pragma solidity 0.6.12;

// SPDX-License-Identifier: GPL-3.0-only

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.
     */
    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.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        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.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.

    struct Set {
        // Storage of set values
        bytes32[] _values;

        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping (bytes32 => uint256) _indexes;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) { // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;

            // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.

            bytes32 lastvalue = set._values[lastIndex];

            // Move the last value to the index where the value to delete is
            set._values[toDeleteIndex] = lastvalue;
            // Update the index for the moved value
            set._indexes[lastvalue] = toDeleteIndex + 1; // All indexes are 1-based

            // Delete the slot where the moved value was stored
            set._values.pop();

            // Delete the index for the deleted slot
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        require(set._values.length > index, "EnumerableSet: index out of bounds");
        return set._values[index];
    }

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(value)));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(value)));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(value)));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint256(_at(set._inner, index)));
    }


    // UintSet

    struct UintSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }
}

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);
            }
        }
    }
}

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;
    }
}

abstract contract AccessControl is Context {
    using EnumerableSet for EnumerableSet.AddressSet;
    using Address for address;

    struct RoleData {
        EnumerableSet.AddressSet members;
        bytes32 adminRole;
    }

    mapping (bytes32 => RoleData) private _roles;

    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     *
     * _Available since v3.1._
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);

    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view returns (bool) {
        return _roles[role].members.contains(account);
    }

    /**
     * @dev Returns the number of accounts that have `role`. Can be used
     * together with {getRoleMember} to enumerate all bearers of a role.
     */
    function getRoleMemberCount(bytes32 role) public view returns (uint256) {
        return _roles[role].members.length();
    }

    /**
     * @dev Returns one of the accounts that have `role`. `index` must be a
     * value between 0 and {getRoleMemberCount}, non-inclusive.
     *
     * Role bearers are not sorted in any particular way, and their ordering may
     * change at any point.
     *
     * WARNING: When using {getRoleMember} and {getRoleMemberCount}, make sure
     * you perform all queries on the same block. See the following
     * https://forum.openzeppelin.com/t/iterating-over-elements-on-enumerableset-in-openzeppelin-contracts/2296[forum post]
     * for more information.
     */
    function getRoleMember(bytes32 role, uint256 index) public view returns (address) {
        return _roles[role].members.at(index);
    }

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view returns (bytes32) {
        return _roles[role].adminRole;
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) public virtual {
        require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to grant");

        _grantRole(role, account);
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) public virtual {
        require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to revoke");

        _revokeRole(role, account);
    }

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) public virtual {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");

        _revokeRole(role, account);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     */
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }

    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     *
     * Emits a {RoleAdminChanged} event.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        emit RoleAdminChanged(role, _roles[role].adminRole, adminRole);
        _roles[role].adminRole = adminRole;
    }

    function _grantRole(bytes32 role, address account) private {
        if (_roles[role].members.add(account)) {
            emit RoleGranted(role, account, _msgSender());
        }
    }

    function _revokeRole(bytes32 role, address account) private {
        if (_roles[role].members.remove(account)) {
            emit RoleRevoked(role, account, _msgSender());
        }
    }
}

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);
}

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 { }
}

abstract contract ERC20Burnable is Context, ERC20 {
    /**
     * @dev Destroys `amount` tokens from the caller.
     *
     * See {ERC20-_burn}.
     */
    function burn(uint256 amount) public virtual {
        _burn(_msgSender(), amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, deducting from the caller's
     * allowance.
     *
     * See {ERC20-_burn} and {ERC20-allowance}.
     *
     * Requirements:
     *
     * - the caller must have allowance for ``accounts``'s tokens of at least
     * `amount`.
     */
    function burnFrom(address account, uint256 amount) public virtual {
        uint256 decreasedAllowance = allowance(account, _msgSender()).sub(amount, "ERC20: burn amount exceeds allowance");

