Cryo Explorer Ethereum Mainnet

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

pragma solidity 0.8.9;

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

abstract contract Pauser is Ownable, Pausable {
    mapping(address => bool) public pausers;

    event PauserAdded(address account);
    event PauserRemoved(address account);

    constructor() {
        _addPauser(msg.sender);
    }

    modifier onlyPauser() {
        require(isPauser(msg.sender), "Caller is not pauser");
        _;
    }

    function pause() public onlyPauser {
        _pause();
    }

    function unpause() public onlyPauser {
        _unpause();
    }

    function isPauser(address account) public view returns (bool) {
        return pausers[account];
    }

    function addPauser(address account) public onlyOwner {
        _addPauser(account);
    }

    function removePauser(address account) public onlyOwner {
        _removePauser(account);
    }

    function renouncePauser() public {
        _removePauser(msg.sender);
    }

    function _addPauser(address account) private {
        require(!isPauser(account), "Account is already pauser");
        pausers[account] = true;
        emit PauserAdded(account);
    }

    function _removePauser(address account) private {
        require(isPauser(account), "Account is not pauser");
        pausers[account] = false;
        emit PauserRemoved(account);
    }
}

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

pragma solidity 0.8.9;

// runtime proto sol library
library Pb {
    enum WireType {
        Varint,
        Fixed64,
        LengthDelim,
        StartGroup,
        EndGroup,
        Fixed32
    }

    struct Buffer {
        uint256 idx; // the start index of next read. when idx=b.length, we're done
        bytes b; // hold serialized proto msg, readonly
    }

    // create a new in-memory Buffer object from raw msg bytes
    function fromBytes(bytes memory raw) internal pure returns (Buffer memory buf) {
        buf.b = raw;
        buf.idx = 0;
    }

    // whether there are unread bytes
    function hasMore(Buffer memory buf) internal pure returns (bool) {
        return buf.idx < buf.b.length;
    }

    // decode current field number and wiretype
    function decKey(Buffer memory buf) internal pure returns (uint256 tag, WireType wiretype) {
        uint256 v = decVarint(buf);
        tag = v / 8;
        wiretype = WireType(v & 7);
    }

    // count tag occurrences, return an array due to no memory map support
    // have to create array for (maxtag+1) size. cnts[tag] = occurrences
    // should keep buf.idx unchanged because this is only a count function
    function cntTags(Buffer memory buf, uint256 maxtag) internal pure returns (uint256[] memory cnts) {
        uint256 originalIdx = buf.idx;
        cnts = new uint256[](maxtag + 1); // protobuf's tags are from 1 rather than 0
        uint256 tag;
        WireType wire;
        while (hasMore(buf)) {
            (tag, wire) = decKey(buf);
            cnts[tag] += 1;
            skipValue(buf, wire);
        }
        buf.idx = originalIdx;
    }

    // read varint from current buf idx, move buf.idx to next read, return the int value
    function decVarint(Buffer memory buf) internal pure returns (uint256 v) {
        bytes10 tmp; // proto int is at most 10 bytes (7 bits can be used per byte)
        bytes memory bb = buf.b; // get buf.b mem addr to use in assembly
        v = buf.idx; // use v to save one additional uint variable
        assembly {
            tmp := mload(add(add(bb, 32), v)) // load 10 bytes from buf.b[buf.idx] to tmp
        }
        uint256 b; // store current byte content
        v = 0; // reset to 0 for return value
        for (uint256 i = 0; i < 10; i++) {
            assembly {
                b := byte(i, tmp) // don't use tmp[i] because it does bound check and costs extra
            }
            v |= (b & 0x7F) << (i * 7);
            if (b & 0x80 == 0) {
                buf.idx += i + 1;
                return v;
            }
        }
        revert(); // i=10, invalid varint stream
    }

    // read length delimited field and return bytes
    function decBytes(Buffer memory buf) internal pure returns (bytes memory b) {
        uint256 len = decVarint(buf);
        uint256 end = buf.idx + len;
        require(end <= buf.b.length); // avoid overflow
        b = new bytes(len);
        bytes memory bufB = buf.b; // get buf.b mem addr to use in assembly
        uint256 bStart;
        uint256 bufBStart = buf.idx;
        assembly {
            bStart := add(b, 32)
            bufBStart := add(add(bufB, 32), bufBStart)
        }
        for (uint256 i = 0; i < len; i += 32) {
            assembly {
                mstore(add(bStart, i), mload(add(bufBStart, i)))
            }
        }
        buf.idx = end;
    }

    // return packed ints
    function decPacked(Buffer memory buf) internal pure returns (uint256[] memory t) {
        uint256 len = decVarint(buf);
        uint256 end = buf.idx + len;
        require(end <= buf.b.length); // avoid overflow
        // array in memory must be init w/ known length
        // so we have to create a tmp array w/ max possible len first
        uint256[] memory tmp = new uint256[](len);
        uint256 i = 0; // count how many ints are there
        while (buf.idx < end) {
            tmp[i] = decVarint(buf);
            i++;
        }
        t = new uint256[](i); // init t with correct length
        for (uint256 j = 0; j < i; j++) {
            t[j] = tmp[j];
        }
        return t;
    }

