Refuel

src/neo/SmartContract/ApplicationEngine.cs

@@ -40,7 +40,7 @@ public partial class ApplicationEngine : ExecutionEngine
 
         private static IApplicationEngineProvider applicationEngineProvider;
         private static Dictionary<uint, InteropDescriptor> services;
-        private readonly long gas_amount;
+        private long gas_amount;
         private List<NotifyEventArgs> notifications;
         private List<IDisposable> disposables;
         private readonly Dictionary<UInt160, int> invocationCounter = new();
@@ -147,6 +147,14 @@ protected internal void AddGas(long gas)
                 throw new InvalidOperationException("Insufficient GAS.");
         }
 
+        internal void Refuel(long gas)
+        {
+            checked
+            {
+                gas_amount += gas;
+            }
+        }
+
         protected override void OnFault(Exception ex)
         {
             FaultException = ex;

src/neo/SmartContract/Native/GasToken.cs

@@ -1,5 +1,8 @@
+#pragma warning disable IDE0051
+
 using Neo.Cryptography.ECC;
 using Neo.Network.P2P.Payloads;
+using System;
 
 namespace Neo.SmartContract.Native
 {
@@ -33,5 +36,14 @@ internal override async ContractTask OnPersist(ApplicationEngine engine)
             UInt160 primary = Contract.CreateSignatureRedeemScript(validators[engine.PersistingBlock.PrimaryIndex]).ToScriptHash();
             await Mint(engine, primary, totalNetworkFee, false);
         }
+
+        [ContractMethod(RequiredCallFlags = CallFlags.States | CallFlags.AllowNotify)]
+        private async ContractTask Refuel(ApplicationEngine engine, UInt160 account, long amount)
+        {
+            if (amount < 0_01000000) throw new ArgumentOutOfRangeException(nameof(amount));
+            if (!engine.CheckWitnessInternal(account)) throw new InvalidOperationException();
+            await Burn(engine, account, amount);
+            engine.Refuel(amount);
+        }
     }
 }