text: // Copyright (c) 2020 Isaac
  // Copyright (c) 2020 The Ubicoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include <script/sign.h>
  
  #include <key.h>
  #include <policy/policy.h>
  #include <primitives/transaction.h>
  #include <script/standard.h>
  #include <uint256.h>
  
  typedef std::vector<unsigned char> valtype;
  
  MutableTransactionSignatureCreator::MutableTransactionSignatureCreator(const CMutableTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, int nHashTypeIn) : txTo(txToIn), nIn(nInIn), nHashType(nHashTypeIn), amount(amountIn), checker(txTo, nIn, amountIn) {}
  
  bool MutableTransactionSignatureCreator::CreateSig(const SigningProvider& provider, std::vector<unsigned char>& vchSig, const CKeyID& address, const CScript& scriptCode, SigVersion sigversion) const
  {
      CKey key;
      if (!provider.GetKey(address, key))
          return false;
  
      // Signing with uncompressed keys is disabled in witness scripts
      if (sigversion == SigVersion::WITNESS_V0 && !key.IsCompressed())
          return false;
  
      uint256 hash = SignatureHash(scriptCode, *txTo, nIn, nHashType, amount, sigversion);
      if (!key.Sign(hash, vchSig))
          return false;
      vchSig.push_back((unsigned char)nHashType);
      return true;
  }
  
  static bool GetCScript(const SigningProvider& provider, const SignatureData& sigdata, const CScriptID& scriptid, CScript& script)
  {
      if (provider.GetCScript(scriptid, script)) {
          return true;
      }
      // Look for scripts in SignatureData
      if (CScriptID(sigdata.redeem_script) == scriptid) {
          script = sigdata.redeem_script;
          return true;
      } else if (CScriptID(sigdata.witness_script) == scriptid) {
          script = sigdata.witness_script;
          return true;
      }
      return false;
  }
  
  static bool GetPubKey(const SigningProvider& provider, SignatureData& sigdata, const CKeyID& address, CPubKey& pubkey)
  {
      if (provider.GetPubKey(address, pubkey)) {
          sigdata.misc_pubkeys.emplace(pubkey.GetID(), pubkey);
          return true;
      }
      // Look for pubkey in all partial sigs
      const auto it = sigdata.signatures.find(address);
      if (it != sigdata.signatures.end()) {
          pubkey = it->second.first;
          return true;
      }
      // Look for pubkey in pubkey list
      const auto& pk_it = sigdata.misc_pubkeys.find(address);
      if (pk_it != sigdata.misc_pubkeys.end()) {
          pubkey = pk_it->second;
          return true;
      }
      return false;
  }
  
  static bool CreateSig(const BaseSignatureCreator& creator, SignatureData& sigdata, const SigningProvider& provider, std::vector<unsigned char>& sig_out, const CPubKey& pubkey, const CScript& scriptcode, SigVersion sigversion)
  {
      CKeyID keyid = pubkey.GetID();
      const auto it = sigdata.signatures.find(keyid);
      if (it != sigdata.signatures.end()) {
          sig_out = it->second.second;
          return true;
      }
      sigdata.misc_pubkeys.emplace(keyid, pubkey);
      if (creator.CreateSig(provider, sig_out, keyid, scriptcode, sigversion)) {
          auto i = sigdata.signatures.emplace(keyid, SigPair(pubkey, sig_out));
          assert(i.second);
          return true;
      }
      return false;
  }
  
