// File: @openzeppelin/contracts-upgradeable/utils/math/MathUpgradeable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/math/Math.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library MathUpgradeable {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow.
        return (a & b) + (a ^ b) / 2;
    }

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a / b + (a % b == 0 ? 0 : 1);
    }
}

// File: @openzeppelin/contracts-upgradeable/utils/math/SafeCastUpgradeable.sol



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

pragma solidity ^0.8.0;

/**
 * @dev Wrappers over Solidity's uintXX/intXX casting operators with added overflow
 * checks.
 *
 * Downcasting from uint256/int256 in Solidity does not revert on overflow. This can
 * easily result in undesired exploitation or bugs, since developers usually
 * assume that overflows raise errors. `SafeCast` restores this intuition by
 * reverting the transaction when such an operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 *
 * Can be combined with {SafeMath} and {SignedSafeMath} to extend it to smaller types, by performing
 * all math on `uint256` and `int256` and then downcasting.
 */
library SafeCastUpgradeable {
    /**
     * @dev Returns the downcasted uint224 from uint256, reverting on
     * overflow (when the input is greater than largest uint224).
     *
     * Counterpart to Solidity's `uint224` operator.
     *
     * Requirements:
     *
     * - input must fit into 224 bits
     */
    function toUint224(uint256 value) internal pure returns (uint224) {
        require(value <= type(uint224).max, "SafeCast: value doesn't fit in 224 bits");
        return uint224(value);
    }

    /**
     * @dev Returns the downcasted uint128 from uint256, reverting on
     * overflow (when the input is greater than largest uint128).
     *
     * Counterpart to Solidity's `uint128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     */
    function toUint128(uint256 value) internal pure returns (uint128) {
        require(value <= type(uint128).max, "SafeCast: value doesn't fit in 128 bits");
        return uint128(value);
    }

    /**
     * @dev Returns the downcasted uint96 from uint256, reverting on
     * overflow (when the input is greater than largest uint96).
     *
     * Counterpart to Solidity's `uint96` operator.
     *
     * Requirements:
     *
     * - input must fit into 96 bits
     */
    function toUint96(uint256 value) internal pure returns (uint96) {
        require(value <= type(uint96).max, "SafeCast: value doesn't fit in 96 bits");
        return uint96(value);
    }

    /**
     * @dev Returns the downcasted uint64 from uint256, reverting on
     * overflow (when the input is greater than largest uint64).
     *
     * Counterpart to Solidity's `uint64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     */
    function toUint64(uint256 value) internal pure returns (uint64) {
        require(value <= type(uint64).max, "SafeCast: value doesn't fit in 64 bits");
        return uint64(value);
    }

    /**
     * @dev Returns the downcasted uint32 from uint256, reverting on
     * overflow (when the input is greater than largest uint32).
     *
     * Counterpart to Solidity's `uint32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     */
    function toUint32(uint256 value) internal pure returns (uint32) {
        require(value <= type(uint32).max, "SafeCast: value doesn't fit in 32 bits");
        return uint32(value);
    }

    /**
     * @dev Returns the downcasted uint16 from uint256, reverting on
     * overflow (when the input is greater than largest uint16).
     *
     * Counterpart to Solidity's `uint16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     */
    function toUint16(uint256 value) internal pure returns (uint16) {
        require(value <= type(uint16).max, "SafeCast: value doesn't fit in 16 bits");
        return uint16(value);
    }

    /**
     * @dev Returns the downcasted uint8 from uint256, reverting on
     * overflow (when the input is greater than largest uint8).
     *
     * Counterpart to Solidity's `uint8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits.
     */
    function toUint8(uint256 value) internal pure returns (uint8) {
        require(value <= type(uint8).max, "SafeCast: value doesn't fit in 8 bits");
        return uint8(value);
    }

    /**
     * @dev Converts a signed int256 into an unsigned uint256.
     *
     * Requirements:
     *
     * - input must be greater than or equal to 0.
     */
    function toUint256(int256 value) internal pure returns (uint256) {
        require(value >= 0, "SafeCast: value must be positive");
        return uint256(value);
    }

    /**
     * @dev Returns the downcasted int128 from int256, reverting on
     * overflow (when the input is less than smallest int128 or
     * greater than largest int128).
     *
     * Counterpart to Solidity's `int128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     *
     * _Available since v3.1._
     */
    function toInt128(int256 value) internal pure returns (int128) {
        require(value >= type(int128).min && value <= type(int128).max, "SafeCast: value doesn't fit in 128 bits");
        return int128(value);
    }

    /**
     * @dev Returns the downcasted int64 from int256, reverting on
     * overflow (when the input is less than smallest int64 or
     * greater than largest int64).
     *
     * Counterpart to Solidity's `int64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     *
     * _Available since v3.1._
     */
    function toInt64(int256 value) internal pure returns (int64) {
        require(value >= type(int64).min && value <= type(int64).max, "SafeCast: value doesn't fit in 64 bits");
        return int64(value);
    }

    /**
     * @dev Returns the downcasted int32 from int256, reverting on
     * overflow (when the input is less than smallest int32 or
     * greater than largest int32).
     *
     * Counterpart to Solidity's `int32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     *
     * _Available since v3.1._
     */
    function toInt32(int256 value) internal pure returns (int32) {
        require(value >= type(int32).min && value <= type(int32).max, "SafeCast: value doesn't fit in 32 bits");
        return int32(value);
    }

    /**
     * @dev Returns the downcasted int16 from int256, reverting on
     * overflow (when the input is less than smallest int16 or
     * greater than largest int16).
     *
     * Counterpart to Solidity's `int16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     *
     * _Available since v3.1._
     */
    function toInt16(int256 value) internal pure returns (int16) {
        require(value >= type(int16).min && value <= type(int16).max, "SafeCast: value doesn't fit in 16 bits");
        return int16(value);
    }

    /**
     * @dev Returns the downcasted int8 from int256, reverting on
     * overflow (when the input is less than smallest int8 or
     * greater than largest int8).
     *
     * Counterpart to Solidity's `int8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits.
     *
     * _Available since v3.1._
     */
    function toInt8(int256 value) internal pure returns (int8) {
        require(value >= type(int8).min && value <= type(int8).max, "SafeCast: value doesn't fit in 8 bits");
        return int8(value);
    }

    /**
     * @dev Converts an unsigned uint256 into a signed int256.
     *
     * Requirements:
     *
     * - input must be less than or equal to maxInt256.
     */
    function toInt256(uint256 value) internal pure returns (int256) {
        // Note: Unsafe cast below is okay because `type(int256).max` is guaranteed to be positive
        require(value <= uint256(type(int256).max), "SafeCast: value doesn't fit in an int256");
        return int256(value);
    }
}

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



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

pragma solidity ^0.8.0;

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

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

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

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

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

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

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

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

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

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

// File: @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

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

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

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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);

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

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



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

pragma solidity ^0.8.0;

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

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

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/SafeCast.sol)
// This file was procedurally generated from scripts/generate/templates/SafeCast.js.

pragma solidity ^0.8.0;

/**
 * @dev Wrappers over Solidity's uintXX/intXX casting operators with added overflow
 * checks.
 *
 * Downcasting from uint256/int256 in Solidity does not revert on overflow. This can
 * easily result in undesired exploitation or bugs, since developers usually
 * assume that overflows raise errors. `SafeCast` restores this intuition by
 * reverting the transaction when such an operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 *
 * Can be combined with {SafeMath} and {SignedSafeMath} to extend it to smaller types, by performing
 * all math on `uint256` and `int256` and then downcasting.
 */
library SafeCast {
    /**
     * @dev Returns the downcasted uint248 from uint256, reverting on
     * overflow (when the input is greater than largest uint248).
     *
     * Counterpart to Solidity's `uint248` operator.
     *
     * Requirements:
     *
     * - input must fit into 248 bits
     *
     * _Available since v4.7._
     */
    function toUint248(uint256 value) internal pure returns (uint248) {
        require(value <= type(uint248).max, "SafeCast: value doesn't fit in 248 bits");
        return uint248(value);
    }

