/*
B.PROTOCOL TERMS OF USE
=======================

THE TERMS OF USE CONTAINED HEREIN (THESE “TERMS”) GOVERN YOUR USE OF B.PROTOCOL, WHICH IS A DECENTRALIZED PROTOCOL ON THE ETHEREUM BLOCKCHAIN (the “PROTOCOL”) THAT enables a backstop liquidity mechanism FOR DECENTRALIZED LENDING PLATFORMS (“DLPs”).  
PLEASE READ THESE TERMS CAREFULLY AT https://github.com/backstop-protocol/Terms-and-Conditions, INCLUDING ALL DISCLAIMERS AND RISK FACTORS, BEFORE USING THE PROTOCOL. BY USING THE PROTOCOL, YOU ARE IRREVOCABLY CONSENTING TO BE BOUND BY THESE TERMS. 
IF YOU DO NOT AGREE TO ALL OF THESE TERMS, DO NOT USE THE PROTOCOL. YOUR RIGHT TO USE THE PROTOCOL IS SUBJECT AND DEPENDENT BY YOUR AGREEMENT TO ALL TERMS AND CONDITIONS SET FORTH HEREIN, WHICH AGREEMENT SHALL BE EVIDENCED BY YOUR USE OF THE PROTOCOL.
Minors Prohibited: The Protocol is not directed to individuals under the age of eighteen (18) or the age of majority in your jurisdiction if the age of majority is greater. If you are under the age of eighteen or the age of majority (if greater), you are not authorized to access or use the Protocol. By using the Protocol, you represent and warrant that you are above such age.

License; No Warranties; Limitation of Liability;
(a) The software underlying the Protocol is licensed for use in accordance with the 3-clause BSD License, which can be accessed here: https://opensource.org/licenses/BSD-3-Clause.
(b) THE PROTOCOL IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS", “WITH ALL FAULTS” and “AS AVAILABLE” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
(c) IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
*/

// Sources flattened with hardhat v2.9.3 https://hardhat.org

// File contracts/Dependencies/SafeMath.sol

// SPDX-License-Identifier: MIT

pragma solidity 0.6.11;

/**
 * Based on OpenZeppelin's SafeMath:
 * https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/math/SafeMath.sol
 *
 * @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, 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) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @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) {
        // 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 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts 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) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message 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.
     *
     * _Available since v2.4.0._
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts 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) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message 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.
     *
     * _Available since v2.4.0._
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}


// File contracts/B.Protocol/TokenAdapter.sol

// : MIT

pragma solidity 0.6.11;

contract TokenAdapter {
    using SafeMath for uint256;

    string public name = "B.AMM";
    string public symbol = "BAMM";
    uint8 constant public decimals = 18;

    uint public totalSupply;

    event Transfer(address indexed from, address indexed to, uint tokens);
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);

    // balanceOf for each account
    mapping(address => uint256) public balanceOf;
 
    // Owner of account approves the transfer of an amount to another account
    mapping(address => mapping (address => uint256)) public allowance;
 
    // Transfer the balance from owner's account to another account
    function transfer(address to, uint tokens) public returns (bool success) {
        balanceOf[msg.sender] = balanceOf[msg.sender].sub(tokens);
        balanceOf[to] = balanceOf[to].add(tokens);
        emit Transfer(msg.sender, to, tokens);
        return true;
    }
 
    // Send `tokens` amount of tokens from address `from` to address `to`
    // The transferFrom method is used for a withdraw workflow, allowing contracts to send
    // tokens on your behalf, for example to "deposit" to a contract address and/or to charge
    // fees in sub-currencies; the command should fail unless the _from account has
    // deliberately authorized the sender of the message via some mechanism; we propose
    // these standardized APIs for approval:
    function transferFrom(address from, address to, uint tokens) public returns (bool success) {
        balanceOf[from] = balanceOf[from].sub(tokens);
        if(allowance[from][msg.sender] != type(uint256).max) {
            allowance[from][msg.sender] = allowance[from][msg.sender].sub(tokens);
        }
        balanceOf[to] = balanceOf[to].add(tokens);
        emit Transfer(from, to, tokens);
        return true;
    }
 