  /**
   * Sign scriptPubKey using signature made with creator.
   * Signatures are returned in scriptSigRet (or returns false if scriptPubKey can't be signed),
   * unless whichTypeRet is TX_SCRIPTHASH, in which case scriptSigRet is the redemption script.
   * Returns false if scriptPubKey could not be completely satisfied.
   */
  static bool SignStep(const SigningProvider& provider, const BaseSignatureCreator& creator, const CScript& scriptPubKey,
                       std::vector<valtype>& ret, txnouttype& whichTypeRet, SigVersion sigversion, SignatureData& sigdata)
  {
      CScript scriptRet;
      uint160 h160;
      ret.clear();
      std::vector<unsigned char> sig;
  
      std::vector<valtype> vSolutions;
      if (!Solver(scriptPubKey, whichTypeRet, vSolutions))
          return false;
  
      switch (whichTypeRet)
      {
      case TX_NONSTANDARD:
      case TX_NULL_DATA:
      case TX_WITNESS_UNKNOWN:
          return false;
      case TX_PUBKEY:
          if (!CreateSig(creator, sigdata, provider, sig, CPubKey(vSolutions[0]), scriptPubKey, sigversion)) return false;
          ret.push_back(std::move(sig));
          return true;
      case TX_PUBKEYHASH: {
          CKeyID keyID = CKeyID(uint160(vSolutions[0]));
          CPubKey pubkey;
          GetPubKey(provider, sigdata, keyID, pubkey);
          if (!CreateSig(creator, sigdata, provider, sig, pubkey, scriptPubKey, sigversion)) return false;
          ret.push_back(std::move(sig));
          ret.push_back(ToByteVector(pubkey));
          return true;
      }
      case TX_SCRIPTHASH:
          if (GetCScript(provider, sigdata, uint160(vSolutions[0]), scriptRet)) {
              ret.push_back(std::vector<unsigned char>(scriptRet.begin(), scriptRet.end()));
              return true;
          }
          return false;
  
      case TX_MULTISIG: {
          size_t required = vSolutions.front()[0];
          ret.push_back(valtype()); // workaround CHECKMULTISIG bug
          for (size_t i = 1; i < vSolutions.size() - 1; ++i) {
              CPubKey pubkey = CPubKey(vSolutions[i]);
              if (ret.size() < required + 1 && CreateSig(creator, sigdata, provider, sig, pubkey, scriptPubKey, sigversion)) {
                  ret.push_back(std::move(sig));
              }
          }
          bool ok = ret.size() == required + 1;
          for (size_t i = 0; i + ret.size() < required + 1; ++i) {
              ret.push_back(valtype());
          }
          return ok;
      }
      case TX_WITNESS_V0_KEYHASH:
          ret.push_back(vSolutions[0]);
          return true;
  
      case TX_WITNESS_V0_SCRIPTHASH:
          CRIPEMD160().Write(&vSolutions[0][0], vSolutions[0].size()).Finalize(h160.begin());
          if (GetCScript(provider, sigdata, h160, scriptRet)) {
              ret.push_back(std::vector<unsigned char>(scriptRet.begin(), scriptRet.end()));
              return true;
          }
          return false;
  
      default:
          return false;
      }
  }
  
  static CScript PushAll(const std::vector<valtype>& values)
  {
      CScript result;
      for (const valtype& v : values) {
          if (v.size() == 0) {
              result << OP_0;
          } else if (v.size() == 1 && v[0] >= 1 && v[0] <= 16) {
              result << CScript::EncodeOP_N(v[0]);
          } else {
              result << v;
          }
      }
      return result;
  }
  
  bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreator& creator, const CScript& fromPubKey, SignatureData& sigdata)
  {
      if (sigdata.complete) return true;
  
      std::vector<valtype> result;
      txnouttype whichType;
      bool solved = SignStep(provider, creator, fromPubKey, result, whichType, SigVersion::BASE, sigdata);
      bool P2SH = false;
      CScript subscript;
      sigdata.scriptWitness.stack.clear();
  
      if (solved && whichType == TX_SCRIPTHASH)
      {
          // Solver returns the subscript that needs to be evaluated;
          // the final scriptSig is the signatures from that
          // and then the serialized subscript:
          subscript = CScript(result[0].begin(), result[0].end());
          sigdata.redeem_script = subscript;
          solved = solved && SignStep(provider, creator, subscript, result, whichType, SigVersion::BASE, sigdata) && whichType != TX_SCRIPTHASH;
          P2SH = true;
      }
  
