pragma solidity ^0.7.0;

// import files from common directory
import { TokenInterface , MemoryInterface } from "../common/interfaces.sol";
import { Stores } from "../common/stores.sol";
import { DSMath } from "../common/math.sol";

interface ICurve {
    function calc_token_amount(uint256[4] calldata amounts, bool deposit) external view returns (uint256 amount);
    function get_dy(int128 sellTokenId, int128 buyTokenId, uint256 sellTokenAmt) external returns (uint256 buyTokenAmt);
    function exchange_underlying(int128 sellTokenId, int128 buyTokenId, uint256 sellTokenAmt, uint256 minBuyToken) external;
    function add_liquidity(uint256[4] calldata amounts, uint256 min_mint_amount) external;
    function remove_liquidity_imbalance(uint256[4] calldata amounts, uint256 max_burn_amount) external;
}

interface ICurveZap {
    function calc_withdraw_one_coin(uint256 _token_amount, int128 i) external returns (uint256 amount);
    function add_liquidity(uint256[4] calldata amounts, uint256 min_mint_amount) external;
    function remove_liquidity_imbalance(uint256[4] calldata amounts, uint256 max_burn_amount) external;
}

interface YTokenInterface {
    function getPricePerFullShare() external view returns (uint256 amount);
}

abstract contract CurveHelpers is Stores, DSMath {
    /**
    * @dev Return ycurve Swap Address
    */
    function getCurveSwapAddr() internal pure returns (address) {
        return 0x45F783CCE6B7FF23B2ab2D70e416cdb7D6055f51;
    }

    /**
    * @dev Return ycurve zap Address
    */
    function getCurveZapAddr() internal pure returns (address) {
        return 0xbBC81d23Ea2c3ec7e56D39296F0cbB648873a5d3;
    }

    /**
    * @dev Return Curve Token Address
    */
    function getCurveTokenAddr() internal pure returns (address) {
        return 0xdF5e0e81Dff6FAF3A7e52BA697820c5e32D806A8;
    }

    function convert18ToDec(uint _dec, uint256 _amt) internal pure returns (uint256 amt) {
        amt = (_amt / 10 ** (18 - _dec));
    }

    function convertTo18(uint _dec, uint256 _amt) internal pure returns (uint256 amt) {
        amt = mul(_amt, 10 ** (18 - _dec));
    }

  function getTokenI(address token) internal pure returns (int128 i) {
    if (token == address(0x6B175474E89094C44Da98b954EedeAC495271d0F)) {
      // DAI Token
      i = 0;
    } else if (token == address(0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48)) {
      // USDC Token
      i = 1;
    } else if (token == address(0xdAC17F958D2ee523a2206206994597C13D831ec7)) {
      // USDT Token
      i = 2;
    } else if (token == address(0x0000000000085d4780B73119b644AE5ecd22b376)) {
      // USDT Token
      i = 3;
    } else {
      revert("token-not-found.");
    }
  }

  function getYtoken(address token) internal pure returns (address yTkn) {
        if (token == address(0x6B175474E89094C44Da98b954EedeAC495271d0F)) {
            // DAI Token
            yTkn = 0x16de59092dAE5CcF4A1E6439D611fd0653f0Bd01;
        } else if (token == address(0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48)) {
            // USDC Token
            yTkn = 0xd6aD7a6750A7593E092a9B218d66C0A814a3436e;
        } else if (token == address(0xdAC17F958D2ee523a2206206994597C13D831ec7)) {
            // USDT Token
            yTkn = 0x83f798e925BcD4017Eb265844FDDAbb448f1707D;
        } else if (token == address(0x0000000000085d4780B73119b644AE5ecd22b376)) {
            // USDT Token
            yTkn = 0x73a052500105205d34Daf004eAb301916DA8190f;
        } else {
        revert("token-not-found.");
        }
    }
}

abstract contract CurveProtocol is CurveHelpers {

  event LogSell(
    address indexed buyToken,
    address indexed sellToken,
    uint256 buyAmt,
    uint256 sellAmt,
    uint256 getId,
    uint256 setId
  );
  event LogDeposit(address token, uint256 amt, uint256 mintAmt, uint256 getId, uint256 setId);
  event LogWithdraw(address token, uint256 amt, uint256 burnAmt, uint256 getId,  uint256 setId);

