// A fuzzer for floating-point formatter.

// For the license information refer to format.h.

#include <fmt/format.h>

#include <cstdint>

#include <cstdlib>

#include <limits>

#include <stdexcept>

#include "fuzzer-common.h"

void check_round_trip(fmt::string_view format_str, double value) {

  auto buffer = fmt::memory_buffer();

  fmt::format_to(std::back_inserter(buffer), format_str, value);

  if (std::isnan(value)) {

    auto nan = std::signbit(value) ? "-nan" : "nan";

    if (fmt::string_view(buffer.data(), buffer.size()) != nan)

      throw std::runtime_error("round trip failure");

    return;

  }

  buffer.push_back('\0');

  char* ptr = nullptr;

  if (std::strtod(buffer.data(), &ptr) != value)

    throw std::runtime_error("round trip failure");

  if (ptr + 1 != buffer.end()) throw std::runtime_error("unparsed output");

}

extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {

  if (size <= sizeof(double) || !std::numeric_limits<double>::is_iec559)

    return 0;

  check_round_trip("{}", assign_from_buf<double>(data));

  // A larger than necessary precision is used to trigger the fallback

  // formatter.

  check_round_trip("{:.50g}", assign_from_buf<double>(data));

  return 0;

}