#ifndef PFOR_PFOR_EXPRESSION_INFO_H
#define PFOR_PFOR_EXPRESSION_INFO_H

#include "access.h"
#include "expression.h"
#include "operandtag.h"
#include "tagger.h"
#include "../mp/pack.h"
#include "../mp/meta.h"

namespace pfor {
namespace expr {

namespace impl {

/**
 * @brief filters variables ids from an expression depending on access category
 */
template<typename, Access> struct RWListImpl;

template<typename Id, Access access, typename Index, typename... Ts, Access accessReq>
struct RWListImpl<Pack<OperandTag<Id, access, Index>, Ts...>, accessReq> {
	using trail = typename RWListImpl<Pack<Ts...>, accessReq>::type;
	using type  = pfor::If<access == accessReq, PackPrepend<trail, Id>, trail>;
};

template<Access access, typename Index, typename... Ts, Access accessReq>
struct RWListImpl<Pack<OperandTag<IgnoredId, access, Index>, Ts...>, accessReq> {
	using type = typename RWListImpl<Pack<Ts...>, accessReq>::type;
};

template<Access accessReq>
struct RWListImpl<Pack<>, accessReq> {
	using type = Pack<>;
};

template<typename E, Access accessReq>
using RWList = typename RWListImpl<E, accessReq>::type;

}

template<typename T>
using ReadList = impl::RWList<T, Access::read>;

template<typename T>
using WriteList = impl::RWList<T, Access::write>;

/**
 * @brief returns informations about the input expression
 */
template<std::size_t, typename> struct ExpressionInfoImpl;

template<std::size_t n, typename T, typename... Ts>
struct ExpressionInfoImpl<n, Pack<T, Ts...>> {
	using trail     = typename ExpressionInfoImpl<n+1, Pack<Ts...>>::type;
	using exprtags  = ExpressionTagger<T>;
	using read      = ReadList<exprtags>;
	using write     = WriteList<exprtags>;
	using type      = PackPrepend<trail, Pack<UIntToType<n>, write, read>>;
};

template<std::size_t n>
struct ExpressionInfoImpl<n, Pack<>> {
	using type = Pack<>;
};

template<typename T>
using ExpressionInfo = typename ExpressionInfoImpl<0, T>::type;

// template<typename T>
// using SortedExpressionInfo = PackSort<ComparatorWritePack, typename ExpressionInfo<T>::type>;

}
}

#endif