text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2016 The Schezuancoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include "script/standard.h"
  
  #include "pubkey.h"
  #include "script/script.h"
  #include "util.h"
  #include "utilstrencodings.h"
  
  
  typedef std::vector<unsigned char> valtype;
  
  bool fAcceptDatacarrier = DEFAULT_ACCEPT_DATACARRIER;
  unsigned nMaxDatacarrierBytes = MAX_OP_RETURN_RELAY;
  
  CScriptID::CScriptID(const CScript& in) : uint160(Hash160(in.begin(), in.end())) {}
  
  const char* GetTxnOutputType(txnouttype t)
  {
      switch (t)
      {
      case TX_NONSTANDARD: return "nonstandard";
      case TX_PUBKEY: return "pubkey";
      case TX_PUBKEYHASH: return "pubkeyhash";
      case TX_SCRIPTHASH: return "scripthash";
      case TX_MULTISIG: return "multisig";
      case TX_NULL_DATA: return "nulldata";
      case TX_WITNESS_V0_KEYHASH: return "witness_v0_keyhash";
      case TX_WITNESS_V0_SCRIPTHASH: return "witness_v0_scripthash";
      case TX_WITNESS_UNKNOWN: return "witness_unknown";
      }
      return nullptr;
  }
  
  bool Solver(const CScript& scriptPubKey, txnouttype& typeRet, std::vector<std::vector<unsigned char> >& vSolutionsRet)
  {
      // Templates
      static std::multimap<txnouttype, CScript> mTemplates;
      if (mTemplates.empty())
      {
          // Standard tx, sender provides pubkey, receiver adds signature
          mTemplates.insert(std::make_pair(TX_PUBKEY, CScript() << OP_PUBKEY << OP_CHECKSIG));
  
          // Schezuancoin address tx, sender provides hash of pubkey, receiver provides signature and pubkey
          mTemplates.insert(std::make_pair(TX_PUBKEYHASH, CScript() << OP_DUP << OP_HASH160 << OP_PUBKEYHASH << OP_EQUALVERIFY << OP_CHECKSIG));
  
          // Sender provides N pubkeys, receivers provides M signatures
          mTemplates.insert(std::make_pair(TX_MULTISIG, CScript() << OP_SMALLINTEGER << OP_PUBKEYS << OP_SMALLINTEGER << OP_CHECKMULTISIG));
      }
  
      vSolutionsRet.clear();
  
      // Shortcut for pay-to-script-hash, which are more constrained than the other types:
      // it is always OP_HASH160 20 [20 byte hash] OP_EQUAL
      if (scriptPubKey.IsPayToScriptHash())
      {
          typeRet = TX_SCRIPTHASH;
          std::vector<unsigned char> hashBytes(scriptPubKey.begin()+2, scriptPubKey.begin()+22);
          vSolutionsRet.push_back(hashBytes);
          return true;
      }
  
      int witnessversion;
      std::vector<unsigned char> witnessprogram;
      if (scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
          if (witnessversion == 0 && witnessprogram.size() == 20) {
              typeRet = TX_WITNESS_V0_KEYHASH;
              vSolutionsRet.push_back(witnessprogram);
              return true;
          }
          if (witnessversion == 0 && witnessprogram.size() == 32) {
              typeRet = TX_WITNESS_V0_SCRIPTHASH;
              vSolutionsRet.push_back(witnessprogram);
              return true;
          }
          if (witnessversion != 0) {
              typeRet = TX_WITNESS_UNKNOWN;
              vSolutionsRet.push_back(std::vector<unsigned char>{(unsigned char)witnessversion});
              vSolutionsRet.push_back(std::move(witnessprogram));
              return true;
          }
          return false;
      }
  
      // Provably prunable, data-carrying output
      //
      // So long as script passes the IsUnspendable() test and all but the first
      // byte passes the IsPushOnly() test we don't care what exactly is in the
      // script.
      if (scriptPubKey.size() >= 1 && scriptPubKey[0] == OP_RETURN && scriptPubKey.IsPushOnly(scriptPubKey.begin()+1)) {
          typeRet = TX_NULL_DATA;
          return true;
      }
  