    // Allow `spender` to withdraw from your account, multiple times, up to the `tokens` amount.
    // If this function is called again it overwrites the current allowance with _value.
    function approve(address spender, uint tokens) public returns (bool success) {
        allowance[msg.sender][spender] = tokens;
        emit Approval(msg.sender, spender, tokens);
        return true;
    }

    function mint(address to, uint tokens) internal {
        balanceOf[to] = balanceOf[to].add(tokens);
        totalSupply = totalSupply.add(tokens);

        emit Transfer(address(0), to, tokens);
    }

    function burn(address owner, uint tokens) internal {
        balanceOf[owner] = balanceOf[owner].sub(tokens);
        totalSupply = totalSupply.sub(tokens);

        emit Transfer(owner, address(0), tokens);        
    }
}


// File contracts/B.Protocol/PriceFormula.sol

// : MIT

pragma solidity 0.6.11;

contract PriceFormula {
    using SafeMath for uint256;

    function getSumFixedPoint(uint x, uint y, uint A) public pure returns(uint) {
        if(x == 0 && y == 0) return 0;

        uint sum = x.add(y);

        for(uint i = 0 ; i < 255 ; i++) {
            uint dP = sum;
            dP = dP.mul(sum) / (x.mul(2)).add(1);
            dP = dP.mul(sum) / (y.mul(2)).add(1);

            uint prevSum = sum;

            uint n = (A.mul(2).mul(x.add(y)).add(dP.mul(2))).mul(sum);
            uint d = (A.mul(2).sub(1).mul(sum));
            sum = n / d.add(dP.mul(3));

            if(sum <= prevSum.add(1) && prevSum <= sum.add(1)) break;
        }

        return sum;
    }

    function getReturn(uint xQty, uint xBalance, uint yBalance, uint A) public pure returns(uint) {
        uint sum = getSumFixedPoint(xBalance, yBalance, A);

        uint c = sum.mul(sum) / (xQty.add(xBalance)).mul(2);
        c = c.mul(sum) / A.mul(4);
        uint b = (xQty.add(xBalance)).add(sum / A.mul(2));
        uint yPrev = 0;
        uint y = sum;

        for(uint i = 0 ; i < 255 ; i++) {
            yPrev = y;
            uint n = (y.mul(y)).add(c);
            uint d = y.mul(2).add(b).sub(sum); 
            y = n / d;

            if(y <= yPrev.add(1) && yPrev <= y.add(1)) break;
        }

        return yBalance.sub(y).sub(1);
    }
}


// File contracts/Interfaces/IPriceFeed.sol

// : MIT

pragma solidity 0.6.11;

interface IPriceFeed {

    // --- Events ---
    event LastGoodPriceUpdated(uint _lastGoodPrice);
   
    // --- Function ---
    function fetchPrice() external returns (uint);
}


// File contracts/Dependencies/Ownable.sol

// : MIT

pragma solidity 0.6.11;

/**
 * Based on OpenZeppelin's Ownable contract:
 * https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/access/Ownable.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.
 *
 * 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.
 */
contract Ownable {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        _owner = msg.sender;
        emit OwnershipTransferred(address(0), msg.sender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return msg.sender == _owner;
    }

    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
        
    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     *
     * NOTE: This function is not safe, as it doesn’t check owner is calling it.
     * Make sure you check it before calling it.
     */
    function _renounceOwnership() internal {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }
}


// File contracts/Dependencies/AggregatorV3Interface.sol

// : MIT
// Code from https://github.com/smartcontractkit/chainlink/blob/master/evm-contracts/src/v0.6/interfaces/AggregatorV3Interface.sol

pragma solidity 0.6.11;

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/utils/ReentrancyGuard.sol@v3.2.0