    /**
     * @dev Returns the downcasted uint240 from uint256, reverting on
     * overflow (when the input is greater than largest uint240).
     *
     * Counterpart to Solidity's `uint240` operator.
     *
     * Requirements:
     *
     * - input must fit into 240 bits
     *
     * _Available since v4.7._
     */
    function toUint240(uint256 value) internal pure returns (uint240) {
        require(value <= type(uint240).max, "SafeCast: value doesn't fit in 240 bits");
        return uint240(value);
    }

    /**
     * @dev Returns the downcasted uint232 from uint256, reverting on
     * overflow (when the input is greater than largest uint232).
     *
     * Counterpart to Solidity's `uint232` operator.
     *
     * Requirements:
     *
     * - input must fit into 232 bits
     *
     * _Available since v4.7._
     */
    function toUint232(uint256 value) internal pure returns (uint232) {
        require(value <= type(uint232).max, "SafeCast: value doesn't fit in 232 bits");
        return uint232(value);
    }

    /**
     * @dev Returns the downcasted uint224 from uint256, reverting on
     * overflow (when the input is greater than largest uint224).
     *
     * Counterpart to Solidity's `uint224` operator.
     *
     * Requirements:
     *
     * - input must fit into 224 bits
     *
     * _Available since v4.2._
     */
    function toUint224(uint256 value) internal pure returns (uint224) {
        require(value <= type(uint224).max, "SafeCast: value doesn't fit in 224 bits");
        return uint224(value);
    }

    /**
     * @dev Returns the downcasted uint216 from uint256, reverting on
     * overflow (when the input is greater than largest uint216).
     *
     * Counterpart to Solidity's `uint216` operator.
     *
     * Requirements:
     *
     * - input must fit into 216 bits
     *
     * _Available since v4.7._
     */
    function toUint216(uint256 value) internal pure returns (uint216) {
        require(value <= type(uint216).max, "SafeCast: value doesn't fit in 216 bits");
        return uint216(value);
    }

    /**
     * @dev Returns the downcasted uint208 from uint256, reverting on
     * overflow (when the input is greater than largest uint208).
     *
     * Counterpart to Solidity's `uint208` operator.
     *
     * Requirements:
     *
     * - input must fit into 208 bits
     *
     * _Available since v4.7._
     */
    function toUint208(uint256 value) internal pure returns (uint208) {
        require(value <= type(uint208).max, "SafeCast: value doesn't fit in 208 bits");
        return uint208(value);
    }

    /**
     * @dev Returns the downcasted uint200 from uint256, reverting on
     * overflow (when the input is greater than largest uint200).
     *
     * Counterpart to Solidity's `uint200` operator.
     *
     * Requirements:
     *
     * - input must fit into 200 bits
     *
     * _Available since v4.7._
     */
    function toUint200(uint256 value) internal pure returns (uint200) {
        require(value <= type(uint200).max, "SafeCast: value doesn't fit in 200 bits");
        return uint200(value);
    }

    /**
     * @dev Returns the downcasted uint192 from uint256, reverting on
     * overflow (when the input is greater than largest uint192).
     *
     * Counterpart to Solidity's `uint192` operator.
     *
     * Requirements:
     *
     * - input must fit into 192 bits
     *
     * _Available since v4.7._
     */
    function toUint192(uint256 value) internal pure returns (uint192) {
        require(value <= type(uint192).max, "SafeCast: value doesn't fit in 192 bits");
        return uint192(value);
    }

    /**
     * @dev Returns the downcasted uint184 from uint256, reverting on
     * overflow (when the input is greater than largest uint184).
     *
     * Counterpart to Solidity's `uint184` operator.
     *
     * Requirements:
     *
     * - input must fit into 184 bits
     *
     * _Available since v4.7._
     */
    function toUint184(uint256 value) internal pure returns (uint184) {
        require(value <= type(uint184).max, "SafeCast: value doesn't fit in 184 bits");
        return uint184(value);
    }

    /**
     * @dev Returns the downcasted uint176 from uint256, reverting on
     * overflow (when the input is greater than largest uint176).
     *
     * Counterpart to Solidity's `uint176` operator.
     *
     * Requirements:
     *
     * - input must fit into 176 bits
     *
     * _Available since v4.7._
     */
    function toUint176(uint256 value) internal pure returns (uint176) {
        require(value <= type(uint176).max, "SafeCast: value doesn't fit in 176 bits");
        return uint176(value);
    }

    /**
     * @dev Returns the downcasted uint168 from uint256, reverting on
     * overflow (when the input is greater than largest uint168).
     *
     * Counterpart to Solidity's `uint168` operator.
     *
     * Requirements:
     *
     * - input must fit into 168 bits
     *
     * _Available since v4.7._
     */
    function toUint168(uint256 value) internal pure returns (uint168) {
        require(value <= type(uint168).max, "SafeCast: value doesn't fit in 168 bits");
        return uint168(value);
    }

    /**
     * @dev Returns the downcasted uint160 from uint256, reverting on
     * overflow (when the input is greater than largest uint160).
     *
     * Counterpart to Solidity's `uint160` operator.
     *
     * Requirements:
     *
     * - input must fit into 160 bits
     *
     * _Available since v4.7._
     */
    function toUint160(uint256 value) internal pure returns (uint160) {
        require(value <= type(uint160).max, "SafeCast: value doesn't fit in 160 bits");
        return uint160(value);
    }

    /**
     * @dev Returns the downcasted uint152 from uint256, reverting on
     * overflow (when the input is greater than largest uint152).
     *
     * Counterpart to Solidity's `uint152` operator.
     *
     * Requirements:
     *
     * - input must fit into 152 bits
     *
     * _Available since v4.7._
     */
    function toUint152(uint256 value) internal pure returns (uint152) {
        require(value <= type(uint152).max, "SafeCast: value doesn't fit in 152 bits");
        return uint152(value);
    }

    /**
     * @dev Returns the downcasted uint144 from uint256, reverting on
     * overflow (when the input is greater than largest uint144).
     *
     * Counterpart to Solidity's `uint144` operator.
     *
     * Requirements:
     *
     * - input must fit into 144 bits
     *
     * _Available since v4.7._
     */
    function toUint144(uint256 value) internal pure returns (uint144) {
        require(value <= type(uint144).max, "SafeCast: value doesn't fit in 144 bits");
        return uint144(value);
    }

    /**
     * @dev Returns the downcasted uint136 from uint256, reverting on
     * overflow (when the input is greater than largest uint136).
     *
     * Counterpart to Solidity's `uint136` operator.
     *
     * Requirements:
     *
     * - input must fit into 136 bits
     *
     * _Available since v4.7._
     */
    function toUint136(uint256 value) internal pure returns (uint136) {
        require(value <= type(uint136).max, "SafeCast: value doesn't fit in 136 bits");
        return uint136(value);
    }

    /**
     * @dev Returns the downcasted uint128 from uint256, reverting on
     * overflow (when the input is greater than largest uint128).
     *
     * Counterpart to Solidity's `uint128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     *
     * _Available since v2.5._
     */
    function toUint128(uint256 value) internal pure returns (uint128) {
        require(value <= type(uint128).max, "SafeCast: value doesn't fit in 128 bits");
        return uint128(value);
    }

    /**
     * @dev Returns the downcasted uint120 from uint256, reverting on
     * overflow (when the input is greater than largest uint120).
     *
     * Counterpart to Solidity's `uint120` operator.
     *
     * Requirements:
     *
     * - input must fit into 120 bits
     *
     * _Available since v4.7._
     */
    function toUint120(uint256 value) internal pure returns (uint120) {
        require(value <= type(uint120).max, "SafeCast: value doesn't fit in 120 bits");
        return uint120(value);
    }

    /**
     * @dev Returns the downcasted uint112 from uint256, reverting on
     * overflow (when the input is greater than largest uint112).
     *
     * Counterpart to Solidity's `uint112` operator.
     *
     * Requirements:
     *
     * - input must fit into 112 bits
     *
     * _Available since v4.7._
     */
    function toUint112(uint256 value) internal pure returns (uint112) {
        require(value <= type(uint112).max, "SafeCast: value doesn't fit in 112 bits");
        return uint112(value);
    }

    /**
     * @dev Returns the downcasted uint104 from uint256, reverting on
     * overflow (when the input is greater than largest uint104).
     *
     * Counterpart to Solidity's `uint104` operator.
     *
     * Requirements:
     *
     * - input must fit into 104 bits
     *
     * _Available since v4.7._
     */
    function toUint104(uint256 value) internal pure returns (uint104) {
        require(value <= type(uint104).max, "SafeCast: value doesn't fit in 104 bits");
        return uint104(value);
    }

