// File: contracts/Vaults/VaultETHUSDC.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.4.25 <0.8.0;
pragma experimental ABIEncoderV2;

import { IVault } from "./IVault.sol";
import { VaultBase } from "./VaultBase.sol";
import { IFujiAdmin } from "../IFujiAdmin.sol";
import { ReentrancyGuard } from "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import {
  AggregatorV3Interface
} from "@chainlink/contracts/src/v0.6/interfaces/AggregatorV3Interface.sol";
import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import { IFujiERC1155 } from "../FujiERC1155/IFujiERC1155.sol";
import { IProvider } from "../Providers/IProvider.sol";
import { IAlphaWhiteList } from "../IAlphaWhiteList.sol";
import { Errors } from "../Libraries/Errors.sol";

interface IVaultHarvester {
  function collectRewards(uint256 _farmProtocolNum) external returns (address claimedToken);
}

contract VaultETHUSDC is IVault, VaultBase, ReentrancyGuard {
  uint256 internal constant _BASE = 1e18;

  struct Factor {
    uint64 a;
    uint64 b;
  }

  // Safety factor
  Factor public safetyF;

  // Collateralization factor
  Factor public collatF;

  //State variables
  address[] public providers;
  address public override activeProvider;

  IFujiAdmin private _fujiAdmin;
  address public override fujiERC1155;
  AggregatorV3Interface public oracle;

  modifier isAuthorized() {
    require(
      msg.sender == owner() || msg.sender == _fujiAdmin.getController(),
      Errors.VL_NOT_AUTHORIZED
    );
    _;
  }

  modifier onlyFlash() {
    require(msg.sender == _fujiAdmin.getFlasher(), Errors.VL_NOT_AUTHORIZED);
    _;
  }

  constructor() public {
    vAssets.collateralAsset = address(0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE); // ETH
    vAssets.borrowAsset = address(0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48); // USDC

    // 1.05
    safetyF.a = 21;
    safetyF.b = 20;

    // 1.269
    collatF.a = 80;
    collatF.b = 63;
  }

  receive() external payable {}

  //Core functions

  /**
   * @dev Deposits collateral and borrows underlying in a single function call from activeProvider
   * @param _collateralAmount: amount to be deposited
   * @param _borrowAmount: amount to be borrowed
   */
  function depositAndBorrow(uint256 _collateralAmount, uint256 _borrowAmount) external payable {
    deposit(_collateralAmount);
    borrow(_borrowAmount);
  }

  /**
   * @dev Paybacks the underlying asset and withdraws collateral in a single function call from activeProvider
   * @param _paybackAmount: amount of underlying asset to be payback, pass -1 to pay full amount
   * @param _collateralAmount: amount of collateral to be withdrawn, pass -1 to withdraw maximum amount
   */
  function paybackAndWithdraw(int256 _paybackAmount, int256 _collateralAmount) external payable {
    payback(_paybackAmount);
    withdraw(_collateralAmount);
  }

  /**
   * @dev Deposit Vault's type collateral to activeProvider
   * call Controller checkrates
   * @param _collateralAmount: to be deposited
   * Emits a {Deposit} event.
   */
  function deposit(uint256 _collateralAmount) public payable override {
    require(msg.value == _collateralAmount && _collateralAmount != 0, Errors.VL_AMOUNT_ERROR);

    // Alpha Whitelist Routine
    require(
      IAlphaWhiteList(_fujiAdmin.getaWhiteList()).whiteListRoutine(
        msg.sender,
        vAssets.collateralID,
        _collateralAmount,
        fujiERC1155
      ),
      Errors.SP_ALPHA_WHITELIST
    );

    // Delegate Call Deposit to current provider
    _deposit(_collateralAmount, address(activeProvider));

