Event.h

#pragma once
 
#include "hnpch.h"
#include "Hana/Core/Core.h"
 
namespace Hana
{
    // Events in Hana are currently blocking, meaning when an event occurs it
    // immediately gets dispatched and must be dealt with right then and there.
    // For the future, a better strategy might be to buffer events in an event
    // bus and process them during the "event" art of the update stage.
 
    enum class EventType
    {
        None = 0,
        WindowClose, WindowResize, WindowFocus, WindowLostFocus, WindowMoved,
        AppTick, AppUpdate, AppRender,
        KeyPressed, KeyReleased, KeyTyped,
        MouseButtonPressed, MouseButtonReleased, MouseMoved, MouseScrolled
    };
 
    enum EventCategory
    {
        None = 0,
        EventCategoryApplication    = BIT(0),
        EventCategoryInput          = BIT(1),
        EventCategoryKeyboard       = BIT(2),
        EventCategoryMouse          = BIT(3),
        EventCategoryMouseButton    = BIT(4)
    };
 
#define EVENT_CLASS_TYPE(type) static EventType GetStaticType() { return EventType::type; }\
                                virtual EventType GetEventType() const override { return GetStaticType(); }\
                                virtual const char* GetName() const override { return #type; }
 
#define EVENT_CLASS_CATEGORY(category) virtual int GetCategoryFlags() const override { return category; }
 
    class Event
    {
    public:
        bool Handled = false;
        
        virtual EventType GetEventType() const = 0;
        virtual const char* GetName() const = 0;
        virtual int GetCategoryFlags() const = 0;
        virtual std::string ToString() const { return GetName(); }
 
        inline bool IsInCategory(EventCategory category)
        {
            return GetCategoryFlags() & category;
        }
    };
 
    class EventDispatcher
    {
    public:
        EventDispatcher(Event& event)
            : m_Event(event)
        {
        }
 
        template<typename T, typename F>
        bool Dispatch(const F& func)
        {
            if (m_Event.GetEventType() == T::GetStaticType())
            {
                m_Event.Handled = func(static_cast<T&>(m_Event));
                return true;
            }
            return false;
        }
    private:
        Event& m_Event;
    };
 
    inline std::ostream& operator<<(std::ostream& os, const Event& e)
    {
        return os << e.ToString();
    }
}