// Released under the MIT License. See LICENSE for details.
// Derived from code licensed as follows:

/*
   base64.cpp and base64.h

   Copyright (C) 2004-2008 René Nyffenegger

   This source code is provided 'as-is', without any express or implied
   warranty. In no event will the author be held liable for any damages
   arising from the use of this software.

   Permission is granted to anyone to use this software for any purpose,
   including commercial applications, and to alter it and redistribute it
   freely, subject to the following restrictions:

   1. The origin of this source code must not be misrepresented; you must not
   claim that you wrote the original source code. If you use this source code
   in a product, an acknowledgment in the product documentation would be
   appreciated but is not required.

   2. Altered source versions must be plainly marked as such, and must not be
   misrepresented as being the original source code.

   3. This notice may not be removed or altered from any source distribution.

   René Nyffenegger rene.nyffenegger@adp-gmbh.ch

*/
#include "ballistica/shared/generic/base64.h"

namespace ballistica {

// NOLINTNEXTLINE(cert-err58-cpp)
static const std::string* base64_chars_non_urlsafe = new std::string(
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789+/");

// NOLINTNEXTLINE(cert-err58-cpp)
static const std::string* base64_chars_urlsafe = new std::string(
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789+/");

static inline auto is_base64(unsigned char c, bool urlsafe) -> bool {
  if (urlsafe) {
    return (isalnum(c) || (c == '-') || (c == '_'));
  } else {
    return (isalnum(c) || (c == '+') || (c == '/'));
  }
}

auto base64_encode(const unsigned char* bytes_to_encode, unsigned int in_len,
                   bool urlsafe) -> std::string {
  std::string ret;
  int i = 0;
  // int j = 0;
  unsigned char char_array_3[3];
  unsigned char char_array_4[4];

  static const std::string& base64_chars =
      urlsafe ? *base64_chars_urlsafe : *base64_chars_non_urlsafe;

  while (in_len--) {
    char_array_3[i++] = *(bytes_to_encode++);
    if (i == 3) {
      char_array_4[0] =
          static_cast<unsigned char>((char_array_3[0] & 0xfcu) >> 2u);
      char_array_4[1] =
          static_cast<unsigned char>(((char_array_3[0] & 0x03u) << 4u)
                                     + ((char_array_3[1] & 0xf0u) >> 4u));
      char_array_4[2] =
          static_cast<unsigned char>(((char_array_3[1] & 0x0fu) << 2u)
                                     + ((char_array_3[2] & 0xc0u) >> 6u));
      char_array_4[3] = static_cast<unsigned char>(char_array_3[2] & 0x3fu);

      for (i = 0; (i < 4); i++) ret += base64_chars[char_array_4[i]];
      i = 0;
    }
  }

  if (i) {
    for (int j = i; j < 3; j++) {
      char_array_3[j] = '\0';
    }
    char_array_4[0] =
        static_cast<unsigned char>((char_array_3[0] & 0xfcu) >> 2u);
    char_array_4[1] = static_cast<unsigned char>(
        ((char_array_3[0] & 0x03u) << 4u) + ((char_array_3[1] & 0xf0u) >> 4u));
    char_array_4[2] = static_cast<unsigned char>(
        ((char_array_3[1] & 0x0fu) << 2u) + ((char_array_3[2] & 0xc0u) >> 6u));
    char_array_4[3] = static_cast<unsigned char>(char_array_3[2u] & 0x3fu);
    for (int j = 0; (j < i + 1); j++) {
      ret += base64_chars[char_array_4[j]];
    }
    while ((i++ < 3)) {
      ret += '=';
    }
  }

  return ret;
}

auto base64_decode(const std::string& encoded_string, bool urlsafe)
    -> std::string {
  int in_len = static_cast<int>(encoded_string.size());
  int i = 0;
  // int j = 0;
  int in_ = 0;
  unsigned char char_array_4[4], char_array_3[3];
  std::string ret;

  static const std::string& base64_chars =
      urlsafe ? *base64_chars_urlsafe : *base64_chars_non_urlsafe;

  while (in_len-- && (encoded_string[in_] != '=')
         && is_base64((unsigned char)encoded_string[in_], urlsafe)) {
    char_array_4[i++] = (unsigned char)encoded_string[in_];
    in_++;
    if (i == 4) {
      for (i = 0; i < 4; i++) {
        char_array_4[i] = static_cast<unsigned char>(
            base64_chars.find(static_cast<char>(char_array_4[i])));
      }

      char_array_3[0] = static_cast<unsigned char>(
          (char_array_4[0] << 2u) + ((char_array_4[1] & 0x30u) >> 4u));
      char_array_3[1] = static_cast<unsigned char>(
          ((char_array_4[1] & 0xfu) << 4u) + ((char_array_4[2] & 0x3cu) >> 2u));
      char_array_3[2] = static_cast<unsigned char>(
          ((char_array_4[2] & 0x3u) << 6u) + char_array_4[3]);

      for (i = 0; (i < 3); i++) ret += static_cast<char>(char_array_3[i]);
      i = 0;
    }
  }
  if (i) {
    for (int j = i; j < 4; j++) {
      char_array_4[j] = 0;
    }
    for (int j = 0; j < 4; j++) {  // NOLINT(modernize-loop-convert)
      char_array_4[j] = static_cast<unsigned char>(
          base64_chars.find(static_cast<char>(char_array_4[j])));
    }
    char_array_3[0] = static_cast<unsigned char>(
        (char_array_4[0] << 2u) + ((char_array_4[1] & 0x30u) >> 4u));
    char_array_3[1] = static_cast<unsigned char>(
        ((char_array_4[1] & 0xfu) << 4u) + ((char_array_4[2] & 0x3cu) >> 2u));
    char_array_3[2] = static_cast<unsigned char>(
        ((char_array_4[2] & 0x3u) << 6u) + char_array_4[3]);
    for (int j = 0; (j < i - 1); j++) {
      ret += static_cast<char>(char_array_3[j]);
    }
  }
  return ret;
}

}  // namespace ballistica
