Fix payback to account for negative interest

src/chainparams.cpp

@@ -137,6 +137,7 @@ class CMainParams : public CChainParams {
         consensus.FortCanningCrunchHeight = 1936000; // June 2, 2022.
         consensus.FortCanningSpringHeight = 2033000; // July 6, 2022.
         consensus.FortCanningGreatWorldHeight = 2212000; // Sep 7th, 2022.
+        consensus.FortCanningEpilogueHeight = std::numeric_limits<int>::max();
 
         consensus.pos.diffLimit = uint256S("00000fffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
 //        consensus.pos.nTargetTimespan = 14 * 24 * 60 * 60; // two weeks
@@ -375,6 +376,7 @@ class CTestNetParams : public CChainParams {
         consensus.FortCanningCrunchHeight = 1011600;
         consensus.FortCanningSpringHeight = 1086000;
         consensus.FortCanningGreatWorldHeight = 1223000;
+        consensus.FortCanningEpilogueHeight = std::numeric_limits<int>::max();
 
         consensus.pos.diffLimit = uint256S("00000fffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
 //        consensus.pos.nTargetTimespan = 14 * 24 * 60 * 60; // two weeks
@@ -568,6 +570,7 @@ class CDevNetParams : public CChainParams {
         consensus.FortCanningCrunchHeight = std::numeric_limits<int>::max();
         consensus.FortCanningSpringHeight = std::numeric_limits<int>::max();
         consensus.FortCanningGreatWorldHeight = std::numeric_limits<int>::max();
+        consensus.FortCanningEpilogueHeight = std::numeric_limits<int>::max();
 
         consensus.pos.diffLimit = uint256S("00000fffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
         consensus.pos.nTargetTimespan = 5 * 60; // 5 min == 10 blocks
@@ -753,6 +756,7 @@ class CRegTestParams : public CChainParams {
         consensus.FortCanningCrunchHeight = 10000000;
         consensus.FortCanningSpringHeight = 10000000;
         consensus.FortCanningGreatWorldHeight = 10000000;
+        consensus.FortCanningEpilogueHeight = 10000000;
 
         consensus.pos.diffLimit = uint256S("00000fffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
         consensus.pos.nTargetTimespan = 14 * 24 * 60 * 60; // two weeks
@@ -977,6 +981,7 @@ void SetupCommonArgActivationParams(Consensus::Params &consensus) {
     UpdateHeightValidation("Fort Canning Spring", "-fortcanningspringheight", consensus.FortCanningSpringHeight);
     UpdateHeightValidation("Fort Canning Great World", "-fortcanninggreatworldheight", consensus.FortCanningGreatWorldHeight);
     UpdateHeightValidation("Fort Canning Great World", "-greatworldheight", consensus.FortCanningGreatWorldHeight);
+    UpdateHeightValidation("Fort Canning Epilogue", "-fortcanningepilogueheight", consensus.FortCanningEpilogueHeight);
 
     if (gArgs.GetBoolArg("-simulatemainnet", false)) {
         consensus.pos.nTargetTimespan = 5 * 60; // 5 min == 10 blocks

src/consensus/params.h

@@ -98,6 +98,7 @@ struct Params {
     int FortCanningCrunchHeight;
     int FortCanningSpringHeight;
     int FortCanningGreatWorldHeight;
+    int FortCanningEpilogueHeight;
 
     /** Foundation share after AMK, normalized to COIN = 100% */
     CAmount foundationShareDFIP1;

src/init.cpp

@@ -503,6 +503,7 @@ void SetupServerArgs()
     gArgs.AddArg("-fortcanningspringheight", "Fort Canning Spring fork activation height (regtest only)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::CHAINPARAMS);
     gArgs.AddArg("-fortcanninggreatworldheight", "Fort Canning Great World fork activation height (regtest only)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::CHAINPARAMS);
     gArgs.AddArg("-greatworldheight", "Alias for Fort Canning Great World fork activation height (regtest only)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::CHAINPARAMS);
+    gArgs.AddArg("-fortcanningepilogueheight", "Alias for Fort Canning Epilogue fork activation height (regtest only)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::CHAINPARAMS);
     gArgs.AddArg("-jellyfish_regtest", "Configure the regtest network for jellyfish testing", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-simulatemainnet", "Configure the regtest network to mainnet target timespan and spacing ", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-dexstats", strprintf("Enable storing live dex data in DB (default: %u)", DEFAULT_DEXSTATS), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);

src/masternodes/mn_checks.cpp

@@ -3133,14 +3133,14 @@ class CCustomTxApplyVisitor : public CCustomTxVisitor
                 const auto totalInterest = TotalInterest(*rate, height);
 
                 if (totalInterest < 0) {
-                    loanAmountChange = currentLoanAmount > std::abs(totalInterest) ? 
+                    loanAmountChange = currentLoanAmount > std::abs(totalInterest) ?
                         // Interest to decrease smaller than overall existing loan amount.
                         // So reduce interest from the borrowing principal. If this is negative,
-                        // we'll reduce from principal. 
-                        tokenAmount + totalInterest : 
+                        // we'll reduce from principal.
+                        tokenAmount + totalInterest :
                         // Interest to decrease is larger than old loan amount.
-                        // We reduce from the borrowing principal. If this is negative, 
-                        // we'll reduce from principal. 
+                        // We reduce from the borrowing principal. If this is negative,
+                        // we'll reduce from principal.
                         tokenAmount - currentLoanAmount;
                     resetInterestToHeight = true;
                 }
@@ -3427,7 +3427,10 @@ class CCustomTxApplyVisitor : public CCustomTxVisitor
                 if (paybackTokenId == loanTokenId)
                 {
                     // If interest was negative remove it from sub amount
-                    res = mnview.SubMintedTokens(loanTokenId, subInterest > 0 ? subLoan : subLoan + subInterest);
+                    if (height >= static_cast<uint32_t>(consensus.FortCanningEpilogueHeight) && subInterest < 0)
+                        subLoan += subInterest;
+
+                    res = mnview.SubMintedTokens(loanTokenId, subLoan);
                     if (!res)
                         return res;
 

src/rpc/blockchain.cpp

@@ -1335,6 +1335,7 @@ UniValue getblockchaininfo(const JSONRPCRequest& request)
     BuriedForkDescPushBack(softforks, "fortcanningcrunch", consensusParams.FortCanningCrunchHeight);
     BuriedForkDescPushBack(softforks, "fortcanningspring", consensusParams.FortCanningSpringHeight);
     BuriedForkDescPushBack(softforks, "fortcanninggreatworld", consensusParams.FortCanningGreatWorldHeight);
+    BuriedForkDescPushBack(softforks, "fortcanningepilogue", consensusParams.FortCanningEpilogueHeight);
     BIP9SoftForkDescPushBack(softforks, "testdummy", consensusParams, Consensus::DEPLOYMENT_TESTDUMMY);
     obj.pushKV("softforks",             softforks);