        _approve(account, _msgSender(), decreasedAllowance);
        _burn(account, amount);
    }
}

contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor () internal {
        _paused = false;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        require(!_paused, "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        require(_paused, "Pausable: not paused");
        _;
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

abstract contract ERC20Pausable is ERC20, Pausable {
    /**
     * @dev See {ERC20-_beforeTokenTransfer}.
     *
     * Requirements:
     *
     * - the contract must not be paused.
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override {
        super._beforeTokenTransfer(from, to, amount);

        require(!paused(), "ERC20Pausable: token transfer while paused");
    }
}

contract ERC20PresetMinterPauser is Context, AccessControl, ERC20Burnable, ERC20Pausable {
    bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
    bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");

    /**
     * @dev Grants `DEFAULT_ADMIN_ROLE`, `MINTER_ROLE` and `PAUSER_ROLE` to the
     * account that deploys the contract.
     *
     * See {ERC20-constructor}.
     */
    constructor(string memory name, string memory symbol) public ERC20(name, symbol) {
        _setupRole(DEFAULT_ADMIN_ROLE, _msgSender());

        _setupRole(MINTER_ROLE, _msgSender());
        _setupRole(PAUSER_ROLE, _msgSender());
    }

    /**
     * @dev Creates `amount` new tokens for `to`.
     *
     * See {ERC20-_mint}.
     *
     * Requirements:
     *
     * - the caller must have the `MINTER_ROLE`.
     */
    function mint(address to, uint256 amount) public virtual {
        require(hasRole(MINTER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have minter role to mint");
        _mint(to, amount);
    }

    /**
     * @dev Pauses all token transfers.
     *
     * See {ERC20Pausable} and {Pausable-_pause}.
     *
     * Requirements:
     *
     * - the caller must have the `PAUSER_ROLE`.
     */
    function pause() public virtual {
        require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to pause");
        _pause();
    }

    /**
     * @dev Unpauses all token transfers.
     *
     * See {ERC20Pausable} and {Pausable-_unpause}.
     *
     * Requirements:
     *
     * - the caller must have the `PAUSER_ROLE`.
     */
    function unpause() public virtual {
        require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to unpause");
        _unpause();
    }

    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override(ERC20, ERC20Pausable) {
        super._beforeTokenTransfer(from, to, amount);
    }
}

interface IRETHToken {
    function getEthValue(uint256 _rethAmount) external view returns (uint256);
    function getRethValue(uint256 _ethAmount) external view returns (uint256);
    function getExchangeRate() external view returns (uint256);
    function getTotalCollateral() external view returns (uint256);
    function getCollateralRate() external view returns (uint256);
    function depositRewards() external payable;
    function depositExcess() external payable;
    function userMint(uint256 _ethAmount, address _to) external;
    function userBurn(uint256 _rethAmount) external;
}

interface IStafiNetworkBalances {
    function getBalancesBlock() external view returns (uint256);
    function getTotalETHBalance() external view returns (uint256);
    function getStakingETHBalance() external view returns (uint256);
    function getTotalRETHSupply() external view returns (uint256);
    function getETHStakingRate() external view returns (uint256);
    function submitBalances(uint256 _block, uint256 _total, uint256 _staking, uint256 _rethSupply) external;
}

interface IStafiUserDeposit {
    function getBalance() external view returns (uint256);
    function getExcessBalance() external view returns (uint256);
    function deposit() external payable;
    function recycleDissolvedDeposit() external payable;
    function recycleWithdrawnDeposit() external payable;
    function assignDeposits() external;
    function withdrawExcessBalance(uint256 _amount) external;
}

interface IStafiStorage {

    // Getters
    function getAddress(bytes32 _key) external view returns (address);
    function getUint(bytes32 _key) external view returns (uint);
    function getString(bytes32 _key) external view returns (string memory);
    function getBytes(bytes32 _key) external view returns (bytes memory);
    function getBool(bytes32 _key) external view returns (bool);
    function getInt(bytes32 _key) external view returns (int);
    function getBytes32(bytes32 _key) external view returns (bytes32);

