#include <cstdlib>
#include <iostream>
#include <vector>
#include <cstring>
#include <limits>
#include <string_view>
#include "fast_float/fast_float.h"
#include <cstdint>

#if __cplusplus >= 202300L
#include <stdfloat>
#endif

// If no characters match the pattern, value must be left unmodified
// (see https://github.com/fastfloat/fast_float/issues/424).
template <typename T> bool check_invalid_input_preserves_value() {
  std::vector<std::string_view> const invalid_inputs{"x",  "",   "-",  ".",
                                                     "e1", "-x", "na", "+"};
  for (auto const &f : invalid_inputs) {
    T result = T(42);
    auto answer = fast_float::from_chars(f.data(), f.data() + f.size(), result);
    if (answer.ec != std::errc::invalid_argument || answer.ptr != f.data()) {
      std::cerr << "Expected invalid_argument for input: \"" << f << "\""
                << std::endl;
      return false;
    }
    if (result != T(42)) {
      std::cerr << "Value modified on invalid input: \"" << f << "\" got "
                << result << std::endl;
      return false;
    }
  }
  // Out-of-range input must still store the documented value.
  std::string_view const too_large = "1e999";
  T result = T(42);
  auto answer = fast_float::from_chars(
      too_large.data(), too_large.data() + too_large.size(), result);
  if (answer.ec != std::errc::result_out_of_range ||
      result != std::numeric_limits<T>::infinity()) {
    std::cerr << "Expected infinity and result_out_of_range for \"1e999\""
              << std::endl;
    return false;
  }
  return true;
}

int main() {
  // Write some testcases for the parsing of floating point numbers in the
  // float32_t type. We use the from_chars function defined in this library.
#ifdef __STDCPP_FLOAT32_T__
  std::vector<std::float32_t> const float32_test_expected{
      123.456f, -78.9f, 0.0001f, 3.40282e+038f};
  std::vector<std::string_view> const float32_test{"123.456", "-78.9", "0.0001",
                                                   "3.40282e+038"};
  std::cout << "runing float32 test" << std::endl;
  for (std::size_t i = 0; i < float32_test.size(); ++i) {
    auto const &f = float32_test[i];
    std::float32_t result;
    auto answer = fast_float::from_chars(f.data(), f.data() + f.size(), result);

    if (answer.ec != std::errc()) {
      std::cerr << "Failed to parse: \"" << f << "\"" << std::endl;
      return EXIT_FAILURE;
    }
    if (result != float32_test_expected[i]) {
      std::cerr << "Test failed for input: \"" << f << "\" expected "
                << float32_test_expected[i] << " got " << result << std::endl;
      return EXIT_FAILURE;
    }
  }
  if (!check_invalid_input_preserves_value<std::float32_t>()) {
    return EXIT_FAILURE;
  }
#else
  std::cout << "No std::float32_t type available." << std::endl;
#endif

#ifdef __STDCPP_FLOAT64_T__
  // Test cases for std::float64_t
  std::vector<std::float64_t> const float64_test_expected{
      1.23e4, -5.67e-8, 1.7976931348623157e+308, -1.7976931348623157e+308};
  std::vector<std::string_view> const float64_test{"1.23e4", "-5.67e-8",
                                                   "1.7976931348623157e+308",
                                                   "-1.7976931348623157e+308"};
  std::cout << "runing float64 test" << std::endl;
  for (std::size_t i = 0; i < float64_test.size(); ++i) {
    auto const &f = float64_test[i];
    std::float64_t result;
    auto answer = fast_float::from_chars(f.data(), f.data() + f.size(), result);

    if (answer.ec != std::errc()) {
      std::cerr << "Failed to parse: \"" << f << "\"" << std::endl;
      return EXIT_FAILURE;
    }
    if (result != float64_test_expected[i]) {
      std::cerr << "Test failed for input: \"" << f << "\" expected "
                << float64_test_expected[i] << " got " << result << std::endl;
      return EXIT_FAILURE;
    }
  }
  if (!check_invalid_input_preserves_value<std::float64_t>()) {
    return EXIT_FAILURE;
  }
#else
  std::cout << "No std::float64_t type available." << std::endl;
#endif
  std::cout << "All tests passed successfully." << std::endl;
  return EXIT_SUCCESS;
}