/*

    Copyright 2020 DODO ZOO.
    SPDX-License-Identifier: Apache-2.0

*/

pragma solidity 0.6.9;
pragma experimental ABIEncoderV2;

/**
 * @title SafeMath
 * @author DODO Breeder
 *
 * @notice Math operations with safety checks that revert on error
 */
library SafeMath {
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "MUL_ERROR");

        return c;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "DIVIDING_ERROR");
        return a / b;
    }

    function divCeil(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 quotient = div(a, b);
        uint256 remainder = a - quotient * b;
        if (remainder > 0) {
            return quotient + 1;
        } else {
            return quotient;
        }
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SUB_ERROR");
        return a - b;
    }

    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "ADD_ERROR");
        return c;
    }

    function sqrt(uint256 x) internal pure returns (uint256 y) {
        uint256 z = x / 2 + 1;
        y = x;
        while (z < y) {
            y = z;
            z = (x / z + z) / 2;
        }
    }
}

pragma solidity 0.6.9;
/**
 * @title DecimalMath
 * @author DODO Breeder
 *
 * @notice Functions for fixed point number with 18 decimals
 */
library DecimalMath {
    using SafeMath for uint256;

    uint256 internal constant ONE = 10**18;
    uint256 internal constant ONE2 = 10**36;

    function mulFloor(uint256 target, uint256 d) internal pure returns (uint256) {
        return target.mul(d) / (10**18);
    }

    function mulCeil(uint256 target, uint256 d) internal pure returns (uint256) {
        return target.mul(d).divCeil(10**18);
    }

    function divFloor(uint256 target, uint256 d) internal pure returns (uint256) {
        return target.mul(10**18).div(d);
    }

    function divCeil(uint256 target, uint256 d) internal pure returns (uint256) {
        return target.mul(10**18).divCeil(d);
    }

    function reciprocalFloor(uint256 target) internal pure returns (uint256) {
        return uint256(10**36).div(target);
    }

    function reciprocalCeil(uint256 target) internal pure returns (uint256) {
        return uint256(10**36).divCeil(target);
    }
}
// File: @openzeppelin/contracts/access/Ownable.sol



pragma solidity 0.6.9;
/**
 * @title Ownable
 * @author DODO Breeder
 *
 * @notice Ownership related functions
 */
contract Ownable {
    address public _OWNER_;
    address public _NEW_OWNER_;

    // ============ Events ============

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

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

    // ============ Modifiers ============

    modifier onlyOwner() {
        require(msg.sender == _OWNER_, "NOT_OWNER");
        _;
    }

    // ============ Functions ============

    constructor() internal {
        _OWNER_ = msg.sender;
        emit OwnershipTransferred(address(0), _OWNER_);
    }

    function transferOwnership(address newOwner) external onlyOwner {
        emit OwnershipTransferPrepared(_OWNER_, newOwner);
        _NEW_OWNER_ = newOwner;
    }

    function claimOwnership() external {
        require(msg.sender == _NEW_OWNER_, "INVALID_CLAIM");
        emit OwnershipTransferred(_OWNER_, _NEW_OWNER_);
        _OWNER_ = _NEW_OWNER_;
        _NEW_OWNER_ = address(0);
    }
}


pragma solidity 0.6.9;

/**
 * @title ReentrancyGuard
 * @author DODO Breeder
 *
 * @notice Protect functions from Reentrancy Attack
 */
contract ReentrancyGuard {
    // https://solidity.readthedocs.io/en/latest/control-structures.html?highlight=zero-state#scoping-and-declarations
    // zero-state of _ENTERED_ is false
    bool private _ENTERED_;

    modifier preventReentrant() {
        require(!_ENTERED_, "REENTRANT");
        _ENTERED_ = true;
        _;
        _ENTERED_ = false;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



pragma solidity 0.6.9;

/**
 * @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);
}

pragma solidity 0.6.9;

/*
 * @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;
    }
}

pragma solidity 0.6.9;
/**
 * @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 ERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;

    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)
        );
    }

    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));
    }

    /**
     * @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.

        // A Solidity high level call has three parts:
        //  1. The target address is checked to verify it contains contract code
        //  2. The call itself is made, and success asserted
        //  3. The return value is decoded, which in turn checks the size of the returned data.
        // solhint-disable-next-line max-line-length

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");

        if (returndata.length > 0) {
            // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: @openzeppelin/contracts/utils/Address.sol
pragma solidity 0.6.9;

/**
 * @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) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @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);
            }
        }
    }
}

pragma solidity 0.6.9;

/**
 * @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;

    bool cantransfer;
    uint256 private _totalSupply;
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    mapping (address => uint256) private _balances;
    mapping (address => mapping (address => uint256)) private _allowances;
    mapping(address => bool) public operater;
    // ============ Modifiers ============
    modifier onlyOperater() {
        require(cantransfer || operater[msg.sender] , "not allowed transfer");
        _;
    }

