#pragma once

#include <optional>

#include "Iterator.Base.tlh"


//-----------------------------------------------------------------------------
//		Function_Iterator
//-----------------------------------------------------------------------------

namespace Iterator
{
	template <typename T>
	class Function_Iterator : public __CoreIterator
	{
		typedef  __CoreIterator  inherited;

	public:
		using FuncType = std::function <std::optional <T> ()>;

	public:
		using value_type = typename T;
		using data_type  = typename T&;
		using deref_type = value_type;

	public:
//		Function_Iterator () = delete;

		Function_Iterator () = default;

		Function_Iterator (FuncType & fun) : m_GetAndNext (fun)
		{
			m_Count = INT_MAX;
			m_Index = 0;
			m_Current = m_GetAndNext ();
		}

	public:
		inline virtual void Next () override
		{
			if (! IsEmpty ())
			{
				m_Current = m_GetAndNext ();
				inherited::Next ();
			}
		}

		inline data_type Current ()     { return m_Current.value (); }
		inline data_type operator () () { return Current (); }
		inline data_type operator *  () { return Current (); }

		inline virtual bool IsEmpty () const override
		{
			if (inherited::IsEmpty ())
				return true;
			return ! m_Current.has_value ();
		}

		inline void Skip (int delta)
		{
			for (; ! IsEmpty () && delta > 0; delta --)
				Next ();
		}

	protected:
		void InitFrom (FuncType & fun)
		{
			m_GetAndNext = fun;
			m_Count = INT_MAX;
			m_Index = 0;
			m_Current = m_GetAndNext ();
		}

	private:
		FuncType m_GetAndNext;

		std::optional <T>  m_Current;
	};
};