    // Setters
    function setAddress(bytes32 _key, address _value) external;
    function setUint(bytes32 _key, uint _value) external;
    function setString(bytes32 _key, string calldata _value) external;
    function setBytes(bytes32 _key, bytes calldata _value) external;
    function setBool(bytes32 _key, bool _value) external;
    function setInt(bytes32 _key, int _value) external;
    function setBytes32(bytes32 _key, bytes32 _value) external;

    // Deleters
    function deleteAddress(bytes32 _key) external;
    function deleteUint(bytes32 _key) external;
    function deleteString(bytes32 _key) external;
    function deleteBytes(bytes32 _key) external;
    function deleteBool(bytes32 _key) external;
    function deleteInt(bytes32 _key) external;
    function deleteBytes32(bytes32 _key) external;

}


abstract contract StafiBase {

    // Version of the contract
    uint8 public version;

    // The main storage contract where primary persistant storage is maintained
    IStafiStorage stafiStorage = IStafiStorage(0);


    /**
    * @dev Throws if called by any sender that doesn't match a network contract
    */
    modifier onlyLatestNetworkContract() {
        require(getBool(keccak256(abi.encodePacked("contract.exists", msg.sender))), "Invalid or outdated network contract");
        _;
    }


    /**
    * @dev Throws if called by any sender that doesn't match one of the supplied contract or is the latest version of that contract
    */
    modifier onlyLatestContract(string memory _contractName, address _contractAddress) {
        require(_contractAddress == getAddress(keccak256(abi.encodePacked("contract.address", _contractName))), "Invalid or outdated contract");
        _;
    }


    /**
    * @dev Throws if called by any sender that isn't a trusted node
    */
    modifier onlyTrustedNode(address _nodeAddress) {
        require(getBool(keccak256(abi.encodePacked("node.trusted", _nodeAddress))), "Invalid trusted node");
        _;
    }


    /**
    * @dev Throws if called by any sender that isn't a registered staking pool
    */
    modifier onlyRegisteredStakingPool(address _stakingPoolAddress) {
        require(getBool(keccak256(abi.encodePacked("stakingpool.exists", _stakingPoolAddress))), "Invalid staking pool");
        _;
    }


    /**
    * @dev Throws if called by any account other than the owner.
    */
    modifier onlyOwner() {
        require(roleHas("owner", msg.sender), "Account is not the owner");
        _;
    }


    /**
    * @dev Modifier to scope access to admins
    */
    modifier onlyAdmin() {
        require(roleHas("admin", msg.sender), "Account is not an admin");
        _;
    }


    /**
    * @dev Modifier to scope access to admins
    */
    modifier onlySuperUser() {
        require(roleHas("owner", msg.sender) || roleHas("admin", msg.sender), "Account is not a super user");
        _;
    }


    /**
    * @dev Reverts if the address doesn't have this role
    */
    modifier onlyRole(string memory _role) {
        require(roleHas(_role, msg.sender), "Account does not match the specified role");
        _;
    }


    /// @dev Set the main Storage address
    constructor(address _stafiStorageAddress) public {
        // Update the contract address
        stafiStorage = IStafiStorage(_stafiStorageAddress);
    }


    /// @dev Get the address of a network contract by name
    function getContractAddress(string memory _contractName) internal view returns (address) {
        // Get the current contract address
        address contractAddress = getAddress(keccak256(abi.encodePacked("contract.address", _contractName)));
        // Check it
        require(contractAddress != address(0x0), "Contract not found");
        // Return
        return contractAddress;
    }


    /// @dev Get the name of a network contract by address
    function getContractName(address _contractAddress) internal view returns (string memory) {
        // Get the contract name
        string memory contractName = getString(keccak256(abi.encodePacked("contract.name", _contractAddress)));
        // Check it
        require(keccak256(abi.encodePacked(contractName)) != keccak256(abi.encodePacked("")), "Contract not found");
        // Return
        return contractName;
    }