    // Collateral Management
    IFujiERC1155(fujiERC1155).mint(msg.sender, vAssets.collateralID, _collateralAmount, "");

    emit Deposit(msg.sender, vAssets.collateralAsset, _collateralAmount);
  }

  /**
   * @dev Withdraws Vault's type collateral from activeProvider
   * call Controller checkrates
   * @param _withdrawAmount: amount of collateral to withdraw
   * otherwise pass -1 to withdraw maximum amount possible of collateral (including safety factors)
   * Emits a {Withdraw} event.
   */
  function withdraw(int256 _withdrawAmount) public override nonReentrant {
    // If call from Normal User do typical, otherwise Fliquidator
    if (msg.sender != _fujiAdmin.getFliquidator()) {
      updateF1155Balances();

      // Get User Collateral in this Vault
      uint256 providedCollateral =
        IFujiERC1155(fujiERC1155).balanceOf(msg.sender, vAssets.collateralID);

      // Check User has collateral
      require(providedCollateral > 0, Errors.VL_INVALID_COLLATERAL);

      // Get Required Collateral with Factors to maintain debt position healthy
      uint256 neededCollateral =
        getNeededCollateralFor(
          IFujiERC1155(fujiERC1155).balanceOf(msg.sender, vAssets.borrowID),
          true
        );

      uint256 amountToWithdraw =
        _withdrawAmount < 0 ? providedCollateral.sub(neededCollateral) : uint256(_withdrawAmount);

      // Check Withdrawal amount, and that it will not fall undercollaterized.
      require(
        amountToWithdraw != 0 && providedCollateral.sub(amountToWithdraw) >= neededCollateral,
        Errors.VL_INVALID_WITHDRAW_AMOUNT
      );

      // Collateral Management before Withdraw Operation
      IFujiERC1155(fujiERC1155).burn(msg.sender, vAssets.collateralID, amountToWithdraw);

      // Delegate Call Withdraw to current provider
      _withdraw(amountToWithdraw, address(activeProvider));

      // Transer Assets to User
      IERC20(vAssets.collateralAsset).uniTransfer(msg.sender, amountToWithdraw);

      emit Withdraw(msg.sender, vAssets.collateralAsset, amountToWithdraw);
    } else {
      // Logic used when called by Fliquidator
      _withdraw(uint256(_withdrawAmount), address(activeProvider));
      IERC20(vAssets.collateralAsset).uniTransfer(msg.sender, uint256(_withdrawAmount));
    }
  }

  /**
   * @dev Borrows Vault's type underlying amount from activeProvider
   * @param _borrowAmount: token amount of underlying to borrow
   * Emits a {Borrow} event.
   */
  function borrow(uint256 _borrowAmount) public override nonReentrant {
    updateF1155Balances();

    uint256 providedCollateral =
      IFujiERC1155(fujiERC1155).balanceOf(msg.sender, vAssets.collateralID);

    // Get Required Collateral with Factors to maintain debt position healthy
    uint256 neededCollateral =
      getNeededCollateralFor(
        _borrowAmount.add(IFujiERC1155(fujiERC1155).balanceOf(msg.sender, vAssets.borrowID)),
        true
      );

    // Check Provided Collateral is not Zero, and greater than needed to maintain healthy position
    require(
      _borrowAmount != 0 && providedCollateral > neededCollateral,
      Errors.VL_INVALID_BORROW_AMOUNT
    );

    // Debt Management
    IFujiERC1155(fujiERC1155).mint(msg.sender, vAssets.borrowID, _borrowAmount, "");

    // Delegate Call Borrow to current provider
    _borrow(_borrowAmount, address(activeProvider));

    // Transer Assets to User
    IERC20(vAssets.borrowAsset).uniTransfer(msg.sender, _borrowAmount);

    emit Borrow(msg.sender, vAssets.borrowAsset, _borrowAmount);
  }

  /**
   * @dev Paybacks Vault's type underlying to activeProvider
   * @param _repayAmount: token amount of underlying to repay, or pass -1 to repay full ammount
   * Emits a {Repay} event.
   */
  function payback(int256 _repayAmount) public payable override {
    // If call from Normal User do typical, otherwise Fliquidator
    if (msg.sender != _fujiAdmin.getFliquidator()) {
      updateF1155Balances();

      uint256 userDebtBalance = IFujiERC1155(fujiERC1155).balanceOf(msg.sender, vAssets.borrowID);

