// File: contracts/currency/ECOx.sol



/* -*- c-basic-offset: 4 -*- */
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./IECO.sol";
import "../policy/PolicedUtils.sol";
import "./ERC20Pausable.sol";

/** @title An ERC20 token interface for ECOx
 *
 * Contains the conversion mechanism for turning ECOx into ECO.
 */
contract ECOx is ERC20Pausable, PolicedUtils {
    // bits of precision used in the exponentiation approximation
    uint8 public constant PRECISION_BITS = 100;

    uint256 public immutable initialSupply;

    // the address of the contract for initial distribution
    address public immutable distributor;

    // the address of the ECO token contract
    IECO public immutable ecoToken;

    constructor(
        Policy _policy,
        address _distributor,
        uint256 _initialSupply,
        IECO _ecoAddr,
        address _initialPauser
    )
        ERC20Pausable("ECOx", "ECOx", address(_policy), _initialPauser)
        PolicedUtils(_policy)
    {
        require(_initialSupply > 0, "initial supply not properly set");
        require(
            address(_ecoAddr) != address(0),
            "Do not set the ECO address as the zero address"
        );

        initialSupply = _initialSupply;
        distributor = _distributor;
        ecoToken = _ecoAddr;
    }

    function initialize(address _self)
        public
        virtual
        override
        onlyConstruction
    {
        super.initialize(_self);
        pauser = ERC20Pausable(_self).pauser();
        _mint(distributor, initialSupply);
    }

    function ecoValueOf(uint256 _ecoXValue) public view returns (uint256) {
        uint256 _ecoSupply = ecoToken.totalSupply();

        return computeValue(_ecoXValue, _ecoSupply);
    }

    function valueAt(uint256 _ecoXValue, uint256 _blockNumber)
        public
        view
        returns (uint256)
    {
        uint256 _ecoSupplyAt = ecoToken.totalSupplyAt(_blockNumber);

        return computeValue(_ecoXValue, _ecoSupplyAt);
    }

    function computeValue(uint256 _ecoXValue, uint256 _ecoSupply)
        internal
        view
        returns (uint256)
    {
        uint256 _preciseRatio = safeLeftShift(_ecoXValue, PRECISION_BITS) /
            initialSupply;

        return
            (generalExp(_preciseRatio, PRECISION_BITS) * _ecoSupply) >>
            PRECISION_BITS;
    }

    function safeLeftShift(uint256 value, uint8 shift)
        internal
        pure
        returns (uint256)
    {
        uint256 _result = value << shift;
        require(
            _result >> shift == value,
            "value too large, shift out of bounds"
        );
        return _result;
    }

    /**
     * @dev this function can be auto-generated by the script 'PrintFunctionGeneralExp.py'.
     * it approximates "e ^ x" via maclaurin summation: "(x^0)/0! + (x^1)/1! + ... + (x^n)/n!".
     * it returns "e ^ (x / 2 ^ precision) * 2 ^ precision", that is, the result is upshifted for accuracy.
     * the global "maxExpArray" maps each "precision" to "((maximumExponent + 1) << (MAX_PRECISION - precision)) - 1".
     * the maximum permitted value for "x" is therefore given by "maxExpArray[precision] >> (MAX_PRECISION - precision)".
     */
    function generalExp(uint256 _x, uint8 _precision)
        internal
        pure
        returns (uint256)
    {
        uint256 xi = _x;
        uint256 res = 0;

        xi = (xi * _x) >> _precision;
        res += xi * 0x3442c4e6074a82f1797f72ac0000000; // add x^02 * (33! / 02!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x116b96f757c380fb287fd0e40000000; // add x^03 * (33! / 03!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x045ae5bdd5f0e03eca1ff4390000000; // add x^04 * (33! / 04!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x00defabf91302cd95b9ffda50000000; // add x^05 * (33! / 05!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x002529ca9832b22439efff9b8000000; // add x^06 * (33! / 06!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x00054f1cf12bd04e516b6da88000000; // add x^07 * (33! / 07!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x0000a9e39e257a09ca2d6db51000000; // add x^08 * (33! / 08!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x000012e066e7b839fa050c309000000; // add x^09 * (33! / 09!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x000001e33d7d926c329a1ad1a800000; // add x^10 * (33! / 10!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x0000002bee513bdb4a6b19b5f800000; // add x^11 * (33! / 11!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x00000003a9316fa79b88eccf2a00000; // add x^12 * (33! / 12!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x0000000048177ebe1fa812375200000; // add x^13 * (33! / 13!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x0000000005263fe90242dcbacf00000; // add x^14 * (33! / 14!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x000000000057e22099c030d94100000; // add x^15 * (33! / 15!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x0000000000057e22099c030d9410000; // add x^16 * (33! / 16!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x00000000000052b6b54569976310000; // add x^17 * (33! / 17!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x00000000000004985f67696bf748000; // add x^18 * (33! / 18!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x000000000000003dea12ea99e498000; // add x^19 * (33! / 19!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x00000000000000031880f2214b6e000; // add x^20 * (33! / 20!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x000000000000000025bcff56eb36000; // add x^21 * (33! / 21!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x000000000000000001b722e10ab1000; // add x^22 * (33! / 22!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x0000000000000000001317c70077000; // add x^23 * (33! / 23!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x00000000000000000000cba84aafa00; // add x^24 * (33! / 24!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x00000000000000000000082573a0a00; // add x^25 * (33! / 25!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x00000000000000000000005035ad900; // add x^26 * (33! / 26!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x000000000000000000000002f881b00; // add x^27 * (33! / 27!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x0000000000000000000000001b29340; // add x^28 * (33! / 28!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x00000000000000000000000000efc40; // add x^29 * (33! / 29!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x0000000000000000000000000007fe0; // add x^30 * (33! / 30!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x0000000000000000000000000000420; // add x^31 * (33! / 31!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x0000000000000000000000000000021; // add x^32 * (33! / 32!)
        xi = (xi * _x) >> _precision;
        res += xi * 0x0000000000000000000000000000001; // add x^33 * (33! / 33!)

