// File: contracts/CollateralWrapperToken.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;

import "./WrapperToken.sol";
import "./interfaces/IBSLendingPair.sol";

////////////////////////////////////////////////////////////////////////////////////////////
/// @title CollateralWrapperToken
/// @author @samparsky
////////////////////////////////////////////////////////////////////////////////////////////

contract CollateralWrapperToken is WrapperToken {

    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal virtual override {
        uint256 maxWithdrawAllowed = IBSLendingPair(this.owner()).getMaxWithdrawAllowed(sender);
        require(amount <= maxWithdrawAllowed, "EXCEEDS_ALLOWED");

        super._transfer(sender, recipient, amount);
    }


}

// File: contracts/WrapperToken.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;

import "./token/ERC20Permit.sol";
import "./interfaces/IRewardDistributorManager.sol";
import "./interfaces/IBSLendingPair.sol";
import "./interfaces/IBSWrapperToken.sol";
import "./token/IERC20Details.sol";
import "./util/Initializable.sol";

////////////////////////////////////////////////////////////////////////////////////////////
/// @title WrapperToken
/// @author @samparsky
/// @dev
///
////////////////////////////////////////////////////////////////////////////////////////////


abstract contract WrapperTokenBase is ERC20Permit, Initializable {

    /// @dev reward distributor Manager
    IRewardDistributorManager public rewardManager;

    /// @dev underlying wrapper token
    address public underlying;

    /// @dev the LendingPair is the "owner" for WrapperTokens
    address internal _owner;


     /**
     * @dev Throws if called by any account other than the lendingpair.
     */
    modifier onlyLendingPair() {
        require(address(_owner) == msg.sender, "ONLY_LENDING_PAIR");
        _;
    }

    function _rewardHook(address _from, address _to) internal {
        rewardManager.accumulateRewards(_from, _to);
    }
}

contract WrapperToken is  IBSWrapperToken, WrapperTokenBase {
    /// @dev wrapper token version
    uint256 constant public VERSION = 0x1;

    /// @notice
    function initialize(
        address __owner,
        address _underlying,
        string memory _tokenName,
        string memory _tokenSymbol,
        IRewardDistributorManager _manager
    ) external virtual override initializer {
        require(__owner != address(0), "invalid owner");
        require(_underlying != address(0), "invalid underlying");

        _owner = __owner;
        uint8 underlyingDecimal = IERC20Details(_underlying).decimals();
        initializeERC20(_tokenName, _tokenSymbol, underlyingDecimal);
        initializeERC20Permit(_tokenName);
        underlying = _underlying;
        rewardManager = _manager;
    }

    /**
    @notice mint is an only owner function that allows the owner to mint new tokens to an input account
    @param _to is the address that will receive the new tokens
    @param _amount is the amount of token they will receive
    **/
    function mint(address _to, uint256 _amount) external virtual override onlyLendingPair {
        _rewardHook(address(0), _to);
        _mint(_to, _amount);
    }

    /**
     * @notice burn is an only owner function that allows the owner to burn  tokens from an input account
     * @dev IMPORTANT: it reverts if user doesn't have enough balance
     * @param _from is the address where the tokens will be burnt
     * @param _amount is the amount of token to be burnt
     **/
    function burn(address _from, uint256 _amount) external virtual override onlyLendingPair {
        _rewardHook(_from, address(0));
        _burn(_from, _amount);
    }

    function owner() external view override returns (address) {
        return _owner;
    }

    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal virtual override {
        _rewardHook(sender, recipient);
        super._transfer(sender, recipient, amount);
    }
}

// File: contracts/interfaces/IBSLendingPair.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.1;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "./IPriceOracleAggregator.sol";
import "./IBSWrapperToken.sol";
import "./IDebtToken.sol";
import "./IBSVault.sol";
import "../DataTypes.sol";

interface IBSLendingPair {
    event Initialized(
        address indexed pair,
        address indexed asset,
        address indexed collateralAsset,
        address pauseGuardian
    );

    /**
     * Emitted on deposit
     *
     * @param pair The pair being interacted with
     * @param asset The asset deposited in the pair
     * @param tokenReceipeint The user the receives the bsTokens
     * @param user The user that made the deposit
     * @param amount The amount deposited
     **/
    event Deposit(
        address indexed pair,
        address indexed asset,
        address indexed tokenReceipeint,
        address user,
        uint256 amount
    );

    event Borrow(address indexed borrower, uint256 amount);

