dsa-polygon-migration/contracts/senders2/aave-v2-migrator/main.sol

pragma solidity >=0.7.0;
pragma experimental ABIEncoderV2;

import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";

import { TokenInterface } from "../../common/interfaces.sol";
import { Helpers } from "./helpers.sol";
import { AaveInterface, ATokenInterface } from "./interfaces.sol";
import { Events } from "./events.sol";

contract LiquidityResolver is Helpers, Events {
    using SafeERC20 for IERC20;

    mapping(address => mapping(address => uint)) public deposits;

    // This will be used to have debt/collateral ratio always 20% less than liquidation
    // TODO: Is this number correct for it?
    uint public safeRatioGap = 20000000000000000; // 20%?

    uint public fee = 200000000000000; // 0.2% on collateral?

    // InstaIndex Address.
    IndexInterface public constant instaIndex = IndexInterface(0x2971AdFa57b20E5a416aE5a708A8655A9c74f723);

    function updateVariables(uint _safeRatioGap, uint _fee) public {
        require(msg.sender == instaIndex.master(), "not-master");
        safeRatioGap = _safeRatioGap;
        fee = _fee;
        // TODO: Add event
    }

    function spell(address _target, bytes memory _data) external {
        require(msg.sender == instaIndex.master(), "not-master");
        require(_target != address(0), "target-invalid");
        assembly {
            let succeeded := delegatecall(gas(), _target, add(_data, 0x20), mload(_data), 0, 0)

            switch iszero(succeeded)
                case 1 {
                    // throw if delegatecall failed
                    let size := returndatasize()
                    returndatacopy(0x00, 0x00, size)
                    revert(0x00, size)
                }
        }
    }

    // TODO: Deposited assets will get deposited into Aave as collateral
    function deposit(address[] calldata tokens, uint[] calldata amts) external payable {
        uint _length = tokens.length;
        require(_length == amts.length, "invalid-length");

        uint[] memory _amts = new uint[](_length);

        for (uint256 i = 0; i < _length; i++) {
            uint _amt;
            address _token = tokens[i];
            if (_token == ethAddr) {
                require(msg.value == amts[i]);
                _amt = msg.value;

                TokenInterface(wethAddr).deposit{value: msg.value}();
            } else {
                IERC20 tokenContract = IERC20(_token);
                _amt = amts[i] == uint(-1) ? tokenContract.balanceOf(msg.sender) : amts[i];
                tokenContract.safeTransferFrom(msg.sender, address(this), _amt);
            }

            _amts[i] = _amt;

            deposits[msg.sender][_token] += _amt;
        }

        emit LogDeposit(msg.sender, tokens, _amts);
    }

    // TODO: If not enough ideal token then withdraw the required amount from Aave. Also, check that it should not make position risky
    function withdraw(address[] calldata tokens, uint[] calldata amts) external {
        uint _length = tokens.length;
        require(_length == amts.length, "invalid-length");

        uint[] memory _amts = new uint[](_length);

        for (uint256 i = 0; i < _length; i++) {
            uint _amt = amts[i];
            address _token = tokens[i];
            uint maxAmt = deposits[msg.sender][_token];

            if (_amt > maxAmt) {
                _amt = maxAmt;
            }

            if (_token == ethAddr) {
                TokenInterface(wethAddr).withdraw(_amt);
                msg.sender.call{value: _amt}("");
            } else {
                IERC20(_token).safeTransfer(msg.sender, _amt);
            }

            _amts[i] = _amt;

            deposits[msg.sender][_token] = sub(maxAmt, _amt);
        }

        emit LogWithdraw(msg.sender, tokens, _amts);
    }

    // TODO: payback if debt else deposit
    // TODO: if ratio is safe then transfer excess collateral to L2 migration contract
    // Always, keep 1000 wei WETH ideal for flashloan
    function settle(address[] calldata tokens) external {
        
    }

}

contract MigrateResolver is LiquidityResolver {
    using SafeERC20 for IERC20;

    function _migrate(AaveDataRaw memory _data, address sourceDsa) internal {
        require(_data.supplyTokens.length > 0, "0-length-not-allowed");
        require(_data.targetDsa != address(0), "invalid-address");
        require(_data.supplyTokens.length == _data.supplyAmts.length, "invalid-length");
        require(
            _data.borrowTokens.length == _data.variableBorrowAmts.length &&
            _data.borrowTokens.length == _data.stableBorrowAmts.length,
            "invalid-length"
        );

        AaveInterface aave = AaveInterface(aaveProvider.getLendingPool());

        (,,,,,uint healthFactor) = aave.getUserAccountData(sourceDsa);
        require(healthFactor > 1e18, "position-not-safe");

        (uint[] stableBorrows, uint[] variableBorrows, uint[] totalBorrows) = _PaybackCalculate(aave, _data, sourceDsa);

        _PaybackStable(_data.borrowTokens.length, aave, _data.borrowTokens, stableBorrows, sourceDsa);
        _PaybackVariable(_data.borrowTokens.length, aave, _data.borrowTokens, variableBorrows, sourceDsa);

        (uint[] totalSupplies) = _getAtokens(aave, _data.supplyTokens, _data.supplyAmts, fee);

        // Aave on Polygon doesn't have stable borrowing so we'll borrow all the debt in variable
        AaveData memory data;

        data.borrowTokens = _data.borrowTokens;
        data.stableBorrowAmts = _data.stableBorrowAmts;
        data.supplyAmts = totalSupplies;
        data.supplyTokens = _data.supplyTokens;
        data.targetDsa = _data.targetDsa;
        data.borrowAmts = totalBorrows;

        // TODO: Check the amount that user is trying to migrate is 20% below the Liquidation
        bool isOk = _checkRatio(data, safeRatioGap);
        require(isOk, "position-risky-to-migrate");

        bytes memory positionData = data; // TODO: Can we do anything else to make the data more secure? (It's secure already)
        stateSender.syncState(polygonReceiver, positionData);

        emit LogAaveV2Migrate(
            sourceDsa,
            data.targetDsa,
            data.supplyTokens,
            data.borrowTokens,
            data.supplyAmts,
            data.variableBorrowAmts,
            data.stableBorrowAmts
        );
    }

    function migrate(AaveDataRaw calldata _data) external {
        _migrate(_data, msg.sender);
    }

    function migrateWithFlash(AaveDataRaw calldata _data, uint ethAmt) external {
        bytes data = abi.encode(_data, msg.sender, ethAmt);
        
        // TODO: integrate dydx flashloan and borrow "ethAmt" and transfer ETH to this address

    }

    function callFunction(
        address sender,
        Account.Info memory account,
        bytes memory data
    ) public override {
        require(sender == address(this), "wrong-sender");
        (address l2DSA, AaveDataRaw memory _data, address sourceDsa, uint ethAmt) = abi.decode(
            data,
            (address, AaveDataRaw, address, uint)
        );
        // TODO: deposit WETH "ethAmt" in Aave
        _migrate(l2DSA, _data, sourceDsa);
        // TODO: withdraw WETH "ethAmt" from Aave
        // TODO: approve WETH "ethAmt + 2" to dydx
    }

}