        return res / 0x688589cc0e9505e2f2fee5580000000 + _x; // divide by 33! and then add x^1 / 1! + x^0 / 0!
    }

    function exchange(uint256 _ecoXValue) external {
        uint256 eco = ecoValueOf(_ecoXValue);

        _burn(msg.sender, _ecoXValue);

        ecoToken.mint(msg.sender, eco);
    }

    function mint(address _to, uint256 _value) external {
        require(
            msg.sender == policyFor(ID_FAUCET),
            "Caller not authorized to mint tokens"
        );

        _mint(_to, _value);
    }
}

// File: contracts/currency/IECO.sol



/* -*- c-basic-offset: 4 -*- */
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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

interface IECO is IERC20 {
    function mint(address to, uint256 amount) external;

    function burn(address from, uint256 amount) external;

    function currentGeneration() external view returns (uint256);

    /**
     *  Returns final votes of an address at the end of a blocknumber
     */
    function getPastVotes(address owner, uint256 blockNumber)
        external
        view
        returns (uint256);

    /**
     * Returns the final total supply at the end of the given block number
     */
    function totalSupplyAt(uint256 blockNumber) external view returns (uint256);
}

// File: contracts/policy/PolicedUtils.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/introspection/IERC1820Registry.sol";

import "../clone/CloneFactory.sol";
import "./Policed.sol";
import "./ERC1820Client.sol";

/** @title Utility providing helpers for policed contracts
 *
 * See documentation for Policed to understand what a policed contract is.
 */
abstract contract PolicedUtils is Policed, CloneFactory {
    bytes32 internal constant ID_FAUCET = keccak256("Faucet");
    bytes32 internal constant ID_ECO = keccak256("ECO");
    bytes32 internal constant ID_ECOX = keccak256("ECOx");
    bytes32 internal constant ID_TIMED_POLICIES = keccak256("TimedPolicies");
    bytes32 internal constant ID_TRUSTED_NODES = keccak256("TrustedNodes");
    bytes32 internal constant ID_POLICY_PROPOSALS =
        keccak256("PolicyProposals");
    bytes32 internal constant ID_POLICY_VOTES = keccak256("PolicyVotes");
    bytes32 internal constant ID_CURRENCY_GOVERNANCE =
        keccak256("CurrencyGovernance");
    bytes32 internal constant ID_CURRENCY_TIMER = keccak256("CurrencyTimer");
    bytes32 internal constant ID_ECOXSTAKING = keccak256("ECOxStaking");

    // The minimum time of a generation.
    uint256 public constant MIN_GENERATION_DURATION = 14 days;
    // The initial generation
    uint256 public constant GENERATION_START = 1000;

    address internal expectedInterfaceSet;

    constructor(Policy _policy) Policed(_policy) {}

    /** ERC1820 permissioning interface
     *
     * @param _addr The address of the contract we might act on behalf of.
     */
    function canImplementInterfaceForAddress(bytes32, address _addr)
        external
        view
        override
        returns (bytes32)
    {
        require(
            _addr == address(policy) || _addr == expectedInterfaceSet,
            "Only the policy or interface contract can set the interface"
        );
        return ERC1820_ACCEPT_MAGIC;
    }

    /** Set the expected interface set
     */
    function setExpectedInterfaceSet(address _addr) public onlyPolicy {
        expectedInterfaceSet = _addr;
    }

    /** Create a clone of this contract
     *
     * Creates a clone of this contract by instantiating a proxy at a new
     * address and initializing it based on the current contract. Uses
     * optionality.io's CloneFactory functionality.
     *
     * This is used to save gas cost during deployments. Rather than including
     * the full contract code in every contract that might instantiate it we
     * can deploy it once and reference the location it was deployed to. Then
     * calls to clone() can be used to create instances as needed without
     * increasing the code size of the instantiating contract.
     */
    function clone() public virtual returns (address) {
        require(
            implementation() == address(this),
            "This method cannot be called on clones"
        );
        address _clone = createClone(address(this));
        PolicedUtils(_clone).initialize(address(this));
        return _clone;
    }