      if (solved && whichType == TX_WITNESS_V0_KEYHASH)
      {
          CScript witnessscript;
          witnessscript << OP_DUP << OP_HASH160 << ToByteVector(result[0]) << OP_EQUALVERIFY << OP_CHECKSIG;
          txnouttype subType;
          solved = solved && SignStep(provider, creator, witnessscript, result, subType, SigVersion::WITNESS_V0, sigdata);
          sigdata.scriptWitness.stack = result;
          sigdata.witness = true;
          result.clear();
      }
      else if (solved && whichType == TX_WITNESS_V0_SCRIPTHASH)
      {
          CScript witnessscript(result[0].begin(), result[0].end());
          sigdata.witness_script = witnessscript;
          txnouttype subType;
          solved = solved && SignStep(provider, creator, witnessscript, result, subType, SigVersion::WITNESS_V0, sigdata) && subType != TX_SCRIPTHASH && subType != TX_WITNESS_V0_SCRIPTHASH && subType != TX_WITNESS_V0_KEYHASH;
          result.push_back(std::vector<unsigned char>(witnessscript.begin(), witnessscript.end()));
          sigdata.scriptWitness.stack = result;
          sigdata.witness = true;
          result.clear();
      } else if (solved && whichType == TX_WITNESS_UNKNOWN) {
          sigdata.witness = true;
      }
  
      if (P2SH) {
          result.push_back(std::vector<unsigned char>(subscript.begin(), subscript.end()));
      }
      sigdata.scriptSig = PushAll(result);
  
      // Test solution
      sigdata.complete = solved && VerifyScript(sigdata.scriptSig, fromPubKey, &sigdata.scriptWitness, STANDARD_SCRIPT_VERIFY_FLAGS, creator.Checker());
      return sigdata.complete;
  }
  
  bool PSBTInputSigned(PSBTInput& input)
  {
      return !input.final_script_sig.empty() || !input.final_script_witness.IsNull();
  }
  
  bool SignPSBTInput(const SigningProvider& provider, PartiallySignedTransaction& psbt, SignatureData& sigdata, int index, int sighash)
  {
      PSBTInput& input = psbt.inputs.at(index);
      const CMutableTransaction& tx = *psbt.tx;
  
      if (PSBTInputSigned(input)) {
          return true;
      }
  
      // Fill SignatureData with input info
      input.FillSignatureData(sigdata);
  
      // Get UTXO
      bool require_witness_sig = false;
      CTxOut utxo;
  
      // Verify input sanity, which checks that at most one of witness or non-witness utxos is provided.
      if (!input.IsSane()) {
          return false;
      }
  
      if (input.non_witness_utxo) {
          // If we're taking our information from a non-witness UTXO, verify that it matches the prevout.
          COutPoint prevout = tx.vin[index].prevout;
          if (input.non_witness_utxo->GetHash() != prevout.hash) {
              return false;
          }
          utxo = input.non_witness_utxo->vout[prevout.n];
      } else if (!input.witness_utxo.IsNull()) {
          utxo = input.witness_utxo;
          // When we're taking our information from a witness UTXO, we can't verify it is actually data from
          // the output being spent. This is safe in case a witness signature is produced (which includes this
          // information directly in the hash), but not for non-witness signatures. Remember that we require
          // a witness signature in this situation.
          require_witness_sig = true;
      } else {
          return false;
      }
  
      MutableTransactionSignatureCreator creator(&tx, index, utxo.nValue, sighash);
      sigdata.witness = false;
      bool sig_complete = ProduceSignature(provider, creator, utxo.scriptPubKey, sigdata);
      // Verify that a witness signature was produced in case one was required.
      if (require_witness_sig && !sigdata.witness) return false;
      input.FromSignatureData(sigdata);
  
