pragma solidity 0.5.16;


contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

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

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);
}

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;
    }
}

contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view 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 returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public 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 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 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 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 {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _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 {
        require(account != address(0), "ERC20: mint to the zero address");

        _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 {
        require(account != address(0), "ERC20: burn from the zero address");

        _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 is 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 {
        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 Destroys `amount` tokens from `account`.`amount` is then deducted
     * from the caller's allowance.
     *
     * See {_burn} and {_approve}.
     */
    function _burnFrom(address account, uint256 amount) internal {
        _burn(account, amount);
        _approve(account, _msgSender(), _allowances[account][_msgSender()].sub(amount, "ERC20: burn amount exceeds allowance"));
    }
}

contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for `name`, `symbol`, and `decimals`. All three of
     * these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }

    /**
     * @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.
     *
     * 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;
    }
}

library SafeMathUint {
    function toInt256Safe(uint256 a) internal pure returns (int256) {
        int256 b = int256(a);
        require(b >= 0);
        return b;
    }
}

library SafeMathInt {
    function mul(int256 a, int256 b) internal pure returns (int256) {
        // Prevent overflow when multiplying INT256_MIN with -1
        // https://github.com/RequestNetwork/requestNetwork/issues/43
        require(!(a == - 2 ** 255 && b == - 1) && !(b == - 2 ** 255 && a == - 1));

        int256 c = a * b;
        require((b == 0) || (c / b == a));
        return c;
    }

    function div(int256 a, int256 b) internal pure returns (int256) {
        // Prevent overflow when dividing INT256_MIN by -1
        // https://github.com/RequestNetwork/requestNetwork/issues/43
        require(!(a == - 2 ** 255 && b == - 1) && (b > 0));

        return a / b;
    }

    function sub(int256 a, int256 b) internal pure returns (int256) {
        require((b >= 0 && a - b <= a) || (b < 0 && a - b > a));

        return a - b;
    }

    function add(int256 a, int256 b) internal pure returns (int256) {
        int256 c = a + b;
        require((b >= 0 && c >= a) || (b < 0 && c < a));
        return c;
    }

    function toUint256Safe(int256 a) internal pure returns (uint256) {
        require(a >= 0);
        return uint256(a);
    }
}

interface IFundsDistributionToken {
    /**
     * @dev Returns the total amount of funds a given address is able to withdraw currently.
     * @param owner Address of FundsDistributionToken holder
     * @return A uint256 representing the available funds for a given account
     */
    function withdrawableFundsOf(address owner) external view returns (uint256);

    /**
     * @dev Withdraws all available funds for a FundsDistributionToken holder.
     */
    function withdrawFunds() external;

    /**
     * @dev This event emits when new funds are distributed
     * @param by the address of the sender who distributed funds
     * @param fundsDistributed the amount of funds received for distribution
     */
    event FundsDistributed(address indexed by, uint256 fundsDistributed);

    /**
     * @dev This event emits when distributed funds are withdrawn by a token holder.
     * @param by the address of the receiver of funds
     * @param fundsWithdrawn the amount of funds that were withdrawn
     */
    event FundsWithdrawn(address indexed by, uint256 fundsWithdrawn);
}

contract FundsDistributionToken is ERC20Detailed, ERC20, IFundsDistributionToken {
    using SafeMath for uint256;
    using SafeMathUint for uint256;
    using SafeMathInt for int256;

    // optimize, see https://github.com/ethereum/EIPs/issues/1726#issuecomment-472352728
    uint256 constant internal pointsMultiplier = 2 ** 128;
    uint256 internal pointsPerShare;

    mapping(address => int256) internal pointsCorrection;
    mapping(address => uint256) internal withdrawnFunds;

    /**
     * prev. distributeDividends
     * @notice Distributes funds to token holders.
     * @dev It reverts if the total supply of tokens is 0.
     * It emits the `FundsDistributed` event if the amount of received ether is greater than 0.
     * About undistributed funds:
     *   In each distribution, there is a small amount of funds which does not get distributed,
     *     which is `(msg.value * pointsMultiplier) % totalSupply()`.
     *   With a well-chosen `pointsMultiplier`, the amount funds that are not getting distributed
     *     in a distribution can be less than 1 (base unit).
     *   We can actually keep track of the undistributed ether in a distribution
     *     and try to distribute it in the next distribution ....... todo implement
     */
    function _distributeFunds(uint256 value) internal {
        require(totalSupply() > 0, "FundsDistributionToken._distributeFunds: SUPPLY_IS_ZERO");

        if (value > 0) {
            pointsPerShare = pointsPerShare.add(
                value.mul(pointsMultiplier) / totalSupply()
            );
            emit FundsDistributed(msg.sender, value);
        }
    }

