/*
* Default Engine
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/

#include <botan/def_eng.h>
#include <botan/parsing.h>
#include <botan/filters.h>
#include <botan/algo_factory.h>
#include <botan/mode_pad.h>
#include <memory>

#if defined(BOTAN_HAS_ECB)
  #include <botan/ecb.h>
#endif

#if defined(BOTAN_HAS_CBC)
  #include <botan/cbc.h>
#endif

#if defined(BOTAN_HAS_CTS)
  #include <botan/cts.h>
#endif

#if defined(BOTAN_HAS_CFB)
  #include <botan/cfb.h>
#endif

#if defined(BOTAN_HAS_OFB)
  #include <botan/ofb.h>
#endif

#if defined(BOTAN_HAS_CTR)
  #include <botan/ctr.h>
#endif

#if defined(BOTAN_HAS_EAX)
  #include <botan/eax.h>
#endif

#if defined(BOTAN_HAS_XTS)
  #include <botan/xts.h>
#endif

namespace Botan {

namespace {

/**
* Get a block cipher padding method by name
*/
BlockCipherModePaddingMethod* get_bc_pad(const std::string& algo_spec)
   {
   SCAN_Name request(algo_spec);

#if defined(BOTAN_HAS_CIPHER_MODE_PADDING)
   if(request.algo_name() == "PKCS7")
      return new PKCS7_Padding;

   if(request.algo_name() == "OneAndZeros")
      return new OneAndZeros_Padding;

   if(request.algo_name() == "X9.23")
      return new ANSI_X923_Padding;

   if(request.algo_name() == "NoPadding")
      return new Null_Padding;
#endif

   throw Algorithm_Not_Found(algo_spec);
   }

}

/*
* Get a cipher object
*/
Keyed_Filter* Default_Engine::get_cipher(const std::string& algo_spec,
                                         Cipher_Dir direction,
                                         Algorithm_Factory& af)
   {
   std::vector<std::string> algo_parts = split_on(algo_spec, '/');
   if(algo_parts.empty())
      throw Invalid_Algorithm_Name(algo_spec);

   const std::string cipher_name = algo_parts[0];

   // check if it is a stream cipher first (easy case)
   const StreamCipher* stream_cipher = af.prototype_stream_cipher(cipher_name);
   if(stream_cipher)
      return new StreamCipher_Filter(stream_cipher->clone());

   const BlockCipher* block_cipher = af.prototype_block_cipher(cipher_name);
   if(!block_cipher)
      return 0;

   if(algo_parts.size() != 2 && algo_parts.size() != 3)
      return 0;

   std::string mode = algo_parts[1];
   u32bit bits = 0;

   if(mode.find("CFB") != std::string::npos ||
      mode.find("EAX") != std::string::npos)
      {
      std::vector<std::string> algo_info = parse_algorithm_name(mode);
      mode = algo_info[0];
      if(algo_info.size() == 1)
         bits = 8*block_cipher->BLOCK_SIZE;
      else if(algo_info.size() == 2)
         bits = to_u32bit(algo_info[1]);
      else
         throw Invalid_Algorithm_Name(algo_spec);
      }

   std::string padding;
   if(algo_parts.size() == 3)
      padding = algo_parts[2];
   else
      padding = (mode == "CBC") ? "PKCS7" : "NoPadding";

   if(mode == "ECB" && padding == "CTS")
      return 0;
   else if((mode != "CBC" && mode != "ECB") && padding != "NoPadding")
      throw Invalid_Algorithm_Name(algo_spec);

#if defined(BOTAN_HAS_OFB)
   if(mode == "OFB")
      return new OFB(block_cipher->clone());
#endif

#if defined(BOTAN_HAS_CTR)
   if(mode == "CTR-BE")
      return new CTR_BE(block_cipher->clone());
#endif

#if defined(BOTAN_HAS_ECB)
   if(mode == "ECB")
      {
      if(direction == ENCRYPTION)
         return new ECB_Encryption(block_cipher->clone(), get_bc_pad(padding));
      else
         return new ECB_Decryption(block_cipher->clone(), get_bc_pad(padding));
      }
#endif

#if defined(BOTAN_HAS_CFB)
   if(mode == "CFB")
      {
      if(direction == ENCRYPTION)
         return new CFB_Encryption(block_cipher->clone(), bits);
      else
         return new CFB_Decryption(block_cipher->clone(), bits);
      }
#endif

   if(mode == "CBC")
      {
      if(padding == "CTS")
         {
#if defined(BOTAN_HAS_CTS)
         if(direction == ENCRYPTION)
            return new CTS_Encryption(block_cipher->clone());
         else
            return new CTS_Decryption(block_cipher->clone());
#else
         return 0;
#endif
         }

#if defined(BOTAN_HAS_CBC)
      if(direction == ENCRYPTION)
         return new CBC_Encryption(block_cipher->clone(),
                                   get_bc_pad(padding));
      else
         return new CBC_Decryption(block_cipher->clone(),
                                   get_bc_pad(padding));
#else
      return 0;
#endif
      }

#if defined(BOTAN_HAS_EAX)
   if(mode == "EAX")
      {
      if(direction == ENCRYPTION)
         return new EAX_Encryption(block_cipher->clone(), bits);
      else
         return new EAX_Decryption(block_cipher->clone(), bits);
      }
#endif

#if defined(BOTAN_HAS_XTS)
   if(mode == "XTS")
      {
      if(direction == ENCRYPTION)
         return new XTS_Encryption(block_cipher->clone());
      else
         return new XTS_Decryption(block_cipher->clone());
      }
#endif

   throw Algorithm_Not_Found("get_mode: " + cipher_name + "/" +
                             mode + "/" + padding);
   }

}