    /**
     * Emitted on Redeem
     *
     * @param pair The pair being interacted with
     * @param asset The asset withdraw in the pair
     * @param user The user that's making the withdrawal
     * @param to The user the receives the withdrawn tokens
     * @param amount The amount being withdrawn
     **/
    event Redeem(
        address indexed pair,
        address indexed asset,
        address indexed user,
        address to,
        uint256 amount,
        uint256 amountofWrappedBurned
    );

    event WithdrawCollateral(address account, uint256 amount);

    event ReserveWithdraw(address user, uint256 shares);

    /**
     * Emitted on repay
     *
     * @param pair The pair being interacted with
     * @param asset The asset repaid in the pair
     * @param beneficiary The user that's getting their debt reduced
     * @param repayer The user that's providing the funds
     * @param amount The amount being repaid
     **/
    event Repay(
        address indexed pair,
        address indexed asset,
        address indexed beneficiary,
        address repayer,
        uint256 amount
    );

    /**
     * Emitted on liquidation
     *
     * @param pair The pair being interacted with
     * @param asset The asset that getting liquidated
     * @param user The user that's getting liquidated
     * @param liquidatedCollateralAmount The of collateral transferred to the liquidator
     * @param liquidator The liquidator
     **/
    event Liquidate(
        address indexed pair,
        address indexed asset,
        address indexed user,
        uint256 liquidatedCollateralAmount,
        address liquidator
    );

    /**
     * @dev Emitted on flashLoan
     * @param target The address of the flash loan receiver contract
     * @param initiator The address initiating the flash loan
     * @param asset The address of the asset being flash borrowed
     * @param amount The amount flash borrowed
     * @param premium The fee flash borrowed
     **/
    event FlashLoan(
        address indexed target,
        address indexed initiator,
        address indexed asset,
        uint256 amount,
        uint256 premium
    );

    /**
     * @dev Emitted on interest accrued
     * @param accrualBlockNumber block number
     * @param borrowIndex borrow index
     * @param totalBorrows total borrows
     * @param totalReserves total reserves
     **/
    event InterestAccrued(
        address indexed pair,
        uint256 accrualBlockNumber,
        uint256 borrowIndex,
        uint256 totalBorrows,
        uint256 totalReserves
    );

    event InterestShortCircuit(uint256 blockNumber);

    event ActionPaused(uint8 action, uint256 timestamp);
    event ActionUnPaused(uint8 action, uint256 timestamp);

    function initialize(
        string memory _name,
        string memory _symbol,
        IERC20 _asset,
        IERC20 _collateralAsset,
        DataTypes.BorrowAssetConfig calldata borrowConfig,
        IBSWrapperToken _wrappedCollateralAsset,
        IInterestRateModel _interestRate,
        address _pauseGuardian
    ) external;

    function asset() external view returns (IERC20);

    function depositBorrowAsset(address _tokenReceipeint, uint256 _amount) external;

    function depositCollateral(address _tokenReceipeint, uint256 _vaultShareAmount) external;

    function redeem(address _to, uint256 _amount) external returns (uint256);

    function collateralOfAccount(address _account) external view returns (uint256);

    function getMaxWithdrawAllowed(address account) external returns (uint256);

    function oracle() external view returns (IPriceOracleAggregator);

    function collateralAsset() external view returns (IERC20);

    function calcBorrowLimit(uint256 amount) external view returns (uint256);

    function accountInterestIndex(address) external view returns (uint256);

    function borrowIndex() external view returns (uint256);

    function debtToken() external view returns (IDebtToken);

    function borrowBalancePrior(address _account) external view returns (uint256);

    function wrapperBorrowedAsset() external view returns (IBSWrapperToken);

    function wrappedCollateralAsset() external view returns (IBSWrapperToken);

    function totalReserves() external view returns (uint256);

    function withdrawFees(uint256 amount) external;

    function liquidate(address user) external;
}

// File: contracts/token/ERC20Permit.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;

import "@openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol";
import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
import "./ERC20.sol";
import "./EIP712.sol";

/**
 * @dev Implementation of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 *
 */

abstract contract ERC20Permit is ERC20, IERC20Permit, EIP712 {
    mapping(address => uint256) private _nonces;

    // solhint-disable-next-line var-name-mixedcase
    bytes32 private immutable _PERMIT_TYPEHASH =
        keccak256(
            "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
        );