      // Check User Debt is greater than Zero and amount is not Zero
      require(_repayAmount != 0 && userDebtBalance > 0, Errors.VL_NO_DEBT_TO_PAYBACK);

      // TODO: Get => corresponding amount of BaseProtocol Debt and FujiDebt

      // If passed argument amount is negative do MAX
      uint256 amountToPayback = _repayAmount < 0 ? userDebtBalance : uint256(_repayAmount);

      // Check User Allowance
      require(
        IERC20(vAssets.borrowAsset).allowance(msg.sender, address(this)) >= amountToPayback,
        Errors.VL_MISSING_ERC20_ALLOWANCE
      );

      // Transfer Asset from User to Vault
      IERC20(vAssets.borrowAsset).transferFrom(msg.sender, address(this), amountToPayback);

      // Delegate Call Payback to current provider
      _payback(amountToPayback, address(activeProvider));

      //TODO: Transfer corresponding Debt Amount to Fuji Treasury

      // Debt Management
      IFujiERC1155(fujiERC1155).burn(msg.sender, vAssets.borrowID, amountToPayback);

      emit Payback(msg.sender, vAssets.borrowAsset, userDebtBalance);
    } else {
      // Logic used when called by Fliquidator
      _payback(uint256(_repayAmount), address(activeProvider));
    }
  }

  /**
   * @dev Changes Vault debt and collateral to newProvider, called by Flasher
   * @param _newProvider new provider's address
   * @param _flashLoanAmount amount of flashloan underlying to repay Flashloan
   * Emits a {Switch} event.
   */
  function executeSwitch(
    address _newProvider,
    uint256 _flashLoanAmount,
    uint256 _fee
  ) external override onlyFlash whenNotPaused {
    // Compute Ratio of transfer before payback
    uint256 ratio =
      (_flashLoanAmount).mul(1e18).div(
        IProvider(activeProvider).getBorrowBalance(vAssets.borrowAsset)
      );

    // Payback current provider
    _payback(_flashLoanAmount, activeProvider);

    // Withdraw collateral proportional ratio from current provider
    uint256 collateraltoMove =
      IProvider(activeProvider).getDepositBalance(vAssets.collateralAsset).mul(ratio).div(1e18);

    _withdraw(collateraltoMove, activeProvider);

    // Deposit to the new provider
    _deposit(collateraltoMove, _newProvider);

    // Borrow from the new provider, borrowBalance + premium
    _borrow(_flashLoanAmount.add(_fee), _newProvider);

    // return borrowed amount to Flasher
    IERC20(vAssets.borrowAsset).uniTransfer(msg.sender, _flashLoanAmount.add(_fee));

    emit Switch(address(this), activeProvider, _newProvider, _flashLoanAmount, collateraltoMove);
  }

  //Setter, change state functions

  /**
   * @dev Sets the fujiAdmin Address
   * @param _newFujiAdmin: FujiAdmin Contract Address
   */
  function setFujiAdmin(address _newFujiAdmin) external onlyOwner {
    _fujiAdmin = IFujiAdmin(_newFujiAdmin);
  }

  /**
   * @dev Sets a new active provider for the Vault
   * @param _provider: fuji address of the new provider
   * Emits a {SetActiveProvider} event.
   */
  function setActiveProvider(address _provider) external override isAuthorized {
    activeProvider = _provider;

    emit SetActiveProvider(_provider);
  }

  //Administrative functions

  /**
   * @dev Sets a fujiERC1155 Collateral and Debt Asset manager for this vault and initializes it.
   * @param _fujiERC1155: fuji ERC1155 address
   */
  function setFujiERC1155(address _fujiERC1155) external isAuthorized {
    fujiERC1155 = _fujiERC1155;

    vAssets.collateralID = IFujiERC1155(_fujiERC1155).addInitializeAsset(
      IFujiERC1155.AssetType.collateralToken,
      address(this)
    );
    vAssets.borrowID = IFujiERC1155(_fujiERC1155).addInitializeAsset(
      IFujiERC1155.AssetType.debtToken,
      address(this)
    );
  }

