From 4e779029a8dedccc398e7af04800cdc8ed937371 Mon Sep 17 00:00:00 2001
From: mike <m1k3cz@pm.me>
Date: Mon, 16 Dec 2024 16:28:30 +0100
Subject: [PATCH] Refactor burn native tokens method

---
 contracts/sfc/SFC.sol | 22 +++++++++++++---------
 test/SFC.ts           | 22 +++++++++++++++++++++-
 2 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/contracts/sfc/SFC.sol b/contracts/sfc/SFC.sol
index 159f91f..ab2a5a6 100644
--- a/contracts/sfc/SFC.sol
+++ b/contracts/sfc/SFC.sol
@@ -216,7 +216,7 @@ contract SFC is OwnableUpgradeable, UUPSUpgradeable, Version {
     );
     event ClaimedRewards(address indexed delegator, uint256 indexed toValidatorID, uint256 rewards);
     event RestakedRewards(address indexed delegator, uint256 indexed toValidatorID, uint256 rewards);
-    event BurntFTM(uint256 amount);
+    event BurntNativeTokens(uint256 amount);
     event UpdatedSlashingRefundRatio(uint256 indexed validatorID, uint256 refundRatio);
     event RefundedSlashedLegacyDelegation(address indexed delegator, uint256 indexed validatorID, uint256 amount);
     event AnnouncedRedirection(address indexed from, address indexed to);
@@ -459,9 +459,12 @@ contract SFC is OwnableUpgradeable, UUPSUpgradeable, Version {
         emit TreasuryFeesResolved(fees);
     }
 
-    /// burnFTM allows SFC to burn an arbitrary amount of FTM tokens.
-    function burnFTM(uint256 amount) external onlyOwner {
-        _burnFTM(amount);
+    /// Burn native tokens by sending them to the SFC contract.
+    function burnNativeTokens() external payable {
+        if (msg.value == 0) {
+            revert ZeroAmount();
+        }
+        _burnNativeTokens(msg.value);
     }
 
     /// Issue tokens to the issued tokens recipient as a counterparty to the burnt FTM tokens.
@@ -753,7 +756,7 @@ contract SFC is OwnableUpgradeable, UUPSUpgradeable, Version {
         if (!sent) {
             revert TransferFailed();
         }
-        _burnFTM(penalty);
+        _burnNativeTokens(penalty);
 
         emit Withdrawn(delegator, toValidatorID, wrID, amount - penalty, penalty);
     }
@@ -817,12 +820,13 @@ contract SFC is OwnableUpgradeable, UUPSUpgradeable, Version {
         return rewards;
     }
 
-    /// Burn FTM tokens.
+    /// Burn native tokens.
     /// The tokens are sent to the zero address.
-    function _burnFTM(uint256 amount) internal {
-        if (amount != 0) {
+    function _burnNativeTokens(uint256 amount) internal {
+        if (amount != 0 && totalSupply >= amount) {
+            totalSupply -= amount;
             payable(address(0)).transfer(amount);
-            emit BurntFTM(amount);
+            emit BurntNativeTokens(amount);
         }
     }
 
diff --git a/test/SFC.ts b/test/SFC.ts
index b3ea8d6..4d7cfbc 100644
--- a/test/SFC.ts
+++ b/test/SFC.ts
@@ -24,7 +24,7 @@ describe('SFC', () => {
     const evmWriter: IEVMWriter = await ethers.deployContract('StubEvmWriter');
     const initializer: UnitTestNetworkInitializer = await ethers.deployContract('UnitTestNetworkInitializer');
 
-    await initializer.initializeAll(0, 0, sfc, nodeDriverAuth, nodeDriver, evmWriter, owner);
+    await initializer.initializeAll(0, ethers.parseEther('100000'), sfc, nodeDriverAuth, nodeDriver, evmWriter, owner);
     const constants: UnitTestConstantsManager = await ethers.getContractAt(
       'UnitTestConstantsManager',
       await sfc.constsAddress(),
@@ -55,6 +55,26 @@ describe('SFC', () => {
     ).to.revertedWithCustomError(this.sfc, 'TransfersNotAllowed');
   });
 
+  describe('Burn native tokens', () => {
+    it('Should revert when no amount sent', async function () {
+      await expect(this.sfc.connect(this.user).burnNativeTokens()).to.be.revertedWithCustomError(
+        this.sfc,
+        'ZeroAmount',
+      );
+    });
+
+    it('Should succeed and burn native tokens', async function () {
+      const amount = ethers.parseEther('1.5');
+      const totalSupply = await this.sfc.totalSupply();
+      const tx = await this.sfc.connect(this.user).burnNativeTokens({ value: amount });
+      await expect(tx).to.emit(this.sfc, 'BurntNativeTokens').withArgs(amount);
+      expect(await this.sfc.totalSupply()).to.equal(totalSupply - amount);
+      await expect(tx).to.changeEtherBalance(this.sfc, 0);
+      await expect(tx).to.changeEtherBalance(this.user, -amount);
+      await expect(tx).to.changeEtherBalance(ethers.ZeroAddress, amount);
+    });
+  });
+
   describe('Genesis validator', () => {
     beforeEach(async function () {
       const validator = ethers.Wallet.createRandom();