    /**
     * @dev Initializes the {EIP712} domain separator using the `name` parameter, and setting `version` to `"1"`.
     *
     * It's a good idea to use the same `name` that is defined as the ERC20 token name.
     */
    function initializeERC20Permit(string memory _name) internal {
        initializeEIP712(_name, "1");
    }

    /**
     * @dev See {IERC20Permit-permit}.
     */
    function permit(
        address owner,
        address spender,
        uint256 amount,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public virtual override {
        // solhint-disable-next-line not-rely-on-time
        require(block.timestamp <= deadline, "ERC20Permit: expired deadline");

        bytes32 structHash =
            keccak256(
                abi.encode(_PERMIT_TYPEHASH, owner, spender, amount, _nonces[owner], deadline)
            );

        bytes32 hash = _hashTypedDataV4(structHash);

        address signer = ECDSA.recover(hash, v, r, s);
        require(signer == owner, "ERC20Permit: invalid signature");

        _nonces[owner]++;
        _approve(owner, spender, amount);
    }

    /**
     * @dev See {IERC20Permit-nonces}.
     */
    function nonces(address owner) public view override returns (uint256) {
        return _nonces[owner];
    }

    /**
     * @dev See {IERC20Permit-DOMAIN_SEPARATOR}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view override returns (bytes32) {
        return _domainSeparatorV4();
    }
}

// File: contracts/interfaces/IRewardDistributorManager.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;
import "./IRewardDistributor.sol";

interface IRewardDistributorManager {
    /// @dev Emitted on Initialization
    event Initialized(address owner, uint256 timestamp);

    event DistributorStatusUpdated(IRewardDistributor distributor, bool approve, uint256 timestamp);
    event AddReward(address tokenAddr, IRewardDistributor distributor, uint256 timestamp);
    event RemoveReward(address tokenAddr, IRewardDistributor distributor, uint256 timestamp);
    event TransferControl(address _newTeam, uint256 timestamp);
    event OwnershipAccepted(address prevOwner, address newOwner, uint256 timestamp);

    function activateReward(address _tokenAddr) external;

    function removeReward(address _tokenAddr, IRewardDistributor _distributor) external;

    function accumulateRewards(address _from, address _to) external;
}

// File: contracts/interfaces/IBSWrapperToken.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "./IRewardDistributorManager.sol";

interface IBSWrapperTokenBase is IERC20 {
    function initialize(
        address _owner,
        address _underlying,
        string memory _tokenName,
        string memory _tokenSymbol,
        IRewardDistributorManager _manager
    ) external;

    function burn(address _from, uint256 _amount) external;

    function owner() external view returns (address);
}

interface IBSWrapperToken is IBSWrapperTokenBase {
    function mint(address _to, uint256 _amount) external;
}

// File: contracts/token/IERC20Details.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;

interface IERC20Details {
    function name() external view returns (string memory);

    function symbol() external view returns (string memory);

    function decimals() external view returns (uint8);
}

// File: contracts/util/Initializable.sol



// SPDX-License-Identifier: MIT

// solhint-disable-next-line compiler-version
pragma solidity ^0.8.0;

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {UpgradeableProxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 */
abstract contract Initializable {
    /**
     * @dev Indicates that the contract has been initialized.
     */
    bool private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Modifier to protect an initializer function from being invoked twice.
     */
    modifier initializer() {
        require(
            _initializing || _isConstructor() || !_initialized,
            "Initializable: contract is already initialized"
        );

        bool isTopLevelCall = !_initializing;
        if (isTopLevelCall) {
            _initializing = true;
            _initialized = true;
        }

        _;

        if (isTopLevelCall) {
            _initializing = false;
        }
    }

    /// @dev Returns true if and only if the function is running in the constructor
    function _isConstructor() private view returns (bool) {
        // extcodesize checks the size of the code stored in an address, and
        // address returns the current address. Since the code is still not
        // deployed when running a constructor, any checks on its code size will
        // yield zero, making it an effective way to detect if a contract is
        // under construction or not.
        address self = address(this);
        uint256 cs;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            cs := extcodesize(self)
        }
        return cs == 0;
    }
}

// File: @openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over `owner`'s tokens,
     * given `owner`'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(address owner, address spender, uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for `permit`, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// File: @openzeppelin/contracts/utils/cryptography/ECDSA.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        // Check the signature length
        if (signature.length != 65) {
            revert("ECDSA: invalid signature length");
        }

        // Divide the signature in r, s and v variables
        bytes32 r;
        bytes32 s;
        uint8 v;

