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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

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

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (utils/math/SafeMath.sol)

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

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

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

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

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

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

    /**
     * @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 a - b;
    }

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

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

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

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

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

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

// File: contracts/interfaces/IBarn.sol



// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.0;
pragma experimental ABIEncoderV2;

interface IBarn {
    // balanceOf returns the current BOND balance of a user (bonus not included)
    function balanceOf(address user) external view returns (uint256);

    // balanceAtTs returns the amount of BOND that the user currently staked (bonus NOT included)
    function balanceAtTs(
        address user,
        uint256 timestamp
    ) external view returns (uint256);
}

// File: contracts/interfaces/IBurnableToken.sol



// SPDX-License-Identifier: AGPL-3.0
pragma solidity ^0.8.0;

import "./IERC20.sol";

interface IBurnableToken is IERC20 {
    function mint(address target, uint256 amount) external returns (bool);

    function burn(uint256 amount) external returns (bool);

    function mintable() external returns (bool);
}

// File: contracts/interfaces/IERC20.sol



// SPDX-License-Identifier: AGPL-3.0
pragma solidity ^0.8.0;

interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the token decimals.
     */
    function decimals() external view returns (uint8);

    /**
     * @dev Returns the token symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the token name.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the bep token owner. (This is a BEP-20 token specific.)
     */
    function getOwner() external view returns (address);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount)
        external
        returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address _owner, address spender)
        external
        view
        returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );
}

// File: contracts/interfaces/ISwapContract.sol



// SPDX-License-Identifier: AGPL-3.0
pragma solidity ^0.8.0;
pragma experimental ABIEncoderV2;

import "./IBurnableToken.sol";

interface ISwapContract {
    function BTCT_ADDR() external returns (address);

    function lpToken() external returns (IBurnableToken);

    function singleTransferERC20(
        address _destToken,
        address _to,
        uint256 _amount,
        uint256 _totalSwapped,
        uint256 _rewardsAmount,
        bytes32[] memory _redeemedFloatTxIds
    ) external returns (bool);

    function multiTransferERC20TightlyPacked(
        address _destToken,
        bytes32[] memory _addressesAndAmounts,
        uint256 _totalSwapped,
        uint256 _rewardsAmount,
        bytes32[] memory _redeemedFloatTxIds
    ) external returns (bool);

    function collectSwapFeesForBTC(
        uint256 _incomingAmount,
        uint256 _minerFee,
        uint256 _rewardsAmount,
        address[] memory _spenders,
        uint256[] memory _swapAmounts
    ) external returns (bool);

    function recordIncomingFloat(
        address _token,
        bytes32 _addressesAndAmountOfFloat,
        bytes32 _txid
    ) external returns (bool);

    function recordOutcomingFloat(
        address _token,
        bytes32 _addressesAndAmountOfLPtoken,
        uint256 _minerFee,
        bytes32 _txid
    ) external returns (bool);

    function recordUTXOSweepMinerFee(
        uint256 _minerFee,
        bytes32 _txid
    ) external returns (bool);

    function churn(
        address _newOwner,
        address[] memory _nodes,
        bool[] memory _isRemoved,
        uint8 _churnedInCount,
        uint8 _tssThreshold
    ) external returns (bool);

    function updateParams(
        address _sbBTCPool,
        address _buybackAddress,
        uint256 _withdrawalFeeBPS,
        uint256 _nodeRewardsRatio,
        uint256 _buybackRewardsRatio
    ) external returns (bool);

    function isTxUsed(bytes32 _txid) external view returns (bool);

    function getCurrentPriceLP() external view returns (uint256);

    function getFloatReserve(
        address _tokenA,
        address _tokenB
    ) external returns (uint256 reserveA, uint256 reserveB);

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

    function isNodeStake(address _user) external returns (bool);
}

// File: contracts/sbBTCPool.sol



// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "./interfaces/IBarn.sol";
import "./interfaces/ISwapContract.sol";

contract sbBTCPool is Ownable {
    using SafeMath for uint256;

    uint256 constant divisor = 10 ** 27;

    uint256 public balanceBefore;
    uint256 public currentMultiplier;
    uint256 public totalNodeStaked;

    mapping(address => uint256) public userMultiplier;
    mapping(address => uint256) public owed;

