// File: contracts/LiquidateUSDP.sol



//SPDX-License-Identifier: None
pragma solidity ^0.8.0;

import "./interfaces/IERC3156FlashBorrower.sol";
import "./interfaces/IERC3156FlashLender.sol";
import "./interfaces/ILiquidationAuction.sol";
import "./interfaces/ICurvePool.sol";
import "./interfaces/IVault.sol";
import "./interfaces/IYearn.sol";
import "./ERC20/IERC20.sol";
import "./ERC20/SafeERC20.sol";
import "./utils/Ownable.sol";

contract LiquidateUSDP is Ownable {
  using SafeERC20 for IERC20;

  IERC3156FlashLender public constant flashLender = IERC3156FlashLender(0x6bdC1FCB2F13d1bA9D26ccEc3983d5D4bf318693); // DyDx
  ILiquidationAuction public constant liqAuction = ILiquidationAuction(0xaEF1ed4C492BF4C57221bE0706def67813D79955);
  ICurvePool public constant pool = ICurvePool(0x42d7025938bEc20B69cBae5A77421082407f053A); // USDP Curve pool
  IVault public constant vault = IVault(0xb1cFF81b9305166ff1EFc49A129ad2AfCd7BCf19);
  IERC20 public constant USDP = IERC20(0x1456688345527bE1f37E9e627DA0837D6f08C925);
  IERC20 public constant USDC = IERC20(0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48);
  int128 usdpIndex = 0;
  int128 usdcIndex = 2;

  struct LiquidationData {
    address asset;
    address user;
    address caller;
    uint256 minProfit;
  }

  function liquidate(address _asset, address _user, uint256 _minProfit) onlyOwner external {
    bytes memory data = abi.encode(LiquidationData({
      asset: _asset,
      user: _user,
      caller: msg.sender,
      minProfit: _minProfit
    }));
    uint256 usdpNeeded = getDebtAmount(_asset, _user);
    uint256 flashAmt = getUsdcNeeded(usdpNeeded);
    require(flashAmt <= flashLender.maxFlashLoan(address(USDC)), "Insufficient lender reserves");
    uint256 _fee = flashLender.flashFee(address(USDC), flashAmt);
    uint256 _repayment = flashAmt + _fee;
    _approve(USDC, address(flashLender), _repayment);
    flashLender.flashLoan(IERC3156FlashBorrower(address(this)), address(USDC), flashAmt, data);
  }

  function onFlashLoan(address initiator, address token, uint256 amount, uint256 fee, bytes calldata data) external returns (bytes32) {
    LiquidationData memory liqData = abi.decode(data, (LiquidationData));
    require(msg.sender == address(flashLender), "Untrusted lender");
    require(token == address(USDC), "Not USDC");
    require(initiator == address(this), "Untrusted loan initiator");
    uint256 amountOwed = amount + fee;

    // Step 1: Convert USDC to USDP
    _approve(USDC, address(pool), amount);
    uint256 usdpReceived = pool.exchange_underlying(usdcIndex, usdpIndex, amount, 0);
    
    // Step 2: Buyout position
    _approve(USDP, address(liqAuction), usdpReceived);
    liqAuction.buyout(liqData.asset, liqData.user);
    uint256 collateralReceived = IERC20(liqData.asset).balanceOf(address(this));

    // Step 3: Convert collateral to USDC [NEED TO WRITE CUSTOM CODE]
    // INSERT CODE HERE
    // INSERT CODE HERE
    // INSERT CODE HERE
    // INSERT CODE HERE
    // INSERT CODE HERE
    // INSERT CODE HERE
    IERC20(0xB4AdA607B9d6b2c9Ee07A275e9616B84AC560139).approve(0xB4AdA607B9d6b2c9Ee07A275e9616B84AC560139, collateralReceived);
    IYearn(0xB4AdA607B9d6b2c9Ee07A275e9616B84AC560139).withdraw(collateralReceived);
    uint256 bal = IERC20(0xd632f22692FaC7611d2AA1C0D552930D43CAEd3B).balanceOf(address(this));
    ICurvePool(0xA79828DF1850E8a3A3064576f380D90aECDD3359).remove_liquidity_one_coin(0xd632f22692FaC7611d2AA1C0D552930D43CAEd3B, bal, 2, 0);

    uint256 usdcReceived = USDC.balanceOf(address(this));