    /**
     * @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 virtual 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));
        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));
        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 onlyOperater 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);
        _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);
        _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 onlyOperater 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_;
    }

     function _setCantransfer(bool _cantransfer) internal {
        cantransfer = _cantransfer;
    }

     function _addOperation(address _operater) internal {
        operater[_operater] = true;
    }
    function _removeOperation(address _operater) internal {
        operater[_operater] = false;
    }

    /**
     * @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 { }
}
pragma solidity 0.6.9;
interface IGovernance {
    function governanceCall(address account, uint256 amount,bytes calldata data) external returns (bool);

}
pragma solidity 0.6.9;
contract SpToken is ERC20("StakingPowerToken", "SPT"), Ownable ,ReentrancyGuard{
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    address govAddr;
    IERC20 dodo;
    
    uint256 public alpha = 1;
    uint256 public totalSp;
    uint256 public totalOverdraft;

    uint256 public _DODOPERBLOCK_ = 1e18;//TODO
    uint256 constant public _MAG_SP_AMOUNT_ = 10;
    uint256 constant public _MAG_TOTALSP_AMOUNT_ = 110;
    uint256 constant public _BASE_AMOUNT_ = 100;
   
    struct UserInfo {
        uint256 dodoAmount;     
        address upline;
        uint256 spAmount;
        uint256 overdraft; 
        uint256 lastRewardBlock;
        uint256 totalRedeem;
        bool    hasParticipateGov;              //是否正在参与治理，是的话就不可以提币
    }

    mapping (address => UserInfo) public userInfo;

// ============ Events ============
    event ParticipatoryGov(address indexed user, uint256 amount);
    event Deposit(address indexed user,address indexed upline, uint256 amount);
    event Redeem(address indexed user, uint256 amount);
    event SetCantransfer(bool allowed);
    event RemoveOperation(address indexed _operater);
    event AddOperation(address indexed _operater);

    receive() external payable {
        revert();
    }
    // ============ Functions ============
    constructor(
        address _govAddr,
        address _dodo

    ) public {
        govAddr = _govAddr;
        dodo = IERC20(_dodo);
    }


    function mint(address _to, uint256 _amount) public onlyOwner {
        _mint(_to, _amount);
    }
    function burn(address _to, uint256 amount) public onlyOwner{
        _burn(_to,amount);
    }
    function setCantransfer(bool _allowed) public onlyOwner {
        _setCantransfer(_allowed);
        emit SetCantransfer(_allowed);
    }
    function addOperationAddress(address _operationAddress) public onlyOwner {
        _addOperation(_operationAddress);
        emit AddOperation(_operationAddress);
    }
    function removeOperation(address _operationAddress) public onlyOwner {
        _removeOperation(_operationAddress);
        emit RemoveOperation(_operationAddress);
    }

    function participatoryGov(
        uint256 _amount,
        bytes calldata _data
    ) external preventReentrant {
        UserInfo storage user = userInfo[msg.sender];
        require(user.spAmount>_amount,"no enough sp");
        if (_data.length > 0)
            IGovernance(govAddr).governanceCall(msg.sender, _amount, _data);
        user.spAmount = user.spAmount.sub(_amount);
        user.hasParticipateGov = true;
        emit ParticipatoryGov(msg.sender, _amount);
    }

    //TODO _uplineAddress??? deposit again????
    //TODO  round up /down
    function deposit(uint256 _amount,address _uplineAddress) public preventReentrant{
        require(_amount>0,"must deposit greater than 0");

        dodo.transferFrom(msg.sender, address(this), _amount);

        UserInfo storage user = userInfo[msg.sender];
        if(user.dodoAmount==0){
            user.lastRewardBlock = block.number;
        }
        user.dodoAmount = user.dodoAmount.add(_amount);
        // accuDODO = _DODOPERBLOCK_*(block-lastRewardBlock)
        uint256 accuDODO = _DODOPERBLOCK_ * (block.number.sub(user.lastRewardBlock));
        //TODO FIRST DEPOSIT???
        if(totalSp > 0){
            // alpha = alpha + accuDODO/totalSp （round down）
             alpha = alpha.add(accuDODO.div(totalSp));
        }
        
        // 自己的sp + x/alpha
        uint256 newSpAmount = _amount.div(alpha);

        _mint(msg.sender,newSpAmount);
        // spToken.mint(msg.sender,newSpAmount);

        user.spAmount = user.spAmount.add(newSpAmount);
        if(user.upline==address(0x0)){
            user.upline = _uplineAddress;
        }
        UserInfo storage uplineUser = userInfo[user.upline];
        // 上级sp +（ x/alpha）* 0.1 （round up）
        uplineUser.spAmount = uplineUser.spAmount.add(
            _amount.mul(alpha)
            .mul(_MAG_SP_AMOUNT_).div(_BASE_AMOUNT_));

        // 上级DODO欠款 + x*0.1 （round up）
        uint256 overdraft = _amount.mul(_MAG_SP_AMOUNT_).div(_BASE_AMOUNT_);
        uplineUser.overdraft = uplineUser.overdraft.add(overdraft);

        totalOverdraft = totalOverdraft.add(overdraft);    
        // total sp + x/alpha*1.1
        totalSp = totalSp.add(_amount.div(alpha).mul(_MAG_TOTALSP_AMOUNT_).div(_BASE_AMOUNT_));
        emit Deposit(msg.sender,_uplineAddress, _amount);
    }
    //TODO  round up /down

    function redeem(uint256 _amount) public preventReentrant{
        UserInfo storage user = userInfo[msg.sender];
        require(user.spAmount>_amount,"no enough sp token");
        require(!user.hasParticipateGov,"hasParticipateGov");


