#pragma once

#include "iterators.h"

class IShape {
	IShape* next = nullptr;
	IShape* prev = nullptr;

public:
	virtual ~IShape() = default;
	virtual void draw() const = 0;
	virtual double area() const = 0;

	void set_next(IShape* n) {
		next = n;
		if (n) n->prev = this;
	}

	IShape* get_next() const { return next; }
	IShape* get_prev() const { return prev; }

	template<typename Policy>
	Traversal<IShape, Policy> traverse() {
		return Traversal<IShape, Policy>(this);
	}

	using forward = IteratorForward<IShape>;
	using backward = IteratorBackward<IShape>;
};

class Circle : public IShape {
	double r;
public:
	Circle(double radius) : r(radius) {}

	void draw() const override {
		std::cout << "Drawing Circle of radius " << r << "\n";
	}

	double area() const override {
		return 3.14159 * r * r;
	}
};