[i].y());
        }
        return result;
    }

    public Pt center()
    // post: returns the center of the bounding box of the triangle
    {
        return new Pt((left()+right())/2,(top()+bottom())/2);
    }

    public void center(Pt p)
    // post: sets the center of the bounding box of triangle to p;
    //       the dimensions remain the same.
    {
        int i;
        Pt old = center();
        int dx = p.x()-old.x();
        int dy = p.y()-old.y();
        for (i = 0; i < n; i++)
        {
            v[i].move(dx,dy);
        }
    }
    
    public void drawOn(DrawingWindow d)
    // post: draws outline of this triangle on window d;
    //       same as d.draw(this)
    {
        int i;
        for (i = 0; i < n; i++)
        {
            d.draw(new Line(v[i],v[(i+1)%n]));
        }
    }

    public void fillOn(DrawingWindow d)
    // post: draws the interior of this triangle on window d;
    //       same as d.fill(this)
    {
        drawOn(d);
    }

    public void clearOn(DrawingWindow d)
    // post: erases this triangle from window d;
    //       same as d.clear(this)
    {
        int i;
        for (i = 0; i < n; i++)
        {
            d.clear(new Line(v[i],v[(i+1)%n]));
        }
    }
}