  /**
   * @dev Set Factors "a" and "b" for a Struct Factor
   * For safetyF;  Sets Safety Factor of Vault, should be > 1, a/b
   * For collatF; Sets Collateral Factor of Vault, should be > 1, a/b
   * @param _newFactorA: Nominator
   * @param _newFactorB: Denominator
   * @param _isSafety: safetyF or collatF
   */
  function setFactor(
    uint64 _newFactorA,
    uint64 _newFactorB,
    bool _isSafety
  ) external isAuthorized {
    if (_isSafety) {
      safetyF.a = _newFactorA;
      safetyF.b = _newFactorB;
    } else {
      collatF.a = _newFactorA;
      collatF.b = _newFactorB;
    }
  }

  /**
   * @dev Sets the Oracle address (Must Comply with AggregatorV3Interface)
   * @param _oracle: new Oracle address
   */
  function setOracle(address _oracle) external isAuthorized {
    oracle = AggregatorV3Interface(_oracle);
  }

  /**
   * @dev Set providers to the Vault
   * @param _providers: new providers' addresses
   */
  function setProviders(address[] calldata _providers) external isAuthorized {
    providers = _providers;
  }

  /**
   * @dev External Function to call updateState in F1155
   */
  function updateF1155Balances() public override {
    uint256 borrowBals;
    uint256 depositBals;

    // take into account all balances across providers
    uint256 length = providers.length;
    for (uint256 i = 0; i < length; i++) {
      borrowBals = borrowBals.add(IProvider(providers[i]).getBorrowBalance(vAssets.borrowAsset));
    }
    for (uint256 i = 0; i < length; i++) {
      depositBals = depositBals.add(
        IProvider(providers[i]).getDepositBalance(vAssets.collateralAsset)
      );
    }

    IFujiERC1155(fujiERC1155).updateState(vAssets.borrowID, borrowBals);
    IFujiERC1155(fujiERC1155).updateState(vAssets.collateralID, depositBals);
  }

  //Getter Functions

  /**
   * @dev Returns an array of the Vault's providers
   */
  function getProviders() external view override returns (address[] memory) {
    return providers;
  }

  /**
   * @dev Returns an amount to be paid as bonus for liquidation
   * @param _amount: Vault underlying type intended to be liquidated
   * @param _flash: Flash or classic type of liquidation, bonus differs
   */
  function getLiquidationBonusFor(uint256 _amount, bool _flash)
    external
    view
    override
    returns (uint256)
  {
    if (_flash) {
      // Bonus Factors for Flash Liquidation
      (uint64 a, uint64 b) = _fujiAdmin.getBonusFlashL();
      return _amount.mul(a).div(b);
    } else {
      //Bonus Factors for Normal Liquidation
      (uint64 a, uint64 b) = _fujiAdmin.getBonusLiq();
      return _amount.mul(a).div(b);
    }
  }

  /**
   * @dev Returns the amount of collateral needed, including or not safety factors
   * @param _amount: Vault underlying type intended to be borrowed
   * @param _withFactors: Inidicate if computation should include safety_Factors
   */
  function getNeededCollateralFor(uint256 _amount, bool _withFactors)
    public
    view
    override
    returns (uint256)
  {
    // Get price of USDC in ETH
    (, int256 latestPrice, , , ) = oracle.latestRoundData();
    uint256 minimumReq = (_amount.mul(1e12).mul(uint256(latestPrice))).div(_BASE);

    if (_withFactors) {
      return minimumReq.mul(collatF.a).mul(safetyF.a).div(collatF.b).div(safetyF.b);
    } else {
      return minimumReq;
    }
  }

  /**
   * @dev Returns the borrow balance of the Vault's underlying at a particular provider
   * @param _provider: address of a provider
   */
  function borrowBalance(address _provider) external view override returns (uint256) {
    return IProvider(_provider).getBorrowBalance(vAssets.borrowAsset);
  }