// : MIT

pragma solidity ^0.6.0;

/**
 * @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].
 */
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 @openzeppelin/contracts/token/ERC20/IERC20.sol@v3.2.0

// : MIT

pragma solidity ^0.6.0;

/**
 * @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/utils/Address.sol@v3.2.0

// : MIT

pragma solidity ^0.6.2;

/**
 * @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 in 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");
        return _functionCallWithValue(target, data, value, errorMessage);
    }

    function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}


// File @openzeppelin/contracts/token/ERC20/SafeERC20.sol@v3.2.0

// : MIT

pragma solidity ^0.6.0;



/**
 * @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/GSN/Context.sol@v3.2.0

// : MIT

pragma solidity ^0.6.0;

/*
 * @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/ERC20.sol@v3.2.0

// : MIT

pragma solidity ^0.6.0;




/**
 * @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}.
 */
contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;
    using Address for address;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
     * a default value of 18.
     *
     * To select a different value for {decimals}, use {_setupDecimals}.
     *
     * All three of these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name, string memory symbol) public {
        _name = name;
        _symbol = symbol;
        _decimals = 18;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
     * called.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20};
     *
     * Requirements:
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `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");

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        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);
    }

    /**
     * @dev Sets {decimals} to a value other than the default one of 18.
     *
     * WARNING: This function should only be called from the constructor. Most
     * applications that interact with token contracts will not expect
     * {decimals} to ever change, and may work incorrectly if it does.
     */
    function _setupDecimals(uint8 decimals_) internal {
        _decimals = decimals_;
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}


// File contracts/B.Protocol/BAMM.sol

// : MIT

pragma solidity 0.6.11;









interface ICToken {
    function balanceOf(address a) external view returns (uint);
    function liquidateBorrow(address borrower, uint amount, address collateral) external returns (uint);
    function underlying() external view returns(IERC20);
    function getCash() external view returns(uint);
    function getAccountSnapshot(address account)
        external
        view
        returns(uint err, uint cTokenBalance, uint borrowBalance, uint exchangeRateMantissa);
    function redeemUnderlying(uint redeemAmount) external returns (uint);
}

interface ICETH {
    function liquidateBorrow(address borrower, address cTokenCollateral) payable external;
}

interface IFlashswap {
    function bammFlashswap(address initiator, uint lusdAmount, uint returnAmount, bytes memory data) external; 
}

contract BAMM is TokenAdapter, PriceFormula, Ownable, ReentrancyGuard {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    IERC20 public immutable LUSD;
    uint public immutable lusdDecimals;
    IERC20[] public collaterals; // IMPORTANT - collateral != LUSD
    mapping(address => AggregatorV3Interface) public priceAggregators;
    mapping(address => uint) public collateralDecimals;
    mapping(address => bool) public cTokens;
    ICToken public immutable cBorrow;
    bool public immutable isCETH;

    address payable public immutable feePool;
    uint public constant MAX_FEE = 100; // 1%
    uint public constant MAX_CALLER_FEE = 100; // 1%
    uint public fee = 0; // fee in bps
    uint public callerFee = 0; // fee in bps
    uint public A = 20;
    uint public constant MIN_A = 20;
    uint public constant MAX_A = 200;    

    uint public immutable maxDiscount; // max discount in bips

    uint constant public PRECISION = 1e18;

    event ParamsSet(uint A, uint fee, uint callerFee);
    event UserDeposit(address indexed user, uint lusdAmount, uint numShares);
    event UserWithdraw(address indexed user, uint lusdAmount, uint numShares);
    event RebalanceSwap(address indexed user, uint lusdAmount, IERC20 token, uint tokenAmount, uint timestamp);

    constructor(
        address _cBorrow,
        bool _isCETH,
        uint _maxDiscount,
        address payable _feePool)
        public
    {
        LUSD = IERC20(_cBorrow);
        lusdDecimals = ERC20(_cBorrow).decimals();
        cBorrow = ICToken(_cBorrow);
        isCETH = _isCETH;

