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Contract Name:
BAMM

Contract Source Code:

File 1 of 1 : BAMM

// Sources flattened with hardhat v2.8.0 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



pragma solidity 0.6.11;

contract TokenAdapter {
    using SafeMath for uint256;

    string constant public name = "B.AMM";
    string constant 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



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



pragma solidity 0.6.11;

interface IPriceFeed {

    // --- Events ---
    event LastGoodPriceUpdated(uint _lastGoodPrice);
   
    // --- Function ---
    function fetchPrice() external returns (uint);
}


// File contracts/Dependencies/Ownable.sol



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


// 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/[email protected]



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/[email protected]



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/math/[email protected]



pragma solidity ^0.6.0;


// File @openzeppelin/contracts/utils/[email protected]



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/[email protected]



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/[email protected]



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/[email protected]



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



pragma solidity 0.6.11;









interface ICToken {
    function redeem(uint redeemTokens) external returns (uint);
    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);
}

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;

    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 _LUSD,
        address _cBorrow,
        uint _maxDiscount,
        address payable _feePool)
        public
    {
        LUSD = IERC20(_LUSD);
        lusdDecimals = ERC20(_LUSD).decimals();
        cBorrow = ICToken(_cBorrow);

        feePool = _feePool;
        maxDiscount = _maxDiscount;

        IERC20(_LUSD).safeApprove(address(_cBorrow), uint(-1));

        require(ERC20(_LUSD).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 = ctoken.underlying();

        // 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 = ctoken.underlying();

        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 withdraw(uint numShares) external nonReentrant {
        uint supplyBefore = totalSupply; // this is to save gas

        uint lusdBal = LUSD.balanceOf(address(this));
        uint lusdAmount = lusdBal.mul(numShares).div(supplyBefore);

        uint[] memory collateralAmounts = new uint[](collaterals.length);
        IERC20[] memory collateralTypes = collaterals;

        for(uint i = 0 ; i < collateralTypes.length ; 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(msg.sender, lusdAmount);
        for(uint i = 0 ; i < collateralTypes.length ; i++) {
            if(collateralAmounts[i] > 0 ) collateralTypes[i].safeTransfer(msg.sender, collateralAmounts[i]);
        }

        emit UserWithdraw(msg.sender, lusdAmount, numShares);            
    }

    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) public nonReentrant returns(uint) {
        require(returnToken != LUSD, "swap: unsupported");

        uint returnAmount = getSwapAmount(lusdAmount, returnToken);

        require(returnAmount >= minReturn, "swap: low return");

        LUSD.safeTransferFrom(msg.sender, address(this), lusdAmount);

        uint feeAmount = addBps(lusdAmount, int(fee)).sub(lusdAmount);
        if(feeAmount > 0) LUSD.safeTransfer(feePool, feeAmount);

        returnToken.safeTransfer(dest, returnAmount);

        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;

        return repayAmount <= LUSD.balanceOf(address(this));
    }

    // callable by anyone
    function liquidateBorrow(address borrower, uint amount, ICToken collateral) external nonReentrant returns (uint) {
        require(cTokens[address(collateral)] || collateral == cBorrow, "liquidateBorrow: invalid collateral");

        IERC20 colToken = IERC20(collateral.underlying());

        uint tokenBalBefore = colToken.balanceOf(address(this));
        require(cBorrow.liquidateBorrow(borrower, amount, address(collateral)) == 0, "liquidateBorrow: liquidation failed");
        require(collateral.redeem(collateral.balanceOf(address(this))) == 0, "liquidateBorrow: collateral redeem failed");       
        uint tokenBalAfter = colToken.balanceOf(address(this));

        uint deltaToken = tokenBalAfter.sub(tokenBalBefore);
        if(collateral == cBorrow) deltaToken = amount;

        uint feeAmount = addBps(deltaToken, int(callerFee)).sub(deltaToken);
        if(feeAmount > 0 ) colToken.safeTransfer(msg.sender, feeAmount);
    }    
}

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