  /**
   * @dev Returns the deposit balance of the Vault's type collateral at a particular provider
   * @param _provider: address of a provider
   */
  function depositBalance(address _provider) external view override returns (uint256) {
    return IProvider(_provider).getDepositBalance(vAssets.collateralAsset);
  }

  /**
   * @dev Harvests the Rewards from baseLayer Protocols
   * @param _farmProtocolNum: number per VaultHarvester Contract for specific farm
   */
  function harvestRewards(uint256 _farmProtocolNum) external onlyOwner {
    address tokenReturned =
      IVaultHarvester(_fujiAdmin.getVaultHarvester()).collectRewards(_farmProtocolNum);
    uint256 tokenBal = IERC20(tokenReturned).balanceOf(address(this));

    require(tokenReturned != address(0) && tokenBal > 0, Errors.VL_HARVESTING_FAILED);
    IERC20(tokenReturned).uniTransfer(payable(_fujiAdmin.getTreasury()), tokenBal);
  }
}

// File: contracts/Vaults/IVault.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;

interface IVault {
  // Events

  // Log Users Deposit
  event Deposit(address indexed userAddrs, address indexed asset, uint256 amount);
  // Log Users withdraw
  event Withdraw(address indexed userAddrs, address indexed asset, uint256 amount);
  // Log Users borrow
  event Borrow(address indexed userAddrs, address indexed asset, uint256 amount);
  // Log Users debt repay
  event Payback(address indexed userAddrs, address indexed asset, uint256 amount);

  // Log New active provider
  event SetActiveProvider(address providerAddr);
  // Log Switch providers
  event Switch(
    address vault,
    address fromProviderAddrs,
    address toProviderAddr,
    uint256 debtamount,
    uint256 collattamount
  );

  // Core Vault Functions

  function deposit(uint256 _collateralAmount) external payable;

  function withdraw(int256 _withdrawAmount) external;

  function borrow(uint256 _borrowAmount) external;

  function payback(int256 _repayAmount) external payable;

  function executeSwitch(
    address _newProvider,
    uint256 _flashLoanDebt,
    uint256 _fee
  ) external;

  //Getter Functions

  function activeProvider() external view returns (address);

  function borrowBalance(address _provider) external view returns (uint256);

  function depositBalance(address _provider) external view returns (uint256);

  function getNeededCollateralFor(uint256 _amount, bool _withFactors)
    external
    view
    returns (uint256);

  function getLiquidationBonusFor(uint256 _amount, bool _flash) external view returns (uint256);

  function getProviders() external view returns (address[] memory);

  function fujiERC1155() external view returns (address);

  //Setter Functions

  function setActiveProvider(address _provider) external;

  function updateF1155Balances() external;
}

// File: contracts/Vaults/VaultBase.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.12;

import { SafeMath } from "@openzeppelin/contracts/math/SafeMath.sol";
import { Ownable } from "@openzeppelin/contracts/access/Ownable.sol";
import { Pausable } from "@openzeppelin/contracts/utils/Pausable.sol";
import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import { UniERC20 } from "../Libraries/LibUniERC20.sol";

contract VaultControl is Ownable, Pausable {
  using SafeMath for uint256;
  using UniERC20 for IERC20;

  //Asset Struct
  struct VaultAssets {
    address collateralAsset;
    address borrowAsset;
    uint64 collateralID;
    uint64 borrowID;
  }

  //Vault Struct for Managed Assets
  VaultAssets public vAssets;

  //Pause Functions

  /**
   * @dev Emergency Call to stop all basic money flow functions.
   */
  function pause() public onlyOwner {
    _pause();
  }

  /**
   * @dev Emergency Call to stop all basic money flow functions.
   */
  function unpause() public onlyOwner {
    _pause();
  }
}

contract VaultBase is VaultControl {
  // Internal functions

  /**
   * @dev Executes deposit operation with delegatecall.
   * @param _amount: amount to be deposited
   * @param _provider: address of provider to be used
   */
  function _deposit(uint256 _amount, address _provider) internal {
    bytes memory data =
      abi.encodeWithSignature("deposit(address,uint256)", vAssets.collateralAsset, _amount);
    _execute(_provider, data);
  }