      // If we have a witness signature, use the smaller witness UTXO.
      if (sigdata.witness) {
          input.witness_utxo = utxo;
          input.non_witness_utxo = nullptr;
      }
  
      return sig_complete;
  }
  
  class SignatureExtractorChecker final : public BaseSignatureChecker
  {
  private:
      SignatureData& sigdata;
      BaseSignatureChecker& checker;
  
  public:
      SignatureExtractorChecker(SignatureData& sigdata, BaseSignatureChecker& checker) : sigdata(sigdata), checker(checker) {}
      bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const override;
  };
  
  bool SignatureExtractorChecker::CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const
  {
      if (checker.CheckSig(scriptSig, vchPubKey, scriptCode, sigversion)) {
          CPubKey pubkey(vchPubKey);
          sigdata.signatures.emplace(pubkey.GetID(), SigPair(pubkey, scriptSig));
          return true;
      }
      return false;
  }
  
  namespace
  {
  struct Stacks
  {
      std::vector<valtype> script;
      std::vector<valtype> witness;
  
      Stacks() = delete;
      Stacks(const Stacks&) = delete;
      explicit Stacks(const SignatureData& data) : witness(data.scriptWitness.stack) {
          EvalScript(script, data.scriptSig, SCRIPT_VERIFY_STRICTENC, BaseSignatureChecker(), SigVersion::BASE);
      }
  };
  }
  
  // Extracts signatures and scripts from incomplete scriptSigs. Please do not extend this, use PSBT instead
  SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nIn, const CTxOut& txout)
  {
      SignatureData data;
      assert(tx.vin.size() > nIn);
      data.scriptSig = tx.vin[nIn].scriptSig;
      data.scriptWitness = tx.vin[nIn].scriptWitness;
      Stacks stack(data);
  
      // Get signatures
      MutableTransactionSignatureChecker tx_checker(&tx, nIn, txout.nValue);
      SignatureExtractorChecker extractor_checker(data, tx_checker);
      if (VerifyScript(data.scriptSig, txout.scriptPubKey, &data.scriptWitness, STANDARD_SCRIPT_VERIFY_FLAGS, extractor_checker)) {
          data.complete = true;
          return data;
      }
  
      // Get scripts
      txnouttype script_type;
      std::vector<std::vector<unsigned char>> solutions;
      Solver(txout.scriptPubKey, script_type, solutions);
      SigVersion sigversion = SigVersion::BASE;
      CScript next_script = txout.scriptPubKey;
  
      if (script_type == TX_SCRIPTHASH && !stack.script.empty() && !stack.script.back().empty()) {
          // Get the redeemScript
          CScript redeem_script(stack.script.back().begin(), stack.script.back().end());
          data.redeem_script = redeem_script;
          next_script = std::move(redeem_script);
  
          // Get redeemScript type
          Solver(next_script, script_type, solutions);
          stack.script.pop_back();
      }
      if (script_type == TX_WITNESS_V0_SCRIPTHASH && !stack.witness.empty() && !stack.witness.back().empty()) {
          // Get the witnessScript
          CScript witness_script(stack.witness.back().begin(), stack.witness.back().end());
          data.witness_script = witness_script;
          next_script = std::move(witness_script);
  
          // Get witnessScript type
          Solver(next_script, script_type, solutions);
          stack.witness.pop_back();
          stack.script = std::move(stack.witness);
          stack.witness.clear();
          sigversion = SigVersion::WITNESS_V0;
      }
      if (script_type == TX_MULTISIG && !stack.script.empty()) {
          // Build a map of pubkey -> signature by matching sigs to pubkeys:
          assert(solutions.size() > 1);
          unsigned int num_pubkeys = solutions.size()-2;
          unsigned int last_success_key = 0;
          for (const valtype& sig : stack.script) {
              for (unsigned int i = last_success_key; i < num_pubkeys; ++i) {
                  const valtype& pubkey = solutions[i+1];
                  // We either have a signature for this pubkey, or we have found a signature and it is valid
                  if (data.signatures.count(CPubKey(pubkey).GetID()) || extractor_checker.CheckSig(sig, pubkey, next_script, sigversion)) {
                      last_success_key = i + 1;
                      break;
                  }
              }
          }
      }
  
      return data;
  }
  
  void UpdateInput(CTxIn& input, const SignatureData& data)
  {
      input.scriptSig = data.scriptSig;
      input.scriptWitness = data.scriptWitness;
  }
  
