From 3b5eb00777ade3a9feeb23d4d56dded917e0ecc1 Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Mon, 1 Jul 2024 14:15:49 +0200
Subject: [PATCH] Deposits can be unpaused

---
 .../ethereum/gateway/L1USDCGateway.sol        | 20 +++++++++--
 test-foundry/L1USDCGateway.t.sol              | 33 +++++++++++++++++++
 2 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/contracts/tokenbridge/ethereum/gateway/L1USDCGateway.sol b/contracts/tokenbridge/ethereum/gateway/L1USDCGateway.sol
index 67a4dddc4..605f6b9f2 100644
--- a/contracts/tokenbridge/ethereum/gateway/L1USDCGateway.sol
+++ b/contracts/tokenbridge/ethereum/gateway/L1USDCGateway.sol
@@ -22,7 +22,7 @@ import {IFiatToken} from "../../libraries/IFiatToken.sol";
  *         This custom gateway differs from standard gateway in the following ways:
  *         - it supports a single parent chain - child chain USDC token pair
  *         - it is ownable
- *         - owner can one-time permanently pause deposits
+ *         - owner can pause and unpause deposits
  *         - owner can set a burner address
  *         - owner can set the amount of USDC tokens to be burned by burner
  *         - burner can trigger burning the amount of USDC tokens locked in the gateway that matches the L2 supply
@@ -39,11 +39,13 @@ contract L1USDCGateway is L1ArbitrumExtendedGateway {
     uint256 public burnAmount;
 
     event DepositsPaused();
+    event DepositsUnpaused();
     event GatewayUsdcBurned(uint256 amount);
     event BurnerSet(address indexed burner);
     event BurnAmountSet(uint256 amount);
 
     error L1USDCGateway_DepositsAlreadyPaused();
+    error L1USDCGateway_DepositsAlreadyUnpaused();
     error L1USDCGateway_DepositsPaused();
     error L1USDCGateway_DepositsNotPaused();
     error L1USDCGateway_InvalidL1USDC();
@@ -85,8 +87,8 @@ contract L1USDCGateway is L1ArbitrumExtendedGateway {
 
     /**
      * @notice Pauses deposits. This can only be called by the owner.
-     * @dev    Pausing is permanent and can't be undone. Pausing is prerequisite for burning escrowed USDC tokens.
-     *         Incoming withdrawals are not affected. Pausing the withdrawals needs to be done separately on the child chain.
+     * @dev    Pausing is prerequisite for burning escrowed USDC tokens.  Incoming withdrawals are not affected.
+     *         Pausing the withdrawals needs to be done separately on the child chain.
      */
     function pauseDeposits() external onlyOwner {
         if (depositsPaused) {
@@ -97,6 +99,18 @@ contract L1USDCGateway is L1ArbitrumExtendedGateway {
         emit DepositsPaused();
     }
 
+    /**
+     * @notice Unpauses deposits. This can only be called by the owner.
+     */
+    function unpauseDeposits() external onlyOwner {
+        if (!depositsPaused) {
+            revert L1USDCGateway_DepositsAlreadyUnpaused();
+        }
+        depositsPaused = false;
+
+        emit DepositsUnpaused();
+    }
+
     /**
      * @notice Owner sets the amount of USDC tokens to be burned by burner account.
      * @dev    This amount should match the L2 supply of bridged USDC. But it's not enforced, so burner
diff --git a/test-foundry/L1USDCGateway.t.sol b/test-foundry/L1USDCGateway.t.sol
index 2b69ea6f1..3b69be656 100644
--- a/test-foundry/L1USDCGateway.t.sol
+++ b/test-foundry/L1USDCGateway.t.sol
@@ -384,6 +384,11 @@ contract L1USDCGatewayTest is L1ArbitrumExtendedGatewayTest {
         assertEq(usdcGateway.burnAmount(), amount, "Invalid burnAmount");
     }
 
+    function test_setBurnAmount_revert_NotOwner() public {
+        vm.expectRevert(abi.encodeWithSelector(L1USDCGateway.L1USDCGateway_NotOwner.selector));
+        usdcGateway.setBurnAmount(100);
+    }
+
     function test_setOwner() public {
         address newOwner = makeAddr("new-owner");
         vm.prank(owner);
@@ -403,10 +408,38 @@ contract L1USDCGatewayTest is L1ArbitrumExtendedGatewayTest {
         usdcGateway.setOwner(owner);
     }
 
+    function test_unpauseDeposits() public {
+        vm.prank(owner);
+        usdcGateway.pauseDeposits();
+        assertEq(usdcGateway.depositsPaused(), true, "Invalid depositPaused");
+
+        vm.expectEmit(true, true, true, true);
+        emit DepositsUnpaused();
+
+        vm.prank(owner);
+        usdcGateway.unpauseDeposits();
+
+        assertEq(usdcGateway.depositsPaused(), false, "Invalid depositPaused");
+    }
+
+    function test_unpauseDeposits_revert_NotOwner() public {
+        vm.expectRevert(abi.encodeWithSelector(L1USDCGateway.L1USDCGateway_NotOwner.selector));
+        usdcGateway.unpauseDeposits();
+    }
+
+    function test_unpauseDeposits_revert_DepositsAlreadyUnpaused() public {
+        vm.prank(owner);
+        vm.expectRevert(
+            abi.encodeWithSelector(L1USDCGateway.L1USDCGateway_DepositsAlreadyUnpaused.selector)
+        );
+        usdcGateway.unpauseDeposits();
+    }
+
     ////
     // Event declarations
     ////
     event DepositsPaused();
+    event DepositsUnpaused();
     event GatewayUsdcBurned(uint256 amount);
     event BurnerSet(address indexed burner);
     event BurnAmountSet(uint256 amount);