    /** Find the policy contract for a particular identifier.
     *
     * This is intended as a helper function for contracts that are managed by
     * a policy framework. A typical use case is checking if the address calling
     * a function is the authorized policy for a particular action.
     *
     * eg:
     * ```
     * function doSomethingPrivileged() public {
     *   require(
     *     msg.sender == policyFor(keccak256("PolicyForDoingPrivilegedThing")),
     *     "Only the privileged contract may call this"
     *     );
     * }
     * ```
     */
    function policyFor(bytes32 _id) internal view returns (address) {
        return ERC1820REGISTRY.getInterfaceImplementer(address(policy), _id);
    }
}

// File: contracts/currency/ERC20Pausable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/security/Pausable.sol";
import "./ERC20.sol";

/**
 * @dev Implementation of the {IERC20} interface with pausability
 * When paused by the pauser admin, transfers revert.
 */
contract ERC20Pausable is ERC20, Pausable {
    address public immutable roleAdmin;

    // initially no-one should have the pauser role
    // it can be granted and revoked by the admin policy
    address public pauser;

    /**
     * @notice event indicating the pauser was updated
     * @param pauser The new pauser
     */
    event PauserAssignment(address indexed pauser);

    constructor(
        string memory name,
        string memory symbol,
        address _roleAdmin,
        address _initialPauser
    ) ERC20(name, symbol) {
        require(
            address(_roleAdmin) != address(0),
            "Unrecoverable: do not set the _roleAdmin as the zero address"
        );
        roleAdmin = _roleAdmin;
        pauser = _initialPauser;
        emit PauserAssignment(_initialPauser);
    }

    modifier onlyAdmin() {
        require(msg.sender == roleAdmin, "ERC20Pausable: not admin");
        _;
    }

    modifier onlyPauser() {
        require(msg.sender == pauser, "ERC20Pausable: not pauser");
        _;
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * If the token is not paused, it will pass through the amount
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual override whenNotPaused returns (uint256) {
        return amount;
    }

    /**
     * @notice pauses transfers of this token
     * @dev only callable by the pauser
     */
    function pause() external onlyPauser {
        _pause();
    }

    /**
     * @notice unpauses transfers of this token
     * @dev only callable by the pauser
     */
    function unpause() external onlyPauser {
        _unpause();
    }

    /**
     * @notice set the given address as the pauser
     * @param _pauser The address that can pause this token
     * @dev only the roleAdmin can call this function
     */
    function setPauser(address _pauser) public onlyAdmin {
        require(_pauser != pauser, "ERC20Pausable: must change pauser");
        pauser = _pauser;
        emit PauserAssignment(_pauser);
    }
}

// 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: contracts/policy/Policed.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/introspection/IERC1820Implementer.sol";
import "../proxy/ForwardTarget.sol";
import "./Policy.sol";

/** @title Policed Contracts
 *
 * A policed contract is any contract managed by a policy.
 */
abstract contract Policed is ForwardTarget, IERC1820Implementer, ERC1820Client {
    bytes32 internal constant ERC1820_ACCEPT_MAGIC =
        keccak256("ERC1820_ACCEPT_MAGIC");

    /** The address of the root policy instance overseeing this instance.
     *
     * This address can be used for ERC1820 lookup of other components, ERC1820
     * lookup of role policies, and interaction with the policy hierarchy.
     */
    Policy public immutable policy;

    /** Restrict method access to the root policy instance only.
     */
    modifier onlyPolicy() {
        require(
            msg.sender == address(policy),
            "Only the policy contract may call this method"
        );
        _;
    }

    constructor(Policy _policy) {
        require(
            address(_policy) != address(0),
            "Unrecoverable: do not set the policy as the zero address"
        );
        policy = _policy;
        ERC1820REGISTRY.setManager(address(this), address(_policy));
    }

    /** ERC1820 permissioning interface
     *
     * @param _addr The address of the contract we might act on behalf of.
     */
    function canImplementInterfaceForAddress(bytes32, address _addr)
        external
        view
        virtual
        override
        returns (bytes32)
    {
        require(
            _addr == address(policy),
            "This contract only implements interfaces for the policy contract"
        );
        return ERC1820_ACCEPT_MAGIC;
    }

    /** Initialize the contract (replaces constructor)
     *
     * Policed contracts are often the targets of proxies, and therefore need a
     * mechanism to initialize internal state when adopted by a new proxy. This
     * replaces the constructor.
     *
     * @param _self The address of the original contract deployment (as opposed
     *              to the address of the proxy contract, which takes the place
     *              of `this`).
     */
    function initialize(address _self)
        public
        virtual
        override
        onlyConstruction
    {
        super.initialize(_self);
        ERC1820REGISTRY.setManager(address(this), address(policy));
    }

    /** Execute code as indicated by the managing policy contract
     *
     * We allow the managing policy contract to execute arbitrary code in our
     * context by allowing it to specify an implementation address and some
     * message data, and then using delegatecall to execute the code at the
     * implementation address, passing in the message data, all within our
     * own address space.
     *
     * @param _delegate The address of the contract to delegate execution to.
     * @param _data The call message/data to execute on.
     */
    function policyCommand(address _delegate, bytes memory _data)
        public
        onlyPolicy
    {
        // solhint-disable-next-line no-inline-assembly
        assembly {
            /* Call the address indicated by _delegate passing the data in _data
             * as the call message using delegatecall. This allows the calling
             * of arbitrary functions on _delegate (by encoding the call message
             * into _data) in the context of the current contract's storage.
             */
            let result := delegatecall(
                gas(),
                _delegate,
                add(_data, 0x20),
                mload(_data),
                0,
                0
            )
            /* Collect up the return data from delegatecall and prepare it for
             * returning to the caller of policyCommand.
             */
            let size := returndatasize()
            returndatacopy(0x0, 0, size)
            /* If the delegated call reverted then revert here too. Otherwise
             * forward the return data prepared above.
             */
            switch result
            case 0 {
                revert(0x0, size)
            }
            default {
                return(0x0, size)
            }
        }
    }
}