  /**
   * @dev Executes withdraw operation with delegatecall.
   * @param _amount: amount to be withdrawn
   * @param _provider: address of provider to be used
   */
  function _withdraw(uint256 _amount, address _provider) internal {
    bytes memory data =
      abi.encodeWithSignature("withdraw(address,uint256)", vAssets.collateralAsset, _amount);
    _execute(_provider, data);
  }

  /**
   * @dev Executes borrow operation with delegatecall.
   * @param _amount: amount to be borrowed
   * @param _provider: address of provider to be used
   */
  function _borrow(uint256 _amount, address _provider) internal {
    bytes memory data =
      abi.encodeWithSignature("borrow(address,uint256)", vAssets.borrowAsset, _amount);
    _execute(_provider, data);
  }

  /**
   * @dev Executes payback operation with delegatecall.
   * @param _amount: amount to be paid back
   * @param _provider: address of provider to be used
   */
  function _payback(uint256 _amount, address _provider) internal {
    bytes memory data =
      abi.encodeWithSignature("payback(address,uint256)", vAssets.borrowAsset, _amount);
    _execute(_provider, data);
  }

  /**
   * @dev Returns byte response of delegatcalls
   */
  function _execute(address _target, bytes memory _data)
    internal
    whenNotPaused
    returns (bytes memory response)
  {
    /* solhint-disable */
    assembly {
      let succeeded := delegatecall(sub(gas(), 5000), _target, add(_data, 0x20), mload(_data), 0, 0)
      let size := returndatasize()

      response := mload(0x40)
      mstore(0x40, add(response, and(add(add(size, 0x20), 0x1f), not(0x1f))))
      mstore(response, size)
      returndatacopy(add(response, 0x20), 0, size)

      switch iszero(succeeded)
        case 1 {
          // throw if delegatecall failed
          revert(add(response, 0x20), size)
        }
    }
    /* solhint-disable */
  }
}

// File: contracts/IFujiAdmin.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.12 <0.8.0;

interface IFujiAdmin {
  function getFlasher() external view returns (address);

  function getFliquidator() external view returns (address);

  function getController() external view returns (address);

  function getTreasury() external view returns (address payable);

  function getaWhiteList() external view returns (address);

  function getVaultHarvester() external view returns (address);

  function getBonusFlashL() external view returns (uint64, uint64);

  function getBonusLiq() external view returns (uint64, uint64);
}

// File: @openzeppelin/contracts/utils/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor () internal {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// File: @chainlink/contracts/src/v0.6/interfaces/AggregatorV3Interface.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0;

interface AggregatorV3Interface {

  function decimals() external view returns (uint8);
  function description() external view returns (string memory);
  function version() external view returns (uint256);

  // getRoundData and latestRoundData should both raise "No data present"
  // if they do not have data to report, instead of returning unset values
  // which could be misinterpreted as actual reported values.
  function getRoundData(uint80 _roundId)
    external
    view
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    );
  function latestRoundData()
    external
    view
    returns (
      uint80 roundId,
      int256 answer,
      uint256 startedAt,
      uint256 updatedAt,
      uint80 answeredInRound
    );

}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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/FujiERC1155/IFujiERC1155.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.12;
pragma experimental ABIEncoderV2;

interface IFujiERC1155 {
  //Asset Types
  enum AssetType {
    //uint8 = 0
    collateralToken,
    //uint8 = 1
    debtToken
  }

  //General Getter Functions

  function getAssetID(AssetType _type, address _assetAddr) external view returns (uint256);

  function qtyOfManagedAssets() external view returns (uint64);

  function balanceOf(address _account, uint256 _id) external view returns (uint256);

  //function splitBalanceOf(address account,uint256 _AssetID) external view  returns (uint256,uint256);

  //function balanceOfBatchType(address account, AssetType _Type) external view returns (uint256);

