#ifndef MATADOR_CONVERT_HPP
#define MATADOR_CONVERT_HPP

#include "matador/utils/types.hpp"
#include "matador/utils/result.hpp"
//#include "matador/utils/date.hpp"
//#include "matador/utils/time.hpp"

//#include "matador/utils/placeholder.hpp"

#include <array>
#include <charconv>
#include <cstring>
#include <string>
#include <type_traits>

/*
 * Conversion matrix
 *       from> | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | bool | float | double | string | date | time | blob | placeholder | null
 *          to |      |       |       |       |       |        |        |        |      |       |        |        |      |      |      |             |
 * ------------+------+-------+-------+-------+-------+--------+--------+--------+------+-------+--------+--------+------+------+------+-------------+-----
 *        int8 |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  ok  |  ok   |  ok    |  try   |  ok  |  ok  |  try |     N/A     | N/A
 *       int16 |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  ok  |  ok   |  ok    |  try   |  ok  |  ok  |  try |     N/A     | N/A
 *       int32 |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  ok  |  ok   |  ok    |  try   |  ok  |  ok  |  try |     N/A     | N/A
 *       int64 |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  ok  |  ok   |  ok    |  try   |  ok  |  ok  |  try |     N/A     | N/A
 *       uint8 |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  ok  |  ok   |  ok    |  try   |  ok  |  ok  |  try |     N/A     | N/A
 *      uint16 |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  ok  |  ok   |  ok    |  try   |  ok  |  ok  |  try |     N/A     | N/A
 *      uint32 |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  ok  |  ok   |  ok    |  try   |  ok  |  ok  |  try |     N/A     | N/A
 *      uint64 |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  ok  |  ok   |  ok    |  try   |  ok  |  ok  |  try |     N/A     | N/A
 *        bool |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  ok  |  ok   |  ok    |  try   |  N/A |  N/A |  try |     N/A     | N/A
 *       float |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  ok  |  ok   |  ok    |  try   |  N/A |  N/A |  try |     N/A     | N/A
 *      double |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  ok  |  ok   |  ok    |  try   |  N/A |  N/A |  try |     N/A     | N/A
 *      string |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  ok  |  ok   |  ok    |   ok   |  ok  |  ok  |  N/A |     N/A     | N/A
 *        date |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  N/A |  N/A  |  N/A   |  try   |  ok  |  ok  |  N/A |     N/A     | N/A
 *        time |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  N/A |  N/A  |  N/A   |  try   |  ok  |  ok  |  N/A |     N/A     | N/A
 *        blob |  ok  |  ok   |  ok   |  ok   |   ok  |   ok   |   ok   |   ok   |  ok  |  ok   |  ok    |   ok   |  ok  |  ok  |  ok  |     N/A     | N/A
 * placeholder | N/A  |  N/A  |  N/A  |  N/A  |   N/A |   N/A  |   N/A  |   N/A  |  N/A |  N/A  |  N/A   |   N/A  |  N/A |  N/A |  N/A |     ok      | N/A
 *        null | N/A  |  N/A  |  N/A  |  N/A  |   N/A |   N/A  |   N/A  |   N/A  |  N/A |  N/A  |  N/A   |   N/A  |  N/A |  N/A |  N/A |     N/A     | ok
 *
 * from integral to date/time works, value is interpreted as std::chrono::timepoint
 * from integral to blob works, bytes of integral data will converted to blob
 * from boolean to blob works, byte of bool data will converted to blob
 * from floating point to blob works, bytes of floating point data will converted to blob
 * from date to blob works, bytes of date will converted to blob
 * from time to blob works, bytes of time will converted to blob
 * from string to blob works, bytes of string data will converted to blob
 * from floating point to integral works, fractions are truncated
 * from date/time to integral works, value will be converted from std::chrono::timepoint
 * from blob to integral works, value will be converted missing is filled with zero, rest is omitted
 * from blob to floating point works, value will be converted missing is filled with zero, rest is omitted
 * from blob to boolean works, value will be converted missing is filled with zero, rest is omitted
 */

namespace matador::utils {

enum class conversion_error {
  Ok,
  NotConvertable,
  MissingData
};

enum class conversion_policy {
  Strict,
  Relax
};