      // Scan templates
      const CScript& script1 = scriptPubKey;
      for (const std::pair<txnouttype, CScript>& tplate : mTemplates)
      {
          const CScript& script2 = tplate.second;
          vSolutionsRet.clear();
  
          opcodetype opcode1, opcode2;
          std::vector<unsigned char> vch1, vch2;
  
          // Compare
          CScript::const_iterator pc1 = script1.begin();
          CScript::const_iterator pc2 = script2.begin();
          while (true)
          {
              if (pc1 == script1.end() && pc2 == script2.end())
              {
                  // Found a match
                  typeRet = tplate.first;
                  if (typeRet == TX_MULTISIG)
                  {
                      // Additional checks for TX_MULTISIG:
                      unsigned char m = vSolutionsRet.front()[0];
                      unsigned char n = vSolutionsRet.back()[0];
                      if (m < 1 || n < 1 || m > n || vSolutionsRet.size()-2 != n)
                          return false;
                  }
                  return true;
              }
              if (!script1.GetOp(pc1, opcode1, vch1))
                  break;
              if (!script2.GetOp(pc2, opcode2, vch2))
                  break;
  
              // Template matching opcodes:
              if (opcode2 == OP_PUBKEYS)
              {
                  while (vch1.size() >= 33 && vch1.size() <= 65)
                  {
                      vSolutionsRet.push_back(vch1);
                      if (!script1.GetOp(pc1, opcode1, vch1))
                          break;
                  }
                  if (!script2.GetOp(pc2, opcode2, vch2))
                      break;
                  // Normal situation is to fall through
                  // to other if/else statements
              }
  
              if (opcode2 == OP_PUBKEY)
              {
                  if (vch1.size() < 33 || vch1.size() > 65)
                      break;
                  vSolutionsRet.push_back(vch1);
              }
              else if (opcode2 == OP_PUBKEYHASH)
              {
                  if (vch1.size() != sizeof(uint160))
                      break;
                  vSolutionsRet.push_back(vch1);
              }
              else if (opcode2 == OP_SMALLINTEGER)
              {   // Single-byte small integer pushed onto vSolutions
                  if (opcode1 == OP_0 ||
                      (opcode1 >= OP_1 && opcode1 <= OP_16))
                  {
                      char n = (char)CScript::DecodeOP_N(opcode1);
                      vSolutionsRet.push_back(valtype(1, n));
                  }
                  else
                      break;
              }
              else if (opcode1 != opcode2 || vch1 != vch2)
              {
                  // Others must match exactly
                  break;
              }
          }
      }
  
      vSolutionsRet.clear();
      typeRet = TX_NONSTANDARD;
      return false;
  }
  
  bool ExtractDestination(const CScript& scriptPubKey, CTxDestination& addressRet)
  {
      std::vector<valtype> vSolutions;
      txnouttype whichType;
      if (!Solver(scriptPubKey, whichType, vSolutions))
          return false;
  
      if (whichType == TX_PUBKEY)
      {
          CPubKey pubKey(vSolutions[0]);
          if (!pubKey.IsValid())
              return false;
  
          addressRet = pubKey.GetID();
          return true;
      }
      else if (whichType == TX_PUBKEYHASH)
      {
          addressRet = CKeyID(uint160(vSolutions[0]));
          return true;
      }
      else if (whichType == TX_SCRIPTHASH)
      {
          addressRet = CScriptID(uint160(vSolutions[0]));
          return true;
      } else if (whichType == TX_WITNESS_V0_KEYHASH) {
          WitnessV0KeyHash hash;
          std::copy(vSolutions[0].begin(), vSolutions[0].end(), hash.begin());
          addressRet = hash;
          return true;
      } else if (whichType == TX_WITNESS_V0_SCRIPTHASH) {
          WitnessV0ScriptHash hash;
          std::copy(vSolutions[0].begin(), vSolutions[0].end(), hash.begin());
          addressRet = hash;
          return true;
      } else if (whichType == TX_WITNESS_UNKNOWN) {
          WitnessUnknown unk;
          unk.version = vSolutions[0][0];
          std::copy(vSolutions[1].begin(), vSolutions[1].end(), unk.program);
          unk.length = vSolutions[1].size();
          addressRet = unk;
          return true;
      }
      // Multisig txns have more than one address...
      return false;
  }
  