    /**
     * @dev Returns the downcasted uint96 from uint256, reverting on
     * overflow (when the input is greater than largest uint96).
     *
     * Counterpart to Solidity's `uint96` operator.
     *
     * Requirements:
     *
     * - input must fit into 96 bits
     *
     * _Available since v4.2._
     */
    function toUint96(uint256 value) internal pure returns (uint96) {
        require(value <= type(uint96).max, "SafeCast: value doesn't fit in 96 bits");
        return uint96(value);
    }

    /**
     * @dev Returns the downcasted uint88 from uint256, reverting on
     * overflow (when the input is greater than largest uint88).
     *
     * Counterpart to Solidity's `uint88` operator.
     *
     * Requirements:
     *
     * - input must fit into 88 bits
     *
     * _Available since v4.7._
     */
    function toUint88(uint256 value) internal pure returns (uint88) {
        require(value <= type(uint88).max, "SafeCast: value doesn't fit in 88 bits");
        return uint88(value);
    }

    /**
     * @dev Returns the downcasted uint80 from uint256, reverting on
     * overflow (when the input is greater than largest uint80).
     *
     * Counterpart to Solidity's `uint80` operator.
     *
     * Requirements:
     *
     * - input must fit into 80 bits
     *
     * _Available since v4.7._
     */
    function toUint80(uint256 value) internal pure returns (uint80) {
        require(value <= type(uint80).max, "SafeCast: value doesn't fit in 80 bits");
        return uint80(value);
    }

    /**
     * @dev Returns the downcasted uint72 from uint256, reverting on
     * overflow (when the input is greater than largest uint72).
     *
     * Counterpart to Solidity's `uint72` operator.
     *
     * Requirements:
     *
     * - input must fit into 72 bits
     *
     * _Available since v4.7._
     */
    function toUint72(uint256 value) internal pure returns (uint72) {
        require(value <= type(uint72).max, "SafeCast: value doesn't fit in 72 bits");
        return uint72(value);
    }

    /**
     * @dev Returns the downcasted uint64 from uint256, reverting on
     * overflow (when the input is greater than largest uint64).
     *
     * Counterpart to Solidity's `uint64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     *
     * _Available since v2.5._
     */
    function toUint64(uint256 value) internal pure returns (uint64) {
        require(value <= type(uint64).max, "SafeCast: value doesn't fit in 64 bits");
        return uint64(value);
    }

    /**
     * @dev Returns the downcasted uint56 from uint256, reverting on
     * overflow (when the input is greater than largest uint56).
     *
     * Counterpart to Solidity's `uint56` operator.
     *
     * Requirements:
     *
     * - input must fit into 56 bits
     *
     * _Available since v4.7._
     */
    function toUint56(uint256 value) internal pure returns (uint56) {
        require(value <= type(uint56).max, "SafeCast: value doesn't fit in 56 bits");
        return uint56(value);
    }

    /**
     * @dev Returns the downcasted uint48 from uint256, reverting on
     * overflow (when the input is greater than largest uint48).
     *
     * Counterpart to Solidity's `uint48` operator.
     *
     * Requirements:
     *
     * - input must fit into 48 bits
     *
     * _Available since v4.7._
     */
    function toUint48(uint256 value) internal pure returns (uint48) {
        require(value <= type(uint48).max, "SafeCast: value doesn't fit in 48 bits");
        return uint48(value);
    }

    /**
     * @dev Returns the downcasted uint40 from uint256, reverting on
     * overflow (when the input is greater than largest uint40).
     *
     * Counterpart to Solidity's `uint40` operator.
     *
     * Requirements:
     *
     * - input must fit into 40 bits
     *
     * _Available since v4.7._
     */
    function toUint40(uint256 value) internal pure returns (uint40) {
        require(value <= type(uint40).max, "SafeCast: value doesn't fit in 40 bits");
        return uint40(value);
    }

    /**
     * @dev Returns the downcasted uint32 from uint256, reverting on
     * overflow (when the input is greater than largest uint32).
     *
     * Counterpart to Solidity's `uint32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     *
     * _Available since v2.5._
     */
    function toUint32(uint256 value) internal pure returns (uint32) {
        require(value <= type(uint32).max, "SafeCast: value doesn't fit in 32 bits");
        return uint32(value);
    }

    /**
     * @dev Returns the downcasted uint24 from uint256, reverting on
     * overflow (when the input is greater than largest uint24).
     *
     * Counterpart to Solidity's `uint24` operator.
     *
     * Requirements:
     *
     * - input must fit into 24 bits
     *
     * _Available since v4.7._
     */
    function toUint24(uint256 value) internal pure returns (uint24) {
        require(value <= type(uint24).max, "SafeCast: value doesn't fit in 24 bits");
        return uint24(value);
    }

    /**
     * @dev Returns the downcasted uint16 from uint256, reverting on
     * overflow (when the input is greater than largest uint16).
     *
     * Counterpart to Solidity's `uint16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     *
     * _Available since v2.5._
     */
    function toUint16(uint256 value) internal pure returns (uint16) {
        require(value <= type(uint16).max, "SafeCast: value doesn't fit in 16 bits");
        return uint16(value);
    }

    /**
     * @dev Returns the downcasted uint8 from uint256, reverting on
     * overflow (when the input is greater than largest uint8).
     *
     * Counterpart to Solidity's `uint8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits
     *
     * _Available since v2.5._
     */
    function toUint8(uint256 value) internal pure returns (uint8) {
        require(value <= type(uint8).max, "SafeCast: value doesn't fit in 8 bits");
        return uint8(value);
    }

    /**
     * @dev Converts a signed int256 into an unsigned uint256.
     *
     * Requirements:
     *
     * - input must be greater than or equal to 0.
     *
     * _Available since v3.0._
     */
    function toUint256(int256 value) internal pure returns (uint256) {
        require(value >= 0, "SafeCast: value must be positive");
        return uint256(value);
    }

    /**
     * @dev Returns the downcasted int248 from int256, reverting on
     * overflow (when the input is less than smallest int248 or
     * greater than largest int248).
     *
     * Counterpart to Solidity's `int248` operator.
     *
     * Requirements:
     *
     * - input must fit into 248 bits
     *
     * _Available since v4.7._
     */
    function toInt248(int256 value) internal pure returns (int248 downcasted) {
        downcasted = int248(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 248 bits");
    }

    /**
     * @dev Returns the downcasted int240 from int256, reverting on
     * overflow (when the input is less than smallest int240 or
     * greater than largest int240).
     *
     * Counterpart to Solidity's `int240` operator.
     *
     * Requirements:
     *
     * - input must fit into 240 bits
     *
     * _Available since v4.7._
     */
    function toInt240(int256 value) internal pure returns (int240 downcasted) {
        downcasted = int240(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 240 bits");
    }

    /**
     * @dev Returns the downcasted int232 from int256, reverting on
     * overflow (when the input is less than smallest int232 or
     * greater than largest int232).
     *
     * Counterpart to Solidity's `int232` operator.
     *
     * Requirements:
     *
     * - input must fit into 232 bits
     *
     * _Available since v4.7._
     */
    function toInt232(int256 value) internal pure returns (int232 downcasted) {
        downcasted = int232(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 232 bits");
    }

    /**
     * @dev Returns the downcasted int224 from int256, reverting on
     * overflow (when the input is less than smallest int224 or
     * greater than largest int224).
     *
     * Counterpart to Solidity's `int224` operator.
     *
     * Requirements:
     *
     * - input must fit into 224 bits
     *
     * _Available since v4.7._
     */
    function toInt224(int256 value) internal pure returns (int224 downcasted) {
        downcasted = int224(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 224 bits");
    }

    /**
     * @dev Returns the downcasted int216 from int256, reverting on
     * overflow (when the input is less than smallest int216 or
     * greater than largest int216).
     *
     * Counterpart to Solidity's `int216` operator.
     *
     * Requirements:
     *
     * - input must fit into 216 bits
     *
     * _Available since v4.7._
     */
    function toInt216(int256 value) internal pure returns (int216 downcasted) {
        downcasted = int216(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 216 bits");
    }