// File: contracts/policy/ERC1820Client.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/introspection/IERC1820Registry.sol";

/** @title Utilities for interfacing with ERC1820
 */
abstract contract ERC1820Client {
    IERC1820Registry internal constant ERC1820REGISTRY =
        IERC1820Registry(0x1820a4B7618BdE71Dce8cdc73aAB6C95905faD24);
}

// File: contracts/clone/CloneFactory.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/*
The MIT License (MIT)

Copyright (c) 2018 Murray Software, LLC.

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/* solhint-disable */

// See the EIP-1167: http://eips.ethereum.org/EIPS/eip-1167 and
// clone-factory: https://github.com/optionality/clone-factory for details.

abstract contract CloneFactory {
    function createClone(address target) internal returns (address result) {
        bytes20 targetBytes = bytes20(target);
        assembly {
            let clone := mload(0x40)
            mstore(
                clone,
                0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000000000000000000000
            )
            mstore(add(clone, 0x14), targetBytes)
            mstore(
                add(clone, 0x28),
                0x5af43d82803e903d91602b57fd5bf30000000000000000000000000000000000
            )
            result := create(0, clone, 0x37)
        }
    }
}

// File: @openzeppelin/contracts/utils/introspection/IERC1820Registry.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (utils/introspection/IERC1820Registry.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the global ERC1820 Registry, as defined in the
 * https://eips.ethereum.org/EIPS/eip-1820[EIP]. Accounts may register
 * implementers for interfaces in this registry, as well as query support.
 *
 * Implementers may be shared by multiple accounts, and can also implement more
 * than a single interface for each account. Contracts can implement interfaces
 * for themselves, but externally-owned accounts (EOA) must delegate this to a
 * contract.
 *
 * {IERC165} interfaces can also be queried via the registry.
 *
 * For an in-depth explanation and source code analysis, see the EIP text.
 */
interface IERC1820Registry {
    event InterfaceImplementerSet(address indexed account, bytes32 indexed interfaceHash, address indexed implementer);

    event ManagerChanged(address indexed account, address indexed newManager);

    /**
     * @dev Sets `newManager` as the manager for `account`. A manager of an
     * account is able to set interface implementers for it.
     *
     * By default, each account is its own manager. Passing a value of `0x0` in
     * `newManager` will reset the manager to this initial state.
     *
     * Emits a {ManagerChanged} event.
     *
     * Requirements:
     *
     * - the caller must be the current manager for `account`.
     */
    function setManager(address account, address newManager) external;

    /**
     * @dev Returns the manager for `account`.
     *
     * See {setManager}.
     */
    function getManager(address account) external view returns (address);

    /**
     * @dev Sets the `implementer` contract as ``account``'s implementer for
     * `interfaceHash`.
     *
     * `account` being the zero address is an alias for the caller's address.
     * The zero address can also be used in `implementer` to remove an old one.
     *
     * See {interfaceHash} to learn how these are created.
     *
     * Emits an {InterfaceImplementerSet} event.
     *
     * Requirements:
     *
     * - the caller must be the current manager for `account`.
     * - `interfaceHash` must not be an {IERC165} interface id (i.e. it must not
     * end in 28 zeroes).
     * - `implementer` must implement {IERC1820Implementer} and return true when
     * queried for support, unless `implementer` is the caller. See
     * {IERC1820Implementer-canImplementInterfaceForAddress}.
     */
    function setInterfaceImplementer(
        address account,
        bytes32 _interfaceHash,
        address implementer
    ) external;

    /**
     * @dev Returns the implementer of `interfaceHash` for `account`. If no such
     * implementer is registered, returns the zero address.
     *
     * If `interfaceHash` is an {IERC165} interface id (i.e. it ends with 28
     * zeroes), `account` will be queried for support of it.
     *
     * `account` being the zero address is an alias for the caller's address.
     */
    function getInterfaceImplementer(address account, bytes32 _interfaceHash) external view returns (address);

    /**
     * @dev Returns the interface hash for an `interfaceName`, as defined in the
     * corresponding
     * https://eips.ethereum.org/EIPS/eip-1820#interface-name[section of the EIP].
     */
    function interfaceHash(string calldata interfaceName) external pure returns (bytes32);

    /**
     * @notice Updates the cache with whether the contract implements an ERC165 interface or not.
     * @param account Address of the contract for which to update the cache.
     * @param interfaceId ERC165 interface for which to update the cache.
     */
    function updateERC165Cache(address account, bytes4 interfaceId) external;

