[Staking][Wallet] Add Multi-Split functionality to stake output splitting

src/masternode-payments.cpp

@@ -327,7 +327,20 @@ void CMasternodePayments::FillBlockPayee(CMutableTransaction& txNew, int64_t nFe
 
             //subtract mn payment from the stake reward
             if (!txNew.vout[1].IsZerocoinMint())
-                txNew.vout[i - 1].nValue -= masternodePayment;
+                if (i == 2) {
+                    // Majority of cases; do it quick and move on
+                    txNew.vout[i - 1].nValue -= masternodePayment;
+                } else if (i > 2) {
+                    // special case, stake is split between (i-1) outputs
+                    unsigned int outputs = i-1;
+                    CAmount mnPaymentSplit = masternodePayment / outputs;
+                    CAmount mnPaymentRemainder = masternodePayment - (mnPaymentSplit * outputs);
+                    for (unsigned int j=1; j<=outputs; j++) {
+                        txNew.vout[j].nValue -= mnPaymentSplit;
+                    }
+                    // in case it's not an even division, take the last bit of dust from the last one
+                    txNew.vout[outputs].nValue -= mnPaymentRemainder;
+                }
         } else {
             txNew.vout.resize(2);
             txNew.vout[1].scriptPubKey = payee;

src/stakeinput.cpp

@@ -224,8 +224,17 @@ bool CPivStake::CreateTxOuts(CWallet* pwallet, std::vector<CTxOut>& vout, CAmoun
     vout.emplace_back(CTxOut(0, scriptPubKey));
 
     // Calculate if we need to split the output
-    if (nTotal / 2 > (CAmount)(pwallet->nStakeSplitThreshold * COIN))
-        vout.emplace_back(CTxOut(0, scriptPubKey));
+    int nSplit = nTotal / (static_cast<CAmount>(pwallet->nStakeSplitThreshold * COIN));
+    if (nSplit > 1) {
+        // if nTotal is twice or more of the threshold; create more outputs
+        int txSizeMax = MAX_STANDARD_TX_SIZE >> 11; // limit splits to <10% of the max TX size (/2048)
+        if (nSplit > txSizeMax)
+            nSplit = txSizeMax;
+        for (int i = nSplit; i > 1; i--) {
+            LogPrintf("%s: StakeSplit: nTotal = %d; adding output %d of %d\n", __func__, nTotal, (nSplit-i)+2, nSplit);
+            vout.emplace_back(CTxOut(0, scriptPubKey));
+        }
+    }
 
     return true;
 }

src/wallet/wallet.cpp

@@ -2425,11 +2425,19 @@ bool CWallet::CreateCoinStake(
             CAmount nMinFee = 0;
             if (!stakeInput->IsZPIV()) {
                 // Set output amount
-                if (txNew.vout.size() == 3) {
-                    txNew.vout[1].nValue = ((nCredit - nMinFee) / 2 / CENT) * CENT;
-                    txNew.vout[2].nValue = nCredit - nMinFee - txNew.vout[1].nValue;
-                } else
-                    txNew.vout[1].nValue = nCredit - nMinFee;
+                unsigned int outputs = txNew.vout.size() - 1;
+                CAmount nRemaining = nCredit - nMinFee;
+                if (outputs > 1) {
+                    // Split the stake across the outputs
+                    CAmount nShare = nRemaining / outputs;
+                    for (int i = 1; i < outputs; i++) {
+                        // loop through all but the last one.
+                        txNew.vout[i].nValue = nShare;
+                        nRemaining -= nShare;
+                    }
+                }
+                // put the remaining on the last output (which all into the first if only one output)
+                txNew.vout[outputs].nValue += nRemaining;
             }
 
             // Limit size