#include <iostream>
#include <iomanip>
#include <vector>

using namespace std;

class Event_Listener
{
public:
    Event_Listener(ostream & os)
        : os {os}
    {}
    virtual ~Event_Listener() = default;
    virtual void update(int coordinate) = 0;
protected:
    ostream & os;
};

class Collision_Listener : public Event_Listener
{
public:
    Collision_Listener(ostream & os, string const& name, int point)
        : Event_Listener{os}, point {point}, name {name}, total_collisions {}
    {}

    virtual void update(int coordinate) override
    {
        if (point == coordinate)
        {
            ++total_collisions;
            os << "Collision at " << coordinate << endl;
            os << " - Total collisions with '" << name << "' is now " << total_collisions << endl;
        }
    }
private:
    int point;
    string name;
    unsigned total_collisions;
};

class Bounds_Listener : public Event_Listener
{
public:
    Bounds_Listener(ostream & os, int min_coord, int max_coord)
        : Event_Listener{os}, min_coord {min_coord}, max_coord{max_coord}
    {}

    virtual void update(int coordinate) override
    {
        if (coordinate > max_coord or coordinate < min_coord)
        {
            os << "Player out of bounds at " << coordinate << endl;
        }
    }
private:
    int min_coord;
    int max_coord;
};

class Event_Manager 
{
public:
    Event_Manager()
        : listeners {}
    {}
    
    void notify(int coordinate)
    {
	for (Event_Listener* elp : listeners)
	{
	    elp->update(coordinate);
	}
    }
    
    void subscribe(Event_Listener* event_listener)
    {
	listeners.push_back(event_listener);
    }
private:
    vector<Event_Listener*> listeners;
};

int main()
{
    Event_Manager event_manager{};

    Bounds_Listener bounds_listener {cout, -5, 5};
    event_manager.subscribe(&bounds_listener);

    Collision_Listener collision1 {cout, "rock", 3};
    event_manager.subscribe(&collision1);

    Collision_Listener collision2 {cout, "tree", -1};
    event_manager.subscribe(&collision2);

    event_manager.notify(5);
    event_manager.notify(3);
    event_manager.notify(8);
    event_manager.notify(-1);
    event_manager.notify(3);
    event_manager.notify(2);
    event_manager.notify(-7);
    event_manager.notify(3);
}