    /**
     * @notice Checks whether a contract implements an ERC165 interface or not.
     * If the result is not cached a direct lookup on the contract address is performed.
     * If the result is not cached or the cached value is out-of-date, the cache MUST be updated manually by calling
     * {updateERC165Cache} with the contract address.
     * @param account Address of the contract to check.
     * @param interfaceId ERC165 interface to check.
     * @return True if `account` implements `interfaceId`, false otherwise.
     */
    function implementsERC165Interface(address account, bytes4 interfaceId) external view returns (bool);

    /**
     * @notice Checks whether a contract implements an ERC165 interface or not without using nor updating the cache.
     * @param account Address of the contract to check.
     * @param interfaceId ERC165 interface to check.
     * @return True if `account` implements `interfaceId`, false otherwise.
     */
    function implementsERC165InterfaceNoCache(address account, bytes4 interfaceId) external view returns (bool);
}

// File: contracts/proxy/ForwardTarget.sol



/* -*- c-basic-offset: 4 -*- */
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/* solhint-disable no-inline-assembly */

/** @title Target for ForwardProxy and EcoInitializable */
abstract contract ForwardTarget {
    // Must match definition in ForwardProxy
    // keccak256("com.eco.ForwardProxy.target")
    uint256 private constant IMPLEMENTATION_SLOT =
        0xf86c915dad5894faca0dfa067c58fdf4307406d255ed0a65db394f82b77f53d4;

    modifier onlyConstruction() {
        require(
            implementation() == address(0),
            "Can only be called during initialization"
        );
        _;
    }

    constructor() {
        setImplementation(address(this));
    }

    /** @notice Storage initialization of cloned contract
     *
     * This is used to initialize the storage of the forwarded contract, and
     * should (typically) copy or repeat any work that would normally be
     * done in the constructor of the proxied contract.
     *
     * Implementations of ForwardTarget should override this function,
     * and chain to super.initialize(_self).
     *
     * @param _self The address of the original contract instance (the one being
     *              forwarded to).
     */
    function initialize(address _self) public virtual onlyConstruction {
        address _implAddress = address(ForwardTarget(_self).implementation());
        require(
            _implAddress != address(0),
            "initialization failure: nothing to implement"
        );
        setImplementation(_implAddress);
    }

    /** Get the address of the proxy target contract.
     */
    function implementation() public view returns (address _impl) {
        assembly {
            _impl := sload(IMPLEMENTATION_SLOT)
        }
    }

    /** @notice Set new implementation */
    function setImplementation(address _impl) internal {
        require(implementation() != _impl, "Implementation already matching");
        assembly {
            sstore(IMPLEMENTATION_SLOT, _impl)
        }
    }
}

// File: contracts/policy/Policy.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/introspection/IERC1820Registry.sol";
import "../proxy/ForwardTarget.sol";
import "./ERC1820Client.sol";

/** @title The policy contract that oversees other contracts
 *
 * Policy contracts provide a mechanism for building pluggable (after deploy)
 * governance systems for other contracts.
 */
contract Policy is ForwardTarget, ERC1820Client {
    mapping(bytes32 => bool) public setters;

    modifier onlySetter(bytes32 _identifier) {
        require(
            setters[_identifier],
            "Identifier hash is not authorized for this action"
        );

        require(
            ERC1820REGISTRY.getInterfaceImplementer(
                address(this),
                _identifier
            ) == msg.sender,
            "Caller is not the authorized address for identifier"
        );

        _;
    }

    /** Remove the specified role from the contract calling this function.
     * This is for cleanup only, so if another contract has taken the
     * role, this does nothing.
     *
     * @param _interfaceIdentifierHash The interface identifier to remove from
     *                                 the registry.
     */
    function removeSelf(bytes32 _interfaceIdentifierHash) external {
        address old = ERC1820REGISTRY.getInterfaceImplementer(
            address(this),
            _interfaceIdentifierHash
        );

        if (old == msg.sender) {
            ERC1820REGISTRY.setInterfaceImplementer(
                address(this),
                _interfaceIdentifierHash,
                address(0)
            );
        }
    }

    /** Find the policy contract for a particular identifier.
     *
     * @param _interfaceIdentifierHash The hash of the interface identifier
     *                                 look up.
     */
    function policyFor(bytes32 _interfaceIdentifierHash)
        public
        view
        returns (address)
    {
        return
            ERC1820REGISTRY.getInterfaceImplementer(
                address(this),
                _interfaceIdentifierHash
            );
    }

    /** Set the policy label for a contract
     *
     * @param _key The label to apply to the contract.
     *
     * @param _implementer The contract to assume the label.
     */
    function setPolicy(
        bytes32 _key,
        address _implementer,
        bytes32 _authKey
    ) public onlySetter(_authKey) {
        ERC1820REGISTRY.setInterfaceImplementer(
            address(this),
            _key,
            _implementer
        );
    }

    /** Enact the code of one of the governance contracts.
     *
     * @param _delegate The contract code to delegate execution to.
     */
    function internalCommand(address _delegate, bytes32 _authKey)
        public
        onlySetter(_authKey)
    {
        // solhint-disable-next-line avoid-low-level-calls
        (bool _success, ) = _delegate.delegatecall(
            abi.encodeWithSignature("enacted(address)", _delegate)
        );
        require(_success, "Command failed during delegatecall");
    }
}