    /**
     * @dev Returns the downcasted int208 from int256, reverting on
     * overflow (when the input is less than smallest int208 or
     * greater than largest int208).
     *
     * Counterpart to Solidity's `int208` operator.
     *
     * Requirements:
     *
     * - input must fit into 208 bits
     *
     * _Available since v4.7._
     */
    function toInt208(int256 value) internal pure returns (int208 downcasted) {
        downcasted = int208(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 208 bits");
    }

    /**
     * @dev Returns the downcasted int200 from int256, reverting on
     * overflow (when the input is less than smallest int200 or
     * greater than largest int200).
     *
     * Counterpart to Solidity's `int200` operator.
     *
     * Requirements:
     *
     * - input must fit into 200 bits
     *
     * _Available since v4.7._
     */
    function toInt200(int256 value) internal pure returns (int200 downcasted) {
        downcasted = int200(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 200 bits");
    }

    /**
     * @dev Returns the downcasted int192 from int256, reverting on
     * overflow (when the input is less than smallest int192 or
     * greater than largest int192).
     *
     * Counterpart to Solidity's `int192` operator.
     *
     * Requirements:
     *
     * - input must fit into 192 bits
     *
     * _Available since v4.7._
     */
    function toInt192(int256 value) internal pure returns (int192 downcasted) {
        downcasted = int192(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 192 bits");
    }

    /**
     * @dev Returns the downcasted int184 from int256, reverting on
     * overflow (when the input is less than smallest int184 or
     * greater than largest int184).
     *
     * Counterpart to Solidity's `int184` operator.
     *
     * Requirements:
     *
     * - input must fit into 184 bits
     *
     * _Available since v4.7._
     */
    function toInt184(int256 value) internal pure returns (int184 downcasted) {
        downcasted = int184(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 184 bits");
    }

    /**
     * @dev Returns the downcasted int176 from int256, reverting on
     * overflow (when the input is less than smallest int176 or
     * greater than largest int176).
     *
     * Counterpart to Solidity's `int176` operator.
     *
     * Requirements:
     *
     * - input must fit into 176 bits
     *
     * _Available since v4.7._
     */
    function toInt176(int256 value) internal pure returns (int176 downcasted) {
        downcasted = int176(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 176 bits");
    }

    /**
     * @dev Returns the downcasted int168 from int256, reverting on
     * overflow (when the input is less than smallest int168 or
     * greater than largest int168).
     *
     * Counterpart to Solidity's `int168` operator.
     *
     * Requirements:
     *
     * - input must fit into 168 bits
     *
     * _Available since v4.7._
     */
    function toInt168(int256 value) internal pure returns (int168 downcasted) {
        downcasted = int168(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 168 bits");
    }

    /**
     * @dev Returns the downcasted int160 from int256, reverting on
     * overflow (when the input is less than smallest int160 or
     * greater than largest int160).
     *
     * Counterpart to Solidity's `int160` operator.
     *
     * Requirements:
     *
     * - input must fit into 160 bits
     *
     * _Available since v4.7._
     */
    function toInt160(int256 value) internal pure returns (int160 downcasted) {
        downcasted = int160(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 160 bits");
    }

    /**
     * @dev Returns the downcasted int152 from int256, reverting on
     * overflow (when the input is less than smallest int152 or
     * greater than largest int152).
     *
     * Counterpart to Solidity's `int152` operator.
     *
     * Requirements:
     *
     * - input must fit into 152 bits
     *
     * _Available since v4.7._
     */
    function toInt152(int256 value) internal pure returns (int152 downcasted) {
        downcasted = int152(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 152 bits");
    }

    /**
     * @dev Returns the downcasted int144 from int256, reverting on
     * overflow (when the input is less than smallest int144 or
     * greater than largest int144).
     *
     * Counterpart to Solidity's `int144` operator.
     *
     * Requirements:
     *
     * - input must fit into 144 bits
     *
     * _Available since v4.7._
     */
    function toInt144(int256 value) internal pure returns (int144 downcasted) {
        downcasted = int144(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 144 bits");
    }

    /**
     * @dev Returns the downcasted int136 from int256, reverting on
     * overflow (when the input is less than smallest int136 or
     * greater than largest int136).
     *
     * Counterpart to Solidity's `int136` operator.
     *
     * Requirements:
     *
     * - input must fit into 136 bits
     *
     * _Available since v4.7._
     */
    function toInt136(int256 value) internal pure returns (int136 downcasted) {
        downcasted = int136(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 136 bits");
    }

    /**
     * @dev Returns the downcasted int128 from int256, reverting on
     * overflow (when the input is less than smallest int128 or
     * greater than largest int128).
     *
     * Counterpart to Solidity's `int128` operator.
     *
     * Requirements:
     *
     * - input must fit into 128 bits
     *
     * _Available since v3.1._
     */
    function toInt128(int256 value) internal pure returns (int128 downcasted) {
        downcasted = int128(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 128 bits");
    }

    /**
     * @dev Returns the downcasted int120 from int256, reverting on
     * overflow (when the input is less than smallest int120 or
     * greater than largest int120).
     *
     * Counterpart to Solidity's `int120` operator.
     *
     * Requirements:
     *
     * - input must fit into 120 bits
     *
     * _Available since v4.7._
     */
    function toInt120(int256 value) internal pure returns (int120 downcasted) {
        downcasted = int120(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 120 bits");
    }

    /**
     * @dev Returns the downcasted int112 from int256, reverting on
     * overflow (when the input is less than smallest int112 or
     * greater than largest int112).
     *
     * Counterpart to Solidity's `int112` operator.
     *
     * Requirements:
     *
     * - input must fit into 112 bits
     *
     * _Available since v4.7._
     */
    function toInt112(int256 value) internal pure returns (int112 downcasted) {
        downcasted = int112(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 112 bits");
    }

    /**
     * @dev Returns the downcasted int104 from int256, reverting on
     * overflow (when the input is less than smallest int104 or
     * greater than largest int104).
     *
     * Counterpart to Solidity's `int104` operator.
     *
     * Requirements:
     *
     * - input must fit into 104 bits
     *
     * _Available since v4.7._
     */
    function toInt104(int256 value) internal pure returns (int104 downcasted) {
        downcasted = int104(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 104 bits");
    }

    /**
     * @dev Returns the downcasted int96 from int256, reverting on
     * overflow (when the input is less than smallest int96 or
     * greater than largest int96).
     *
     * Counterpart to Solidity's `int96` operator.
     *
     * Requirements:
     *
     * - input must fit into 96 bits
     *
     * _Available since v4.7._
     */
    function toInt96(int256 value) internal pure returns (int96 downcasted) {
        downcasted = int96(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 96 bits");
    }

    /**
     * @dev Returns the downcasted int88 from int256, reverting on
     * overflow (when the input is less than smallest int88 or
     * greater than largest int88).
     *
     * Counterpart to Solidity's `int88` operator.
     *
     * Requirements:
     *
     * - input must fit into 88 bits
     *
     * _Available since v4.7._
     */
    function toInt88(int256 value) internal pure returns (int88 downcasted) {
        downcasted = int88(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 88 bits");
    }

    /**
     * @dev Returns the downcasted int80 from int256, reverting on
     * overflow (when the input is less than smallest int80 or
     * greater than largest int80).
     *
     * Counterpart to Solidity's `int80` operator.
     *
     * Requirements:
     *
     * - input must fit into 80 bits
     *
     * _Available since v4.7._
     */
    function toInt80(int256 value) internal pure returns (int80 downcasted) {
        downcasted = int80(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 80 bits");
    }

    /**
     * @dev Returns the downcasted int72 from int256, reverting on
     * overflow (when the input is less than smallest int72 or
     * greater than largest int72).
     *
     * Counterpart to Solidity's `int72` operator.
     *
     * Requirements:
     *
     * - input must fit into 72 bits
     *
     * _Available since v4.7._
     */
    function toInt72(int256 value) internal pure returns (int72 downcasted) {
        downcasted = int72(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 72 bits");
    }

    /**
     * @dev Returns the downcasted int64 from int256, reverting on
     * overflow (when the input is less than smallest int64 or
     * greater than largest int64).
     *
     * Counterpart to Solidity's `int64` operator.
     *
     * Requirements:
     *
     * - input must fit into 64 bits
     *
     * _Available since v3.1._
     */
    function toInt64(int256 value) internal pure returns (int64 downcasted) {
        downcasted = int64(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 64 bits");
    }