        // ecrecover takes the signature parameters, and the only way to get them
        // currently is to use assembly.
        // solhint-disable-next-line no-inline-assembly
        assembly {
            r := mload(add(signature, 0x20))
            s := mload(add(signature, 0x40))
            v := byte(0, mload(add(signature, 0x60)))
        }

        return recover(hash, v, r, s);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `v`,
     * `r` and `s` signature fields separately.
     */
    function recover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal pure returns (address) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        require(uint256(s) <= 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0, "ECDSA: invalid signature 's' value");
        require(v == 27 || v == 28, "ECDSA: invalid signature 'v' value");

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        require(signer != address(0), "ECDSA: invalid signature");

        return signer;
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }

    /**
     * @dev Returns an Ethereum Signed Typed Data, created from a
     * `domainSeparator` and a `structHash`. This produces hash corresponding
     * to the one signed with the
     * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
     * JSON-RPC method as part of EIP-712.
     *
     * See {recover}.
     */
    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
    }
}

// File: contracts/token/ERC20.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 *
 * !!! samparsky modified: use initializeERC20 to replace constructor for proxy
 */
contract ERC20 is IERC20 {
    mapping(address => uint256) internal _balances;

    mapping(address => mapping(address => uint256)) internal _allowances;

    uint256 internal _totalSupply;

    string public name;
    uint8 public decimals;
    string public symbol;

    function initializeERC20(
        string memory name_,
        string memory symbol_,
        uint8 decimals_
    ) internal {
        name = name_;
        symbol = symbol_;
        decimals = decimals_;
    }

    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    function totalSupply() external view override returns (uint256) {
        return _totalSupply;
    }

    function transfer(address recipient, uint256 amount) external virtual override returns (bool) {
        _transfer(msg.sender, recipient, amount);
        return true;
    }

    function allowance(address owner, address spender)
        external
        view
        virtual
        override
        returns (uint256)
    {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 amount) external virtual override returns (bool) {
        _approve(msg.sender, spender, amount);
        return true;
    }

    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, msg.sender, _allowances[sender][msg.sender] - amount);
        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(msg.sender, spender, _allowances[msg.sender][spender] + addedValue);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue)
        public
        virtual
        returns (bool)
    {
        _approve(msg.sender, spender, _allowances[msg.sender][spender] - subtractedValue);
        return true;
    }

    function _mint(address _account, uint256 _amount) internal virtual {
        require(_account != address(0), "ERC20: mint to the zero address");

        _totalSupply += _amount;
        _balances[_account] += _amount;
        emit Transfer(address(0), _account, _amount);
    }

    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _balances[sender] = _balances[sender] - amount;
        _balances[recipient] = _balances[recipient] + amount;
        emit Transfer(sender, recipient, amount);
    }

    function _burn(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: burn from the zero address");

        _balances[account] = _balances[account] - amount;
        _totalSupply = _totalSupply - amount;
        emit Transfer(account, address(0), amount);
    }
}

// File: contracts/token/EIP712.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;

/**
 * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
 *
 * The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
 * thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
 * they need in their contracts using a combination of `abi.encode` and `keccak256`.
 *
 * This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
 * scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
 * ({_hashTypedDataV4}).
 *
 * The implementation of the domain separator was designed to be as efficient as possible while still properly updating
 * the chain id to protect against replay attacks on an eventual fork of the chain.
 *
 * NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
 * https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
 *
 */

abstract contract EIP712 {
    /* solhint-disable var-name-mixedcase */
    // Cache the domain separator as an immutable value, but also store the chain id that it corresponds to, in order to
    // invalidate the cached domain separator if the chain id changes.
    // samparsky: remove immutable to be initiated, it should only be set once in initialize
    bytes32 private _CACHED_DOMAIN_SEPARATOR;
    uint256 private _CACHED_CHAIN_ID;

    bytes32 private _HASHED_NAME;
    bytes32 private _HASHED_VERSION;
    bytes32 private _TYPE_HASH;

    /* solhint-enable var-name-mixedcase */

    /**
     * @dev Initializes the domain separator and parameter caches.
     *
     * The meaning of `name` and `version` is specified in
     * https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
     *
     * - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
     * - `version`: the current major version of the signing domain.
     *
     * NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
     * contract upgrade].
     */
    function initializeEIP712(string memory name, string memory version) internal {
        bytes32 hashedName = keccak256(bytes(name));
        bytes32 hashedVersion = keccak256(bytes(version));
        bytes32 typeHash =
            keccak256(
                "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
            );
        _HASHED_NAME = hashedName;
        _HASHED_VERSION = hashedVersion;
        _CACHED_CHAIN_ID = _getChainId();
        _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator(typeHash, hashedName, hashedVersion);
        _TYPE_HASH = typeHash;
    }

