#include <openssl/err.h>
#include <openssl/rand.h>

#include "HybridRandom.hpp"
#include "QuickCryptoUtils.hpp"

namespace margelo::nitro::crypto {

size_t checkSize(double size) {
  if (!CheckIsUint32(size)) {
    throw std::runtime_error("size must be uint32");
  }
  if (static_cast<uint32_t>(size) > pow(2, 31) - 1) {
    throw std::runtime_error("size must be less than 2^31 - 1");
  }
  return static_cast<size_t>(size);
}

size_t checkOffset(double offset) {
  if (!CheckIsUint32(offset)) {
    throw std::runtime_error("offset must be uint32");
  }
  return static_cast<size_t>(offset);
}

std::shared_ptr<Promise<std::shared_ptr<ArrayBuffer>>> HybridRandom::randomFill(const std::shared_ptr<ArrayBuffer>& buffer, double dOffset,
                                                                                double dSize) {
  // get owned NativeArrayBuffer before passing to sync function
  auto nativeBuffer = ToNativeArrayBuffer(buffer);

  return Promise<std::shared_ptr<ArrayBuffer>>::async(
      [this, nativeBuffer, dOffset, dSize]() { return this->randomFillSync(nativeBuffer, dOffset, dSize); });
};

std::shared_ptr<ArrayBuffer> HybridRandom::randomFillSync(const std::shared_ptr<ArrayBuffer>& buffer, double dOffset, double dSize) {
  size_t size = checkSize(dSize);
  size_t offset = checkOffset(dOffset);
  if (offset + size > buffer->size()) {
    throw std::runtime_error("offset + size must not exceed buffer length");
  }
  uint8_t* data = buffer->data();
  if (RAND_bytes(data + offset, static_cast<int>(size)) != 1) {
    throw std::runtime_error("error calling RAND_bytes: " + std::to_string(ERR_get_error()));
  }
  return buffer;
};

} // namespace margelo::nitro::crypto