    // Step 4: Ensure profit (usdcReceived - (flashAmt + flashFee)) is > minProfit and send to caller
    require(usdcReceived > amountOwed + liqData.minProfit, "Less than minProfit");
    USDC.safeTransfer(liqData.caller, usdcReceived - amountOwed);
    return keccak256("ERC3156FlashBorrower.onFlashLoan");
  }

  function getUsdcNeeded(uint256 _usdpNeeded) public view returns (uint256) {
    uint256 usdcNeeded = _usdpNeeded;
    uint256 amountOut = pool.get_dy_underlying(usdcIndex, usdpIndex, usdcNeeded);
    while (amountOut < _usdpNeeded) {
      usdcNeeded += usdcNeeded / 20; // increment by 5% until amountOut > usdpNeeded
      amountOut = pool.get_dy_underlying(usdcIndex, usdpIndex, usdcNeeded);
    }
    return usdcNeeded;
  }

  function getDebtAmount(address _asset, address _user) public view returns (uint256) {
    return vault.getTotalDebt(_asset, _user);
  }

  function _approve(IERC20 _token, address _spender, uint256 _amount) internal {
    if (_token.allowance(address(this), _spender) < _amount) {
        _token.safeApprove(_spender, type(uint256).max);
    }
  }
}

// File: contracts/interfaces/IERC3156FlashBorrower.sol



// SPDX-License-Identifier: No License

pragma solidity ^0.8.0;

interface IERC3156FlashBorrower {

  /**
    * @dev Receive a flash loan.
    * @param initiator The initiator of the loan.
    * @param token The loan currency.
    * @param amount The amount of tokens lent.
    * @param fee The additional amount of tokens to repay.
    * @param data Arbitrary data structure, intended to contain user-defined parameters.
    * @return The keccak256 hash of "ERC3156FlashBorrower.onFlashLoan"
    */
  function onFlashLoan(
      address initiator,
      address token,
      uint256 amount,
      uint256 fee,
      bytes calldata data
  ) external returns (bytes32);
}
// File: contracts/interfaces/IERC3156FlashLender.sol




// SPDX-License-Identifier: No License

pragma solidity ^0.8.0;

import "./IERC3156FlashBorrower.sol";

interface IERC3156FlashLender {
  /**
    * @dev The amount of currency available to be lent.
    * @param token The loan currency.
    * @return The amount of `token` that can be borrowed.
    */
  function maxFlashLoan(
      address token
  ) external view returns (uint256);

  /**
    * @dev The fee to be charged for a given loan.
    * @param token The loan currency.
    * @param amount The amount of tokens lent.
    * @return The amount of `token` to be charged for the loan, on top of the returned principal.
    */
  function flashFee(
      address token,
      uint256 amount
  ) external view returns (uint256);

  /**
    * @dev Initiate a flash loan.
    * @param receiver The receiver of the tokens in the loan, and the receiver of the callback.
    * @param token The loan currency.
    * @param amount The amount of tokens lent.
    * @param data Arbitrary data structure, intended to contain user-defined parameters.
    */
  function flashLoan(
      IERC3156FlashBorrower receiver,
      address token,
      uint256 amount,
      bytes calldata data
  ) external returns (bool);
}
// File: contracts/interfaces/ILiquidationAuction.sol



// SPDX-License-Identifier: No License

pragma solidity ^0.8.0;

interface ILiquidationAuction {
    function buyout(address _asset, address _user) external;
}

// File: contracts/interfaces/ICurvePool.sol



// SPDX-License-Identifier: No License

pragma solidity ^0.8.0;

interface ICurvePool {
    function get_dy_underlying(int128, int128, uint256) external view returns (uint256);
    function exchange_underlying(int128, int128, uint256, uint256) external returns (uint256);
    function remove_liquidity_one_coin(address, uint256, int128, uint256) external;
}

// File: contracts/interfaces/IVault.sol



// SPDX-License-Identifier: No License

pragma solidity ^0.8.0;

interface IVault {
    function getTotalDebt(address _asset, address _user) external view returns (uint256 _totalDebt);
    function collaterals(address _asset, address _user) external view returns (uint256 _totalCollateral);
}

// File: contracts/interfaces/IYearn.sol



// SPDX-License-Identifier: No License

pragma solidity ^0.8.0;

interface IYearn {
    function withdraw(uint256 amount) external;
}

// File: contracts/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}
// File: contracts/ERC20/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC20.sol";
import "../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}
// File: contracts/utils/Ownable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _setOwner(_msgSender());
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _setOwner(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}
// File: contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return _functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        return _functionCallWithValue(target, data, value, errorMessage);
    }

    function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}
// File: contracts/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}