// template < typename DestType, typename SourceType >
// result<DestType, conversion_error> to(const SourceType &/*from*/);
// result<DestType, conversion_error> to(const SourceType &/*from*/, conversion_policy /*policy*/ = conversion_policy::Strict);

// {
  // return failure(conversion_error::NotConvertable);
// }

/*
 * Integral, Floating point & bool conversion
 */
template < typename DestType, typename SourceType >
result<DestType, conversion_error> to(const SourceType &source, std::enable_if_t<std::is_arithmetic_v<DestType> && std::is_arithmetic_v<SourceType>>* = nullptr)
{
  return ok(static_cast<DestType>(source));
}

template < typename DestType, typename SourceType >
result<DestType, conversion_error> to(const SourceType &source, std::enable_if_t<std::is_same_v<std::string, DestType> && std::is_same_v<std::string, SourceType>>* = nullptr)
{
  return ok(source);
}

template < typename DestType, typename SourceType >
result<DestType, conversion_error> to(const SourceType &source, std::enable_if_t<std::is_integral_v<SourceType> && !std::is_same_v<bool, SourceType> && std::is_same_v<DestType, std::string>>* = nullptr)
{
  std::array<char, 128> buffer{};
  auto [ptr, ec] = std::to_chars(buffer.data(), buffer.data() + buffer.size(), source, 10);
  if (ec == std::errc{}) {
    return ok(std::string(buffer.data(), ptr));
  }

  // return failure({ec, "couldn't convert value to std::string"});
  return failure(conversion_error::NotConvertable/*, "couldn't convert value to std::string"}*/);
}

template < typename DestType, typename SourceType >
result<DestType, conversion_error> to(const SourceType &source, std::enable_if_t<std::is_floating_point_v<SourceType> && std::is_same_v<DestType, std::string>>* = nullptr)
{
  std::array<char, 128> buffer{};
  auto [ptr, ec] = std::to_chars(buffer.data(), buffer.data() + buffer.size(), source, std::chars_format::general);
  if (ec == std::errc{}) {
    return ok(std::string(buffer.data(), ptr));
  }

  // return failure({ec, "couldn't convert value to std::string"});
  return failure(conversion_error::NotConvertable/*, "couldn't convert value to std::string"}*/);
}

template < typename DestType >
result<DestType, conversion_error> to(const std::string &source, std::enable_if_t<std::is_integral_v<DestType> && std::is_signed_v<DestType>>* = nullptr)
{
  if (source.empty()) {
    return failure(conversion_error::MissingData/*, "failed to convert empty string"}*/);
  }
  char *end;
  errno = 0;
  const auto result = strtoll(source.c_str(), &end, 10);
  if (errno == ERANGE) {
    return failure(conversion_error::NotConvertable/*, "failed to convert string value"}*/);
  }

  return ok(static_cast<DestType>(result));
}

template < typename DestType >
result<DestType, conversion_error> to(const std::string &source, std::enable_if_t<std::is_integral_v<DestType> && std::is_unsigned_v<DestType> && !std::is_same_v<DestType, bool>>* = nullptr)
{
  if (source.empty()) {
    return failure(conversion_error::MissingData/*, "failed to convert empty string"}*/);
  }
  char *end;
  errno = 0;
  const auto result = strtoull(source.c_str(), &end, 10);
  if (errno == ERANGE) {
    return failure(conversion_error::NotConvertable/*, "failed to convert string value"}*/);
  }

  return ok(static_cast<DestType>(result));
}

template < typename DestType >
result<DestType, conversion_error> to(const std::string &source, std::enable_if_t<std::is_floating_point_v<DestType>>* = nullptr)
{
  if (source.empty()) {
    return failure(conversion_error::MissingData/*, "failed to convert empty string"}*/);
  }
  char *end;
  errno = 0;
  const auto result = strtod(source.c_str(), &end);
  if (errno == ERANGE) {
    return failure(conversion_error::NotConvertable/*, "failed to convert string value"}*/);
  }

  return ok(static_cast<DestType>(result));
}

template < typename DestType >
result<DestType, conversion_error> to(const blob &source, std::enable_if_t<std::is_same_v<DestType, blob>>* = nullptr) {
  return ok(source);
}

