text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2019 The Bitcoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #ifndef BITCOIN_PRIMITIVES_TRANSACTION_H
  #define BITCOIN_PRIMITIVES_TRANSACTION_H
  
  #include <stdint.h>
  #include <amount.h>
  #include <script/script.h>
  #include <serialize.h>
  #include <uint256.h>
  
  #include <version.h>
  
  static const int SERIALIZE_TRANSACTION_NO_WITNESS = 0x40000000;
  
  /** An outpoint - a combination of a transaction hash and an index n into its vout */
  class COutPoint
  {
  public:
      uint256 hash;
      uint32_t n;
  
      static constexpr uint32_t NULL_INDEX = std::numeric_limits<uint32_t>::max();
  
      COutPoint(): n(NULL_INDEX) { }
      COutPoint(const uint256& hashIn, uint32_t nIn): hash(hashIn), n(nIn) { }
  
      ADD_SERIALIZE_METHODS;
  
      template <typename Stream, typename Operation>
      inline void SerializationOp(Stream& s, Operation ser_action) {
          READWRITE(hash);
          READWRITE(n);
      }
  
      void SetNull() { hash.SetNull(); n = NULL_INDEX; }
      bool IsNull() const { return (hash.IsNull() && n == NULL_INDEX); }
  
      friend bool operator<(const COutPoint& a, const COutPoint& b)
      {
          int cmp = a.hash.Compare(b.hash);
          return cmp < 0 || (cmp == 0 && a.n < b.n);
      }
  
      friend bool operator==(const COutPoint& a, const COutPoint& b)
      {
          return (a.hash == b.hash && a.n == b.n);
      }
  
      friend bool operator!=(const COutPoint& a, const COutPoint& b)
      {
          return !(a == b);
      }
  
      std::string ToString() const;
  };
  
  /** An input of a transaction.  It contains the location of the previous
   * transaction's output that it claims and a signature that matches the
   * output's public key.
   */
  class CTxIn
  {
  public:
      COutPoint prevout;
      CScript scriptSig;
      uint32_t nSequence;
      CScriptWitness scriptWitness; //!< Only serialized through CTransaction
  
      /* Setting nSequence to this value for every input in a transaction
       * disables nLockTime. */
      static const uint32_t SEQUENCE_FINAL = 0xffffffff;
  
      /* Below flags apply in the context of BIP 68*/
      /* If this flag set, CTxIn::nSequence is NOT interpreted as a
       * relative lock-time. */
      static const uint32_t SEQUENCE_LOCKTIME_DISABLE_FLAG = (1U << 31);
  
      /* If CTxIn::nSequence encodes a relative lock-time and this flag
       * is set, the relative lock-time has units of 512 seconds,
       * otherwise it specifies blocks with a granularity of 1. */
      static const uint32_t SEQUENCE_LOCKTIME_TYPE_FLAG = (1 << 22);
  
      /* If CTxIn::nSequence encodes a relative lock-time, this mask is
       * applied to extract that lock-time from the sequence field. */
      static const uint32_t SEQUENCE_LOCKTIME_MASK = 0x0000ffff;
  
      /* In order to use the same number of bits to encode roughly the
       * same wall-clock duration, and because blocks are naturally
       * limited to occur every 600s on average, the minimum granularity
       * for time-based relative lock-time is fixed at 512 seconds.
       * Converting from CTxIn::nSequence to seconds is performed by
       * multiplying by 512 = 2^9, or equivalently shifting up by
       * 9 bits. */
      static const int SEQUENCE_LOCKTIME_GRANULARITY = 9;
  
      CTxIn()
      {
          nSequence = SEQUENCE_FINAL;
      }
  
      explicit CTxIn(COutPoint prevoutIn, CScript scriptSigIn=CScript(), uint32_t nSequenceIn=SEQUENCE_FINAL);
      CTxIn(uint256 hashPrevTx, uint32_t nOut, CScript scriptSigIn=CScript(), uint32_t nSequenceIn=SEQUENCE_FINAL);
  
      ADD_SERIALIZE_METHODS;
  
      template <typename Stream, typename Operation>
      inline void SerializationOp(Stream& s, Operation ser_action) {
          READWRITE(prevout);
          READWRITE(scriptSig);
          READWRITE(nSequence);
      }
  
      friend bool operator==(const CTxIn& a, const CTxIn& b)
      {
          return (a.prevout   == b.prevout &&
                  a.scriptSig == b.scriptSig &&
                  a.nSequence == b.nSequence);
      }
  
      friend bool operator!=(const CTxIn& a, const CTxIn& b)
      {
          return !(a == b);
      }
  
      std::string ToString() const;
  };
  