        feePool = _feePool;
        maxDiscount = _maxDiscount;

        if(! _isCETH) IERC20(ICToken(_cBorrow).underlying()).safeApprove(address(_cBorrow), uint(-1));

        require(ERC20(_cBorrow).decimals() <= 18, "unsupported decimals");
    }

    function setParams(uint _A, uint _fee, uint _callerFee) external onlyOwner {
        require(_fee <= MAX_FEE, "setParams: fee is too big");
        require(_callerFee <= MAX_CALLER_FEE, "setParams: caller fee is too big");        
        require(_A >= MIN_A, "setParams: A too small");
        require(_A <= MAX_A, "setParams: A too big");

        fee = _fee;
        callerFee = _callerFee;
        A = _A;

        emit ParamsSet(_A, _fee, _callerFee);
    }

    function addCollateral(ICToken ctoken, AggregatorV3Interface feed) external onlyOwner {
        IERC20 token = IERC20(address(ctoken));

        // validations
        require(token != LUSD, "addCollateral: LUSD cannot be collateral");
        require(feed != AggregatorV3Interface(0x0), "addCollateral: invalid feed");
        require(! cTokens[address(ctoken)], "addCollateral: collateral listed");
        require(priceAggregators[address(token)] == AggregatorV3Interface(0x0), "addCollateral: underlying already added");

        // add the token
        collaterals.push(token);
        priceAggregators[address(token)] = feed;
        collateralDecimals[address(token)] = ERC20(address(token)).decimals();
        cTokens[address(ctoken)] = true;        
    }

    function removeCollateral(ICToken ctoken) external onlyOwner {
        IERC20 token = IERC20(address(ctoken));

        for(uint i = 0 ; i < collaterals.length ; i++) {
            if(collaterals[i] == token) {
                collaterals[i] = collaterals[collaterals.length - 1];
                collaterals.pop();
                priceAggregators[address(token)] = AggregatorV3Interface(0x0);
                cTokens[address(ctoken)] = false;
                break;
            }
        }
    }

    function fetchPrice(IERC20 token) public view returns(uint) {
        AggregatorV3Interface priceAggregator = priceAggregators[address(token)];
        if(priceAggregator == AggregatorV3Interface(address(0x0))) return 0;

        uint chainlinkDecimals;
        uint chainlinkLatestAnswer;
        uint chainlinkTimestamp;

        // First, try to get current decimal precision:
        try priceAggregator.decimals() returns (uint8 decimals) {
            // If call to Chainlink succeeds, record the current decimal precision
            chainlinkDecimals = decimals;
        } catch {
            // If call to Chainlink aggregator reverts, return a zero response with success = false
            return 0;
        }

        // Secondly, try to get latest price data:
        try priceAggregator.latestRoundData() returns
        (
            uint80 /* roundId */,
            int256 answer,
            uint256 /* startedAt */,
            uint256 timestamp,
            uint80 /* answeredInRound */
        )
        {
            // If call to Chainlink succeeds, return the response and success = true
            chainlinkLatestAnswer = uint(answer);
            chainlinkTimestamp = timestamp;
        } catch {
            // If call to Chainlink aggregator reverts, return a zero response with success = false
            return 0;
        }

        if(chainlinkTimestamp + 1 hours < now) return 0; // price is down

        int chainlinkDecimalFactor = int(chainlinkDecimals + collateralDecimals[address(token)]) - int(lusdDecimals);
        if(chainlinkDecimalFactor >= 0) {
            return chainlinkLatestAnswer.mul(PRECISION) / (10 ** uint(chainlinkDecimalFactor));
        }
        else {
            return chainlinkLatestAnswer.mul(PRECISION) * (10 ** uint(-1 * chainlinkDecimalFactor));
        }
    }

    function getCollateralValue() public view returns(bool succ, uint value) {
        value = 0;
        succ = true;

