#ifndef STATES_H
#define STATES_H

#include <SFML/Graphics.hpp>
#include <functional>
#include "states/ids.h"
#include "resourceManager.h"
#include "resourceIds.h"

class StateStack;

class State {
    public:
        using Ptr = std::unique_ptr<State>;

        struct Context{
            sf::RenderWindow *window;
            TextureManager *textures;
            TextureFontManager *textureFonts;
            // add IO controller
        };
        State(StateStack &stack, State::Context context);
        virtual void update(sf::Time dt) =0;
        virtual void render() =0;
        virtual void handleEvent(const sf::Event &event) =0;

    protected:
        void requestPush(States::Id state_id);
        void requestPop();
        void requestClear();

        Context context_;
        StateStack *stack_;
};

class StateStack{
    public:
        enum class OpId{
            Push,
            Pop,
            Clear
        };

        struct Op{
            Op(OpId op_id, States::Id state_id = States::None)
                : id(op_id)
                , state(state_id){}
            OpId id;
            States::Id state;
        };

    private:
        std::vector<Op> pendingOps_;
        std::vector<State::Ptr> states_;
        std::map<States::Id, std::function<State::Ptr()>> stateFactory_;

        State::Context context_;

    public:
        StateStack(State::Context context);

        void update(sf::Time dt);
        void render();
        void handleEvent(const sf::Event &event);

        void requestOp(Op op);

        void push(States::Id state_id);
        void pop();
        void clear();

        void applyPending();

        bool isEmpty() const;

        template<typename T>
        void registerState(States::Id id);


        State::Ptr createState(States::Id id);
};


template<typename T>
void StateStack::registerState(States::Id id){
    static_assert(std::is_base_of<State, T>::value,
      "StateStack: attempting to registerState something that is not a State");
    stateFactory_[id] = [this] ()
    {
        return State::Ptr(new T(*this, context_));
    };
}

#endif // STATES_H