    /**
     * @dev Returns the domain separator for the current chain.
     */
    function _domainSeparatorV4() internal view returns (bytes32) {
        if (_getChainId() == _CACHED_CHAIN_ID) {
            return _CACHED_DOMAIN_SEPARATOR;
        } else {
            return _buildDomainSeparator(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION);
        }
    }

    function _buildDomainSeparator(
        bytes32 typeHash,
        bytes32 name,
        bytes32 version
    ) private view returns (bytes32) {
        return keccak256(abi.encode(typeHash, name, version, _getChainId(), address(this)));
    }

    /**
     * @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
     * function returns the hash of the fully encoded EIP712 message for this domain.
     *
     * This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
     *
     * ```solidity
     * bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
     *     keccak256("Mail(address to,string contents)"),
     *     mailTo,
     *     keccak256(bytes(mailContents))
     * )));
     * address signer = ECDSA.recover(digest, signature);
     * ```
     */
    function _hashTypedDataV4(bytes32 structHash) internal view returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x01", _domainSeparatorV4(), structHash));
    }

    function _getChainId() private view returns (uint256 chainId) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        // solhint-disable-next-line no-inline-assembly
        assembly {
            chainId := chainid()
        }
    }
}

// File: @openzeppelin/contracts/token/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: @openzeppelin/contracts/token/ERC20/utils/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'
        // 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) + 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
            // 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 ^0.8.0;

/**
 * @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);
            }
        }
    }
}

// File: contracts/interfaces/IRewardDistributor.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

interface IRewardDistributor {
    event Initialized(
        IERC20 indexed _rewardToken,
        uint256 _amountDistributePerSecond,
        uint256 _startTimestamp,
        uint256 _endTimestamp,
        address _guardian,
        uint256 timestamp
    );

    function accumulateReward(address _tokenAddr, address _user) external;

    function endTimestamp() external returns (uint256);

    function initialize(
        string calldata _name,
        IERC20 _rewardToken,
        uint256 _amountDistributePerSecond,
        uint256 _startTimestamp,
        uint256 _endTimestamp,
        address _guardian
    ) external;
}

// File: contracts/interfaces/IPriceOracleAggregator.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "./IOracle.sol";

interface IPriceOracleAggregator {
    event UpdateOracle(IERC20 token, IOracle oracle);

    function getPriceInUSD(IERC20 _token) external view returns (uint256);

    function getPriceInUSDMultiple(IERC20[] calldata _tokens)
        external
        view
        returns (uint256[] memory);

    function setOracleForAsset(IERC20[] calldata _asset, IOracle[] calldata _oracle) external;

    event OwnershipAccepted(address prevOwner, address newOwner, uint256 timestamp);
    event TransferControl(address _newTeam, uint256 timestamp);
    event StableTokenAdded(IERC20 _token, uint256 timestamp);
}

// File: contracts/interfaces/IDebtToken.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;
import {IBSWrapperTokenBase} from "./IBSWrapperToken.sol";

interface IDebtToken is IBSWrapperTokenBase {
    event DelegateBorrow(address from, address to, uint256 amount, uint256 timestamp);

    function increaseTotalDebt(uint256 _amount) external;

    function principal(address _account) external view returns (uint256);

    function mint(
        address _to,
        address _owner,
        uint256 _amount
    ) external;
}

// File: contracts/interfaces/IBSVault.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "./IERC3156FlashLender.sol";

interface IBSVault is IERC3156FlashLender {
    // ************** //
    // *** EVENTS *** //
    // ************** //

    /// @notice Emitted on deposit
    /// @param token being deposited
    /// @param from address making the depsoit
    /// @param to address to credit the tokens being deposited
    /// @param amount being deposited
    /// @param shares the represent the amount deposited in the vault
    event Deposit(
        IERC20 indexed token,
        address indexed from,
        address indexed to,
        uint256 amount,
        uint256 shares
    );