    /// @dev Storage get methods
    function getAddress(bytes32 _key) internal view returns (address) { return stafiStorage.getAddress(_key); }
    function getUint(bytes32 _key) internal view returns (uint256) { return stafiStorage.getUint(_key); }
    function getString(bytes32 _key) internal view returns (string memory) { return stafiStorage.getString(_key); }
    function getBytes(bytes32 _key) internal view returns (bytes memory) { return stafiStorage.getBytes(_key); }
    function getBool(bytes32 _key) internal view returns (bool) { return stafiStorage.getBool(_key); }
    function getInt(bytes32 _key) internal view returns (int256) { return stafiStorage.getInt(_key); }
    function getBytes32(bytes32 _key) internal view returns (bytes32) { return stafiStorage.getBytes32(_key); }
    function getAddressS(string memory _key) internal view returns (address) { return stafiStorage.getAddress(keccak256(abi.encodePacked(_key))); }
    function getUintS(string memory _key) internal view returns (uint256) { return stafiStorage.getUint(keccak256(abi.encodePacked(_key))); }
    function getStringS(string memory _key) internal view returns (string memory) { return stafiStorage.getString(keccak256(abi.encodePacked(_key))); }
    function getBytesS(string memory _key) internal view returns (bytes memory) { return stafiStorage.getBytes(keccak256(abi.encodePacked(_key))); }
    function getBoolS(string memory _key) internal view returns (bool) { return stafiStorage.getBool(keccak256(abi.encodePacked(_key))); }
    function getIntS(string memory _key) internal view returns (int256) { return stafiStorage.getInt(keccak256(abi.encodePacked(_key))); }
    function getBytes32S(string memory _key) internal view returns (bytes32) { return stafiStorage.getBytes32(keccak256(abi.encodePacked(_key))); }

    /// @dev Storage set methods
    function setAddress(bytes32 _key, address _value) internal { stafiStorage.setAddress(_key, _value); }
    function setUint(bytes32 _key, uint256 _value) internal { stafiStorage.setUint(_key, _value); }
    function setString(bytes32 _key, string memory _value) internal { stafiStorage.setString(_key, _value); }
    function setBytes(bytes32 _key, bytes memory _value) internal { stafiStorage.setBytes(_key, _value); }
    function setBool(bytes32 _key, bool _value) internal { stafiStorage.setBool(_key, _value); }
    function setInt(bytes32 _key, int256 _value) internal { stafiStorage.setInt(_key, _value); }
    function setBytes32(bytes32 _key, bytes32 _value) internal { stafiStorage.setBytes32(_key, _value); }
    function setAddressS(string memory _key, address _value) internal { stafiStorage.setAddress(keccak256(abi.encodePacked(_key)), _value); }
    function setUintS(string memory _key, uint256 _value) internal { stafiStorage.setUint(keccak256(abi.encodePacked(_key)), _value); }
    function setStringS(string memory _key, string memory _value) internal { stafiStorage.setString(keccak256(abi.encodePacked(_key)), _value); }
    function setBytesS(string memory _key, bytes memory _value) internal { stafiStorage.setBytes(keccak256(abi.encodePacked(_key)), _value); }
    function setBoolS(string memory _key, bool _value) internal { stafiStorage.setBool(keccak256(abi.encodePacked(_key)), _value); }
    function setIntS(string memory _key, int256 _value) internal { stafiStorage.setInt(keccak256(abi.encodePacked(_key)), _value); }
    function setBytes32S(string memory _key, bytes32 _value) internal { stafiStorage.setBytes32(keccak256(abi.encodePacked(_key)), _value); }

