Switch from raw ETH to ERC20

contracts/src/ActivePool.sol

@@ -2,9 +2,14 @@
 
 pragma solidity 0.8.18;
 
-import './Interfaces/IActivePool.sol';
+import "openzeppelin-contracts/contracts/token/ERC20/utils/SafeERC20.sol";
+
 import "./Dependencies/Ownable.sol";
 import "./Dependencies/CheckContract.sol";
+import './Interfaces/IDefaultPool.sol';
+import './Interfaces/IActivePool.sol';
+
+// import "forge-std/console.sol";
 
 /*
  * The Active Pool holds the ETH collateral and Bold debt (but not Bold tokens) for all active troves.
@@ -14,13 +19,16 @@ import "./Dependencies/CheckContract.sol";
  *
  */
 contract ActivePool is Ownable, CheckContract, IActivePool {
+    using SafeERC20 for IERC20;
+
     string constant public NAME = "ActivePool";
 
+    IERC20 public immutable ETH;
     address public borrowerOperationsAddress;
     address public troveManagerAddress;
     address public stabilityPoolAddress;
     address public defaultPoolAddress;
-    uint256 internal ETH;  // deposited ether tracker
+    uint256 internal ETHBalance;  // deposited ether tracker
     uint256 internal boldDebt;
 
     // --- Events ---
@@ -31,7 +39,12 @@ contract ActivePool is Ownable, CheckContract, IActivePool {
     event BorrowerOperationsAddressChanged(address _newBorrowerOperationsAddress);
     event TroveManagerAddressChanged(address _newTroveManagerAddress);
     event ActivePoolBoldDebtUpdated(uint _boldDebt);
-    event ActivePoolETHBalanceUpdated(uint _ETH);
+    event ActivePoolETHBalanceUpdated(uint _ETHBalance);
+
+    constructor(address _ETHAddress) {
+        checkContract(_ETHAddress);
+        ETH = IERC20(_ETHAddress);
+    }
 
     // --- Contract setters ---
 
@@ -59,6 +72,9 @@ contract ActivePool is Ownable, CheckContract, IActivePool {
         emit StabilityPoolAddressChanged(_stabilityPoolAddress);
         emit DefaultPoolAddressChanged(_defaultPoolAddress);
 
+        // Allow funds movements between Liquity contracts
+        ETH.approve(_defaultPoolAddress, type(uint256).max);
+
         _renounceOwnership();
     }
 
@@ -69,8 +85,8 @@ contract ActivePool is Ownable, CheckContract, IActivePool {
     *
     *Not necessarily equal to the the contract's raw ETH balance - ether can be forcibly sent to contracts.
     */
-    function getETH() external view override returns (uint) {
-        return ETH;
+    function getETHBalance() external view override returns (uint) {
+        return ETHBalance;
     }
 
     function getBoldDebt() external view override returns (uint) {
@@ -81,12 +97,38 @@ contract ActivePool is Ownable, CheckContract, IActivePool {
 
     function sendETH(address _account, uint _amount) external override {
         _requireCallerIsBOorTroveMorSP();
-        ETH = ETH - _amount;
-        emit ActivePoolETHBalanceUpdated(ETH);
+
+        _accountForSendETH(_account, _amount);
+
+        ETH.safeTransfer(_account, _amount);
+    }
+
+    function sendETHToDefaultPool(uint _amount) external override {
+        _requireCallerIsTroveManager();
+
+        address defaultPoolAddressCached = defaultPoolAddress;
+        _accountForSendETH(defaultPoolAddressCached, _amount);
+
+        IDefaultPool(defaultPoolAddressCached).receiveETH(_amount);
+    }
+
+    function _accountForSendETH(address _account, uint _amount) internal {
+        uint256 newETHBalance = ETHBalance - _amount;
+        ETHBalance = newETHBalance;
+        emit ActivePoolETHBalanceUpdated(newETHBalance);
         emit EtherSent(_account, _amount);
+    }
+
+    function receiveETH(uint256 _amount) external {
+        _requireCallerIsBorrowerOperationsOrDefaultPool();
 
-        (bool success, ) = _account.call{ value: _amount }("");
-        require(success, "ActivePool: sending ETH failed");
+        uint256 newETHBalance = ETHBalance + _amount;
+        ETHBalance = newETHBalance;
+
+        // Pull ETH tokens from sender
+        ETH.safeTransferFrom(msg.sender, address(this), _amount);
+
+        emit ActivePoolETHBalanceUpdated(newETHBalance);
     }
 
     function increaseBoldDebt(uint _amount) external override {
@@ -125,11 +167,9 @@ contract ActivePool is Ownable, CheckContract, IActivePool {
             "ActivePool: Caller is neither BorrowerOperations nor TroveManager");
     }
 
-    // --- Fallback function ---
-
-    receive() external payable {
-        _requireCallerIsBorrowerOperationsOrDefaultPool();
-        ETH = ETH + msg.value;
-        emit ActivePoolETHBalanceUpdated(ETH);
+    function _requireCallerIsTroveManager() internal view {
+        require(
+            msg.sender == troveManagerAddress,
+            "ActivePool: Caller is not TroveManager");
     }
 }

contracts/src/BoldToken.sol

@@ -157,8 +157,9 @@ contract BoldToken is CheckContract, IBoldToken {
     }
 
     // --- EIP 2612 Functionality ---
+    // TODO: remove and replace by openzeppelin implementation
 
-    function domainSeparator() public view override returns (bytes32) {    
+    function DOMAIN_SEPARATOR() public view override returns (bytes32) {
         if (_chainID() == _CACHED_CHAIN_ID) {
             return _CACHED_DOMAIN_SEPARATOR;
         } else {
@@ -181,7 +182,7 @@ contract BoldToken is CheckContract, IBoldToken {
     {            
         require(deadline >= block.timestamp, 'Bold: expired deadline');
         bytes32 digest = keccak256(abi.encodePacked('\x19\x01', 
-                         domainSeparator(), keccak256(abi.encode(
+                         DOMAIN_SEPARATOR(), keccak256(abi.encode(
                          _PERMIT_TYPEHASH, owner, spender, amount, 
                          _nonces[owner]++, deadline))));
         address recoveredAddress = ecrecover(digest, v, r, s);
@@ -297,8 +298,4 @@ contract BoldToken is CheckContract, IBoldToken {
     function version() external pure override returns (string memory) {
         return _VERSION;
     }
-
-    function permitTypeHash() external pure override returns (bytes32) {
-        return _PERMIT_TYPEHASH;
-    }
 }