    /**
     * prev. withdrawDividend
     * @notice Prepares funds withdrawal
     * @dev It emits a `FundsWithdrawn` event if the amount of withdrawn ether is greater than 0.
     */
    function _prepareWithdraw() internal returns (uint256) {
        uint256 _withdrawableDividend = withdrawableFundsOf(msg.sender);

        withdrawnFunds[msg.sender] = withdrawnFunds[msg.sender].add(_withdrawableDividend);

        emit FundsWithdrawn(msg.sender, _withdrawableDividend);

        return _withdrawableDividend;
    }

    /**
     * prev. withdrawableDividendOf
     * @notice View the amount of funds that an address can withdraw.
     * @param _owner The address of a token holder.
     * @return The amount funds that `_owner` can withdraw.
     */
    function withdrawableFundsOf(address _owner) public view returns (uint256) {
        return accumulativeFundsOf(_owner).sub(withdrawnFunds[_owner]);
    }

    /**
     * prev. withdrawnDividendOf
     * @notice View the amount of funds that an address has withdrawn.
     * @param _owner The address of a token holder.
     * @return The amount of funds that `_owner` has withdrawn.
     */
    function withdrawnFundsOf(address _owner) external view returns (uint256) {
        return withdrawnFunds[_owner];
    }

    /**
     * prev. accumulativeDividendOf
     * @notice View the amount of funds that an address has earned in total.
     * @dev accumulativeFundsOf(_owner) = withdrawableFundsOf(_owner) + withdrawnFundsOf(_owner)
     * = (pointsPerShare * balanceOf(_owner) + pointsCorrection[_owner]) / pointsMultiplier
     * @param _owner The address of a token holder.
     * @return The amount of funds that `_owner` has earned in total.
     */
    function accumulativeFundsOf(address _owner) public view returns (uint256) {
        return pointsPerShare.mul(balanceOf(_owner)).toInt256Safe()
        .add(pointsCorrection[_owner]).toUint256Safe() / pointsMultiplier;
    }

    /**
     * @dev Internal function that transfer tokens from one address to another.
     * Update pointsCorrection to keep funds unchanged.
     * @param from The address to transfer from.
     * @param to The address to transfer to.
     * @param value The amount to be transferred.
     */
    function _transfer(address from, address to, uint256 value) internal {
        super._transfer(from, to, value);

        int256 _magCorrection = pointsPerShare.mul(value).toInt256Safe();
        pointsCorrection[from] = pointsCorrection[from].add(_magCorrection);
        pointsCorrection[to] = pointsCorrection[to].sub(_magCorrection);
    }

    /**
     * @dev Internal function that mints tokens to an account.
     * Update pointsCorrection to keep funds unchanged.
     * @param account The account that will receive the created tokens.
     * @param value The amount that will be created.
     */
    function _mint(address account, uint256 value) internal {
        super._mint(account, value);

        pointsCorrection[account] = pointsCorrection[account]
        .sub((pointsPerShare.mul(value)).toInt256Safe());
    }
}

contract J2TD is FundsDistributionToken {
    using SafeMathUint for uint256;
    using SafeMathInt for int256;

    // balance of fundsToken that the FundsDistributionToken currently holds
    uint256 public fundsTokenBalance;

    constructor()public ERC20Detailed("J2TX Token Dividends", "J2TD", 18){
        _mint(msg.sender, 100000000 * 10 ** uint256(18));
    }

    /**
     * @notice Withdraws all available funds for a token holder
     */
    function withdrawFunds() external {
        uint256 withdrawableFunds = _prepareWithdraw();
        address payable to = msg.sender;
        to.transfer(withdrawableFunds);
        _updateFundsTokenBalance();
    }

    /**
     * @dev Updates the current funds token balance
     * and returns the difference of new and previous funds token balances
     * @return A int256 representing the difference of the new and previous funds token balance
     */
    function _updateFundsTokenBalance() internal returns (int256) {
        uint256 prevFundsTokenBalance = fundsTokenBalance;
        fundsTokenBalance = (address(this).balance);
        return int256(fundsTokenBalance).sub(int256(prevFundsTokenBalance));
    }

    /**
     * @notice Register a payment of funds in tokens. May be called directly after a deposit is made.
     * @dev Calls _updateFundsTokenBalance(), whereby the contract computes the delta of the previous and the new
     * funds token balance and increments the total received funds (cumulative) by delta by calling _registerFunds()
     */
    function updateFundsReceived() external {
        int256 newFunds = _updateFundsTokenBalance();

        if (newFunds > 0) {
            _distributeFunds(newFunds.toUint256Safe());
        }
    }

    /**
     * @notice  j2tx
     */
    function getTechInfo(address owner) external view returns (
        uint256 balance,
        int256 correction,
        uint256 withdrawn,
        uint256 withdrawable
    ){
        balance = balanceOf(owner);
        correction = pointsCorrection[owner];
        withdrawn = withdrawnFunds[owner];
        withdrawable = withdrawableFundsOf(owner);
    }

    /**
     * @notice Payable function, for receive funds.
     */
    function() external payable {}
}