  /** An output of a transaction.  It contains the public key that the next input
   * must be able to sign with to claim it.
   */
  class CTxOut
  {
  public:
      CAmount nValue;
      CScript scriptPubKey;
  
      CTxOut()
      {
          SetNull();
      }
  
      CTxOut(const CAmount& nValueIn, CScript scriptPubKeyIn);
  
      ADD_SERIALIZE_METHODS;
  
      template <typename Stream, typename Operation>
      inline void SerializationOp(Stream& s, Operation ser_action) {
          READWRITE(nValue);
          READWRITE(scriptPubKey);
      }
  
      void SetNull()
      {
          nValue = -1;
          scriptPubKey.clear();
      }
  
      bool IsNull() const
      {
          return (nValue == -1);
      }
  
      void SetEmpty()
      {
          nValue = 0;
          scriptPubKey.clear();
      }
  
      bool IsEmpty() const
      {
          return (nValue == 0 && scriptPubKey.empty());
      }
  
      friend bool operator==(const CTxOut& a, const CTxOut& b)
      {
          return (a.nValue       == b.nValue &&
                  a.scriptPubKey == b.scriptPubKey);
      }
  
      friend bool operator!=(const CTxOut& a, const CTxOut& b)
      {
          return !(a == b);
      }
  
      std::string ToString() const;
  };
  
  struct CMutableTransaction;
  
  /**
   * Basic transaction serialization format:
   * - int32_t nVersion
   * - std::vector<CTxIn> vin
   * - std::vector<CTxOut> vout
   * - uint32_t nLockTime
   *
   * Extended transaction serialization format:
   * - int32_t nVersion
   * - unsigned char dummy = 0x00
   * - unsigned char flags (!= 0)
   * - std::vector<CTxIn> vin
   * - std::vector<CTxOut> vout
   * - if (flags & 1):
   *   - CTxWitness wit;
   * - uint32_t nLockTime
   */
  template<typename Stream, typename TxType>
  inline void UnserializeTransaction(TxType& tx, Stream& s) {
      const bool fAllowWitness = !(s.GetVersion() & SERIALIZE_TRANSACTION_NO_WITNESS);
  
      s >> tx.nVersion;
      s >> tx.nTime;
      unsigned char flags = 0;
      tx.vin.clear();
      tx.vout.clear();
      /* Try to read the vin. In case the dummy is there, this will be read as an empty vector. */
      s >> tx.vin;
      if (tx.vin.size() == 0 && fAllowWitness) {
          /* We read a dummy or an empty vin. */
          s >> flags;
          if (flags != 0) {
              s >> tx.vin;
              s >> tx.vout;
          }
      } else {
          /* We read a non-empty vin. Assume a normal vout follows. */
          s >> tx.vout;
      }
      if ((flags & 1) && fAllowWitness) {
          /* The witness flag is present, and we support witnesses. */
          flags ^= 1;
          for (size_t i = 0; i < tx.vin.size(); i++) {
              s >> tx.vin[i].scriptWitness.stack;
          }
          if (!tx.HasWitness()) {
              /* It's illegal to encode witnesses when all witness stacks are empty. */
              throw std::ios_base::failure("Superfluous witness record");
          }
      }
      if (flags) {
          /* Unknown flag in the serialization */
          throw std::ios_base::failure("Unknown transaction optional data");
      }
      s >> tx.nLockTime;
  }
  
  template<typename Stream, typename TxType>
  inline void SerializeTransaction(const TxType& tx, Stream& s) {
      const bool fAllowWitness = !(s.GetVersion() & SERIALIZE_TRANSACTION_NO_WITNESS);
  
      s << tx.nVersion;
      s << tx.nTime;
      unsigned char flags = 0;
      // Consistency check
      if (fAllowWitness) {
          /* Check whether witnesses need to be serialized. */
          if (tx.HasWitness()) {
              flags |= 1;
          }
      }
      if (flags) {
          /* Use extended format in case witnesses are to be serialized. */
          std::vector<CTxIn> vinDummy;
          s << vinDummy;
          s << flags;
      }
      s << tx.vin;
      s << tx.vout;
      if (flags & 1) {
          for (size_t i = 0; i < tx.vin.size(); i++) {
              s << tx.vin[i].scriptWitness.stack;
          }
      }
      s << tx.nLockTime;
  }
  
  /** The basic transaction that is broadcasted on the network and contained in
   * blocks.  A transaction can contain multiple inputs and outputs.
   */
  class CTransaction
  {
  public:
      // Default transaction version.
      static const int32_t CURRENT_VERSION=1; //slmTODO - change this to 2 after BIP68 fork happens.
  