    /// @dev Storage delete methods
    function deleteAddress(bytes32 _key) internal { stafiStorage.deleteAddress(_key); }
    function deleteUint(bytes32 _key) internal { stafiStorage.deleteUint(_key); }
    function deleteString(bytes32 _key) internal { stafiStorage.deleteString(_key); }
    function deleteBytes(bytes32 _key) internal { stafiStorage.deleteBytes(_key); }
    function deleteBool(bytes32 _key) internal { stafiStorage.deleteBool(_key); }
    function deleteInt(bytes32 _key) internal { stafiStorage.deleteInt(_key); }
    function deleteBytes32(bytes32 _key) internal { stafiStorage.deleteBytes32(_key); }
    function deleteAddressS(string memory _key) internal { stafiStorage.deleteAddress(keccak256(abi.encodePacked(_key))); }
    function deleteUintS(string memory _key) internal { stafiStorage.deleteUint(keccak256(abi.encodePacked(_key))); }
    function deleteStringS(string memory _key) internal { stafiStorage.deleteString(keccak256(abi.encodePacked(_key))); }
    function deleteBytesS(string memory _key) internal { stafiStorage.deleteBytes(keccak256(abi.encodePacked(_key))); }
    function deleteBoolS(string memory _key) internal { stafiStorage.deleteBool(keccak256(abi.encodePacked(_key))); }
    function deleteIntS(string memory _key) internal { stafiStorage.deleteInt(keccak256(abi.encodePacked(_key))); }
    function deleteBytes32S(string memory _key) internal { stafiStorage.deleteBytes32(keccak256(abi.encodePacked(_key))); }


    /**
    * @dev Check if an address has this role
    */
    function roleHas(string memory _role, address _address) internal view returns (bool) {
        return getBool(keccak256(abi.encodePacked("access.role", _role, _address)));
    }

}

// rETH is backed by ETH (subject to liquidity) at a variable exchange rate
contract RETHToken is StafiBase, ERC20PresetMinterPauser, IRETHToken {

    // Libs
    using SafeMath for uint256;

    // Events
    event EtherDeposited(address indexed from, uint256 amount, uint256 time);
    event TokensMinted(address indexed to, uint256 amount, uint256 ethAmount, uint256 time);
    event TokensBurned(address indexed from, uint256 amount, uint256 ethAmount, uint256 time);

    // Construct
    constructor(address _stafiStorageAddress) StafiBase(_stafiStorageAddress) ERC20PresetMinterPauser("StaFi", "rETH") public {
        version = 1;
        // Migrate from the old contract to the new contract
        _mint(address(0xB61959B37AADFF714Af150580559858483459b8E), 24132334000000000000);
        _mint(address(0xa7DeBb68F2684074Ec4354B68E36C34AF363Fd57), 1500000000000000000);
        _mint(address(0xBABf7e6b5bcE0BD749FD3C527374bEf8919cC7A9), 10000000000000000);
    }

    // Calculate the amount of ETH backing an amount of rETH
    function getEthValue(uint256 _rethAmount) override public view returns (uint256) {
        // Get network balances
        IStafiNetworkBalances stafiNetworkBalances = IStafiNetworkBalances(getContractAddress("stafiNetworkBalances"));
        uint256 totalEthBalance = stafiNetworkBalances.getTotalETHBalance();
        uint256 rethSupply = stafiNetworkBalances.getTotalRETHSupply();
        // Use 1:1 ratio if no rETH is minted
        if (rethSupply == 0) { return _rethAmount; }
        // Calculate and return
        return _rethAmount.mul(totalEthBalance).div(rethSupply);
    }

    // Calculate the amount of rETH backed by an amount of ETH
    function getRethValue(uint256 _ethAmount) override public view returns (uint256) {
        // Get network balances
        IStafiNetworkBalances stafiNetworkBalances = IStafiNetworkBalances(getContractAddress("stafiNetworkBalances"));
        uint256 totalEthBalance = stafiNetworkBalances.getTotalETHBalance();
        uint256 rethSupply = stafiNetworkBalances.getTotalRETHSupply();
        // Use 1:1 ratio if no rETH is minted
        if (rethSupply == 0) { return _ethAmount; }
        // Check network ETH balance
        require(totalEthBalance > 0, "Cannot calculate rETH token amount while total network balance is zero");
        // Calculate and return
        return _ethAmount.mul(rethSupply).div(totalEthBalance);
    }

