/*
 * Copyright (c) 2015 Cryptonomex, Inc., and contributors.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
 *
 * 1. Any modified source or binaries are used only with the BitShares network.
 *
 * 2. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
 *
 * 3. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <graphene/chain/protocol/memo.hpp>
#include <fc/crypto/aes.hpp>

namespace graphene { namespace chain {

void memo_data::set_message(const fc::ecc::private_key& priv, const fc::ecc::public_key& pub,
                            const string& msg, uint64_t custom_nonce)
{
   if( priv != fc::ecc::private_key() && public_key_type(pub) != public_key_type() )
   {
      from = priv.get_public_key();
      to = pub;
      if( custom_nonce == 0 )
      {
         uint64_t entropy = fc::sha224::hash(fc::ecc::private_key::generate())._hash[0];
         entropy <<= 32;
         entropy                                                     &= 0xff00000000000000;
         nonce = (fc::time_point::now().time_since_epoch().count()   &  0x00ffffffffffffff) | entropy;
      } else
         nonce = custom_nonce;
      auto secret = priv.get_shared_secret(pub);
      auto nonce_plus_secret = fc::sha512::hash(fc::to_string(nonce) + secret.str());
      string text = memo_message(digest_type::hash(msg)._hash[0], msg).serialize();
      message = fc::aes_encrypt( nonce_plus_secret, vector<char>(text.begin(), text.end()) );
   }
   else
   {
      auto text = memo_message(0, msg).serialize();
      message = vector<char>(text.begin(), text.end());
   }
}

string memo_data::get_message(const fc::ecc::private_key& priv,
                              const fc::ecc::public_key& pub)const
{
   if( from != public_key_type() )
   {
      auto secret = priv.get_shared_secret(pub);
      auto nonce_plus_secret = fc::sha512::hash(fc::to_string(nonce) + secret.str());
      auto plain_text = fc::aes_decrypt( nonce_plus_secret, message );
      auto result = memo_message::deserialize(string(plain_text.begin(), plain_text.end()));
      FC_ASSERT( result.checksum == uint32_t(digest_type::hash(result.text)._hash[0]) );
      return result.text;
   }
   else
   {
      return memo_message::deserialize(string(message.begin(), message.end())).text;
   }
}

string memo_message::serialize() const
{
   auto serial_checksum = string(sizeof(checksum), ' ');
   (uint32_t&)(*serial_checksum.data()) = checksum;
   return serial_checksum + text;
}

memo_message memo_message::deserialize(const string& serial)
{
   memo_message result;
   FC_ASSERT( serial.size() >= sizeof(result.checksum) );
   result.checksum = ((uint32_t&)(*serial.data()));
   result.text = serial.substr(sizeof(result.checksum));
   return result;
}

} } // graphene::chain