// template < typename DestType >
// result<DestType, conversion_error> to(const std::string &source, std::enable_if_t<std::is_same_v<DestType, blob>>* = nullptr) {
//     if (source.empty()) {
//         return failure(conversion_error::MissingData/*, "failed to convert empty string"}*/);
//     }
//
// }
//
static std::unordered_map<std::string, bool> string_to_bool_map = {
  {"true", true},
  {"t", true},
  {"on", true},
  {"1", true},
  {"false", false},
  {"f", false},
  {"off", false},
  {"0", false}
};

template < typename DestType >
result<DestType, conversion_error> to(const std::string &source, std::enable_if_t<std::is_same_v<DestType, bool>>* = nullptr) {
  if (source.empty()) {
    return failure(conversion_error::MissingData);
  }
  const auto it = string_to_bool_map.find(source);
  if (it == string_to_bool_map.end()) {
    return failure(conversion_error::NotConvertable);
  }
  return ok(it->second);
}

template < typename DestType >
result<DestType, conversion_error> to(const char *source, std::enable_if_t<std::is_same_v<DestType, bool>>* = nullptr) {
  if (strlen(source) == 0) {
    return failure(conversion_error::MissingData);
  }
  const auto it = string_to_bool_map.find(source);
  if (it == string_to_bool_map.end()) {
    return failure(conversion_error::NotConvertable);
  }
  return ok(it->second);
}

template < typename DestType, typename SourceType >
result<DestType, conversion_error> to(const SourceType &source, std::enable_if_t<std::is_same_v<SourceType, bool> &&std::is_same_v<DestType, std::string>>* = nullptr) {
  return ok(std::string(source ? "true" : "false"));
}

template < typename DestType, typename SourceType >
result<DestType, conversion_error> to(const SourceType &/*source*/, std::enable_if_t<std::is_same_v<SourceType, blob> &&std::is_same_v<DestType, std::string>>* = nullptr) {
  return failure(conversion_error::NotConvertable);
}

template < typename DestType, typename SourceType >
result<DestType, conversion_error> to(const SourceType &source, std::enable_if_t<std::is_same_v<SourceType, const char*> &&std::is_same_v<DestType, std::string>>* = nullptr) {
  if (source == nullptr) {
    return ok(std::string{});
  }
  return ok(std::string(source));
}

template < typename DestType, typename SourceType >
result<DestType, conversion_error> to(const SourceType &/*source*/, std::enable_if_t<std::is_arithmetic_v<DestType> && std::is_same_v<SourceType, blob>>* = nullptr) {
  return failure(conversion_error::NotConvertable);
}

template < typename DestType, typename SourceType >
result<DestType, conversion_error> to(const SourceType &source, std::enable_if_t<std::is_integral_v<SourceType> && std::is_same_v<DestType, blob>>* = nullptr) {
  DestType result;
  result.resize(sizeof(source));
  std::memcpy(result.data(), &source, sizeof(source));

  return ok(result);
}

template < typename DestType, typename SourceType >
result<DestType, conversion_error> to(const SourceType &/*source*/, std::enable_if_t<std::is_floating_point_v<SourceType> && std::is_same_v<DestType, blob>>* = nullptr) {
  return failure(conversion_error::NotConvertable);
}

template < typename DestType, typename SourceType >
result<DestType, conversion_error> to(const SourceType &/*source*/, std::enable_if_t<std::is_same_v<SourceType, std::string> && std::is_same_v<DestType, blob>>* = nullptr) {
  return failure(conversion_error::NotConvertable);
}

template < typename DestType, typename SourceType >
result<DestType, conversion_error> to(const SourceType &/*source*/, std::enable_if_t<std::is_same_v<SourceType, const char*> && std::is_same_v<DestType, blob>>* = nullptr) {
  return failure(conversion_error::NotConvertable);
}

}

#endif //MATADOR_CONVERT_HPP