    /**
     * @dev Returns the downcasted int56 from int256, reverting on
     * overflow (when the input is less than smallest int56 or
     * greater than largest int56).
     *
     * Counterpart to Solidity's `int56` operator.
     *
     * Requirements:
     *
     * - input must fit into 56 bits
     *
     * _Available since v4.7._
     */
    function toInt56(int256 value) internal pure returns (int56 downcasted) {
        downcasted = int56(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 56 bits");
    }

    /**
     * @dev Returns the downcasted int48 from int256, reverting on
     * overflow (when the input is less than smallest int48 or
     * greater than largest int48).
     *
     * Counterpart to Solidity's `int48` operator.
     *
     * Requirements:
     *
     * - input must fit into 48 bits
     *
     * _Available since v4.7._
     */
    function toInt48(int256 value) internal pure returns (int48 downcasted) {
        downcasted = int48(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 48 bits");
    }

    /**
     * @dev Returns the downcasted int40 from int256, reverting on
     * overflow (when the input is less than smallest int40 or
     * greater than largest int40).
     *
     * Counterpart to Solidity's `int40` operator.
     *
     * Requirements:
     *
     * - input must fit into 40 bits
     *
     * _Available since v4.7._
     */
    function toInt40(int256 value) internal pure returns (int40 downcasted) {
        downcasted = int40(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 40 bits");
    }

    /**
     * @dev Returns the downcasted int32 from int256, reverting on
     * overflow (when the input is less than smallest int32 or
     * greater than largest int32).
     *
     * Counterpart to Solidity's `int32` operator.
     *
     * Requirements:
     *
     * - input must fit into 32 bits
     *
     * _Available since v3.1._
     */
    function toInt32(int256 value) internal pure returns (int32 downcasted) {
        downcasted = int32(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 32 bits");
    }

    /**
     * @dev Returns the downcasted int24 from int256, reverting on
     * overflow (when the input is less than smallest int24 or
     * greater than largest int24).
     *
     * Counterpart to Solidity's `int24` operator.
     *
     * Requirements:
     *
     * - input must fit into 24 bits
     *
     * _Available since v4.7._
     */
    function toInt24(int256 value) internal pure returns (int24 downcasted) {
        downcasted = int24(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 24 bits");
    }

    /**
     * @dev Returns the downcasted int16 from int256, reverting on
     * overflow (when the input is less than smallest int16 or
     * greater than largest int16).
     *
     * Counterpart to Solidity's `int16` operator.
     *
     * Requirements:
     *
     * - input must fit into 16 bits
     *
     * _Available since v3.1._
     */
    function toInt16(int256 value) internal pure returns (int16 downcasted) {
        downcasted = int16(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 16 bits");
    }

    /**
     * @dev Returns the downcasted int8 from int256, reverting on
     * overflow (when the input is less than smallest int8 or
     * greater than largest int8).
     *
     * Counterpart to Solidity's `int8` operator.
     *
     * Requirements:
     *
     * - input must fit into 8 bits
     *
     * _Available since v3.1._
     */
    function toInt8(int256 value) internal pure returns (int8 downcasted) {
        downcasted = int8(value);
        require(downcasted == value, "SafeCast: value doesn't fit in 8 bits");
    }

    /**
     * @dev Converts an unsigned uint256 into a signed int256.
     *
     * Requirements:
     *
     * - input must be less than or equal to maxInt256.
     *
     * _Available since v3.0._
     */
    function toInt256(uint256 value) internal pure returns (int256) {
        // Note: Unsafe cast below is okay because `type(int256).max` is guaranteed to be positive
        require(value <= uint256(type(int256).max), "SafeCast: value doesn't fit in an int256");
        return int256(value);
    }
}

// File: @thesis/solidity-contracts/contracts/token/ERC20WithPermit.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

import "@openzeppelin/contracts/access/Ownable.sol";

import "./IERC20WithPermit.sol";
import "./IReceiveApproval.sol";

/// @title  ERC20WithPermit
/// @notice Burnable ERC20 token with EIP2612 permit functionality. User can
///         authorize a transfer of their token with a signature conforming
///         EIP712 standard instead of an on-chain transaction from their
///         address. Anyone can submit this signature on the user's behalf by
///         calling the permit function, as specified in EIP2612 standard,
///         paying gas fees, and possibly performing other actions in the same
///         transaction.
contract ERC20WithPermit is IERC20WithPermit, Ownable {
    /// @notice The amount of tokens owned by the given account.
    mapping(address => uint256) public override balanceOf;

    /// @notice The remaining number of tokens that spender will be
    ///         allowed to spend on behalf of owner through `transferFrom` and
    ///         `burnFrom`. This is zero by default.
    mapping(address => mapping(address => uint256)) public override allowance;

    /// @notice Returns the current nonce for EIP2612 permission for the
    ///         provided token owner for a replay protection. Used to construct
    ///         EIP2612 signature provided to `permit` function.
    mapping(address => uint256) public override nonce;

    uint256 public immutable cachedChainId;
    bytes32 public immutable cachedDomainSeparator;

    /// @notice Returns EIP2612 Permit message hash. Used to construct EIP2612
    ///         signature provided to `permit` function.
    bytes32 public constant override PERMIT_TYPEHASH =
        keccak256(
            "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
        );

    /// @notice The amount of tokens in existence.
    uint256 public override totalSupply;

    /// @notice The name of the token.
    string public override name;

    /// @notice The symbol of the token.
    string public override symbol;

    /// @notice The decimals places of the token.
    uint8 public constant override decimals = 18;

    constructor(string memory _name, string memory _symbol) {
        name = _name;
        symbol = _symbol;

        cachedChainId = block.chainid;
        cachedDomainSeparator = buildDomainSeparator();
    }

    /// @notice Moves `amount` tokens from the caller's account to `recipient`.
    /// @return True if the operation succeeded, reverts otherwise.
    /// @dev Requirements:
    ///       - `recipient` cannot be the zero address,
    ///       - the caller must have a balance of at least `amount`.
    function transfer(address recipient, uint256 amount)
        external
        override
        returns (bool)
    {
        _transfer(msg.sender, recipient, amount);
        return true;
    }

    /// @notice Moves `amount` tokens from `spender` to `recipient` using the
    ///         allowance mechanism. `amount` is then deducted from the caller's
    ///         allowance unless the allowance was made for `type(uint256).max`.
    /// @return True if the operation succeeded, reverts otherwise.
    /// @dev Requirements:
    ///      - `spender` and `recipient` cannot be the zero address,
    ///      - `spender` must have a balance of at least `amount`,
    ///      - the caller must have allowance for `spender`'s tokens of at least
    ///        `amount`.
    function transferFrom(
        address spender,
        address recipient,
        uint256 amount
    ) external override returns (bool) {
        uint256 currentAllowance = allowance[spender][msg.sender];
        if (currentAllowance != type(uint256).max) {
            require(
                currentAllowance >= amount,
                "Transfer amount exceeds allowance"
            );
            _approve(spender, msg.sender, currentAllowance - amount);
        }
        _transfer(spender, recipient, amount);
        return true;
    }

    /// @notice EIP2612 approval made with secp256k1 signature.
    ///         Users can authorize a transfer of their tokens with a signature
    ///         conforming EIP712 standard, rather than an on-chain transaction
    ///         from their address. Anyone can submit this signature on the
    ///         user's behalf by calling the permit function, paying gas fees,
    ///         and possibly performing other actions in the same transaction.
    /// @dev    The deadline argument can be set to `type(uint256).max to create
    ///         permits that effectively never expire.  If the `amount` is set
    ///         to `type(uint256).max` then `transferFrom` and `burnFrom` will
    ///         not reduce an allowance.
    function permit(
        address owner,
        address spender,
        uint256 amount,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external override {
        /* solhint-disable-next-line not-rely-on-time */
        require(deadline >= block.timestamp, "Permission expired");