    // move idx pass current value field, to beginning of next tag or msg end
    function skipValue(Buffer memory buf, WireType wire) internal pure {
        if (wire == WireType.Varint) {
            decVarint(buf);
        } else if (wire == WireType.LengthDelim) {
            uint256 len = decVarint(buf);
            buf.idx += len; // skip len bytes value data
            require(buf.idx <= buf.b.length); // avoid overflow
        } else {
            revert();
        } // unsupported wiretype
    }

    // type conversion help utils
    function _bool(uint256 x) internal pure returns (bool v) {
        return x != 0;
    }

    function _uint256(bytes memory b) internal pure returns (uint256 v) {
        require(b.length <= 32); // b's length must be smaller than or equal to 32
        assembly {
            v := mload(add(b, 32))
        } // load all 32bytes to v
        v = v >> (8 * (32 - b.length)); // only first b.length is valid
    }

    function _address(bytes memory b) internal pure returns (address v) {
        v = _addressPayable(b);
    }

    function _addressPayable(bytes memory b) internal pure returns (address payable v) {
        require(b.length == 20);
        //load 32bytes then shift right 12 bytes
        assembly {
            v := div(mload(add(b, 32)), 0x1000000000000000000000000)
        }
    }

    function _bytes32(bytes memory b) internal pure returns (bytes32 v) {
        require(b.length == 32);
        assembly {
            v := mload(add(b, 32))
        }
    }

    // uint[] to uint8[]
    function uint8s(uint256[] memory arr) internal pure returns (uint8[] memory t) {
        t = new uint8[](arr.length);
        for (uint256 i = 0; i < t.length; i++) {
            t[i] = uint8(arr[i]);
        }
    }

    function uint32s(uint256[] memory arr) internal pure returns (uint32[] memory t) {
        t = new uint32[](arr.length);
        for (uint256 i = 0; i < t.length; i++) {
            t[i] = uint32(arr[i]);
        }
    }

    function uint64s(uint256[] memory arr) internal pure returns (uint64[] memory t) {
        t = new uint64[](arr.length);
        for (uint256 i = 0; i < t.length; i++) {
            t[i] = uint64(arr[i]);
        }
    }

    function bools(uint256[] memory arr) internal pure returns (bool[] memory t) {
        t = new bool[](arr.length);
        for (uint256 i = 0; i < t.length; i++) {
            t[i] = arr[i] != 0;
        }
    }
}

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

pragma solidity 0.8.9;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import {DataTypes as dt} from "./libraries/DataTypes.sol";
import "./interfaces/ISigsVerifier.sol";
import "./libraries/PbFarming.sol";
import "./Pauser.sol";

contract FarmingRewards is Pauser {
    using SafeERC20 for IERC20;

    ISigsVerifier public immutable sigsVerifier;

    // recipient => tokenAddress => amount
    mapping(address => mapping(address => uint256)) public claimedRewardAmounts;

    event FarmingRewardClaimed(address indexed recipient, address indexed token, uint256 reward);
    event FarmingRewardContributed(address indexed contributor, address indexed token, uint256 contribution);

    constructor(ISigsVerifier _sigsVerifier) {
        sigsVerifier = _sigsVerifier;
    }

    /**
     * @notice Claim rewards
     * @dev Here we use cumulative reward to make claim process idempotent
     * @param _rewardsRequest rewards request bytes coded in protobuf
     * @param _sigs list of signatures sorted by signer addresses
     * @param _signers sorted list of current signers
     * @param _powers powers of current signers
     */
    function claimRewards(
        bytes calldata _rewardsRequest,
        bytes[] calldata _sigs,
        address[] calldata _signers,
        uint256[] calldata _powers
    ) external whenNotPaused {
        bytes32 domain = keccak256(abi.encodePacked(block.chainid, address(this), "FarmingRewards"));
        sigsVerifier.verifySigs(abi.encodePacked(domain, _rewardsRequest), _sigs, _signers, _powers);
        PbFarming.FarmingRewards memory rewards = PbFarming.decFarmingRewards(_rewardsRequest);
        bool hasNewReward;
        for (uint256 i = 0; i < rewards.tokenAddresses.length; i++) {
            address token = rewards.tokenAddresses[i];
            uint256 cumulativeRewardAmount = rewards.cumulativeRewardAmounts[i];
            uint256 newReward = cumulativeRewardAmount - claimedRewardAmounts[rewards.recipient][token];
            if (newReward > 0) {
                hasNewReward = true;
                claimedRewardAmounts[rewards.recipient][token] = cumulativeRewardAmount;
                IERC20(token).safeTransfer(rewards.recipient, newReward);
                emit FarmingRewardClaimed(rewards.recipient, token, newReward);
            }
        }
        require(hasNewReward, "No new reward");
    }

