text: // Copyright (c) 2012-2016, The CryptoNote developers, The Bytecoin developers
  // Copyright (c) 2016-2020, Karbo developers
  //
  // This file is part of Karbo.
  //
  // Karbo is free software: you can redistribute it and/or modify
  // it under the terms of the GNU Lesser General Public License as published by
  // the Free Software Foundation, either version 3 of the License, or
  // (at your option) any later version.
  //
  // Karbo is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  // GNU Lesser General Public License for more details.
  //
  // You should have received a copy of the GNU Lesser General Public License
  // along with Karbo.  If not, see <http://www.gnu.org/licenses/>.
  
  #pragma once
  
  #include <algorithm>
  #include <vector>
  #include <boost/variant.hpp>
  
  #include <CryptoNote.h>
  
  #define TX_EXTRA_PADDING_MAX_COUNT          255
  #define TX_EXTRA_NONCE_MAX_COUNT            255
  
  #define TX_EXTRA_TAG_PADDING                0x00
  #define TX_EXTRA_TAG_PUBKEY                 0x01
  #define TX_EXTRA_NONCE                      0x02
  #define TX_EXTRA_MERGE_MINING_TAG           0x03
  
  #define TX_EXTRA_NONCE_PAYMENT_ID           0x00
  
  namespace CryptoNote {
  
  struct TransactionExtraPadding {
    size_t size;
  };
  
  struct TransactionExtraPublicKey {
    Crypto::PublicKey publicKey;
  };
  
  struct TransactionExtraNonce {
    std::vector<uint8_t> nonce;
  };
  
  struct TransactionExtraMergeMiningTag {
    size_t depth;
    Crypto::Hash merkleRoot;
  };
  
  // tx_extra_field format, except tx_extra_padding and tx_extra_pub_key:
  //   varint tag;
  //   varint size;
  //   varint data[];
  typedef boost::variant<TransactionExtraPadding, TransactionExtraPublicKey, TransactionExtraNonce, TransactionExtraMergeMiningTag> TransactionExtraField;
  
  
  
  template<typename T>
  bool findTransactionExtraFieldByType(const std::vector<TransactionExtraField>& tx_extra_fields, T& field) {
    auto it = std::find_if(tx_extra_fields.begin(), tx_extra_fields.end(),
      [](const TransactionExtraField& f) { return typeid(T) == f.type(); });
  
    if (tx_extra_fields.end() == it)
      return false;
  
    field = boost::get<T>(*it);
    return true;
  }
  
  bool parseTransactionExtra(const std::vector<uint8_t>& tx_extra, std::vector<TransactionExtraField>& tx_extra_fields);
  bool writeTransactionExtra(std::vector<uint8_t>& tx_extra, const std::vector<TransactionExtraField>& tx_extra_fields);
  
  Crypto::PublicKey getTransactionPublicKeyFromExtra(const std::vector<uint8_t>& tx_extra);
  bool addTransactionPublicKeyToExtra(std::vector<uint8_t>& tx_extra, const Crypto::PublicKey& tx_pub_key);
  bool addExtraNonceToTransactionExtra(std::vector<uint8_t>& tx_extra, const BinaryArray& extra_nonce);
  void setPaymentIdToTransactionExtraNonce(BinaryArray& extra_nonce, const Crypto::Hash& payment_id);
  bool getPaymentIdFromTransactionExtraNonce(const BinaryArray& extra_nonce, Crypto::Hash& payment_id);
  bool appendMergeMiningTagToExtra(std::vector<uint8_t>& tx_extra, const TransactionExtraMergeMiningTag& mm_tag);
  bool getMergeMiningTagFromExtra(const std::vector<uint8_t>& tx_extra, TransactionExtraMergeMiningTag& mm_tag);
  
  bool createTxExtraWithPaymentId(const std::string& paymentIdString, std::vector<uint8_t>& extra);
  //returns false if payment id is not found or parse error
  bool getPaymentIdFromTxExtra(const std::vector<uint8_t>& extra, Crypto::Hash& paymentId);
  bool parsePaymentId(const std::string& paymentIdString, Crypto::Hash& paymentId);
  
  }
  