// Purpose. Facade design pattern

// 1. Identify the desired unified interface for a set of subsystems
// 2. Design a "wrapper" class that can encapsulate the use of the subsystems
// 3. The client uses (is coupled to) the Facade
// 4. The facade/wrapper "maps" to the APIs of the subsystems

class PointCarte { // 1. Subsystem
private double x, y;
public PointCarte( double xx, double yy ) { x = xx; y = yy; }
public void move( int dx, int dy ) { x += dx; y += dy; }
public String toString() { return "(" + x + "," + y + ")"; }
public double getX() { return x; } public double getY() { return y; }
}

class PointPolar { // 1. Subsystem
private double radius, angle;
public PointPolar( double r, double a ) { radius = r; angle = a; }
public void rotate( int ang ) { angle += ang % 360; }
public String toString() { return "[" + radius + "@" + angle + "]"; }
}

class Point { // 1. Desired i/f: move(), rotate()
private PointCarte pc; // 2. Design a "wrapper" class
public Point( double xx, double yy ) { pc = new PointCarte( xx,yy ); }
public String toString() { return pc.toString(); }
public void move( int dx, int dy ) { pc.move( dx,dy ); } // 4. Wrapper maps
public void rotate( int angle, Point o ) {
double x = pc.getX() - o.pc.getX(), y = pc.getY() - o.pc.getY();
PointPolar pp = new PointPolar( Math.sqrt(x*x+y*y),
Math.atan2(y,x)*180/Math.PI );
pp.rotate( angle ); // 4. Wrapper maps
System.out.println( " PointPolar is " + pp );
String str = pp.toString(); int i = str.indexOf( '@' );
double r = Double.parseDouble( str.substring(1,i) );
double a = Double.parseDouble( str.substring(i+1,str.length()-1) );
pc = new PointCarte(r*Math.cos(a*Math.PI/180) + o.pc.getX(),
r*Math.sin(a*Math.PI/180) + o.pc.getY() );
} }

class Line {
private Point o, e;
public Line( Point ori, Point end ) { o = ori; e = end; }
public void move( int dx, int dy ) { o.move( dx, dy ); e.move( dx, dy ); }
public void rotate( int angle ) { e.rotate( angle, o ); }
public String toString() { return "origin is " + o + ", end is " + e; }
}

class FacadeDemo {
public static void main( String[] args ) {
Line line1 = new Line( new Point(2,4), new Point(5,7) ); // 3. Client
line1.move(-2,-4); // uses the
System.out.println( "after move: " + line1 ); // Facade
line1.rotate(45);
System.out.println( "after rotate: " + line1 );
Line line2 = new Line( new Point(2,1), new Point(2.866,1.5) );
line2.rotate(30);
System.out.println( "30 degrees to 60 degrees: " + line2 );
} }

// after move: origin is (0.0,0.0), end is (3.0,3.0)
// PointPolar is [4.242@90.0]
// after rotate: origin is (0.0,0.0), end is (0.000,4.242)
// PointPolar is [0.999@60.0]
// 30 degrees to 60 degrees: origin is (2.0,1.0), end is (2.499,1.866)