  void SignatureData::MergeSignatureData(SignatureData sigdata)
  {
      if (complete) return;
      if (sigdata.complete) {
          *this = std::move(sigdata);
          return;
      }
      if (redeem_script.empty() && !sigdata.redeem_script.empty()) {
          redeem_script = sigdata.redeem_script;
      }
      if (witness_script.empty() && !sigdata.witness_script.empty()) {
          witness_script = sigdata.witness_script;
      }
      signatures.insert(std::make_move_iterator(sigdata.signatures.begin()), std::make_move_iterator(sigdata.signatures.end()));
  }
  
  bool SignSignature(const SigningProvider &provider, const CScript& fromPubKey, CMutableTransaction& txTo, unsigned int nIn, const CAmount& amount, int nHashType)
  {
      assert(nIn < txTo.vin.size());
  
      MutableTransactionSignatureCreator creator(&txTo, nIn, amount, nHashType);
  
      SignatureData sigdata;
      bool ret = ProduceSignature(provider, creator, fromPubKey, sigdata);
      UpdateInput(txTo.vin.at(nIn), sigdata);
      return ret;
  }
  
  bool SignSignature(const SigningProvider &provider, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType)
  {
      assert(nIn < txTo.vin.size());
      CTxIn& txin = txTo.vin[nIn];
      assert(txin.prevout.n < txFrom.vout.size());
      const CTxOut& txout = txFrom.vout[txin.prevout.n];
  
      return SignSignature(provider, txout.scriptPubKey, txTo, nIn, txout.nValue, nHashType);
  }
  
  namespace {
  /** Dummy signature checker which accepts all signatures. */
  class DummySignatureChecker final : public BaseSignatureChecker
  {
  public:
      DummySignatureChecker() {}
      bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const override { return true; }
  };
  const DummySignatureChecker DUMMY_CHECKER;
  
  class DummySignatureCreator final : public BaseSignatureCreator {
  private:
      char m_r_len = 32;
      char m_s_len = 32;
  public:
      DummySignatureCreator(char r_len, char s_len) : m_r_len(r_len), m_s_len(s_len) {}
      const BaseSignatureChecker& Checker() const override { return DUMMY_CHECKER; }
      bool CreateSig(const SigningProvider& provider, std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const override
      {
          // Create a dummy signature that is a valid DER-encoding
          vchSig.assign(m_r_len + m_s_len + 7, '\000');
          vchSig[0] = 0x30;
          vchSig[1] = m_r_len + m_s_len + 4;
          vchSig[2] = 0x02;
          vchSig[3] = m_r_len;
          vchSig[4] = 0x01;
          vchSig[4 + m_r_len] = 0x02;
          vchSig[5 + m_r_len] = m_s_len;
          vchSig[6 + m_r_len] = 0x01;
          vchSig[6 + m_r_len + m_s_len] = SIGHASH_ALL;
          return true;
      }
  };
  
  template<typename M, typename K, typename V>
  bool LookupHelper(const M& map, const K& key, V& value)
  {
      auto it = map.find(key);
      if (it != map.end()) {
          value = it->second;
          return true;
      }
      return false;
  }
  
  }
  
  const BaseSignatureCreator& DUMMY_SIGNATURE_CREATOR = DummySignatureCreator(32, 32);
  const BaseSignatureCreator& DUMMY_MAXIMUM_SIGNATURE_CREATOR = DummySignatureCreator(33, 32);
  const SigningProvider& DUMMY_SIGNING_PROVIDER = SigningProvider();
  
