/***********************************************
 *  CS2510 Fall 2011 
 *  Lecture #3
 *  Data and Methods (instance functions)
 ***********************************************/

// IShape represents a shape
interface IShape {
    
    // shapeDistTo0 returns the distance from the shape to the origin
    double shapeDistTo0();
}

// A Circle (as a type of IShape)
class Circle implements IShape {
    int rad;
    Posn center;
    
    Circle(int rad, Posn center) {
        this.rad = rad;
        this.center = center;
    }
    
    // shapeDistTo0: The distance from the center of the circle to the origin
    public double shapeDistTo0() {
        return center.distTo0();
    }
}

//A Rectangle (as a type of IShape)
class Rect implements IShape {
    int h;
    int w;
    Posn center;
    
    Rect(int h, int w, Posn center) {
        this.h = h;
        this.w = w;
        this.center = center;
    }

    // shapeDistTo0: The distance from the center of the rectangle to the origin
    public double shapeDistTo0() {
        return center.distTo0();
    }
}

class Overlay implements IShape{
    IShape s1;
    IShape s2;
    
    Overlay(IShape s1, IShape s2) {
        this.s1 = s1;
        this.s2 = s2;
    }

    // shapeDistTo0: The distance from the closest sub-shape to the origin
    public double shapeDistTo0() {
        return Math.min(s1.shapeDistTo0(),s2.shapeDistTo0());
    }
}

/* Posn template... the laundry list

 ** Fields of "this" class
   ... this.x ...  -- int
   ... this.y ...  -- int
   
 ** We also add methods that we implement (and test)  
   ... this.moveUp(int dy) ... -- Posn
   ... this.distTo0() ...  -- double
   ... this.moveUpBy(Posn p) -- Posn

 ** If we have methods that we can call on fields
      of "this" then they go HERE
   ...
 */

/* We still do purpose statements, but the contract and
 *   header are now part of the (Java-like) language  */ 
class Posn {
    int x;
    int y;
    
    Posn(int xcoord, int ycoord) {
        this.x = xcoord;
        this.y = ycoord;
    }
    
    // moveUp returns a new Posn shifted up by dy
    Posn moveUp(int dy) {
        return new Posn(this.x, this.y+dy);
    }
    
    // moveUpBy returns a new Posn shifted by p.x and p.y
    Posn moveUpBy(Posn p) {
        return new Posn(this.x + p.x, this.y + p.y);
    }
    
    // distTo0 returns the distance from this posn to 0
    double distTo0() {
        return Math.sqrt(Math.pow(this.x,2) + Math.pow(this.y,2));
    }
    
}

class Examples {
    
    //Examples of shapes
    Circle c = new Circle(5,new Posn(1,2));
    Rect r = new Rect(2,3,new Posn(5,4));
    Overlay o = new Overlay(c,r);
    Overlay o2 = new Overlay(o,c);
    
    // Examples of Posns and posn methods
    Posn p1 = new Posn(1,2);
    Posn p2 = p1.moveUp(10);
    Posn p3 = p2.moveUpBy(p1.moveUp(5));
    Double p1dist = p1.distTo0();
    
    // Examples of Shape Methods
    Double cdist = c.shapeDistTo0();
    Double o2dist = o2.shapeDistTo0();
    
    Examples() {
    }
}