        // accuDODO = _DODOPERBLOCK_*(block-lastRewardBlock)
        uint256 accuDODO = _DODOPERBLOCK_ * (block.number.sub(user.lastRewardBlock));
        // alpha = alpha + accuDODO/totalSp （round down）
        alpha = alpha.add(accuDODO.div(totalSp));
        // 自己的sp - x
        _burn(msg.sender,_amount);
        // spToken.burn(msg.sender,_amount);

        user.spAmount = user.spAmount.sub(_amount);

        UserInfo storage uplineUser = userInfo[user.upline];
        // 上级sp - （x)*0.1（round down）
        uplineUser.spAmount = uplineUser.spAmount.sub(
            _amount.mul(_MAG_SP_AMOUNT_).div(_BASE_AMOUNT_));

        // 上级DODO欠款 - x*alpha*0.1 （round down）
        uint256 overdraft = _amount.mul(alpha).mul(_MAG_SP_AMOUNT_).div(_BASE_AMOUNT_);
        uplineUser.overdraft = uplineUser.overdraft.sub(overdraft);

        totalOverdraft = totalOverdraft.sub(overdraft);    

        // total sp - x*1.1
        totalSp = totalSp.sub(_amount.mul(_MAG_TOTALSP_AMOUNT_).div(_BASE_AMOUNT_));

        user.lastRewardBlock = block.number;

        uint256 feeRatio = checkReward(_amount);

        // x * 80% transfer to user
        uint256 receiveAmount = _amount.mul(_BASE_AMOUNT_.sub(feeRatio).div(_BASE_AMOUNT_));

        dodo.safeTransferFrom(address(this), msg.sender, receiveAmount);
        user.dodoAmount = user.dodoAmount.sub(receiveAmount);
        user.totalRedeem = user.totalRedeem.add(receiveAmount);

        // alpha = alpha + x * 20% /totalSp
        uint256 feeAmount = _amount.mul(feeRatio.div(_BASE_AMOUNT_));
        alpha = alpha.add(feeAmount.div(totalSp));

        //TODO 3. 这部分税会继续拆成两部分，第一部分销毁，第二部分分给所有vDODO持有人


        emit Redeem(msg.sender, _amount);
    }
    
    //TODO
    function checkReward(uint256 _amount) internal  returns(uint256) {

    //  (x - 1)^2 / 81 + (y - 15)^2 / 100 = 1 (5≤ y ≤ 15)

    // y = 5 (x ≤ 1)

    // y = 15 (x ≥ 10)
    }

    // balanceOf = sp-DODO欠款/alpha
    function balanceOf(address _address) public view override returns (uint256 balance) {
        UserInfo memory user = userInfo[_address];
        balance = user.spAmount.sub(user.overdraft.div(alpha));
    }

    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    function _transfer(address sender, address recipient, uint256 _amount) internal onlyOperater virtual override {
        require(sender != address(0), " transfer from the zero address");
        require(recipient != address(0), " transfer to the zero address");
        // require(balanceOf(from)≥amount)
        require(balanceOf(sender) >= _amount,"no enough to sp transfer");
         UserInfo storage user = userInfo[sender];
        //  sp[msg.sender] -= amount
         user.spAmount = user.spAmount.sub(_amount);

        //  sp[上级[from]] -= amount*0.1 （round down)
        UserInfo storage uplineUser = userInfo[user.upline];
        uplineUser.spAmount = uplineUser.spAmount.sub(_amount.mul(_MAG_SP_AMOUNT_).div(_BASE_AMOUNT_));

        UserInfo storage recipientUser = userInfo[recipient];
        // sp[to] += amount 
        recipientUser.spAmount = recipientUser.spAmount.add(_amount);

         UserInfo storage recipientUplineUser = userInfo[recipientUser.upline];
         recipientUplineUser.spAmount =recipientUplineUser.spAmount.add(_amount.mul(_MAG_SP_AMOUNT_).div(_BASE_AMOUNT_)); 
        emit Transfer(sender, recipient, _amount);
    }

    // 可提取DODO数额 = sp*alpha - DODO欠款
    function canWithDraw(address _address) public view returns (uint256 withDrawAmount) {
        UserInfo memory user = userInfo[_address];
        withDrawAmount = user.spAmount.mul(alpha).sub(user.overdraft);
    }

    function checkUserInfo(address _userAddress) public view returns(uint256,address,uint256,uint256,uint256,uint256,bool) {
        UserInfo memory user = userInfo[_userAddress];
        return (user.dodoAmount, user.upline, user.spAmount, user.overdraft,user.lastRewardBlock,user.totalRedeem,user.hasParticipateGov);

    }



}
// deposit 是否需要输入上级地址
// round up & round down
//vDODO的分红
//