/*Shape_Bridge.cpp
Example for Bridge Pattern (GoF)
Feza BUZLUCA, Lecture Notes
*/
#include <iostream>
using std::cout;
using std::endl;

/* DP1 and DP2 are external drawing programs */
class DP1 {    // First drawing program
public:
	void static draw_a_line(double x1, double y1, double x2, double y2)
	{
		cout << "DP1: Line from " << x1 << "," << y1 << " to " << x2 << "," << y2 << endl;
	}
	void static draw_a_circle(double x, double y, double r)
	{
		cout << "DP1: Circle with the center " << x << "," << y << " and radius " << r << endl;
	}
};
class DP2 {   // Second drawing program
public:
	void static drawline(double x1, double x2, double y1, double y2)
	{
		cout << "DP2: Line from " << x1 << "," << y1 << " to " << x2 << "," << y2 << endl;
	}
	void static drawcircle(double x, double y, double r)
	{
		cout << "DP2: Circle with the center " << x << "," << y << " and radius " << r << endl;
	}
};

/* Adapters to access the external drawing programs (implementation) */
class Drawing {             // Abstract base class of adapters
public:
	virtual void drawLine(double, double, double, double) = 0;
	virtual void drawCircle(double, double, double) = 0;
};
class V1Drawing : public Drawing {    // Adapter for DP1
public:
	void drawLine(double x1, double y1, double x2, double y2);
	void drawCircle(double x, double y, double r);
};

void V1Drawing::drawLine(double x1, double y1, double x2, double y2) {
	DP1::draw_a_line(x1, y1, x2, y2);	// Access to DP1
}
void V1Drawing::drawCircle(double x, double y, double r) {
	DP1::draw_a_circle(x, y, r);
}

class V2Drawing : public Drawing {       // Adapter for DP2
public:
	void drawLine(double x1, double y1, double x2, double y2);
	void drawCircle(double x, double y, double r);
};
void V2Drawing::drawLine(double x1, double y1, double x2, double y2) {
	DP2::drawline(x1, x2, y1, y2); // Access to DP2
}
void V2Drawing::drawCircle(double x, double y, double r) {
	DP2::drawcircle(x, y, r);
}

/* Shapes (Abstraction) */
class Shape {     		// Abstract base class of Shapes
public:
	Shape(Drawing *);        // Constructor: Parameter is pointer to a drawing program (Adapter)
	virtual void draw() = 0;
protected:
	void drawLine(double, double, double, double);
	void drawCircle(double, double, double);
private:
	Drawing *drawProg;                // Pointer to the related adapter of a drawing program (bridge)
};

Shape::Shape(Drawing* dp) : drawProg{dp}    // Constructor: Connection to the related implementation
{}

void Shape::drawLine(double x1, double y1, double x2, double y2){
	drawProg->drawLine(x1, y1, x2, y2);    // Currently connected drawing program is used 
}

void Shape::drawCircle(double x, double y, double r){
	drawProg->drawCircle(x, y, r);
}

/* Concrete shape classes */
// Rectangle
class Rectangle : public Shape{
public:
	Rectangle(Drawing *, double, double, double, double);
	void draw();
private:
	double m_x1, m_y1, m_x2, m_y2;
};

Rectangle::Rectangle(Drawing* dp, double x1, double y1, double x2, double y2)
	                    : Shape{ dp }, m_x1{x1}, m_x2{ x2 }, m_y1{ y1 }, m_y2{ y2 }
{}

void Rectangle::draw() {
	drawLine(m_x1, m_y1, m_x2, m_y1);      // drawLine is inherited fro the Base class Shape
	drawLine(m_x2, m_y1, m_x2, m_y2);
	drawLine(m_x2, m_y2, m_x1, m_y2);
	drawLine(m_x1, m_y2, m_x1, m_y1);
}

// Circle
class Circle : public Shape{
public:
	Circle(Drawing *, double, double, double);
	void draw();
private:
	double m_x, m_y, m_r;
};

Circle::Circle(Drawing *dp, double x, double y, double r)
	                                   : Shape(dp), m_x{ x }, m_y{ y }, m_r{r}
{}

void Circle::draw() {
	drawCircle(m_x, m_y, m_r);           // drawCircle is inherited fro the Base class Shape
}

/* The Client  (user) class that uses the Shapes library written for testing purposes */
class Client{
public:
	Client(Shape* inputShape) : m_shapePtr{ inputShape }        //Initial shape to be used
	{}
	void setShape(Shape * inputShape) {             //change current shape
		m_shapePtr = inputShape;
	}
	void operate();		          	      // Responsibility of the Client
private:
	Shape *m_shapePtr;		                   // It can point to any type of Shape
};

void Client::operate() {
	m_shapePtr->draw();		            //The client does not know the type of the shape
}

/* The main function for testing purposes */
int main() {              	       
	// Adapter objects for Drawing programs. In a real application, they will be created by the Factory.
	Drawing *dp1, *dp2;
	dp1 = new V1Drawing;
	dp2 = new V2Drawing;

	// Shape objects
	Rectangle* rectangle1 = new Rectangle{ dp1, 1, 1, 2, 2 };            // Rectangle1 uses dp1
	Rectangle* rectangle2 = new Rectangle{ dp2, 10, 15, 20, 30 };     // Rectangle2 uses dp2
	Circle* circle = new Circle{ dp2, 2, 2, 4 };                                  // Circle uses dp2

	Client user{ rectangle1 }; 		      //The client (user) will use the rectangle1
	user.operate();
	user.setShape(circle);		     //The client (user) will use the circle
	user.operate();
	user.setShape(rectangle2);		     //The client (user) will use the rectangle2
	user.operate();

	delete rectangle1; delete rectangle2; delete circle;     // Housekeeping
	delete dp1; delete dp2;
	return 0;
}