  /**
  * @dev Sell Stable ERC20_Token.
  * @param buyAddr buying token address.
    * @param sellAddr selling token amount.
    * @param sellAmt selling token amount.
    * @param unitAmt unit amount of buyAmt/sellAmt with slippage.
    * @param getId Get token amount at this ID from `InstaMemory` Contract.
    * @param setId Set token amount at this ID in `InstaMemory` Contract.
    */
  function sell(
    address buyAddr,
    address sellAddr,
    uint sellAmt,
    uint unitAmt,
    uint getId,
    uint setId
  ) external payable {
    uint _sellAmt = getUint(getId, sellAmt);
    ICurve curve = ICurve(getCurveSwapAddr());
    TokenInterface _buyToken = TokenInterface(buyAddr);
    TokenInterface _sellToken = TokenInterface(sellAddr);
    _sellAmt = _sellAmt == uint(-1) ? _sellToken.balanceOf(address(this)) : _sellAmt;
    _sellToken.approve(address(curve), _sellAmt);

    uint _slippageAmt = convert18ToDec(_buyToken.decimals(), wmul(unitAmt, convertTo18(_sellToken.decimals(), _sellAmt)));

    uint intialBal = _buyToken.balanceOf(address(this));
    curve.exchange_underlying(getTokenI(sellAddr), getTokenI(buyAddr), _sellAmt, _slippageAmt);
    uint finalBal = _buyToken.balanceOf(address(this));

    uint _buyAmt = sub(finalBal, intialBal);

    setUint(setId, _buyAmt);

    emit LogSell(buyAddr, sellAddr, _buyAmt, _sellAmt, getId, setId);

  }

    /**
    * @dev Deposit Token.
    * @param token token address.
    * @param amt token amount.
    * @param unitAmt unit amount of curve_amt/token_amt with slippage.
    * @param getId Get token amount at this ID from `InstaMemory` Contract.
    * @param setId Set token amount at this ID in `InstaMemory` Contract.
    */
    function deposit(
        address token,
        uint amt,
        uint unitAmt,
        uint getId,
        uint setId
    ) external payable {
        uint256 _amt = getUint(getId, amt);
        TokenInterface tokenContract = TokenInterface(token);

        _amt = _amt == uint(-1) ? tokenContract.balanceOf(address(this)) : _amt;
        uint[4] memory _amts;
        _amts[uint(getTokenI(token))] = _amt;

        tokenContract.approve(getCurveZapAddr(), _amt);

        uint _amt18 = convertTo18(tokenContract.decimals(), _amt);
        uint _slippageAmt = wmul(unitAmt, _amt18);

        TokenInterface curveTokenContract = TokenInterface(getCurveTokenAddr());
        uint initialCurveBal = curveTokenContract.balanceOf(address(this));

        ICurve(getCurveSwapAddr()).add_liquidity(_amts, _slippageAmt);

        uint finalCurveBal = curveTokenContract.balanceOf(address(this));

        uint mintAmt = sub(finalCurveBal, initialCurveBal);

        setUint(setId, mintAmt);

        emit LogDeposit(token, _amt, mintAmt, getId, setId);
    }

    /**
    * @dev Withdraw Token.
    * @param token token address.
        * @param amt token amount.
        * @param unitAmt unit amount of curve_amt/token_amt with slippage.
        * @param getId Get token amount at this ID from `InstaMemory` Contract.
        * @param setId Set token amount at this ID in `InstaMemory` Contract.
        */
    function withdraw(
        address token,
        uint256 amt,
        uint256 unitAmt,
        uint getId,
        uint setId
    ) external payable {
        uint _amt = getUint(getId, amt);
        int128 tokenId = getTokenI(token);

        TokenInterface curveTokenContract = TokenInterface(getCurveTokenAddr());
        ICurveZap curveZap = ICurveZap(getCurveZapAddr());
        ICurve curveSwap = ICurve(getCurveSwapAddr());

        uint _curveAmt;
        uint[4] memory _amts;
        if (_amt == uint(-1)) {
            _curveAmt = curveTokenContract.balanceOf(address(this));
            _amt = curveZap.calc_withdraw_one_coin(_curveAmt, tokenId);
            _amts[uint(tokenId)] = _amt;
        } else {
            _amts[uint(tokenId)] = _amt;
            _curveAmt = curveSwap.calc_token_amount(_amts, false);
        }


        uint _amt18 = convertTo18(TokenInterface(token).decimals(), _amt);
        uint _slippageAmt = wmul(unitAmt, _amt18);

        curveTokenContract.approve(address(curveZap), 0);
        curveTokenContract.approve(address(curveZap), _slippageAmt);

        curveZap.remove_liquidity_imbalance(_amts, _slippageAmt);

        setUint(setId, _amt);

        emit LogWithdraw(token, _amt, _curveAmt, getId, setId);
    }

}

contract ConnectCurveY is CurveProtocol {
  string public name = "Curve-y-v1";
}