    // Get the current ETH : rETH exchange rate
    // Returns the amount of ETH backing 1 rETH
    function getExchangeRate() override public view returns (uint256) {
        return getEthValue(1 ether);
    }

    // Get the total amount of collateral available
    // Includes rETH contract balance & excess deposit pool balance
    function getTotalCollateral() override public view returns (uint256) {
        IStafiUserDeposit stafiUserDeposit = IStafiUserDeposit(getContractAddress("stafiUserDeposit"));
        return stafiUserDeposit.getExcessBalance().add(address(this).balance);
    }

    // Get the current ETH collateral rate
    // Returns the portion of rETH backed by ETH in the contract as a fraction of 1 ether
    function getCollateralRate() override public view returns (uint256) {
        uint256 calcBase = 1 ether;
        uint256 totalEthValue = getEthValue(totalSupply());
        if (totalEthValue == 0) { return calcBase; }
        return calcBase.mul(address(this).balance).div(totalEthValue);
    }

    // Deposit ETH rewards
    // Only accepts calls from the StafiNetworkWithdrawal contract
    function depositRewards() override external payable onlyLatestContract("stafiNetworkWithdrawal", msg.sender) {
        // Emit ether deposited event
        emit EtherDeposited(msg.sender, msg.value, now);
    }

    // Deposit excess ETH from deposit pool
    // Only accepts calls from the StafiUserDeposit contract
    function depositExcess() override external payable onlyLatestContract("stafiUserDeposit", msg.sender) {
        // Emit ether deposited event
        emit EtherDeposited(msg.sender, msg.value, now);
    }

    // Mint rETH
    // Only accepts calls from the StafiUserDeposit contract
    function userMint(uint256 _ethAmount, address _to) override external onlyLatestContract("stafiUserDeposit", msg.sender) {
        // Get rETH amount
        uint256 rethAmount = getRethValue(_ethAmount);
        // Check rETH amount
        require(rethAmount > 0, "Invalid token mint amount");

        // Update balance & supply
        _mint(_to, rethAmount);
        // Emit tokens minted event
        emit TokensMinted(_to, rethAmount, _ethAmount, now);
    }

    // Burn rETH for ETH
    function userBurn(uint256 _rethAmount) override external {
        // Check deposit settings
        require(getBurnEnabled(), "Burn is currently disabled");
        // Check rETH amount
        require(_rethAmount > 0, "Invalid token burn amount");
        require(balanceOf(msg.sender) >= _rethAmount, "Insufficient rETH balance");
        // Get ETH amount
        uint256 ethAmount = getEthValue(_rethAmount);
        // Get & check ETH balance
        uint256 ethBalance = getTotalCollateral();
        require(ethBalance >= ethAmount, "Insufficient ETH balance for exchange");
        // Update balance & supply
        _burn(msg.sender, _rethAmount);
        // Withdraw ETH from deposit pool if required
        withdrawDepositCollateral(ethAmount);
        // Transfer ETH to sender
        msg.sender.transfer(ethAmount);
        // Emit tokens burned event
        emit TokensBurned(msg.sender, _rethAmount, ethAmount, now);
    }

    // Withdraw ETH from the deposit pool for collateral if required
    function withdrawDepositCollateral(uint256 _ethRequired) private {
        // Check rETH contract balance
        uint256 ethBalance = address(this).balance;
        if (ethBalance >= _ethRequired) { return; }
        // Withdraw
        IStafiUserDeposit stafiUserDeposit = IStafiUserDeposit(getContractAddress("stafiUserDeposit"));
        stafiUserDeposit.withdrawExcessBalance(_ethRequired.sub(ethBalance));
    }

    // Burn currently enabled
    function getBurnEnabled() public view returns (bool) {
        return getBoolS("settings.reth.burn.enabled");
    }
    
    function setBurnEnabled(bool _value) public onlySuperUser {
        setBoolS("settings.reth.burn.enabled", _value);
    }

}

{
  "compilationTarget": {
    "RETHToken.sol": "RETHToken"
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}