  bool ExtractDestinations(const CScript& scriptPubKey, txnouttype& typeRet, std::vector<CTxDestination>& addressRet, int& nRequiredRet)
  {
      addressRet.clear();
      typeRet = TX_NONSTANDARD;
      std::vector<valtype> vSolutions;
      if (!Solver(scriptPubKey, typeRet, vSolutions))
          return false;
      if (typeRet == TX_NULL_DATA){
          // This is data, not addresses
          return false;
      }
  
      if (typeRet == TX_MULTISIG)
      {
          nRequiredRet = vSolutions.front()[0];
          for (unsigned int i = 1; i < vSolutions.size()-1; i++)
          {
              CPubKey pubKey(vSolutions[i]);
              if (!pubKey.IsValid())
                  continue;
  
              CTxDestination address = pubKey.GetID();
              addressRet.push_back(address);
          }
  
          if (addressRet.empty())
              return false;
      }
      else
      {
          nRequiredRet = 1;
          CTxDestination address;
          if (!ExtractDestination(scriptPubKey, address))
             return false;
          addressRet.push_back(address);
      }
  
      return true;
  }
  
  namespace
  {
  class CScriptVisitor : public boost::static_visitor<bool>
  {
  private:
      CScript *script;
  public:
      explicit CScriptVisitor(CScript *scriptin) { script = scriptin; }
  
      bool operator()(const CNoDestination &dest) const {
          script->clear();
          return false;
      }
  
      bool operator()(const CKeyID &keyID) const {
          script->clear();
          *script << OP_DUP << OP_HASH160 << ToByteVector(keyID) << OP_EQUALVERIFY << OP_CHECKSIG;
          return true;
      }
  
      bool operator()(const CScriptID &scriptID) const {
          script->clear();
          *script << OP_HASH160 << ToByteVector(scriptID) << OP_EQUAL;
          return true;
      }
  
      bool operator()(const WitnessV0KeyHash& id) const
      {
          script->clear();
          *script << OP_0 << ToByteVector(id);
          return true;
      }
  
      bool operator()(const WitnessV0ScriptHash& id) const
      {
          script->clear();
          *script << OP_0 << ToByteVector(id);
          return true;
      }
  
      bool operator()(const WitnessUnknown& id) const
      {
          script->clear();
          *script << CScript::EncodeOP_N(id.version) << std::vector<unsigned char>(id.program, id.program + id.length);
          return true;
      }
  };
  } // namespace
  
  CScript GetScriptForDestination(const CTxDestination& dest)
  {
      CScript script;
  
      boost::apply_visitor(CScriptVisitor(&script), dest);
      return script;
  }
  
  CScript GetScriptForRawPubKey(const CPubKey& pubKey)
  {
      return CScript() << std::vector<unsigned char>(pubKey.begin(), pubKey.end()) << OP_CHECKSIG;
  }
  
  CScript GetScriptForMultisig(int nRequired, const std::vector<CPubKey>& keys)
  {
      CScript script;
  
      script << CScript::EncodeOP_N(nRequired);
      for (const CPubKey& key : keys)
          script << ToByteVector(key);
      script << CScript::EncodeOP_N(keys.size()) << OP_CHECKMULTISIG;
      return script;
  }
  
  CScript GetScriptForWitness(const CScript& redeemscript)
  {
      CScript ret;
  
      txnouttype typ;
      std::vector<std::vector<unsigned char> > vSolutions;
      if (Solver(redeemscript, typ, vSolutions)) {
          if (typ == TX_PUBKEY) {
              unsigned char h160[20];
              CHash160().Write(&vSolutions[0][0], vSolutions[0].size()).Finalize(h160);
              ret << OP_0 << std::vector<unsigned char>(&h160[0], &h160[20]);
              return ret;
          } else if (typ == TX_PUBKEYHASH) {
             ret << OP_0 << vSolutions[0];
             return ret;
          }
      }
      uint256 hash;
      CSHA256().Write(&redeemscript[0], redeemscript.size()).Finalize(hash.begin());
      ret << OP_0 << ToByteVector(hash);
      return ret;
  }
  
  bool IsValidDestination(const CTxDestination& dest) {
      return dest.which() != 0;
  }
  