#include <cpp-utils/data/SerializationHelper.h>

#include "RandomPadding.h"

#include "../logging/logging.h"

#include "../random/Random.h"

using boost::optional;

using namespace cpputils::logging;

namespace cpputils {

Data RandomPadding::add(const Data &data, size_t targetSize) {

uint32_t size = data.size();

if (size >= targetSize - sizeof(size)) {

throw std::runtime_error("Data too large. We should increase padding target size.");

}

Data randomData = Random::PseudoRandom().get(targetSize-sizeof(size)-size);

ASSERT(sizeof(size) + size + randomData.size() == targetSize, "Calculated size of randomData incorrectly");

Data result(targetSize);

serialize<uint32_t>(result.data(), size);

std::memcpy(result.dataOffset(sizeof(size)), data.data(), size);

std::memcpy(result.dataOffset(sizeof(size)+size), randomData.data(), randomData.size());

return result;

}

optional<Data> RandomPadding::remove(const Data &data) {

uint32_t size = deserialize<uint32_t>(data.data());

if(sizeof(size) + size >= data.size()) {

LOG(ERR, "Config file is invalid: Invalid padding.");

return boost::none;

};

Data result(size);

std::memcpy(result.data(), data.dataOffset(sizeof(size)), size);

return result;

}

}