// File: @openzeppelin/contracts/utils/introspection/IERC1820Implementer.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC1820Implementer.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface for an ERC1820 implementer, as defined in the
 * https://eips.ethereum.org/EIPS/eip-1820#interface-implementation-erc1820implementerinterface[EIP].
 * Used by contracts that will be registered as implementers in the
 * {IERC1820Registry}.
 */
interface IERC1820Implementer {
    /**
     * @dev Returns a special value (`ERC1820_ACCEPT_MAGIC`) if this contract
     * implements `interfaceHash` for `account`.
     *
     * See {IERC1820Registry-setInterfaceImplementer}.
     */
    function canImplementInterfaceForAddress(bytes32 interfaceHash, address account) external view returns (bytes32);
}

// File: contracts/currency/ERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../utils/StringPacker.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";
import "./ERC20Permit.sol";

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
// internal _name and _symbol are stored immutable as bytes32 and unpacked via StringPacker
contract ERC20 is ERC20Permit {
    mapping(address => uint256) internal _balances;

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

    uint256 internal _totalSupply;

    bytes32 internal immutable _name;
    bytes32 internal immutable _symbol;

    /**
     * @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 Sets the values for {name} and {symbol}.
     *
     * The default value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) ERC20Permit(name_) {
        _name = StringPacker.pack(name_);
        _symbol = StringPacker.pack(symbol_);
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual returns (string memory) {
        return StringPacker.unpack(_name);
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual returns (string memory) {
        return StringPacker.unpack(_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 this function is
     * overridden;
     *
     * 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 virtual returns (uint8) {
        return 18;
    }

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

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

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender)
        public
        view
        virtual
        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
        returns (bool)
    {
        _approve(msg.sender, 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 returns (bool) {
        _transfer(sender, recipient, amount);

        uint256 currentAllowance = _allowances[sender][msg.sender];
        require(
            currentAllowance >= amount,
            "ERC20: transfer amount exceeds allowance"
        );
        unchecked {
            _approve(sender, msg.sender, currentAllowance - amount);
        }

        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue)
        public
        virtual
        returns (bool)
    {
        _approve(
            msg.sender,
            spender,
            _allowances[msg.sender][spender] + 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)
    {
        uint256 currentAllowance = _allowances[msg.sender][spender];
        require(
            currentAllowance >= subtractedValue,
            "ERC20: decreased allowance below zero"
        );
        unchecked {
            _approve(msg.sender, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `sender` to `recipient`.
     *
     * This 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 originalAmount
    ) internal virtual {
        require(recipient != address(0), "ERC20: transfer to the zero address");

        uint256 amount = _beforeTokenTransfer(
            sender,
            recipient,
            originalAmount
        );

        uint256 senderBalance = _balances[sender];
        require(
            senderBalance >= amount,
            "ERC20: transfer amount exceeds balance"
        );
        unchecked {
            _balances[sender] = senderBalance - amount;
        }
        _balances[recipient] += amount;

        emit Transfer(sender, recipient, originalAmount);

        _afterTokenTransfer(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:
     *
     * - `account` cannot be the zero address.
     */
    function _mint(address account, uint256 originalAmount)
        internal
        virtual
        returns (uint256)
    {
        require(account != address(0), "ERC20: mint to the zero address");

        uint256 amount = _beforeTokenTransfer(
            address(0),
            account,
            originalAmount
        );

        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, originalAmount);

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

        return 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 originalAmount)
        internal
        virtual
        returns (uint256)
    {
        uint256 amount = _beforeTokenTransfer(
            account,
            address(0),
            originalAmount
        );

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
        }
        _totalSupply -= amount;

        emit Transfer(account, address(0), originalAmount);

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

        return 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 override {
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @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 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 returns (uint256) {
        return amount;
    }

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been 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 _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}

// File: @openzeppelin/contracts/security/Pausable.sol



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

pragma solidity ^0.8.0;

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

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract 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() {
        _paused = false;
    }

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

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        _requirePaused();
        _;
    }

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

    /**
     * @dev Throws if the contract is paused.
     */
    function _requireNotPaused() internal view virtual {
        require(!paused(), "Pausable: paused");
    }

    /**
     * @dev Throws if the contract is not paused.
     */
    function _requirePaused() internal view virtual {
        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());
    }
}

// File: contracts/utils/StringPacker.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

library StringPacker {
    // takes a string of 31 or less characters and converts it to bytes32
    function pack(string memory unpacked)
        internal
        pure
        returns (bytes32 packed)
    {
        // do not use this function in a lossy way, it will not work
        // only strings with 31 or less characters are stored in memory packed with their length value
        require(bytes(unpacked).length < 32);
        // shift the memory pointer to pack the length of the string into the high byte
        // by assigning this to the return value, the type of bytes32 means that, when returning,
        // the pointer continues to read into the string data
        assembly {
            packed := mload(add(unpacked, 31))
        }
    }