    IBarn public barn;
    IERC20 public rewardToken;
    ISwapContract public swapContract;

    event Claim(address indexed user, uint256 amount);

    // setBarn sets the address of the BarnBridge Barn into the state variable
    function setBarnAndSwap(address _barn, address _swap) public {
        require(_barn != address(0), "barn address must not be 0x0");
        require(_swap != address(0), "swap contract address must not be 0x0");
        require(msg.sender == owner(), "!owner");
        swapContract = ISwapContract(_swap);
        rewardToken = IERC20(swapContract.lpToken());
        barn = IBarn(_barn);
    }

    // update all node rewards.
    function updateAll(uint256 _timestamp) public onlyOwner {
        updateStakes(_timestamp);
        // Getting rewards
        ackFunds();
        // Update all distribution.
        address[] memory nodes = swapContract.getActiveNodes();
        for (uint256 i = 0; i < nodes.length; i++) {
            _updateOwed(nodes[i], _timestamp);
        }
    }

    // check all active nodes to calculate current stakes.
    function updateStakes(uint256 _timestamp) internal {
        address[] memory nodes = swapContract.getActiveNodes();
        uint256 newTotalNodeStaked;
        for (uint256 i = 0; i < nodes.length; i++) {
            newTotalNodeStaked = newTotalNodeStaked.add(
                barn.balanceAtTs(nodes[i], _timestamp)
            );
            if (userMultiplier[nodes[i]] == 0) {
                userMultiplier[nodes[i]] = currentMultiplier;
            }
        }
        // only change when stakers had actions.
        if (totalNodeStaked != newTotalNodeStaked) {
            totalNodeStaked = newTotalNodeStaked;
        }
    }

    function resetUnstakedNode(address _node) public {
        require(!swapContract.isNodeStake(_node), "node is staker");
        userMultiplier[_node] = 0;
    }

    // claim calculates the currently owed reward and transfers the funds to the user
    function claim() public returns (uint256) {
        require(swapContract.isNodeStake(msg.sender), "caller is not node");

        updateStakes(block.timestamp);

        ackFunds();

        _updateOwed(msg.sender, block.timestamp);

        uint256 amount = owed[msg.sender];
        require(amount > 0, "nothing to claim");

        owed[msg.sender] = 0;

        rewardToken.transfer(msg.sender, amount);

        // acknowledge the amount that was transferred to the user
        ackFunds();

        emit Claim(msg.sender, amount);

        return amount;
    }

    // ackFunds checks the difference between the last known balance of `token` and the current one
    // if it goes up, the multiplier is re-calculated
    // if it goes down, it only updates the known balance
    function ackFunds() public {
        uint256 balanceNow = rewardToken.balanceOf(address(this));

        if (balanceNow == 0 || balanceNow <= balanceBefore) {
            balanceBefore = balanceNow;
            return;
        }
        if (totalNodeStaked == 0) {
            return;
        }

        uint256 diff = balanceNow.sub(balanceBefore);
        uint256 multiplier = currentMultiplier.add(
            diff.mul(divisor).div(totalNodeStaked)
        );

        balanceBefore = balanceNow;
        currentMultiplier = multiplier;
    }

    function emergencyWithdraw() public {
        require(msg.sender == owner(), "!owner");
        rewardToken.transfer(msg.sender, rewardToken.balanceOf(address(this)));
        swapContract = ISwapContract(address(0));
    }

    // _updateOwed calculates and updates the total amount that is owed to an user and updates the user's multiplier
    // to the current value
    // it automatically attempts to pull the token from the source and acknowledge the funds
    function _updateOwed(address user, uint256 timestamp) internal {
        uint256 reward = _userPendingReward(user, timestamp);
        owed[user] = owed[user].add(reward);
        userMultiplier[user] = currentMultiplier;
    }

    // _userPendingReward calculates the reward that should be based on the current multiplier / anything that's not included in the `owed[user]` value
    // it does not represent the entire reward that's due to the user unless added on top of `owed[user]`
    function _userPendingReward(
        address user,
        uint256 timestamp
    ) internal view returns (uint256) {
        uint256 multiplier = currentMultiplier.sub(userMultiplier[user]);
        return barn.balanceAtTs(user, timestamp).mul(multiplier).div(divisor);
    }
}