#include <graphene/peerplays_sidechain/ethereum/transaction.hpp>

#include <boost/algorithm/hex.hpp>
#include <boost/property_tree/json_parser.hpp>
#include <boost/property_tree/ptree.hpp>

#include <secp256k1.h>
#include <sha3/sha3.h>

#include <fc/crypto/elliptic.hpp>
#include <fc/crypto/hex.hpp>

#include <graphene/peerplays_sidechain/ethereum/encoders.hpp>
#include <graphene/peerplays_sidechain/ethereum/decoders.hpp>
#include <graphene/peerplays_sidechain/ethereum/types.hpp>
#include <graphene/peerplays_sidechain/ethereum/utils.hpp>

namespace graphene { namespace peerplays_sidechain { namespace ethereum {


namespace
{

int is_even(char last_char)
{
   switch (last_char)
   {
   case '0':
      return 1;
   case '2':
      return 1;
   case '4':
      return 1;
   case '6':
      return 1;
   case '8':
      return 1;
   case 'A':
      return 1;
   case 'C':
      return 1;
   case 'E':
      return 1;
   default:
      return -1;
   }
}

}

const secp256k1_context *eth_context() {
   static secp256k1_context *ctx = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY | SECP256K1_CONTEXT_SIGN);
   return ctx;
}

//! transaction

const transaction& transaction::sign(const std::string& private_key) const
{
   return *this;
}

std::string transaction::serialize() const
{
   boost::property_tree::ptree pt;
   pt.put("from", from);
   pt.put("to", to);
   pt.put("data", data);

   std::stringstream ss;
   boost::property_tree::json_parser::write_json(ss, pt);
   return ss.str();
}

void transaction::deserialize(const std::string& raw_tx)
{
   std::stringstream ss_tx(raw_tx);
   boost::property_tree::ptree tx_json;
   boost::property_tree::read_json(ss_tx, tx_json);

   if(tx_json.count("from"))
      from = tx_json.get<std::string>("from");
   if(tx_json.count("to"))
      to = tx_json.get<std::string>("to");
   if(tx_json.count("data"))
      data = tx_json.get<std::string>("data");
}

//! raw_transaction

signed_transaction raw_transaction::sign(const std::string& private_key) const
{
   //! Prepare signed transaction
   signed_transaction tr;
   tr.nonce = nonce;
   tr.gas_price = gas_price;
   tr.gas_limit = gas_limit;
   tr.to = to;
   tr.value = value;
   tr.data = data;

   //! Calculate keccak hash of transaction
   bytes hash;
   hash.resize(32);
   const auto transaction_string = boost::algorithm::unhex( serialize() );
   keccak_256((const unsigned char *) transaction_string.data(), transaction_string.size(), (unsigned char *) hash.data());

   const bytes priv_key = parse_hex(private_key);

   secp256k1_ecdsa_signature sign;
   FC_ASSERT(secp256k1_ecdsa_sign(eth_context(), &sign, (const unsigned char *)hash.data(), (const unsigned char *)priv_key.data(), secp256k1_nonce_function_rfc6979, nullptr));

   fc::ecc::compact_signature result;
   FC_ASSERT(secp256k1_ecdsa_signature_serialize_compact(eth_context(), (unsigned char*) result.begin() + 1, &sign));

   bytes r;
   for(int i = 1; i < 33; i++)
      r.emplace_back((char) result.at(i));
   bytes s;
   for(int i = 33; i < 65; i++)
      s.emplace_back((char) result.at(i));

   bytes v;
   if(is_even(r.back()))
      v = {37};
   else
      v = {38};

   tr.v = fc::to_hex((char *)&v[0], v.size());
   tr.r = fc::to_hex((char *)&r[0], r.size());
   tr.s = fc::to_hex((char *)&s[0], s.size());

   return tr;
}

std::string raw_transaction::serialize() const
{
   rlp_encoder encoder;
   const std::string serialized = encoder.encode(nonce) +
                                  encoder.encode(gas_price) +
                                  encoder.encode(gas_limit) +
                                  encoder.encode(to) +
                                  encoder.encode(value) +
                                  encoder.encode(data) +
                                  encoder.encode(chain_id) +
                                  encoder.encode("") +
                                  encoder.encode("");

   return bytes2hex( encoder.encode_length(serialized.size(), 192) + serialized );
}

void raw_transaction::deserialize(const std::string& raw_tx)
{
   rlp_decoder decoder;
   const auto rlp_array = decoder.decode(raw_tx);
   FC_ASSERT(rlp_array.size() >= 7, "Wrong rlp format");

   nonce = rlp_array.at(0);
   gas_price = rlp_array.at(1);
   gas_limit = rlp_array.at(2);
   to = rlp_array.at(3);
   value = rlp_array.at(4);
   data = rlp_array.at(5);
   chain_id = rlp_array.at(6);
}

//! signed_transaction

std::string signed_transaction::serialize() const
{
   rlp_encoder encoder;
   const std::string serialized = encoder.encode(nonce) +
                                  encoder.encode(gas_price) +
                                  encoder.encode(gas_limit) +
                                  encoder.encode(to) +
                                  encoder.encode(value) +
                                  encoder.encode(data) +
                                  encoder.encode(v) +
                                  encoder.encode(r) +
                                  encoder.encode(s);

   return bytes2hex( encoder.encode_length(serialized.size(), 192) + serialized );
}

void signed_transaction::deserialize(const std::string& raw_tx)
{
   rlp_decoder decoder;
   const auto rlp_array = decoder.decode(raw_tx);
   FC_ASSERT(rlp_array.size() >= 9, "Wrong rlp format");

   nonce = rlp_array.at(0);
   gas_price = rlp_array.at(1);
   gas_limit = rlp_array.at(2);
   to = rlp_array.at(3);
   value = rlp_array.at(4);
   data = rlp_array.at(5);
   v = rlp_array.at(6);
   r = rlp_array.at(7);
   s = rlp_array.at(8);
}

}}} // namespace graphene::peerplays_sidechain::ethereum