/*

* Hex Encoding and Decoding

* (C) 2010,2020 Jack Lloyd

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#include <botan/hex.h>

#include <botan/exceptn.h>

#include <botan/mem_ops.h>

#include <botan/internal/charset.h>

#include <botan/internal/ct_utils.h>

#include <botan/internal/fmt.h>

namespace Botan {

namespace {

char hex_encode_nibble(uint8_t n, bool uppercase) {

   BOTAN_DEBUG_ASSERT(n <= 15);

   const auto in_09 = CT::Mask<uint8_t>::is_lt(n, 10);

   const char c_09 = n + '0';

   const char c_af = n + (uppercase ? 'A' : 'a') - 10;

   return in_09.select(c_09, c_af);

}

}  // namespace

void hex_encode(char output[], const uint8_t input[], size_t input_length, bool uppercase) {

   for(size_t i = 0; i != input_length; ++i) {

      const uint8_t n0 = (input[i] >> 4) & 0xF;

      const uint8_t n1 = (input[i]) & 0xF;

      output[2 * i] = hex_encode_nibble(n0, uppercase);

      output[2 * i + 1] = hex_encode_nibble(n1, uppercase);

   }

}

std::string hex_encode(const uint8_t input[], size_t input_length, bool uppercase) {

   std::string output(2 * input_length, 0);

   if(input_length) {

      hex_encode(&output.front(), input, input_length, uppercase);

   }

   return output;

}

namespace {

uint8_t hex_char_to_bin(char input) {

   const uint8_t c = static_cast<uint8_t>(input);

   const auto is_alpha_upper = CT::Mask<uint8_t>::is_within_range(c, uint8_t('A'), uint8_t('F'));

   const auto is_alpha_lower = CT::Mask<uint8_t>::is_within_range(c, uint8_t('a'), uint8_t('f'));

   const auto is_decimal = CT::Mask<uint8_t>::is_within_range(c, uint8_t('0'), uint8_t('9'));

   const auto is_whitespace =

      CT::Mask<uint8_t>::is_any_of(c, {uint8_t(' '), uint8_t('\t'), uint8_t('\n'), uint8_t('\r')});

   const uint8_t c_upper = c - uint8_t('A') + 10;

   const uint8_t c_lower = c - uint8_t('a') + 10;

   const uint8_t c_decim = c - uint8_t('0');

   uint8_t ret = 0xFF;  // default value

   ret = is_alpha_upper.select(c_upper, ret);

   ret = is_alpha_lower.select(c_lower, ret);

   ret = is_decimal.select(c_decim, ret);

   ret = is_whitespace.select(0x80, ret);

   return ret;

}

}  // namespace

size_t hex_decode(uint8_t output[], const char input[], size_t input_length, size_t& input_consumed, bool ignore_ws) {

   uint8_t* out_ptr = output;

   bool top_nibble = true;

   clear_mem(output, input_length / 2);

   for(size_t i = 0; i != input_length; ++i) {

      const uint8_t bin = hex_char_to_bin(input[i]);

      if(bin >= 0x10) {

         if(bin == 0x80 && ignore_ws) {

            continue;

         }

         throw Invalid_Argument(fmt("hex_decode: invalid character '{}'", format_char_for_display(input[i])));

      }

      if(top_nibble) {

         *out_ptr |= bin << 4;

      } else {

         *out_ptr |= bin;

      }

      top_nibble = !top_nibble;

      if(top_nibble) {

         ++out_ptr;

      }

   }

   input_consumed = input_length;

   size_t written = (out_ptr - output);

   /*

   * We only got half of a uint8_t at the end; zap the half-written

   * output and mark it as unread

   */

   if(!top_nibble) {

      *out_ptr = 0;

      input_consumed -= 1;

   }

   return written;

}

size_t hex_decode(uint8_t output[], const char input[], size_t input_length, bool ignore_ws) {

   size_t consumed = 0;

   size_t written = hex_decode(output, input, input_length, consumed, ignore_ws);

   if(consumed != input_length) {

      throw Invalid_Argument("hex_decode: input did not have full bytes");

   }

   return written;

}

size_t hex_decode(uint8_t output[], std::string_view input, bool ignore_ws) {

   return hex_decode(output, input.data(), input.length(), ignore_ws);

}

size_t hex_decode(std::span<uint8_t> output, std::string_view input, bool ignore_ws) {

   return hex_decode(output.data(), input.data(), input.length(), ignore_ws);

}

secure_vector<uint8_t> hex_decode_locked(const char input[], size_t input_length, bool ignore_ws) {

   secure_vector<uint8_t> bin(1 + input_length / 2);

   size_t written = hex_decode(bin.data(), input, input_length, ignore_ws);

   bin.resize(written);

   return bin;

}

secure_vector<uint8_t> hex_decode_locked(std::string_view input, bool ignore_ws) {

   return hex_decode_locked(input.data(), input.size(), ignore_ws);

}

std::vector<uint8_t> hex_decode(const char input[], size_t input_length, bool ignore_ws) {

   std::vector<uint8_t> bin(1 + input_length / 2);

   size_t written = hex_decode(bin.data(), input, input_length, ignore_ws);

   bin.resize(written);

   return bin;

}

std::vector<uint8_t> hex_decode(std::string_view input, bool ignore_ws) {

   return hex_decode(input.data(), input.size(), ignore_ws);

}

}  // namespace Botan