    // takes a bytes32 packed in the format above and unpacks it into a string
    function unpack(bytes32 packed)
        internal
        pure
        returns (string memory unpacked)
    {
        // get the high byte which stores the length of the string when unpacked
        uint256 len = uint256(packed >> 248);
        // ensure that the length of the unpacked string doesn't read beyond the input value
        require(len < 32);
        // initialize the return value with the length
        unpacked = string(new bytes(len));
        // shift the pointer so that the length will be at the bottom of the word to match string encoding
        // then store the packed value
        assembly {
            // Potentially writes into unallocated memory as the length in the packed form will trail off the end
            // This is fine as there are no other relevant memory values to overwrite
            mstore(add(unpacked, 31), packed)
        }
    }
}

// File: contracts/currency/ERC20Permit.sol



// SPDX-License-Identifier: MIT
// Heavily inspired by:
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-ERC20Permit.sol)

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/utils/Counters.sol";
import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
import "@openzeppelin/contracts/utils/cryptography/draft-EIP712.sol";

/**
 * @dev Implementation of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 *
 * _Available since v3.4._
 */
abstract contract ERC20Permit is IERC20Permit, EIP712 {
    using Counters for Counters.Counter;

    mapping(address => Counters.Counter) private _nonces;

    // solhint-disable-next-line var-name-mixedcase
    bytes32 private immutable _PERMIT_TYPEHASH =
        keccak256(
            "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
        );

    /**
     * @dev Initializes the {EIP712} domain separator using the `name` parameter, and setting `version` to `"1"`.
     *
     * It's a good idea to use the same `name` that is defined as the ERC20 token name.
     */
    constructor(string memory name) EIP712(name, "1") {
        //empty block in order to pass parameters to the parent EIP712 constructor
    }

    /**
     * @dev See {IERC20Permit-permit}.
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public virtual override {
        require(block.timestamp <= deadline, "ERC20Permit: expired deadline");

        bytes32 structHash = keccak256(
            abi.encode(
                _PERMIT_TYPEHASH,
                owner,
                spender,
                value,
                _useNonce(owner),
                deadline
            )
        );

        bytes32 hash = _hashTypedDataV4(structHash);

        address signer = ECDSA.recover(hash, v, r, s);
        require(signer == owner, "ERC20Permit: invalid signature");

        _approve(owner, spender, value);
    }

    /**
     * @dev See {IERC20Permit-nonces}.
     */
    function nonces(address owner)
        public
        view
        virtual
        override
        returns (uint256)
    {
        return _nonces[owner].current();
    }

    /**
     * @dev See {IERC20Permit-DOMAIN_SEPARATOR}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view override returns (bytes32) {
        return _domainSeparatorV4();
    }

    /**
     * @dev "Consume a nonce": return the current value and increment.
     *
     * _Available since v4.1._
     */
    function _useNonce(address owner)
        internal
        virtual
        returns (uint256 current)
    {
        Counters.Counter storage nonce = _nonces[owner];
        current = nonce.current();
        nonce.increment();
    }

    /**
     * @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;
}

// 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/utils/Counters.sol



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

pragma solidity ^0.8.0;

/**
 * @title Counters
 * @author Matt Condon (@shrugs)
 * @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
 * of elements in a mapping, issuing ERC721 ids, or counting request ids.
 *
 * Include with `using Counters for Counters.Counter;`
 */
library Counters {
    struct Counter {
        // This variable should never be directly accessed by users of the library: interactions must be restricted to
        // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
        // this feature: see https://github.com/ethereum/solidity/issues/4637
        uint256 _value; // default: 0
    }

    function current(Counter storage counter) internal view returns (uint256) {
        return counter._value;
    }

    function increment(Counter storage counter) internal {
        unchecked {
            counter._value += 1;
        }
    }

    function decrement(Counter storage counter) internal {
        uint256 value = counter._value;
        require(value > 0, "Counter: decrement overflow");
        unchecked {
            counter._value = value - 1;
        }
    }

    function reset(Counter storage counter) internal {
        counter._value = 0;
    }
}

// File: @openzeppelin/contracts/utils/cryptography/ECDSA.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.3) (utils/cryptography/ECDSA.sol)

pragma solidity ^0.8.0;

import "../Strings.sol";

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    enum RecoverError {
        NoError,
        InvalidSignature,
        InvalidSignatureLength,
        InvalidSignatureS,
        InvalidSignatureV
    }

    function _throwError(RecoverError error) private pure {
        if (error == RecoverError.NoError) {
            return; // no error: do nothing
        } else if (error == RecoverError.InvalidSignature) {
            revert("ECDSA: invalid signature");
        } else if (error == RecoverError.InvalidSignatureLength) {
            revert("ECDSA: invalid signature length");
        } else if (error == RecoverError.InvalidSignatureS) {
            revert("ECDSA: invalid signature 's' value");
        } else if (error == RecoverError.InvalidSignatureV) {
            revert("ECDSA: invalid signature 'v' value");
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature` or error string. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     *
     * Documentation for signature generation:
     * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
     * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
     *
     * _Available since v4.3._
     */
    function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
        if (signature.length == 65) {
            bytes32 r;
            bytes32 s;
            uint8 v;
            // ecrecover takes the signature parameters, and the only way to get them
            // currently is to use assembly.
            /// @solidity memory-safe-assembly
            assembly {
                r := mload(add(signature, 0x20))
                s := mload(add(signature, 0x40))
                v := byte(0, mload(add(signature, 0x60)))
            }
            return tryRecover(hash, v, r, s);
        } else {
            return (address(0), RecoverError.InvalidSignatureLength);
        }
    }

