#include <iostream>
#include <memory>

using namespace std;

class Texture {
public:
    Texture() = default;
    virtual ~Texture() = default;

    virtual const string& show_texture() = 0;
};

class Shape {
protected:
    shared_ptr<Texture> t;
public:
    Shape(shared_ptr<Texture> t) : t(t) {}
    virtual void draw() = 0;
};


class Square : public Shape {
    int x1;
    int y1;
    int x2;
    int y2;
public:
    Square(shared_ptr<Texture> t, int x1, int y1, int x2, int y2) :
    Shape(t), x1(x1), y1(y1), x2(x2), y2(y2) {}

    virtual void draw() {
        // Maybe you have to use different show_texture. For example,
        // show_texture_square for Square, show_texture_circle for Circle,
        // so that the actions is M*N, but that is unavoidable, and the
        // class's count is M+N.
        cout << "draw square: " << x1 << " " << y1 << " " << x2 << " " << y2
             << " with texture " << t->show_texture() << endl;
    }
};

class Circle : public Shape {
    int x;
    int y;
    int r;
public:
    Circle(shared_ptr<Texture> t, int x, int y, int r) :
    Shape(t), x(x), y(y), r(r) {}

    virtual void draw() override {
        cout << "draw circle: " << x << " " << y << " " << r << " with texture "
             << t->show_texture() << endl;
    }
};

class SoilTexture : public Texture {
    string s;
public:
    SoilTexture(int level) : s("Soil") { s += to_string(level); }
    virtual const string& show_texture() override {
        return s;
    }
};

class WaterTexture : public Texture {
    string s;
public:
    WaterTexture(int level) : s("Water") { s += to_string(level + 256); }
    virtual const string& show_texture() override {
        return s;
    }
};

int main() {
    shared_ptr<Texture> ts = make_shared<SoilTexture>(123);
    shared_ptr<Texture> tw = make_shared<WaterTexture>(11);
    // When you want to create a new texture, you just need to create one
    // texture class and use it when generating shape.
    // you don't need to create a set of shapes.
    // You can switch different Textures esaily when running.

    auto c = make_shared<Circle>(ts, 1, 2, 3);
    auto s = make_shared<Square>(tw, 1, 2, 3, 4);
    c->draw();
    s->draw();
}