        for(uint i = 0 ; i < collaterals.length ; i++) {
            IERC20 token = collaterals[i];
            uint bal = token.balanceOf(address(this));
            if(bal > 0) {
                uint price = fetchPrice(token);
                if(price == 0) {
                    succ = false;
                    break;
                }

                value = value.add(bal.mul(price) / PRECISION);                
            }
        }
    }


    function deposit(uint lusdAmount) external nonReentrant {        
        // update share
        uint lusdValue = LUSD.balanceOf(address(this));
        (bool succ, uint colValue) = getCollateralValue();

        require(succ, "deposit: chainlink is down");

        uint totalValue = lusdValue.add(colValue);

        // this is in theory not reachable. if it is, better halt deposits
        // the condition is equivalent to: (totalValue = 0) ==> (totalSupply = 0)
        require(totalValue > 0 || totalSupply == 0, "deposit: system is rekt");

        uint newShare = PRECISION;
        if(totalSupply > 0) newShare = totalSupply.mul(lusdAmount) / totalValue;

        // deposit
        LUSD.safeTransferFrom(msg.sender, address(this), lusdAmount);

        // update LP token
        mint(msg.sender, newShare);

        emit UserDeposit(msg.sender, lusdAmount, newShare);        
    }

    function efficientWithdraw(uint numShares, address to, bool withdrawCollateral, uint minLusd) public nonReentrant {
        uint supplyBefore = totalSupply; // this is to save gas

        uint lusdBal = LUSD.balanceOf(address(this));
        uint lusdAmount = lusdBal.mul(numShares).div(supplyBefore);
        require(lusdAmount >= minLusd, "efficientWithdraw: insufficient lusd amount");

        uint[] memory collateralAmounts = new uint[](collaterals.length);
        IERC20[] memory collateralTypes = collaterals;

        for(uint i = 0 ; (i < collateralTypes.length) && withdrawCollateral ; i++) {
            uint bal = collateralTypes[i].balanceOf(address(this));
            collateralAmounts[i] = bal.mul(numShares).div(supplyBefore);
        }

        // update LP token
        burn(msg.sender, numShares);

        // send lusd and collateral leftovers
        if(lusdAmount > 0) LUSD.safeTransfer(to, lusdAmount);
        for(uint i = 0 ; i < collateralTypes.length ; i++) {
            if(collateralAmounts[i] > 0 ) collateralTypes[i].safeTransfer(to, collateralAmounts[i]);
        }

        emit UserWithdraw(msg.sender, lusdAmount, numShares);            
    }

    function withdraw(uint numShares) external {
        efficientWithdraw(numShares, msg.sender, true, 0);
    }

    function addBps(uint n, int bps) internal pure returns(uint) {
        require(bps <= 10000, "reduceBps: bps exceeds max");
        require(bps >= -10000, "reduceBps: bps exceeds min");

        return n.mul(uint(10000 + bps)) / 10000;
    }

    function getSwapAmount(uint lusdQty, IERC20 token) public view returns(uint tokenAmount) {
        uint lusdBalance = LUSD.balanceOf(address(this));
        uint tokenBalance  = token.balanceOf(address(this));

        (bool succ, uint collateralValue) = getCollateralValue();
        if(! succ) return 0; // chainlink is down

        uint token2usdPrice = fetchPrice(token);
        if(token2usdPrice == 0) return 0; // chainlink is down

        uint maxReturn = addBps(lusdQty.mul(PRECISION) / token2usdPrice, int(maxDiscount));

        uint xQty = lusdQty;
        uint xBalance = lusdBalance;
        uint yBalance = lusdBalance.add(collateralValue.mul(2));
        
        uint usdReturn = getReturn(xQty, xBalance, yBalance, A);
        uint basicTokenReturn = usdReturn.mul(PRECISION) / token2usdPrice;

        if(tokenBalance < basicTokenReturn) basicTokenReturn = tokenBalance; // cannot give more than balance 
        if(maxReturn < basicTokenReturn) basicTokenReturn = maxReturn;

        tokenAmount = basicTokenReturn;
    }

    // get token in return to LUSD
    function swap(uint lusdAmount, IERC20 returnToken, uint minReturn, address payable dest, bytes memory data) public nonReentrant returns(uint) {
        require(returnToken != LUSD, "swap: unsupported");

        uint returnAmount = getSwapAmount(lusdAmount, returnToken);

        require(returnAmount >= minReturn, "swap: low return");

        uint feeAmount = addBps(lusdAmount, int(fee)).sub(lusdAmount);

