Refactor ZC-specific staking functionality.

In preparation for defining a RingCTStakeInput type, move more
zerocoin-specific stuff behind a CStakeInput interface.

Author: Zannick

src/veil/proofofstake/kernel.cpp

@@ -16,7 +16,6 @@
 #include "util/system.h"
 #include "stakeinput.h"
 #include "veil/zerocoin/zchain.h"
-#include "libzerocoin/bignum.h"
 #include <versionbits.h>
 
 using namespace std;
@@ -47,21 +46,6 @@ bool CheckStake(const CDataStream& ssUniqueID, CAmount nValueIn, const uint64_t
 }
 
 
-//Sets nValueIn with the weighted amount given a certain zerocoin denomination
-void WeightStake(CAmount& nValueIn, const libzerocoin::CoinDenomination denom)
-{
-    if (denom == libzerocoin::CoinDenomination::ZQ_ONE_HUNDRED) {
-        //10% reduction
-        nValueIn = (nValueIn * 90) / 100;
-    } else if (denom == libzerocoin::CoinDenomination::ZQ_ONE_THOUSAND) {
-        //20% reduction
-        nValueIn = (nValueIn * 80) / 100;
-    } else if (denom == libzerocoin::CoinDenomination::ZQ_TEN_THOUSAND) {
-        //30% reduction
-        nValueIn = (nValueIn * 70) / 100;
-    }
-}
-
 std::set<uint256> setFoundStakes;
 bool Stake(CStakeInput* stakeInput, unsigned int nBits, unsigned int nTimeBlockFrom, unsigned int& nTimeTx, const CBlockIndex* pindexBest, uint256& hashProofOfStake, bool fWeightStake)
 {
@@ -84,11 +68,8 @@ bool Stake(CStakeInput* stakeInput, unsigned int nBits, unsigned int nTimeBlockF
     int64_t nMaxTime = (int)GetAdjustedTime() + MAX_FUTURE_BLOCK_TIME - 40;
 
     CDataStream ssUniqueID = stakeInput->GetUniqueness();
-    CAmount nValueIn = stakeInput->GetValue();
-
-    //Adjust stake weights to larger denoms
-    if (fWeightStake)
-        WeightStake(nValueIn, stakeInput->GetDenomination());
+    // Adjust stake weights
+    CAmount nValueIn = fWeightStake ? stakeInput->GetWeight() : stakeInput->GetValue();
 
     int nBestHeight = pindexBest->nHeight;
     uint256 hashBestBlock = pindexBest->GetBlockHash();
@@ -167,11 +148,12 @@ bool CheckProofOfStake(CBlockIndex* pindexCheck, const CTransactionRef txRef, co
 
     unsigned int nBlockFromTime = blockprev.nTime;
     unsigned int nTxTime = nTimeBlock;
-    CAmount nValue = stake->GetValue();
 
     // Enforce VIP-1 after it was activated
-    if ((int)nTxTime > Params().EnforceWeightReductionTime())
-        WeightStake(nValue, stake->GetDenomination());
+    CAmount nValue = (int)nTxTime > Params().EnforceWeightReductionTime()
+        ? stake->GetWeight()
+        : stake->GetValue();
+
 
     if (!CheckStake(stake->GetUniqueness(), nValue, nStakeModifier, ArithToUint256(bnTargetPerCoinDay), nBlockFromTime,
                     nTxTime, hashProofOfStake)) {

src/veil/proofofstake/stakeinput.cpp

@@ -166,6 +166,21 @@ CAmount ZerocoinStake::GetValue()
     return denom * COIN;
 }
 
+CAmount ZerocoinStake::GetWeight()
+{
+    if (denom == libzerocoin::CoinDenomination::ZQ_ONE_HUNDRED) {
+        //10% reduction
+        return (denom * COIN * 9) / 10;
+    } else if (denom == libzerocoin::CoinDenomination::ZQ_ONE_THOUSAND) {
+        //20% reduction
+        return (denom * COIN * 8) / 10;
+    } else if (denom == libzerocoin::CoinDenomination::ZQ_TEN_THOUSAND) {
+        //30% reduction
+        return (denom * COIN * 7) / 10;
+    }
+    return denom * COIN;
+}
+
 int ZerocoinStake::HeightToModifierHeight(int nHeight)
 {
     //Nearest multiple of KernelModulus that is over KernelModulus bocks deep in the chain
@@ -277,6 +292,13 @@ bool ZerocoinStake::CreateTxOuts(CWallet* pwallet, std::vector<CTxOut>& vout, CA
 #endif
 }
 
