Add support for two tokens in erc to native

contracts/interfaces/IScdMcdMigration.sol

@@ -8,3 +8,7 @@ interface IScdMcdMigration {
 interface IDaiAdapter {
     function dai() public returns (address);
 }
+
+interface ISaiTop {
+    function caged() public returns (uint256);
+}

contracts/upgradeable_contracts/BaseBridgeValidators.sol

@@ -102,4 +102,23 @@ contract BaseBridgeValidators is InitializableBridge, Ownable {
     function setNextValidator(address _prevValidator, address _validator) internal {
         addressStorage[keccak256(abi.encodePacked("validatorsList", _prevValidator))] = _validator;
     }
+
+    function isValidatorDuty(address _validator) external view returns (bool) {
+        uint256 counter = 0;
+        address next = getNextValidator(F_ADDR);
+        require(next != address(0));
+
+        while (next != F_ADDR) {
+            if (next == _validator) {
+                return (block.number % validatorCount() == counter);
+            }
+
+            next = getNextValidator(next);
+            counter++;
+
+            require(next != address(0));
+        }
+
+        return false;
+    }
 }

contracts/upgradeable_contracts/erc20_to_native/ForeignBridgeErcToNative.sol

@@ -8,6 +8,9 @@ import "../../interfaces/IScdMcdMigration.sol";
 contract ForeignBridgeErcToNative is BasicForeignBridge, ERC20Bridge, OtherSideBridgeStorage {
     event TokensSwapped(address indexed from, address indexed to, uint256 value);
 
+    bytes32 internal constant MIN_HDTOKEN_BALANCE = 0x48649cf195feb695632309f41e61252b09f537943654bde13eb7bb1bca06964e; // keccak256(abi.encodePacked("minHDTokenBalance"))
+    bytes4 internal constant SWAP_TOKENS = 0x73d00224; // swapTokens()
+
     function initialize(
         address _validatorContract,
         address _erc20token,
@@ -61,6 +64,11 @@ contract ForeignBridgeErcToNative is BasicForeignBridge, ERC20Bridge, OtherSideB
 
     function claimTokens(address _token, address _to) public {
         require(_token != address(erc20token()));
+        if (_token == address(halfDuplexErc20token())) {
+            // SCD is not claimable if the bridge accepts deposits of this token
+            // solhint-disable-next-line not-rely-on-time
+            require(!isTokenSwapAllowed(now));
+        }
         super.claimTokens(_token, _to);
     }
 
@@ -71,7 +79,13 @@ contract ForeignBridgeErcToNative is BasicForeignBridge, ERC20Bridge, OtherSideB
     ) internal returns (bool) {
         setTotalExecutedPerDay(getCurrentDay(), totalExecutedPerDay(getCurrentDay()).add(_amount));
         uint256 amount = _amount.div(10**decimalShift());
-        return erc20token().transfer(_recipient, amount);
+        bool res = erc20token().transfer(_recipient, amount);
+
+        if (AddressUtils.isContract(halfDuplexErc20token()) && tokenBalance(halfDuplexErc20token()) > 0) {
+            address(this).call(abi.encodeWithSelector(SWAP_TOKENS));
+        }
+
+        return res;
     }
 
     function onFailedMessage(address, uint256, bytes32) internal {
@@ -102,4 +116,100 @@ contract ForeignBridgeErcToNative is BasicForeignBridge, ERC20Bridge, OtherSideB
         emit TokensSwapped(saiContract, erc20token(), curBalance);
         boolStorage[storageAddress] = true;
     }
+
+    function saiTopContract() internal pure returns (ISaiTop) {
+        return ISaiTop(0x9b0ccf7C8994E19F39b2B4CF708e0A7DF65fA8a3);
+    }
+
+    function isTokenSwapAllowed(uint256 _ts) public view returns (bool) {
+        uint256 esTs = saiTopContract().caged();
+        if ((esTs > 0) && (_ts > esTs)) {
+            return false;
+        }
+        return true;
+    }
+
+    function halfDuplexErc20token() public pure returns (ERC20) {
+        return ERC20(0x89d24A6b4CcB1B6fAA2625fE562bDD9a23260359);
+    }
+
+    function setMinHDTokenBalance(uint256 _minBalance) external onlyOwner {
+        uintStorage[MIN_HDTOKEN_BALANCE] = _minBalance;
+    }
+
+    function minHDTokenBalance() public view returns (uint256) {
+        return uintStorage[MIN_HDTOKEN_BALANCE];
+    }
+
+    function isHDTokenBalanceAboveMinBalance() public view returns (bool) {
+        if (tokenBalance(halfDuplexErc20token()) > minHDTokenBalance()) {
+            return true;
+        }
+        return false;
+    }
+
+    function tokenBalance(ERC20 _token) internal view returns (uint256) {
+        return _token.balanceOf(address(this));
+    }
+
+    function migrationContract() internal pure returns (IScdMcdMigration) {
+        return IScdMcdMigration(0xc73e0383F3Aff3215E6f04B0331D58CeCf0Ab849);
+    }
+
+    function swapTokens() public {
+        // solhint-disable-next-line not-rely-on-time
+        require(isTokenSwapAllowed(now));
+
+        IScdMcdMigration mcdMigrationContract = migrationContract();
+        ERC20 hdToken = halfDuplexErc20token();
+        ERC20 fdToken = erc20token();
+
+        uint256 curHDTokenBalance = tokenBalance(hdToken);
+        require(curHDTokenBalance > 0);
+
+        uint256 curFDTokenBalance = tokenBalance(fdToken);
+
+        require(hdToken.approve(mcdMigrationContract, curHDTokenBalance));
+        mcdMigrationContract.swapSaiToDai(curHDTokenBalance);
+
+        require(tokenBalance(fdToken) - curFDTokenBalance == curHDTokenBalance);
+
+        emit TokensSwapped(hdToken, fdToken, curHDTokenBalance);
+    }
+
+    function relayTokens(address _from, address _receiver, uint256 _amount, address _token) external {
+        require(_from == msg.sender || _from == _receiver);
+        _relayTokens(_from, _receiver, _amount, _token);
+    }
+
+    function relayTokens(address _receiver, uint256 _amount, address _token) external {
+        _relayTokens(msg.sender, _receiver, _amount, _token);
+    }
+
+    function _relayTokens(address _sender, address _receiver, uint256 _amount, address _token) internal {
+        require(_receiver != bridgeContractOnOtherSide());
+        require(_receiver != address(0));
+        require(_receiver != address(this));
+        require(_amount > 0);
+        require(withinLimit(_amount));
+
+        ERC20 tokenToOperate = ERC20(_token);
+        ERC20 hdToken = halfDuplexErc20token();
+        ERC20 fdToken = erc20token();
+
+        if (tokenToOperate == ERC20(0x0)) {
+            tokenToOperate = fdToken;
+        }
+
+        require(tokenToOperate == fdToken || tokenToOperate == hdToken);
+
+        setTotalSpentPerDay(getCurrentDay(), totalSpentPerDay(getCurrentDay()).add(_amount));
+
+        tokenToOperate.transferFrom(_sender, address(this), _amount);
+        emit UserRequestForAffirmation(_receiver, _amount);
+
+        if (tokenToOperate == hdToken) {
+            swapTokens();
+        }
+    }
 }