  //Permit Controlled  Functions
  function mint(
    address _account,
    uint256 _id,
    uint256 _amount,
    bytes memory _data
  ) external;

  function burn(
    address _account,
    uint256 _id,
    uint256 _amount
  ) external;

  function updateState(uint256 _assetID, uint256 _newBalance) external;

  function addInitializeAsset(AssetType _type, address _addr) external returns (uint64);
}

// File: contracts/Providers/IProvider.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.4.25 <0.7.0;

interface IProvider {
  //Basic Core Functions

  function deposit(address _collateralAsset, uint256 _collateralAmount) external payable;

  function borrow(address _borrowAsset, uint256 _borrowAmount) external payable;

  function withdraw(address _collateralAsset, uint256 _collateralAmount) external payable;

  function payback(address _borrowAsset, uint256 _borrowAmount) external payable;

  // returns the borrow annualized rate for an asset in ray (1e27)
  //Example 8.5% annual interest = 0.085 x 10^27 = 85000000000000000000000000 or 85*(10**24)
  function getBorrowRateFor(address _asset) external view returns (uint256);

  function getBorrowBalance(address _asset) external view returns (uint256);

  function getDepositBalance(address _asset) external view returns (uint256);

  function getBorrowBalanceOf(address _asset, address _who) external returns (uint256);
}

// File: contracts/IAlphaWhiteList.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.12 <0.8.0;

interface IAlphaWhiteList {
  function whiteListRoutine(
    address _usrAddrs,
    uint64 _assetId,
    uint256 _amount,
    address _erc1155
  ) external returns(bool);
}

// File: contracts/Libraries/Errors.sol



// SPDX-License-Identifier: agpl-3.0
pragma solidity <0.8.0;

/**
 * @title Errors library
 * @author Fuji
 * @notice Defines the error messages emitted by the different contracts of the Aave protocol
 * @dev Error messages prefix glossary:
 *  - VL = Validation Logic 100 series
 *  - MATH = Math libraries 200 series
 *  - RF = Refinancing 300 series
 *  - VLT = vault 400 series
 *  - SP = Special 900 series
 */
library Errors {
  //Errors
  string public constant VL_INDEX_OVERFLOW = "100"; // index overflows uint128
  string public constant VL_INVALID_MINT_AMOUNT = "101"; //invalid amount to mint
  string public constant VL_INVALID_BURN_AMOUNT = "102"; //invalid amount to burn
  string public constant VL_AMOUNT_ERROR = "103"; //Input value >0, and for ETH msg.value and amount shall match
  string public constant VL_INVALID_WITHDRAW_AMOUNT = "104"; //Withdraw amount exceeds provided collateral, or falls undercollaterized
  string public constant VL_INVALID_BORROW_AMOUNT = "105"; //Borrow amount does not meet collaterization
  string public constant VL_NO_DEBT_TO_PAYBACK = "106"; //Msg sender has no debt amount to be payback
  string public constant VL_MISSING_ERC20_ALLOWANCE = "107"; //Msg sender has not approved ERC20 full amount to transfer
  string public constant VL_USER_NOT_LIQUIDATABLE = "108"; //User debt position is not liquidatable
  string public constant VL_DEBT_LESS_THAN_AMOUNT = "109"; //User debt is less than amount to partial close
  string public constant VL_PROVIDER_ALREADY_ADDED = "110"; // Provider is already added in Provider Array
  string public constant VL_NOT_AUTHORIZED = "111"; //Not authorized
  string public constant VL_INVALID_COLLATERAL = "112"; //There is no Collateral, or Collateral is not in active in vault
  string public constant VL_NO_ERC20_BALANCE = "113"; //User does not have ERC20 balance
  string public constant VL_INPUT_ERROR = "114"; //Check inputs. For ERC1155 batch functions, array sizes should match.
  string public constant VL_ASSET_EXISTS = "115"; //Asset intended to be added already exists in FujiERC1155
  string public constant VL_ZERO_ADDR_1155 = "116"; //ERC1155: balance/transfer for zero address
  string public constant VL_NOT_A_CONTRACT = "117"; //Address is not a contract.
  string public constant VL_INVALID_ASSETID_1155 = "118"; //ERC1155 Asset ID is invalid.
  string public constant VL_NO_ERC1155_BALANCE = "119"; //ERC1155: insufficient balance for transfer.
  string public constant VL_MISSING_ERC1155_APPROVAL = "120"; //ERC1155: transfer caller is not owner nor approved.
  string public constant VL_RECEIVER_REJECT_1155 = "121"; //ERC1155Receiver rejected tokens
  string public constant VL_RECEIVER_CONTRACT_NON_1155 = "122"; //ERC1155: transfer to non ERC1155Receiver implementer
  string public constant VL_OPTIMIZER_FEE_SMALL = "123"; //Fuji OptimizerFee has to be > 1 RAY (1e27)
  string public constant VL_UNDERCOLLATERIZED_ERROR = "124"; // Flashloan-Flashclose cannot be used when User's collateral is worth less than intended debt position to close.
  string public constant VL_MINIMUM_PAYBACK_ERROR = "125"; // Minimum Amount payback should be at least Fuji Optimizerfee accrued interest.
  string public constant VL_HARVESTING_FAILED = "126"; //Harvesting Function failed, check provided _farmProtocolNum or no claimable balance.