+bool ZerocoinStake::CompleteTx(CWallet* pwallet, CMutableTransaction& txNew)
+{
+    if (!MarkSpent(pwallet, txNew.GetHash()))
+        return error("%s: failed to mark mint as used\n", __func__);
+    return true;
+}
+
 bool ZerocoinStake::GetTxFrom(CTransaction& tx)
 {
     return false;

src/veil/proofofstake/stakeinput.h

@@ -1,5 +1,5 @@
 // Copyright (c) 2017-2019 The PIVX developers
-// Copyright (c) 2019 The Veil developers
+// Copyright (c) 2019-2022 The Veil developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -25,14 +25,17 @@ class CStakeInput
 public:
     virtual ~CStakeInput(){};
     virtual CBlockIndex* GetIndexFrom() = 0;
-    virtual bool CreateTxIn(CWallet* pwallet, CTxIn& txIn, uint256 hashTxOut = uint256()) = 0;
     virtual bool GetTxFrom(CTransaction& tx) = 0;
     virtual CAmount GetValue() = 0;
-    virtual bool CreateTxOuts(CWallet* pwallet, std::vector<CTxOut>& vout, CAmount nTotal) = 0;
+    virtual CAmount GetWeight() = 0;
     virtual bool GetModifier(uint64_t& nStakeModifier, const CBlockIndex* pindexChainPrev) = 0;
     virtual bool IsZerocoins() = 0;
     virtual CDataStream GetUniqueness() = 0;
     libzerocoin::CoinDenomination GetDenomination() {return denom;};
+
+    virtual bool CreateTxIn(CWallet* pwallet, CTxIn& txIn, uint256 hashTxOut = uint256()) = 0;
+    virtual bool CreateTxOuts(CWallet* pwallet, std::vector<CTxOut>& vout, CAmount nTotal) = 0;
+    virtual bool CompleteTx(CWallet* pwallet, CMutableTransaction& txNew) = 0;
 };
 
 
@@ -60,12 +63,15 @@ class ZerocoinStake : public CStakeInput
     CBlockIndex* GetIndexFrom() override;
     bool GetTxFrom(CTransaction& tx) override;
     CAmount GetValue() override;
+    CAmount GetWeight() override;
     bool GetModifier(uint64_t& nStakeModifier, const CBlockIndex* pindexChainPrev) override;
     CDataStream GetUniqueness() override;
     bool CreateTxIn(CWallet* pwallet, CTxIn& txIn, uint256 hashTxOut = uint256()) override;
     bool CreateTxOuts(CWallet* pwallet, std::vector<CTxOut>& vout, CAmount nTotal) override;
-    bool MarkSpent(CWallet* pwallet, const uint256& txid);
+    bool CompleteTx(CWallet* pwallet, CMutableTransaction& txNew) override;
     bool IsZerocoins() override { return true; }
+
+    bool MarkSpent(CWallet* pwallet, const uint256& txid);
     int GetChecksumHeightFromMint();
     int GetChecksumHeightFromSpend();
     uint256 GetChecksum();

src/wallet/wallet.cpp

@@ -3884,10 +3884,10 @@ bool CWallet::CreateCoinStake(const CBlockIndex* pindexBest, unsigned int nBits,
     if (GetAdjustedTime() - chainActive.Tip()->GetBlockTime() < 1)
         UninterruptibleSleep(std::chrono::milliseconds{2500});
 
-    CAmount nCredit = 0;
     CScript scriptPubKeyKernel;
     bool fKernelFound = false;
     for (std::unique_ptr<ZerocoinStake>& stakeInput : listInputs) {
+        CAmount nCredit = 0;
         // Make sure the wallet is unlocked and shutdown hasn't been requested
         if (IsLocked() || ShutdownRequested())
             return false;
@@ -3964,16 +3964,14 @@ bool CWallet::CreateCoinStake(const CBlockIndex* pindexBest, unsigned int nBits,
                     LogPrintf("%s : failed to create TxIn\n", __func__);
                     txNew.vin.clear();
                     txNew.vpout.clear();
-                    nCredit = 0;
                     continue;
                 }
             }
             txNew.vin.emplace_back(in);
 
             //Mark mints as spent
-            auto* z = (ZerocoinStake*)stakeInput.get();
-            if (!z->MarkSpent(this, txNew.GetHash()))
-                return error("%s: failed to mark mint as used\n", __func__);
+            if (!stakeInput->CompleteTx(this, txNew))
+                return false;
 
             fKernelFound = true;
             break;