      // Changing the default transaction version requires a two step process: first
      // adapting relay policy by bumping MAX_STANDARD_VERSION, and then later date
      // bumping the default CURRENT_VERSION at which point both CURRENT_VERSION and
      // MAX_STANDARD_VERSION will be equal.
      static const int32_t MAX_STANDARD_VERSION=1;
  
      // The local variables are made const to prevent unintended modification
      // without updating the cached hash value. However, CTransaction is not
      // actually immutable; deserialization and assignment are implemented,
      // and bypass the constness. This is safe, as they update the entire
      // structure, including the hash.
      const std::vector<CTxIn> vin;
      const std::vector<CTxOut> vout;
      const int32_t nVersion;
      const uint32_t nTime;
      const uint32_t nLockTime;
  
  private:
      /** Memory only. */
      const uint256 hash;
      const uint256 m_witness_hash;
  
      uint256 ComputeHash() const;
      uint256 ComputeWitnessHash() const;
  
  public:
      /** Construct a CTransaction that qualifies as IsNull() */
      CTransaction();
  
      /** Convert a CMutableTransaction into a CTransaction. */
      explicit CTransaction(const CMutableTransaction &tx);
      CTransaction(CMutableTransaction &&tx);
  
      template <typename Stream>
      inline void Serialize(Stream& s) const {
          SerializeTransaction(*this, s);
      }
  
      /** This deserializing constructor is provided instead of an Unserialize method.
       *  Unserialize is not possible, since it would require overwriting const fields. */
      template <typename Stream>
      CTransaction(deserialize_type, Stream& s) : CTransaction(CMutableTransaction(deserialize, s)) {}
  
      bool IsNull() const {
          return vin.empty() && vout.empty();
      }
  
      const uint256& GetHash() const { return hash; }
      const uint256& GetWitnessHash() const { return m_witness_hash; };
  
      // Return sum of txouts.
      CAmount GetValueOut() const;
      // GetValueIn() is a method on CCoinsViewCache, because
      // inputs must be known to compute value in.
  
      /**
       * Get the total transaction size in bytes, including witness data.
       * "Total Size" defined in BIP141 and BIP144.
       * @return Total transaction size in bytes
       */
      unsigned int GetTotalSize() const;
  
      bool IsCoinBase() const
      {
          return (vin.size() == 1 && vin[0].prevout.IsNull() && vout.size() >= 1);
      }
  
      bool IsCoinStake() const
      {
          // slimcoin: the coin stake transaction is marked with the first output empty
          return (vin.size() > 0 && (!vin[0].prevout.IsNull()) && vout.size() >= 2 && vout[0].IsEmpty());
      }
  
      friend bool operator==(const CTransaction& a, const CTransaction& b)
      {
          return a.hash == b.hash;
      }
  
      friend bool operator!=(const CTransaction& a, const CTransaction& b)
      {
          return a.hash != b.hash;
      }
  
      std::string ToString() const;
  
      bool HasWitness() const
      {
          for (size_t i = 0; i < vin.size(); i++) {
              if (!vin[i].scriptWitness.IsNull()) {
                  return true;
              }
          }
          return false;
      }
  };
  
  /** A mutable version of CTransaction. */
  struct CMutableTransaction
  {
      std::vector<CTxIn> vin;
      std::vector<CTxOut> vout;
      int32_t nVersion;
      uint32_t nTime;
      uint32_t nLockTime;
  
      CMutableTransaction();
      explicit CMutableTransaction(const CTransaction& tx);
  
      template <typename Stream>
      inline void Serialize(Stream& s) const {
          SerializeTransaction(*this, s);
      }
  
  
      template <typename Stream>
      inline void Unserialize(Stream& s) {
          UnserializeTransaction(*this, s);
      }
  
      template <typename Stream>
      CMutableTransaction(deserialize_type, Stream& s) {
          Unserialize(s);
      }
  
      /** Compute the hash of this CMutableTransaction. This is computed on the
       * fly, as opposed to GetHash() in CTransaction, which uses a cached result.
       */
      uint256 GetHash() const;
  
      bool HasWitness() const
      {
          for (size_t i = 0; i < vin.size(); i++) {
              if (!vin[i].scriptWitness.IsNull()) {
                  return true;
              }
          }
          return false;
      }
  };
  
  typedef std::shared_ptr<const CTransaction> CTransactionRef;
  static inline CTransactionRef MakeTransactionRef() { return std::make_shared<const CTransaction>(); }
  template <typename Tx> static inline CTransactionRef MakeTransactionRef(Tx&& txIn) { return std::make_shared<const CTransaction>(std::forward<Tx>(txIn)); }
  
  #endif // BITCOIN_PRIMITIVES_TRANSACTION_H
  