        // Validate `s` and `v` values for a malleability concern described in EIP2.
        // Only signatures with `s` value in the lower half of the secp256k1
        // curve's order and `v` value of 27 or 28 are considered valid.
        require(
            uint256(s) <=
                0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0,
            "Invalid signature 's' value"
        );
        require(v == 27 || v == 28, "Invalid signature 'v' value");

        bytes32 digest = keccak256(
            abi.encodePacked(
                "\x19\x01",
                DOMAIN_SEPARATOR(),
                keccak256(
                    abi.encode(
                        PERMIT_TYPEHASH,
                        owner,
                        spender,
                        amount,
                        nonce[owner]++,
                        deadline
                    )
                )
            )
        );
        address recoveredAddress = ecrecover(digest, v, r, s);
        require(
            recoveredAddress != address(0) && recoveredAddress == owner,
            "Invalid signature"
        );
        _approve(owner, spender, amount);
    }

    /// @notice Creates `amount` tokens and assigns them to `account`,
    ///         increasing the total supply.
    /// @dev Requirements:
    ///      - `recipient` cannot be the zero address.
    function mint(address recipient, uint256 amount) external onlyOwner {
        require(recipient != address(0), "Mint to the zero address");

        beforeTokenTransfer(address(0), recipient, amount);

        totalSupply += amount;
        balanceOf[recipient] += amount;
        emit Transfer(address(0), recipient, amount);
    }

    /// @notice Destroys `amount` tokens from the caller.
    /// @dev Requirements:
    ///       - the caller must have a balance of at least `amount`.
    function burn(uint256 amount) external override {
        _burn(msg.sender, amount);
    }

    /// @notice Destroys `amount` of tokens from `account` using the allowance
    ///         mechanism. `amount` is then deducted from the caller's allowance
    ///         unless the allowance was made for `type(uint256).max`.
    /// @dev Requirements:
    ///      - `account` must have a balance of at least `amount`,
    ///      - the caller must have allowance for `account`'s tokens of at least
    ///        `amount`.
    function burnFrom(address account, uint256 amount) external override {
        uint256 currentAllowance = allowance[account][msg.sender];
        if (currentAllowance != type(uint256).max) {
            require(
                currentAllowance >= amount,
                "Burn amount exceeds allowance"
            );
            _approve(account, msg.sender, currentAllowance - amount);
        }
        _burn(account, amount);
    }

    /// @notice Calls `receiveApproval` function on spender previously approving
    ///         the spender to withdraw from the caller multiple times, up to
    ///         the `amount` amount. If this function is called again, it
    ///         overwrites the current allowance with `amount`. Reverts if the
    ///         approval reverted or if `receiveApproval` call on the spender
    ///         reverted.
    /// @return True if both approval and `receiveApproval` calls succeeded.
    /// @dev If the `amount` is set to `type(uint256).max` then
    ///      `transferFrom` and `burnFrom` will not reduce an allowance.
    function approveAndCall(
        address spender,
        uint256 amount,
        bytes memory extraData
    ) external override returns (bool) {
        if (approve(spender, amount)) {
            IReceiveApproval(spender).receiveApproval(
                msg.sender,
                amount,
                address(this),
                extraData
            );
            return true;
        }
        return false;
    }

    /// @notice Sets `amount` as the allowance of `spender` over the caller's
    ///         tokens.
    /// @return True if the operation succeeded.
    /// @dev If the `amount` is set to `type(uint256).max` then
    ///      `transferFrom` and `burnFrom` will not reduce an allowance.
    ///      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
    function approve(address spender, uint256 amount)
        public
        override
        returns (bool)
    {
        _approve(msg.sender, spender, amount);
        return true;
    }

    /// @notice Returns hash of EIP712 Domain struct with the token name as
    ///         a signing domain and token contract as a verifying contract.
    ///         Used to construct EIP2612 signature provided to `permit`
    ///         function.
    /* solhint-disable-next-line func-name-mixedcase */
    function DOMAIN_SEPARATOR() public view override returns (bytes32) {
        // As explained in EIP-2612, if the DOMAIN_SEPARATOR contains the
        // chainId and is defined at contract deployment instead of
        // reconstructed for every signature, there is a risk of possible replay
        // attacks between chains in the event of a future chain split.
        // To address this issue, we check the cached chain ID against the
        // current one and in case they are different, we build domain separator
        // from scratch.
        if (block.chainid == cachedChainId) {
            return cachedDomainSeparator;
        } else {
            return buildDomainSeparator();
        }
    }

    /// @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.
    // slither-disable-next-line dead-code
    function beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}

    function _burn(address account, uint256 amount) internal {
        uint256 currentBalance = balanceOf[account];
        require(currentBalance >= amount, "Burn amount exceeds balance");

        beforeTokenTransfer(account, address(0), amount);

        balanceOf[account] = currentBalance - amount;
        totalSupply -= amount;
        emit Transfer(account, address(0), amount);
    }

    function _transfer(
        address spender,
        address recipient,
        uint256 amount
    ) private {
        require(spender != address(0), "Transfer from the zero address");
        require(recipient != address(0), "Transfer to the zero address");
        require(recipient != address(this), "Transfer to the token address");

        beforeTokenTransfer(spender, recipient, amount);

        uint256 spenderBalance = balanceOf[spender];
        require(spenderBalance >= amount, "Transfer amount exceeds balance");
        balanceOf[spender] = spenderBalance - amount;
        balanceOf[recipient] += amount;
        emit Transfer(spender, recipient, amount);
    }

    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) private {
        require(owner != address(0), "Approve from the zero address");
        require(spender != address(0), "Approve to the zero address");
        allowance[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    function buildDomainSeparator() private view returns (bytes32) {
        return
            keccak256(
                abi.encode(
                    keccak256(
                        "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
                    ),
                    keccak256(bytes(name)),
                    keccak256(bytes("1")),
                    block.chainid,
                    address(this)
                )
            );
    }
}

// File: @thesis/solidity-contracts/contracts/token/IApproveAndCall.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

/// @notice An interface that should be implemented by tokens supporting
///         `approveAndCall`/`receiveApproval` pattern.
interface IApproveAndCall {
    /// @notice Executes `receiveApproval` function on spender as specified in
    ///         `IReceiveApproval` interface. Approves spender to withdraw from
    ///         the caller multiple times, up to the `amount`. If this
    ///         function is called again, it overwrites the current allowance
    ///         with `amount`. Reverts if the approval reverted or if
    ///         `receiveApproval` call on the spender reverted.
    function approveAndCall(
        address spender,
        uint256 amount,
        bytes memory extraData
    ) external returns (bool);
}

// File: @thesis/solidity-contracts/contracts/token/IERC20WithPermit.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";

import "./IApproveAndCall.sol";

/// @title  IERC20WithPermit
/// @notice Burnable ERC20 token with EIP2612 permit functionality. User can
///         authorize a transfer of their token with a signature conforming
///         EIP712 standard instead of an on-chain transaction from their
///         address. Anyone can submit this signature on the user's behalf by
///         calling the permit function, as specified in EIP2612 standard,
///         paying gas fees, and possibly performing other actions in the same
///         transaction.
interface IERC20WithPermit is IERC20, IERC20Metadata, IApproveAndCall {
    /// @notice EIP2612 approval made with secp256k1 signature.
    ///         Users can authorize a transfer of their tokens with a signature
    ///         conforming EIP712 standard, rather than an on-chain transaction
    ///         from their address. Anyone can submit this signature on the
    ///         user's behalf by calling the permit function, paying gas fees,
    ///         and possibly performing other actions in the same transaction.
    /// @dev    The deadline argument can be set to `type(uint256).max to create
    ///         permits that effectively never expire.
    function permit(
        address owner,
        address spender,
        uint256 amount,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /// @notice Destroys `amount` tokens from the caller.
    function burn(uint256 amount) external;

    /// @notice Destroys `amount` of tokens from `account`, deducting the amount
    ///         from caller's allowance.
    function burnFrom(address account, uint256 amount) external;

    /// @notice Returns hash of EIP712 Domain struct with the token name as
    ///         a signing domain and token contract as a verifying contract.
    ///         Used to construct EIP2612 signature provided to `permit`
    ///         function.
    /* solhint-disable-next-line func-name-mixedcase */
    function DOMAIN_SEPARATOR() external view returns (bytes32);

    /// @notice Returns the current nonce for EIP2612 permission for the
    ///         provided token owner for a replay protection. Used to construct
    ///         EIP2612 signature provided to `permit` function.
    function nonce(address owner) external view returns (uint256);

