#pragma once

#include "schema.hpp"

#include <forstio/buffer.hpp>
#include <forstio/error.hpp>

#include <cstdint>
#include <cstring>

namespace saw {
/**
 * Helper class to encode/decode any primitive type into/from litte endian.
 * The shift class does this by shifting bytes. This type of procedure is
 * platform independent. So it does not matter if the memory layout is
 * little endian or big endian
 */
template<typename T> class shift_stream_value {
	static_assert(always_false<T>, "Shift Stream Value only supports Primitives");
};

template <typename T, size_t N> class shift_stream_value<schema::Primitive<T,N>> {
public:
	inline static error_or<void> decode(typename native_data_type<schema::Primitive<T,N>>::type &val, buffer &buff) {
		if (buff.read_composite_length() < N) {
			return make_error<err::buffer_exhausted>();
		}

		typename native_data_type<schema::Primitive<schema::UnsignedInteger,N>>::type raw = 0;

		for (size_t i = 0; i < N; ++i) {
			raw |= (static_cast<typename native_data_type<schema::Primitive<T,N>>::type>(buff.read(i)) << (i * 8));
		}

		memcpy(&val, &raw, N);
		buff.read_advance(N);

		return void_t{};
	}

	inline static error_or<void> encode(const typename native_data_type<schema::Primitive<T,N>>::type &val, buffer &buff) {
		error err = buff.write_require_length(N);
		if (err.failed()) {
			return err;
		}

		typename native_data_type<schema::Primitive<schema::UnsignedInteger,N>>::type raw{};
		memcpy(&raw, &val, N);

		for (size_t i = 0; i < N; ++i) {
			buff.write(i) = raw >> (i * 8);
		}

		buff.write_advance(N);

		return void_t{};
	}

	inline static size_t size() { return N; }
};

template <typename T> using stream_value = shift_stream_value<T>;

} // namespace saw