Add DeFiErrors abstraction for error messages (#1758)

* Add DeFiErrors abstraction for error messages

* Fix lint

src/Makefile.am

@@ -175,6 +175,7 @@ DEFI_CORE_H = \
   masternodes/mn_checks.h \
   masternodes/mn_rpc.h \
   masternodes/res.h \
+  masternodes/errors.h \
   masternodes/oracles.h \
   masternodes/poolpairs.h \
   masternodes/proposals.h \

src/masternodes/errors.h

@@ -0,0 +1,32 @@
+// Copyright (c) 2023 The DeFi Foundation
+// Distributed under the MIT software license, see the accompanying
+// file LICENSE or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef DEFI_MASTERNODES_ERRORS_H
+#define DEFI_MASTERNODES_ERRORS_H
+
+#include <amount.h>
+#include <masternodes/res.h>
+
+class DeFiErrors {
+public:
+    static Res MNInvalid(const std::string &nodeRefString) { 
+        return Res::Err("node %s does not exists", nodeRefString);
+    }
+
+    static Res MNInvalidAltMsg(const std::string &nodeRefString) { 
+        return Res::Err("masternode %s does not exist", nodeRefString);
+    }
+
+    static Res MNStateNotEnabled(const std::string &nodeRefString) { 
+        return Res::Err("Masternode %s is not in 'ENABLED' state", nodeRefString);
+    }
+
+    static Res ICXBTCBelowMinSwap(const CAmount amount, const CAmount minSwap) {
+        // TODO: Change error in later version to include amount. Retaining old msg for compatibility
+        return Res::Err("Below minimum swapable amount, must be at least %s BTC", GetDecimaleString(minSwap));
+    }
+};
+
+#endif  // DEFI_MASTERNODES_ERRORS_H
+

src/masternodes/mn_checks.cpp

@@ -7,6 +7,7 @@
 #include <masternodes/historywriter.h>
 #include <masternodes/mn_checks.h>
 #include <masternodes/vaulthistory.h>
+#include <masternodes/errors.h>
 
 #include <core_io.h>
 #include <index/txindex.h>
@@ -845,7 +846,7 @@ class CCustomTxApplyVisitor : public CCustomTxVisitor {
 
     Res operator()(const CResignMasterNodeMessage &obj) const {
         auto node = mnview.GetMasternode(obj);
-        Require(node, "node %s does not exists", obj.ToString());
+        if (!node) return DeFiErrors::MNInvalid(obj.ToString());
 
         Require(HasCollateralAuth(node->collateralTx.IsNull() ? static_cast<uint256>(obj) : node->collateralTx));
         return mnview.ResignMasternode(*node, obj, tx.GetHash(), height);
@@ -861,13 +862,16 @@ class CCustomTxApplyVisitor : public CCustomTxVisitor {
         }
 
         auto node = mnview.GetMasternode(obj.mnId);
-        Require(node, "masternode %s does not exist", obj.mnId.ToString());
+        if (!node)
+            return DeFiErrors::MNInvalidAltMsg(obj.mnId.ToString());
 
         const auto collateralTx = node->collateralTx.IsNull() ? obj.mnId : node->collateralTx;
         Require(HasCollateralAuth(collateralTx));
 
         auto state = node->GetState(height, mnview);
-        Require(state == CMasternode::ENABLED, "Masternode %s is not in 'ENABLED' state", obj.mnId.ToString());
+        if (state != CMasternode::ENABLED) {
+            return DeFiErrors::MNStateNotEnabled(obj.mnId.ToString());
+        }
 
         const auto attributes = mnview.GetAttributes();
         assert(attributes);
@@ -1556,8 +1560,9 @@ class CCustomTxApplyVisitor : public CCustomTxVisitor {
         CDataStructureV0 minSwapKey{AttributeTypes::Param, ParamIDs::DFIP2201, DFIPKeys::MinSwap};
         auto minSwap = attributes->GetValue(minSwapKey, CAmount{0});
 
-        Require(amount >= minSwap,
-                "Below minimum swapable amount, must be at least " + GetDecimaleString(minSwap) + " BTC");
+        if (amount < minSwap) {
+            return DeFiErrors::ICXBTCBelowMinSwap(amount, minSwap);
+        }
 
         const auto token = mnview.GetToken(id);
         Require(token, "Specified token not found");