  string public constant MATH_DIVISION_BY_ZERO = "201";
  string public constant MATH_ADDITION_OVERFLOW = "202";
  string public constant MATH_MULTIPLICATION_OVERFLOW = "203";

  string public constant RF_NO_GREENLIGHT = "300"; // Conditions for refinancing are not met, greenLight, deltaAPRThreshold, deltatimestampThreshold
  string public constant RF_INVALID_RATIO_VALUES = "301"; // Ratio Value provided is invalid, _ratioA/_ratioB <= 1, and > 0, or activeProvider borrowBalance = 0
  string public constant RF_CHECK_RATES_FALSE = "302"; //Check Rates routine returned False

  string public constant VLT_CALLER_MUST_BE_VAULT = "401"; // The caller of this function must be a vault

  string public constant SP_ALPHA_WHITELIST = "901"; // One ETH cap value for Alpha Version < 1 ETH
}

// File: @openzeppelin/contracts/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "../utils/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 () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), 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 {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: @openzeppelin/contracts/utils/Pausable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "./Context.sol";

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor () internal {
        _paused = false;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        require(!paused(), "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        require(paused(), "Pausable: not paused");
        _;
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

// File: contracts/Libraries/LibUniERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.6.12;

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

library UniERC20 {
  using SafeERC20 for IERC20;

  IERC20 private constant _ETH_ADDRESS = IERC20(0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE);
  IERC20 private constant _ZERO_ADDRESS = IERC20(0);

  function isETH(IERC20 token) internal pure returns (bool) {
    return (token == _ZERO_ADDRESS || token == _ETH_ADDRESS);
  }

  function uniBalanceOf(IERC20 token, address account) internal view returns (uint256) {
    if (isETH(token)) {
      return account.balance;
    } else {
      return token.balanceOf(account);
    }
  }

  function uniTransfer(
    IERC20 token,
    address payable to,
    uint256 amount
  ) internal {
    if (amount > 0) {
      if (isETH(token)) {
        to.transfer(amount);
      } else {
        token.safeTransfer(to, amount);
      }
    }
  }

  function uniApprove(
    IERC20 token,
    address to,
    uint256 amount
  ) internal {
    require(!isETH(token), "Approve called on ETH");

    if (amount == 0) {
      token.safeApprove(to, 0);
    } else {
      uint256 allowance = token.allowance(address(this), to);
      if (allowance < amount) {
        if (allowance > 0) {
          token.safeApprove(to, 0);
        }
        token.safeApprove(to, amount);
      }
    }
  }
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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 GSN 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 payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "./IERC20.sol";
import "../../math/SafeMath.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 SafeMath for uint256;
    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'
        // solhint-disable-next-line max-line-length
        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).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _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
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
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) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @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");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        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);
            }
        }
    }
}