  bool IsSolvable(const SigningProvider& provider, const CScript& script)
  {
      // This check is to make sure that the script we created can actually be solved for and signed by us
      // if we were to have the private keys. This is just to make sure that the script is valid and that,
      // if found in a transaction, we would still accept and relay that transaction. In particular,
      // it will reject witness outputs that require signing with an uncompressed public key.
      SignatureData sigs;
      // Make sure that STANDARD_SCRIPT_VERIFY_FLAGS includes SCRIPT_VERIFY_WITNESS_PUBKEYTYPE, the most
      // important property this function is designed to test for.
      static_assert(STANDARD_SCRIPT_VERIFY_FLAGS & SCRIPT_VERIFY_WITNESS_PUBKEYTYPE, "IsSolvable requires standard script flags to include WITNESS_PUBKEYTYPE");
      if (ProduceSignature(provider, DUMMY_SIGNATURE_CREATOR, script, sigs)) {
          // VerifyScript check is just defensive, and should never fail.
          assert(VerifyScript(sigs.scriptSig, script, &sigs.scriptWitness, STANDARD_SCRIPT_VERIFY_FLAGS, DUMMY_CHECKER));
          return true;
      }
      return false;
  }
  
  PartiallySignedTransaction::PartiallySignedTransaction(const CTransaction& tx) : tx(tx)
  {
      inputs.resize(tx.vin.size());
      outputs.resize(tx.vout.size());
  }
  
  bool PartiallySignedTransaction::IsNull() const
  {
      return !tx && inputs.empty() && outputs.empty() && unknown.empty();
  }
  
  void PartiallySignedTransaction::Merge(const PartiallySignedTransaction& psbt)
  {
      for (unsigned int i = 0; i < inputs.size(); ++i) {
          inputs[i].Merge(psbt.inputs[i]);
      }
      for (unsigned int i = 0; i < outputs.size(); ++i) {
          outputs[i].Merge(psbt.outputs[i]);
      }
      unknown.insert(psbt.unknown.begin(), psbt.unknown.end());
  }
  
  bool PartiallySignedTransaction::IsSane() const
  {
      for (PSBTInput input : inputs) {
          if (!input.IsSane()) return false;
      }
      return true;
  }
  
  bool PSBTInput::IsNull() const
  {
      return !non_witness_utxo && witness_utxo.IsNull() && partial_sigs.empty() && unknown.empty() && hd_keypaths.empty() && redeem_script.empty() && witness_script.empty();
  }
  
  void PSBTInput::FillSignatureData(SignatureData& sigdata) const
  {
      if (!final_script_sig.empty()) {
          sigdata.scriptSig = final_script_sig;
          sigdata.complete = true;
      }
      if (!final_script_witness.IsNull()) {
          sigdata.scriptWitness = final_script_witness;
          sigdata.complete = true;
      }
      if (sigdata.complete) {
          return;
      }
  
      sigdata.signatures.insert(partial_sigs.begin(), partial_sigs.end());
      if (!redeem_script.empty()) {
          sigdata.redeem_script = redeem_script;
      }
      if (!witness_script.empty()) {
          sigdata.witness_script = witness_script;
      }
      for (const auto& key_pair : hd_keypaths) {
          sigdata.misc_pubkeys.emplace(key_pair.first.GetID(), key_pair.first);
      }
  }
  
  void PSBTInput::FromSignatureData(const SignatureData& sigdata)
  {
      if (sigdata.complete) {
          partial_sigs.clear();
          hd_keypaths.clear();
          redeem_script.clear();
          witness_script.clear();
  
          if (!sigdata.scriptSig.empty()) {
              final_script_sig = sigdata.scriptSig;
          }
          if (!sigdata.scriptWitness.IsNull()) {
              final_script_witness = sigdata.scriptWitness;
          }
          return;
      }
  
      partial_sigs.insert(sigdata.signatures.begin(), sigdata.signatures.end());
      if (redeem_script.empty() && !sigdata.redeem_script.empty()) {
          redeem_script = sigdata.redeem_script;
      }
      if (witness_script.empty() && !sigdata.witness_script.empty()) {
          witness_script = sigdata.witness_script;
      }
  }
  
  void PSBTInput::Merge(const PSBTInput& input)
  {
      if (!non_witness_utxo && input.non_witness_utxo) non_witness_utxo = input.non_witness_utxo;
      if (witness_utxo.IsNull() && !input.witness_utxo.IsNull()) {
          witness_utxo = input.witness_utxo;
          non_witness_utxo = nullptr; // Clear out any non-witness utxo when we set a witness one.
      }
  