        // first send the return
        returnToken.safeTransfer(dest, returnAmount);

        // now dest can prepare the lusd - and send it to msg.sender
        if(data.length != 0) IFlashswap(dest).bammFlashswap(msg.sender, lusdAmount, returnAmount, data);

        // get the lusd
        LUSD.safeTransferFrom(msg.sender, address(this), lusdAmount);
        // send fees
        if(feeAmount > 0) LUSD.safeTransfer(feePool, feeAmount);

        emit RebalanceSwap(msg.sender, lusdAmount, returnToken, returnAmount, now);

        return returnAmount;
    }

    receive() external payable {}

    function canLiquidate(
        ICToken cTokenBorrowed,
        ICToken cTokenCollateral,
        uint repayAmount
    )
        external
        view
        returns(bool)
    {
        if(cTokenBorrowed != cBorrow) return false;
        if((! cTokens[address(cTokenCollateral)]) && (cTokenCollateral != cTokenBorrowed)) return false;

        // check if there is sufficient balance at the backstop
        (uint err, uint ctokenBalance, /* borrow balance */, uint exchangeRateMantissa) = cBorrow.getAccountSnapshot(address(this));
        if(err != 0) return false;

        uint underlyingBalance = ctokenBalance.mul(exchangeRateMantissa) / 1e18;

        if(repayAmount > underlyingBalance) return false;
        if(repayAmount > cBorrow.getCash()) return false;

        return true;
    }

    // callable by anyone
    function liquidateBorrow(address borrower, uint amount, ICToken collateral) public virtual nonReentrant returns (uint) {
        require(cTokens[address(collateral)] || collateral == cBorrow, "liquidateBorrow: invalid collateral");

        IERC20 colToken = IERC20(address(collateral));

        uint tokenBalBefore = colToken.balanceOf(address(this));
        require(cBorrow.redeemUnderlying(amount) == 0, "liquidateBorrow: redeem failed");
        if(isCETH) {
            ICETH(address(cBorrow)).liquidateBorrow{value: amount}(borrower, address(collateral));            
        }
        else {
            require(cBorrow.liquidateBorrow(borrower, amount, address(collateral)) == 0, "liquidateBorrow: liquidation failed");
        }

        uint tokenBalAfter = colToken.balanceOf(address(this));

        // if collateral == cBorrow, then caller fee will be quite small, but this is a feature
        uint deltaToken = tokenBalAfter.sub(tokenBalBefore);

        uint feeAmount = addBps(deltaToken, int(callerFee)).sub(deltaToken);
        if(feeAmount > 0 ) colToken.safeTransfer(msg.sender, feeAmount);
    }    
}


// File contracts/B.Protocol/HundredBAMM.sol

// : MIT

pragma solidity 0.6.11;

interface SymbolLike {
    function symbol() view external returns(string memory);
}

contract HundredBAMM is BAMM {
    constructor(
        address _cBorrow,
        bool _isCETH,
        uint _maxDiscount,
        address payable _feePool)
        public
        BAMM(_cBorrow, _isCETH, _maxDiscount, _feePool)
    {
        string memory ctokenSymbol = SymbolLike(_cBorrow).symbol();
        symbol = string(abi.encodePacked(string("b"), ctokenSymbol));
        name = symbol;
    }

    function collateralCount() public view returns(uint) {
        return collaterals.length;
    }
}