    /// @notice Returns EIP2612 Permit message hash. Used to construct EIP2612
    ///         signature provided to `permit` function.
    /* solhint-disable-next-line func-name-mixedcase */
    function PERMIT_TYPEHASH() external pure returns (bytes32);
}

// File: @thesis/solidity-contracts/contracts/token/IReceiveApproval.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

/// @notice An interface that should be implemented by contracts supporting
///         `approveAndCall`/`receiveApproval` pattern.
interface IReceiveApproval {
    /// @notice Receives approval to spend tokens. Called as a result of
    ///         `approveAndCall` call on the token.
    function receiveApproval(
        address from,
        uint256 amount,
        address token,
        bytes calldata extraData
    ) external;
}

// File: @threshold-network/solidity-contracts/contracts/governance/Checkpoints.sol



// SPDX-License-Identifier: GPL-3.0-or-later

// ██████████████     ▐████▌     ██████████████
// ██████████████     ▐████▌     ██████████████
//               ▐████▌    ▐████▌
//               ▐████▌    ▐████▌
// ██████████████     ▐████▌     ██████████████
// ██████████████     ▐████▌     ██████████████
//               ▐████▌    ▐████▌
//               ▐████▌    ▐████▌
//               ▐████▌    ▐████▌
//               ▐████▌    ▐████▌
//               ▐████▌    ▐████▌
//               ▐████▌    ▐████▌

pragma solidity 0.8.9;

import "./IVotesHistory.sol";
import "@openzeppelin/contracts-upgradeable/utils/math/MathUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/utils/math/SafeCastUpgradeable.sol";

/// @title Checkpoints
/// @dev Abstract contract to support checkpoints for Compound-like voting and
///      delegation. This implementation supports token supply up to 2^96 - 1.
///      This contract keeps a history (checkpoints) of each account's vote
///      power. Vote power can be delegated either by calling the {delegate}
///      function directly, or by providing a signature to be used with
///      {delegateBySig}. Voting power can be publicly queried through
///      {getVotes} and {getPastVotes}.
///      NOTE: Extracted from OpenZeppelin ERCVotes.sol.
/// @dev This contract is upgrade-safe.
abstract contract Checkpoints is IVotesHistory {
    struct Checkpoint {
        uint32 fromBlock;
        uint96 votes;
    }

    // slither-disable-next-line uninitialized-state
    mapping(address => address) internal _delegates;
    mapping(address => uint128[]) internal _checkpoints;
    uint128[] internal _totalSupplyCheckpoints;

    // Reserved storage space in case we need to add more variables,
    // since there are upgradeable contracts that inherit from this one.
    // See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
    // slither-disable-next-line unused-state
    uint256[47] private __gap;

    /// @notice Emitted when an account changes their delegate.
    event DelegateChanged(
        address indexed delegator,
        address indexed fromDelegate,
        address indexed toDelegate
    );

    /// @notice Emitted when a balance or delegate change results in changes
    ///         to an account's voting power.
    event DelegateVotesChanged(
        address indexed delegate,
        uint256 previousBalance,
        uint256 newBalance
    );

    function checkpoints(address account, uint32 pos)
        public
        view
        virtual
        returns (Checkpoint memory checkpoint)
    {
        (uint32 fromBlock, uint96 votes) = decodeCheckpoint(
            _checkpoints[account][pos]
        );
        checkpoint = Checkpoint(fromBlock, votes);
    }

    /// @notice Get number of checkpoints for `account`.
    function numCheckpoints(address account)
        public
        view
        virtual
        returns (uint32)
    {
        return SafeCastUpgradeable.toUint32(_checkpoints[account].length);
    }

    /// @notice Get the address `account` is currently delegating to.
    function delegates(address account) public view virtual returns (address) {
        return _delegates[account];
    }

    /// @notice Gets the current votes balance for `account`.
    /// @param account The address to get votes balance
    /// @return The number of current votes for `account`
    function getVotes(address account) public view returns (uint96) {
        uint256 pos = _checkpoints[account].length;
        return pos == 0 ? 0 : decodeValue(_checkpoints[account][pos - 1]);
    }

    /// @notice Determine the prior number of votes for an account as of
    ///         a block number.
    /// @dev Block number must be a finalized block or else this function will
    ///      revert to prevent misinformation.
    /// @param account The address of the account to check
    /// @param blockNumber The block number to get the vote balance at
    /// @return The number of votes the account had as of the given block
    function getPastVotes(address account, uint256 blockNumber)
        public
        view
        returns (uint96)
    {
        return lookupCheckpoint(_checkpoints[account], blockNumber);
    }

    /// @notice Retrieve the `totalSupply` at the end of `blockNumber`.
    ///         Note, this value is the sum of all balances, but it is NOT the
    ///         sum of all the delegated votes!
    /// @param blockNumber The block number to get the total supply at
    /// @dev `blockNumber` must have been already mined
    function getPastTotalSupply(uint256 blockNumber)
        public
        view
        returns (uint96)
    {
        return lookupCheckpoint(_totalSupplyCheckpoints, blockNumber);
    }

    /// @notice Change delegation for `delegator` to `delegatee`.
    // slither-disable-next-line dead-code
    function delegate(address delegator, address delegatee) internal virtual;

    /// @notice Moves voting power from one delegate to another
    /// @param src Address of old delegate
    /// @param dst Address of new delegate
    /// @param amount Voting power amount to transfer between delegates
    function moveVotingPower(
        address src,
        address dst,
        uint256 amount
    ) internal {
        if (src != dst && amount > 0) {
            if (src != address(0)) {
                // https://github.com/crytic/slither/issues/960
                // slither-disable-next-line variable-scope
                (uint256 oldWeight, uint256 newWeight) = writeCheckpoint(
                    _checkpoints[src],
                    subtract,
                    amount
                );
                emit DelegateVotesChanged(src, oldWeight, newWeight);
            }

            if (dst != address(0)) {
                // https://github.com/crytic/slither/issues/959
                // slither-disable-next-line uninitialized-local
                (uint256 oldWeight, uint256 newWeight) = writeCheckpoint(
                    _checkpoints[dst],
                    add,
                    amount
                );
                emit DelegateVotesChanged(dst, oldWeight, newWeight);
            }
        }
    }

    /// @notice Writes a new checkpoint based on operating last stored value
    ///         with a `delta`. Usually, said operation is the `add` or
    ///         `subtract` functions from this contract, but more complex
    ///         functions can be passed as parameters.
    /// @param ckpts The checkpoints array to use
    /// @param op The function to apply over the last value and the `delta`
    /// @param delta Variation with respect to last stored value to be used
    ///              for new checkpoint
    function writeCheckpoint(
        uint128[] storage ckpts,
        function(uint256, uint256) view returns (uint256) op,
        uint256 delta
    ) internal returns (uint256 oldWeight, uint256 newWeight) {
        uint256 pos = ckpts.length;
        oldWeight = pos == 0 ? 0 : decodeValue(ckpts[pos - 1]);
        newWeight = op(oldWeight, delta);

        if (pos > 0) {
            uint32 fromBlock = decodeBlockNumber(ckpts[pos - 1]);
            // slither-disable-next-line incorrect-equality
            if (fromBlock == block.number) {
                ckpts[pos - 1] = encodeCheckpoint(
                    fromBlock,
                    SafeCastUpgradeable.toUint96(newWeight)
                );
                return (oldWeight, newWeight);
            }
        }

        ckpts.push(
            encodeCheckpoint(
                SafeCastUpgradeable.toUint32(block.number),
                SafeCastUpgradeable.toUint96(newWeight)
            )
        );
    }

