#ifndef SIMDUTF_ERROR_H

#define SIMDUTF_ERROR_H

#include <string_view>

namespace simdutf {

enum error_code {

  SUCCESS = 0,

  HEADER_BITS, // Any byte must have fewer than 5 header bits.

  TOO_SHORT,   // The leading byte must be followed by N-1 continuation bytes,

               // where N is the UTF-8 character length This is also the error

               // when the input is truncated.

  TOO_LONG,    // We either have too many consecutive continuation bytes or the

               // string starts with a continuation byte.

  OVERLONG, // The decoded character must be above U+7F for two-byte characters,

            // U+7FF for three-byte characters, and U+FFFF for four-byte

            // characters.

  TOO_LARGE, // The decoded character must be less than or equal to

             // U+10FFFF,less than or equal than U+7F for ASCII OR less than

             // equal than U+FF for Latin1

  SURROGATE, // The decoded character must be not be in U+D800...DFFF (UTF-8 or

             // UTF-32)

             // OR

             // a high surrogate must be followed by a low surrogate

             // and a low surrogate must be preceded by a high surrogate

             // (UTF-16)

             // OR

             // there must be no surrogate at all and one is

             // found (Latin1 functions)

             // OR

             // *specifically* for the function

             // utf8_length_from_utf16_with_replacement, a surrogate (whether

             // in error or not) has been found (I.e., whether we are in the

             // Basic Multilingual Plane or not).

  INVALID_BASE64_CHARACTER, // Found a character that cannot be part of a valid

                            // base64 string. This may include a misplaced

                            // padding character ('=').

  BASE64_INPUT_REMAINDER,   // The base64 input terminates with a single

                            // character, excluding padding (=). It is also used

                            // in strict mode when padding is not adequate.

  BASE64_EXTRA_BITS,        // The base64 input terminates with non-zero

                            // padding bits.

  OUTPUT_BUFFER_TOO_SMALL,  // The provided buffer is too small.

  OTHER                     // Not related to validation/transcoding.

};

inline std::string_view error_to_string(error_code code) noexcept {

  switch (code) {

  case SUCCESS:

    return "SUCCESS";

  case HEADER_BITS:

    return "HEADER_BITS";

  case TOO_SHORT:

    return "TOO_SHORT";

  case TOO_LONG:

    return "TOO_LONG";

  case OVERLONG:

    return "OVERLONG";

  case TOO_LARGE:

    return "TOO_LARGE";

  case SURROGATE:

    return "SURROGATE";

  case INVALID_BASE64_CHARACTER:

    return "INVALID_BASE64_CHARACTER";

  case BASE64_INPUT_REMAINDER:

    return "BASE64_INPUT_REMAINDER";

  case BASE64_EXTRA_BITS:

    return "BASE64_EXTRA_BITS";

  case OUTPUT_BUFFER_TOO_SMALL:

    return "OUTPUT_BUFFER_TOO_SMALL";

  default:

    return "OTHER";

  }

}

struct result {

  error_code error;

  size_t count; // In case of error, indicates the position of the error. In

                // case of success, indicates the number of code units

                // validated/written.

  simdutf_really_inline simdutf_constexpr23 result() noexcept

      : error{error_code::SUCCESS}, count{0} {}

  simdutf_really_inline simdutf_constexpr23 result(error_code err,

                                                   size_t pos) noexcept

      : error{err}, count{pos} {}

  simdutf_really_inline simdutf_constexpr23 bool is_ok() const noexcept {

    return error == error_code::SUCCESS;

  }

  simdutf_really_inline simdutf_constexpr23 bool is_err() const noexcept {

    return error != error_code::SUCCESS;

  }

};

struct full_result {

  error_code error;

  size_t input_count;

  size_t output_count;

  bool padding_error = false; // true if the error is due to padding, only

                              // meaningful when error is not SUCCESS

  simdutf_really_inline simdutf_constexpr23 full_result() noexcept

      : error{error_code::SUCCESS}, input_count{0}, output_count{0} {}

  simdutf_really_inline simdutf_constexpr23 full_result(error_code err,

                                                        size_t pos_in,

                                                        size_t pos_out) noexcept

      : error{err}, input_count{pos_in}, output_count{pos_out} {}

  simdutf_really_inline simdutf_constexpr23 full_result(

      error_code err, size_t pos_in, size_t pos_out, bool padding_err) noexcept

      : error{err}, input_count{pos_in}, output_count{pos_out},

        padding_error{padding_err} {}

  simdutf_really_inline simdutf_constexpr23 operator result() const noexcept {

    if (error == error_code::SUCCESS) {

      return result{error, output_count};

    } else {

      return result{error, input_count};

    }

  }

};

struct utf8_result {

  error_code error;

  size_t input_count;

  size_t continuation_count;

  size_t four_byte_count;

  simdutf_really_inline simdutf_constexpr23 utf8_result() noexcept

      : error{error_code::SUCCESS}, input_count{0}, continuation_count{0},

        four_byte_count{0} {}

  simdutf_really_inline simdutf_constexpr23

  utf8_result(error_code err, size_t pos_in, size_t continuation_count_,

              size_t four_byte_count_) noexcept

      : error{err}, input_count{pos_in},

        continuation_count{continuation_count_},

        four_byte_count{four_byte_count_} {}

  simdutf_really_inline simdutf_constexpr23 size_t

  utf16_length() const noexcept {

    return input_count - continuation_count + four_byte_count;

  }

  // The number of code points in the valid prefix, which is also the number of

  // UTF-32 code units.

  simdutf_really_inline simdutf_constexpr23 size_t

  utf32_length() const noexcept {

    return input_count - continuation_count;

  }

};

// UTF-16 size of a possibly ill-formed UTF-8 string, plus the first few

// ill-formed subsequences. Pass this to convert_utf8_to_utf16_with_replacement

// on the same bytes. error_offset entries are byte indexes from the start of

// that input. count is always the full number of char16_t. more_errors is

// true when the input has ill-formed subsequences past the stored ones.

struct utf8_to_utf16_result {

  static constexpr size_t max_errors = 16;

  error_code error;

  size_t count;

  size_t error_count;

  bool more_errors;

  size_t error_offset[max_errors];

  simdutf_really_inline simdutf_constexpr23 utf8_to_utf16_result() noexcept

      : error{error_code::SUCCESS}, count{0}, error_count{0},

        more_errors{false}, error_offset{} {}

};

} // namespace simdutf

#endif