    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, signature);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
     *
     * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address, RecoverError) {
        bytes32 s = vs & bytes32(0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
        uint8 v = uint8((uint256(vs) >> 255) + 27);
        return tryRecover(hash, v, r, s);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
     *
     * _Available since v4.2._
     */
    function recover(
        bytes32 hash,
        bytes32 r,
        bytes32 vs
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, r, vs);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
     * `r` and `s` signature fields separately.
     *
     * _Available since v4.3._
     */
    function tryRecover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address, RecoverError) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
            return (address(0), RecoverError.InvalidSignatureS);
        }
        if (v != 27 && v != 28) {
            return (address(0), RecoverError.InvalidSignatureV);
        }

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        if (signer == address(0)) {
            return (address(0), RecoverError.InvalidSignature);
        }

        return (signer, RecoverError.NoError);
    }

    /**
     * @dev Overload of {ECDSA-recover} that receives the `v`,
     * `r` and `s` signature fields separately.
     */
    function recover(
        bytes32 hash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address) {
        (address recovered, RecoverError error) = tryRecover(hash, v, r, s);
        _throwError(error);
        return recovered;
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from `s`. This
     * produces hash corresponding to the one signed with the
     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
     * JSON-RPC method as part of EIP-191.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n", Strings.toString(s.length), s));
    }

    /**
     * @dev Returns an Ethereum Signed Typed Data, created from a
     * `domainSeparator` and a `structHash`. This produces hash corresponding
     * to the one signed with the
     * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
     * JSON-RPC method as part of EIP-712.
     *
     * See {recover}.
     */
    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
    }
}

// File: @openzeppelin/contracts/utils/cryptography/draft-EIP712.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/cryptography/draft-EIP712.sol)

pragma solidity ^0.8.0;

import "./ECDSA.sol";

/**
 * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
 *
 * The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
 * thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
 * they need in their contracts using a combination of `abi.encode` and `keccak256`.
 *
 * This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
 * scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
 * ({_hashTypedDataV4}).
 *
 * The implementation of the domain separator was designed to be as efficient as possible while still properly updating
 * the chain id to protect against replay attacks on an eventual fork of the chain.
 *
 * NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
 * https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
 *
 * _Available since v3.4._
 */
abstract contract EIP712 {
    /* solhint-disable var-name-mixedcase */
    // Cache the domain separator as an immutable value, but also store the chain id that it corresponds to, in order to
    // invalidate the cached domain separator if the chain id changes.
    bytes32 private immutable _CACHED_DOMAIN_SEPARATOR;
    uint256 private immutable _CACHED_CHAIN_ID;
    address private immutable _CACHED_THIS;

    bytes32 private immutable _HASHED_NAME;
    bytes32 private immutable _HASHED_VERSION;
    bytes32 private immutable _TYPE_HASH;

    /* solhint-enable var-name-mixedcase */

    /**
     * @dev Initializes the domain separator and parameter caches.
     *
     * The meaning of `name` and `version` is specified in
     * https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
     *
     * - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
     * - `version`: the current major version of the signing domain.
     *
     * NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
     * contract upgrade].
     */
    constructor(string memory name, string memory version) {
        bytes32 hashedName = keccak256(bytes(name));
        bytes32 hashedVersion = keccak256(bytes(version));
        bytes32 typeHash = keccak256(
            "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
        );
        _HASHED_NAME = hashedName;
        _HASHED_VERSION = hashedVersion;
        _CACHED_CHAIN_ID = block.chainid;
        _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator(typeHash, hashedName, hashedVersion);
        _CACHED_THIS = address(this);
        _TYPE_HASH = typeHash;
    }

    /**
     * @dev Returns the domain separator for the current chain.
     */
    function _domainSeparatorV4() internal view returns (bytes32) {
        if (address(this) == _CACHED_THIS && block.chainid == _CACHED_CHAIN_ID) {
            return _CACHED_DOMAIN_SEPARATOR;
        } else {
            return _buildDomainSeparator(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION);
        }
    }

    function _buildDomainSeparator(
        bytes32 typeHash,
        bytes32 nameHash,
        bytes32 versionHash
    ) private view returns (bytes32) {
        return keccak256(abi.encode(typeHash, nameHash, versionHash, block.chainid, address(this)));
    }

    /**
     * @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
     * function returns the hash of the fully encoded EIP712 message for this domain.
     *
     * This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
     *
     * ```solidity
     * bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
     *     keccak256("Mail(address to,string contents)"),
     *     mailTo,
     *     keccak256(bytes(mailContents))
     * )));
     * address signer = ECDSA.recover(digest, signature);
     * ```
     */
    function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
        return ECDSA.toTypedDataHash(_domainSeparatorV4(), structHash);
    }
}

// File: @openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

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



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

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
    uint8 private constant _ADDRESS_LENGTH = 20;

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
     */
    function toHexString(address addr) internal pure returns (string memory) {
        return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
    }
}

// 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;
    }
}