#pragma once
#include <Interpreters/HashJoin/HashJoin.h>


namespace DB
{
template <typename Mapped>
class KeyGetterEmpty
{
public:
    struct MappedType
    {
        using mapped_type = Mapped;
    };

    using FindResult = ColumnsHashing::columns_hashing_impl::FindResultImpl<Mapped, true>;

    KeyGetterEmpty() = default;

    FindResult findKey(MappedType, size_t, const Arena &) { return FindResult(); }
};

template <HashJoin::Type type, typename Value, typename Mapped>
struct KeyGetterForTypeImpl;

constexpr bool use_offset = true;

template <typename Value, typename Mapped> struct KeyGetterForTypeImpl<HashJoin::Type::key8, Value, Mapped>
{
    using Type = ColumnsHashing::HashMethodOneNumber<Value, Mapped, UInt8, false, use_offset>;
};
template <typename Value, typename Mapped> struct KeyGetterForTypeImpl<HashJoin::Type::key16, Value, Mapped>
{
    using Type = ColumnsHashing::HashMethodOneNumber<Value, Mapped, UInt16, false, use_offset>;
};
template <typename Value, typename Mapped> struct KeyGetterForTypeImpl<HashJoin::Type::key32, Value, Mapped>
{
    using Type = ColumnsHashing::HashMethodOneNumber<Value, Mapped, UInt32, false, use_offset>;
};
template <typename Value, typename Mapped> struct KeyGetterForTypeImpl<HashJoin::Type::key64, Value, Mapped>
{
    using Type = ColumnsHashing::HashMethodOneNumber<Value, Mapped, UInt64, false, use_offset>;
};
template <typename Value, typename Mapped> struct KeyGetterForTypeImpl<HashJoin::Type::key_string, Value, Mapped>
{
    using Type = ColumnsHashing::HashMethodString<Value, Mapped, true, false, use_offset>;
};
template <typename Value, typename Mapped> struct KeyGetterForTypeImpl<HashJoin::Type::key_fixed_string, Value, Mapped>
{
    using Type = ColumnsHashing::HashMethodFixedString<Value, Mapped, true, false, use_offset>;
};
template <typename Value, typename Mapped> struct KeyGetterForTypeImpl<HashJoin::Type::keys128, Value, Mapped>
{
    using Type = ColumnsHashing::HashMethodKeysFixed<Value, UInt128, Mapped, false, false, false, use_offset>;
};
template <typename Value, typename Mapped> struct KeyGetterForTypeImpl<HashJoin::Type::keys256, Value, Mapped>
{
    using Type = ColumnsHashing::HashMethodKeysFixed<Value, UInt256, Mapped, false, false, false, use_offset>;
};
template <typename Value, typename Mapped> struct KeyGetterForTypeImpl<HashJoin::Type::hashed, Value, Mapped>
{
    using Type = ColumnsHashing::HashMethodHashed<Value, Mapped, false, use_offset>;
};

template <HashJoin::Type type, typename Data>
struct KeyGetterForType
{
    using Value = typename Data::value_type;
    using Mapped_t = typename Data::mapped_type;
    using Mapped = std::conditional_t<std::is_const_v<Data>, const Mapped_t, Mapped_t>;
    using Type = typename KeyGetterForTypeImpl<type, Value, Mapped>::Type;
};
}