/*

* Character Set Handling

* (C) 1999-2007,2021 Jack Lloyd

*

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

*/

#include <botan/internal/charset.h>

#include <botan/internal/loadstor.h>

#include <botan/exceptn.h>

namespace Botan {

namespace {

void append_utf8_for(std::string& s, uint32_t c)

   {

   if(c >= 0xD800 && c < 0xE000)

      throw Decoding_Error("Invalid Unicode character");

   if(c <= 0x7F)

      {

      const uint8_t b0 = static_cast<uint8_t>(c);

      s.push_back(static_cast<char>(b0));

      }

   else if(c <= 0x7FF)

      {

      const uint8_t b0 = 0xC0 | static_cast<uint8_t>(c >> 6);

      const uint8_t b1 = 0x80 | static_cast<uint8_t>(c & 0x3F);

      s.push_back(static_cast<char>(b0));

      s.push_back(static_cast<char>(b1));

      }

   else if(c <= 0xFFFF)

      {

      const uint8_t b0 = 0xE0 | static_cast<uint8_t>(c >> 12);

      const uint8_t b1 = 0x80 | static_cast<uint8_t>((c >> 6) & 0x3F);

      const uint8_t b2 = 0x80 | static_cast<uint8_t>(c & 0x3F);

      s.push_back(static_cast<char>(b0));

      s.push_back(static_cast<char>(b1));

      s.push_back(static_cast<char>(b2));

      }

   else if(c <= 0x10FFFF)

      {

      const uint8_t b0 = 0xF0 | static_cast<uint8_t>(c >> 18);

      const uint8_t b1 = 0x80 | static_cast<uint8_t>((c >> 12) & 0x3F);

      const uint8_t b2 = 0x80 | static_cast<uint8_t>((c >> 6) & 0x3F);

      const uint8_t b3 = 0x80 | static_cast<uint8_t>(c & 0x3F);

      s.push_back(static_cast<char>(b0));

      s.push_back(static_cast<char>(b1));

      s.push_back(static_cast<char>(b2));

      s.push_back(static_cast<char>(b3));

      }

   else

      throw Decoding_Error("Invalid Unicode character");

   }

}

std::string ucs2_to_utf8(const uint8_t ucs2[], size_t len)

   {

   if(len % 2 != 0)

      throw Decoding_Error("Invalid length for UCS-2 string");

   const size_t chars = len / 2;

   std::string s;

   for(size_t i = 0; i != chars; ++i)

      {

      const uint32_t c = load_be<uint16_t>(ucs2, i);

      append_utf8_for(s, c);

      }

   return s;

   }

std::string ucs4_to_utf8(const uint8_t ucs4[], size_t len)

   {

   if(len % 4 != 0)

      throw Decoding_Error("Invalid length for UCS-4 string");

   const size_t chars = len / 4;

   std::string s;

   for(size_t i = 0; i != chars; ++i)

      {

      const uint32_t c = load_be<uint32_t>(ucs4, i);

      append_utf8_for(s, c);

      }

   return s;

   }

/*

* Convert from ISO 8859-1 to UTF-8

*/

std::string latin1_to_utf8(const uint8_t chars[], size_t len)

   {

   std::string s;

   for(size_t i = 0; i != len; ++i)

      {

      const uint32_t c = static_cast<uint8_t>(chars[i]);

      append_utf8_for(s, c);

      }

   return s;

   }

}