    /// @notice Lookup a value in a list of (sorted) checkpoints.
    /// @param ckpts The checkpoints array to use
    /// @param blockNumber Block number when we want to get the checkpoint at
    function lookupCheckpoint(uint128[] storage ckpts, uint256 blockNumber)
        internal
        view
        returns (uint96)
    {
        // We run a binary search to look for the earliest checkpoint taken
        // after `blockNumber`. During the loop, the index of the wanted
        // checkpoint remains in the range [low-1, high). With each iteration,
        // either `low` or `high` is moved towards the middle of the range to
        // maintain the invariant.
        // - If the middle checkpoint is after `blockNumber`,
        //   we look in [low, mid)
        // - If the middle checkpoint is before or equal to `blockNumber`,
        //   we look in [mid+1, high)
        // Once we reach a single value (when low == high), we've found the
        // right checkpoint at the index high-1, if not out of bounds (in that
        // case we're looking too far in the past and the result is 0).
        // Note that if the latest checkpoint available is exactly for
        // `blockNumber`, we end up with an index that is past the end of the
        // array, so we technically don't find a checkpoint after
        // `blockNumber`, but it works out the same.
        require(blockNumber < block.number, "Block not yet determined");

        uint256 high = ckpts.length;
        uint256 low = 0;
        while (low < high) {
            uint256 mid = MathUpgradeable.average(low, high);
            uint32 midBlock = decodeBlockNumber(ckpts[mid]);
            if (midBlock > blockNumber) {
                high = mid;
            } else {
                low = mid + 1;
            }
        }

        return high == 0 ? 0 : decodeValue(ckpts[high - 1]);
    }

    /// @notice Maximum token supply. Defaults to `type(uint96).max` (2^96 - 1)
    // slither-disable-next-line dead-code
    function maxSupply() internal view virtual returns (uint96) {
        return type(uint96).max;
    }

    /// @notice Encodes a `blockNumber` and `value` into a single `uint128`
    ///         checkpoint.
    /// @dev `blockNumber` is stored in the first 32 bits, while `value` in the
    ///      remaining 96 bits.
    function encodeCheckpoint(uint32 blockNumber, uint96 value)
        internal
        pure
        returns (uint128)
    {
        return (uint128(blockNumber) << 96) | uint128(value);
    }

    /// @notice Decodes a block number from a `uint128` `checkpoint`.
    function decodeBlockNumber(uint128 checkpoint)
        internal
        pure
        returns (uint32)
    {
        return uint32(bytes4(bytes16(checkpoint)));
    }

    /// @notice Decodes a voting value from a `uint128` `checkpoint`.
    function decodeValue(uint128 checkpoint) internal pure returns (uint96) {
        return uint96(checkpoint);
    }

    /// @notice Decodes a block number and voting value from a `uint128`
    ///         `checkpoint`.
    function decodeCheckpoint(uint128 checkpoint)
        internal
        pure
        returns (uint32 blockNumber, uint96 value)
    {
        blockNumber = decodeBlockNumber(checkpoint);
        value = decodeValue(checkpoint);
    }

    // slither-disable-next-line dead-code
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    // slither-disable-next-line dead-code
    function subtract(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }
}

// File: @threshold-network/solidity-contracts/contracts/governance/IVotesHistory.sol



// SPDX-License-Identifier: GPL-3.0-or-later

// ██████████████     ▐████▌     ██████████████
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pragma solidity 0.8.9;

interface IVotesHistory {
    function getPastVotes(address account, uint256 blockNumber)
        external
        view
        returns (uint96);

    function getPastTotalSupply(uint256 blockNumber)
        external
        view
        returns (uint96);
}

// File: contracts/UnderwriterToken.sol



// ▓▓▌ ▓▓ ▐▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▄
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓    ▓▓▓▓▓▓▓▀    ▐▓▓▓▓▓▓    ▐▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▄▄▓▓▓▓▓▓▓▀      ▐▓▓▓▓▓▓▄▄▄▄         ▓▓▓▓▓▓▄▄▄▄         ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▓▓▓▓▓▓▓▀        ▐▓▓▓▓▓▓▓▓▓▓         ▓▓▓▓▓▓▓▓▓▓         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓▀▀▓▓▓▓▓▓▄       ▐▓▓▓▓▓▓▀▀▀▀         ▓▓▓▓▓▓▀▀▀▀         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▀
//   ▓▓▓▓▓▓   ▀▓▓▓▓▓▓▄     ▐▓▓▓▓▓▓     ▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌
// ▓▓▓▓▓▓▓▓▓▓ █▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
//
//                           Trust math, not hardware.

// SPDX-License-Identifier: MIT

pragma solidity 0.8.9;

import "@openzeppelin/contracts/utils/math/SafeCast.sol";
import "@thesis/solidity-contracts/contracts/token/ERC20WithPermit.sol";
import "@threshold-network/solidity-contracts/contracts/governance/Checkpoints.sol";

/// @title  UnderwriterToken
/// @notice Underwriter tokens represent an ownership share in the underlying
///         collateral of the asset-specific pool. Underwriter tokens are minted
///         when a user deposits ERC20 tokens into asset-specific pool and they
///         are burned when a user exits the position. Underwriter tokens
///         natively support meta transactions. Users can authorize a transfer
///         of their underwriter tokens with a signature conforming EIP712
///         standard instead of an on-chain transaction from their address.
///         Anyone can submit this signature on the user's behalf by calling the
///         permit function, as specified in EIP2612 standard, paying gas fees,
///         and possibly performing other actions in the same transaction.
// slither-disable-next-line missing-inheritance
contract UnderwriterToken is ERC20WithPermit, Checkpoints {
    /// @notice The EIP-712 typehash for the delegation struct used by
    ///         `delegateBySig`.
    bytes32 public constant DELEGATION_TYPEHASH =
        keccak256(
            "Delegation(address delegatee,uint256 nonce,uint256 deadline)"
        );

    constructor(string memory _name, string memory _symbol)
        ERC20WithPermit(_name, _symbol)
    {}

    /// @notice Delegates votes from signatory to `delegatee`
    /// @param delegatee The address to delegate votes to
    /// @param deadline The time at which to expire the signature
    /// @param v The recovery byte of the signature
    /// @param r Half of the ECDSA signature pair
    /// @param s Half of the ECDSA signature pair
    function delegateBySig(
        address signatory,
        address delegatee,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external {
        /* solhint-disable-next-line not-rely-on-time */
        require(deadline >= block.timestamp, "Delegation expired");

        // Validate `s` and `v` values for a malleability concern described in EIP2.
        // Only signatures with `s` value in the lower half of the secp256k1
        // curve's order and `v` value of 27 or 28 are considered valid.
        require(
            uint256(s) <=
                0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0,
            "Invalid signature 's' value"
        );
        require(v == 27 || v == 28, "Invalid signature 'v' value");

        bytes32 digest = keccak256(
            abi.encodePacked(
                "\x19\x01",
                DOMAIN_SEPARATOR(),
                keccak256(
                    abi.encode(
                        DELEGATION_TYPEHASH,
                        delegatee,
                        nonce[signatory]++,
                        deadline
                    )
                )
            )
        );

        address recoveredAddress = ecrecover(digest, v, r, s);
        require(
            recoveredAddress != address(0) && recoveredAddress == signatory,
            "Invalid signature"
        );

        return delegate(signatory, delegatee);
    }

    /// @notice Delegate votes from `msg.sender` to `delegatee`.
    /// @param delegatee The address to delegate votes to
    function delegate(address delegatee) public virtual {
        return delegate(msg.sender, delegatee);
    }

    /// @notice Moves voting power when tokens are minted, burned or transferred.
    /// @dev Overrides the empty function from the parent contract.
    /// @param from The address that loses tokens and voting power
    /// @param to The address that gains tokens and voting power
    /// @param amount The amount of tokens and voting power that is transferred
    // slither-disable-next-line dead-code
    function beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal override {
        // When minting:
        if (from == address(0)) {
            // Does not allow to mint more than uint96 can fit. Otherwise, the
            // Checkpoint might not fit the balance.
            require(
                totalSupply + amount <= maxSupply(),
                "Maximum total supply exceeded"
            );
            writeCheckpoint(_totalSupplyCheckpoints, add, amount);
        }

        // When burning:
        if (to == address(0)) {
            writeCheckpoint(_totalSupplyCheckpoints, subtract, amount);
        }

        moveVotingPower(delegates(from), delegates(to), amount);
    }

    /// @notice Delegate votes from `delegator` to `delegatee`.
    /// @param delegator The address to delegate votes from
    /// @param delegatee The address to delegate votes to
    function delegate(address delegator, address delegatee) internal override {
        address currentDelegate = delegates(delegator);
        uint96 delegatorBalance = SafeCast.toUint96(balanceOf[delegator]);
        _delegates[delegator] = delegatee;

        emit DelegateChanged(delegator, currentDelegate, delegatee);

        moveVotingPower(currentDelegate, delegatee, delegatorBalance);
    }
}