      partial_sigs.insert(input.partial_sigs.begin(), input.partial_sigs.end());
      hd_keypaths.insert(input.hd_keypaths.begin(), input.hd_keypaths.end());
      unknown.insert(input.unknown.begin(), input.unknown.end());
  
      if (redeem_script.empty() && !input.redeem_script.empty()) redeem_script = input.redeem_script;
      if (witness_script.empty() && !input.witness_script.empty()) witness_script = input.witness_script;
      if (final_script_sig.empty() && !input.final_script_sig.empty()) final_script_sig = input.final_script_sig;
      if (final_script_witness.IsNull() && !input.final_script_witness.IsNull()) final_script_witness = input.final_script_witness;
  }
  
  bool PSBTInput::IsSane() const
  {
      // Cannot have both witness and non-witness utxos
      if (!witness_utxo.IsNull() && non_witness_utxo) return false;
  
      // If we have a witness_script or a scriptWitness, we must also have a witness utxo
      if (!witness_script.empty() && witness_utxo.IsNull()) return false;
      if (!final_script_witness.IsNull() && witness_utxo.IsNull()) return false;
  
      return true;
  }
  
  void PSBTOutput::FillSignatureData(SignatureData& sigdata) const
  {
      if (!redeem_script.empty()) {
          sigdata.redeem_script = redeem_script;
      }
      if (!witness_script.empty()) {
          sigdata.witness_script = witness_script;
      }
      for (const auto& key_pair : hd_keypaths) {
          sigdata.misc_pubkeys.emplace(key_pair.first.GetID(), key_pair.first);
      }
  }
  
  void PSBTOutput::FromSignatureData(const SignatureData& sigdata)
  {
      if (redeem_script.empty() && !sigdata.redeem_script.empty()) {
          redeem_script = sigdata.redeem_script;
      }
      if (witness_script.empty() && !sigdata.witness_script.empty()) {
          witness_script = sigdata.witness_script;
      }
  }
  
  bool PSBTOutput::IsNull() const
  {
      return redeem_script.empty() && witness_script.empty() && hd_keypaths.empty() && unknown.empty();
  }
  
  void PSBTOutput::Merge(const PSBTOutput& output)
  {
      hd_keypaths.insert(output.hd_keypaths.begin(), output.hd_keypaths.end());
      unknown.insert(output.unknown.begin(), output.unknown.end());
  
      if (redeem_script.empty() && !output.redeem_script.empty()) redeem_script = output.redeem_script;
      if (witness_script.empty() && !output.witness_script.empty()) witness_script = output.witness_script;
  }
  
  bool PublicOnlySigningProvider::GetCScript(const CScriptID &scriptid, CScript& script) const
  {
      return m_provider->GetCScript(scriptid, script);
  }
  
  bool PublicOnlySigningProvider::GetPubKey(const CKeyID &address, CPubKey& pubkey) const
  {
      return m_provider->GetPubKey(address, pubkey);
  }
  
  bool FlatSigningProvider::GetCScript(const CScriptID& scriptid, CScript& script) const { return LookupHelper(scripts, scriptid, script); }
  bool FlatSigningProvider::GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const { return LookupHelper(pubkeys, keyid, pubkey); }
  bool FlatSigningProvider::GetKey(const CKeyID& keyid, CKey& key) const { return LookupHelper(keys, keyid, key); }
  
  FlatSigningProvider Merge(const FlatSigningProvider& a, const FlatSigningProvider& b)
  {
      FlatSigningProvider ret;
      ret.scripts = a.scripts;
      ret.scripts.insert(b.scripts.begin(), b.scripts.end());
      ret.pubkeys = a.pubkeys;
      ret.pubkeys.insert(b.pubkeys.begin(), b.pubkeys.end());
      ret.keys = a.keys;
      ret.keys.insert(b.keys.begin(), b.keys.end());
      return ret;
  }
  