    /// @notice Emitted on withdraw
    /// @param token being deposited
    /// @param from address making the depsoit
    /// @param to address to credit the tokens being withdrawn
    /// @param amount Amount of underlying being withdrawn
    /// @param shares the represent the amount withdraw from the vault
    event Withdraw(
        IERC20 indexed token,
        address indexed from,
        address indexed to,
        uint256 shares,
        uint256 amount
    );

    event Transfer(IERC20 indexed token, address indexed from, address indexed to, uint256 amount);

    event FlashLoan(
        address indexed borrower,
        IERC20 indexed token,
        uint256 amount,
        uint256 feeAmount,
        address indexed receiver
    );

    event TransferControl(address _newTeam, uint256 timestamp);

    event UpdateFlashLoanRate(uint256 newRate);

    event Approval(address indexed user, address indexed allowed, bool status);

    event OwnershipAccepted(address prevOwner, address newOwner, uint256 timestamp);

    event RegisterProtocol(address sender);

    event AllowContract(address whitelist, bool status);

    event RescueFunds(IERC20 token, uint256 amount);

    // ************** //
    // *** FUNCTIONS *** //
    // ************** //

    function initialize(uint256 _flashLoanRate, address _owner) external;

    function approveContract(
        address _user,
        address _contract,
        bool _status,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    function deposit(
        IERC20 _token,
        address _from,
        address _to,
        uint256 _amount
    ) external returns (uint256, uint256);

    function withdraw(
        IERC20 _token,
        address _from,
        address _to,
        uint256 _amount
    ) external returns (uint256);

    function balanceOf(IERC20, address) external view returns (uint256);

    function transfer(
        IERC20 _token,
        address _from,
        address _to,
        uint256 _shares
    ) external;

    function toShare(
        IERC20 token,
        uint256 amount,
        bool ceil
    ) external view returns (uint256);

    function toUnderlying(IERC20 token, uint256 share) external view returns (uint256);
}

// File: contracts/DataTypes.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;
import "./interfaces/IInterestRateModel.sol";
import "./interfaces/IBSWrapperToken.sol";
import "./interfaces/IDebtToken.sol";

////////////////////////////////////////////////////////////////////////////////////////////
/// @title DataTypes
/// @author @samparsky
////////////////////////////////////////////////////////////////////////////////////////////

library DataTypes {
    struct BorrowAssetConfig {
        uint256 initialExchangeRateMantissa;
        uint256 reserveFactorMantissa;
        uint256 collateralFactor;
        IBSWrapperToken wrappedBorrowAsset;
        uint256 liquidationFee;
        IDebtToken debtToken;
    }

    function validBorrowAssetConfig(BorrowAssetConfig memory self, address _owner) internal view {
        require(self.initialExchangeRateMantissa > 0, "E");
        require(self.reserveFactorMantissa > 0, "F");
        require(self.collateralFactor > 0, "C");
        require(self.liquidationFee > 0, "L");
        require(address(self.wrappedBorrowAsset) != address(0), "B");
        require(address(self.debtToken) != address(0), "IB");
        require(self.wrappedBorrowAsset.owner() == _owner, "IW");
        require(self.debtToken.owner() == _owner, "IVW");
    }
}

// File: contracts/interfaces/IOracle.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;

interface IOracle {
    /// @notice Price update event
    /// @param asset the asset
    /// @param newPrice price of the asset
    event PriceUpdated(address asset, uint256 newPrice);

    /// @dev returns latest answer
    function latestAnswer() external view returns (int256);

}

// File: contracts/interfaces/IERC3156FlashLender.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.8.1;
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/IERC3156FlashBorrower.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.1;

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/IInterestRateModel.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.1;

interface IInterestRateModel {
    /**
     * @notice Calculates the current borrow interest rate per block
     * @param cash The total amount of cash the market has
     * @param borrows The total amount of borrows the market has outstanding
     * @param reserves The total amount of reserves the market has
     * @return The borrow rate per block (as a percentage, and scaled by 1e18)
     */
    function getBorrowRate(
        uint256 cash,
        uint256 borrows,
        uint256 reserves
    ) external view returns (uint256);

    /**
     * @notice Calculates the current supply interest rate per block
     * @param cash The total amount of cash the market has
     * @param borrows The total amount of borrows the market has outstanding
     * @param reserves The total amount of reserves the market has
     * @param reserveFactorMantissa The current reserve factor the market has
     * @return The supply rate per block (as a percentage, and scaled by 1e18)
     */
    function getSupplyRate(
        uint256 cash,
        uint256 borrows,
        uint256 reserves,
        uint256 reserveFactorMantissa
    ) external view returns (uint256);
}