    /**
     * @notice Contribute reward tokens to the reward pool
     * @param _token the address of the token to contribute
     * @param _amount the amount of the token to contribute
     */
    function contributeToRewardPool(address _token, uint256 _amount) external whenNotPaused {
        address contributor = msg.sender;
        IERC20(_token).safeTransferFrom(contributor, address(this), _amount);

        emit FarmingRewardContributed(contributor, _token, _amount);
    }

    /**
     * @notice Owner drains tokens when the contract is paused
     * @dev emergency use only
     * @param _token the address of the token to drain
     * @param _amount drained token amount
     */
    function drainToken(address _token, uint256 _amount) external whenPaused onlyOwner {
        IERC20(_token).safeTransfer(msg.sender, _amount);
    }
}

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

pragma solidity 0.8.9;

library DataTypes {
    uint256 constant CELR_DECIMAL = 1e18;
    uint256 constant MAX_INT = 2**256 - 1;
    uint256 constant COMMISSION_RATE_BASE = 10000; // 1 commissionRate means 0.01%
    uint256 constant MAX_UNDELEGATION_ENTRIES = 10;
    uint256 constant SLASH_FACTOR_DECIMAL = 1e6;

    enum ValidatorStatus {
        Null,
        Unbonded,
        Unbonding,
        Bonded
    }

    enum ParamName {
        ProposalDeposit,
        VotingPeriod,
        UnbondingPeriod,
        MaxBondedValidators,
        MinValidatorTokens,
        MinSelfDelegation,
        AdvanceNoticePeriod,
        ValidatorBondInterval,
        MaxSlashFactor
    }

    struct Undelegation {
        uint256 shares;
        uint256 creationBlock;
    }

    struct Undelegations {
        mapping(uint256 => Undelegation) queue;
        uint32 head;
        uint32 tail;
    }

    struct Delegator {
        uint256 shares;
        Undelegations undelegations;
    }

    struct Validator {
        ValidatorStatus status;
        address signer;
        uint256 tokens; // sum of all tokens delegated to this validator
        uint256 shares; // sum of all delegation shares
        uint256 undelegationTokens; // tokens being undelegated
        uint256 undelegationShares; // shares of tokens being undelegated
        mapping(address => Delegator) delegators;
        uint256 minSelfDelegation;
        uint64 bondBlock; // cannot become bonded before this block
        uint64 unbondBlock; // cannot become unbonded before this block
        uint64 commissionRate; // equal to real commission rate * COMMISSION_RATE_BASE
    }

    // used for external view output
    struct ValidatorTokens {
        address valAddr;
        uint256 tokens;
    }

    // used for external view output
    struct ValidatorInfo {
        address valAddr;
        ValidatorStatus status;
        address signer;
        uint256 tokens;
        uint256 shares;
        uint256 minSelfDelegation;
        uint64 commissionRate;
    }

    // used for external view output
    struct DelegatorInfo {
        address valAddr;
        uint256 tokens;
        uint256 shares;
        Undelegation[] undelegations;
        uint256 undelegationTokens;
        uint256 withdrawableUndelegationTokens;
    }
}

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

// Code generated by protoc-gen-sol. DO NOT EDIT.
// source: contracts/libraries/proto/farming.proto
pragma solidity 0.8.9;
import "./Pb.sol";

library PbFarming {
    using Pb for Pb.Buffer; // so we can call Pb funcs on Buffer obj

    struct FarmingRewards {
        address recipient; // tag: 1
        address[] tokenAddresses; // tag: 2
        uint256[] cumulativeRewardAmounts; // tag: 3
    } // end struct FarmingRewards

    function decFarmingRewards(bytes memory raw) internal pure returns (FarmingRewards memory m) {
        Pb.Buffer memory buf = Pb.fromBytes(raw);

        uint256[] memory cnts = buf.cntTags(3);
        m.tokenAddresses = new address[](cnts[2]);
        cnts[2] = 0; // reset counter for later use
        m.cumulativeRewardAmounts = new uint256[](cnts[3]);
        cnts[3] = 0; // reset counter for later use

        uint256 tag;
        Pb.WireType wire;
        while (buf.hasMore()) {
            (tag, wire) = buf.decKey();
            if (false) {}
            // solidity has no switch/case
            else if (tag == 1) {
                m.recipient = Pb._address(buf.decBytes());
            } else if (tag == 2) {
                m.tokenAddresses[cnts[2]] = Pb._address(buf.decBytes());
                cnts[2]++;
            } else if (tag == 3) {
                m.cumulativeRewardAmounts[cnts[3]] = Pb._uint256(buf.decBytes());
                cnts[3]++;
            } else {
                buf.skipValue(wire);
            } // skip value of unknown tag
        }
    } // end decoder FarmingRewards
}

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

pragma solidity 0.8.9;

interface ISigsVerifier {
    /**
     * @notice Verifies that a message is signed by a quorum among the signers.
     * @param _msg signed message
     * @param _sigs list of signatures sorted by signer addresses
     * @param _signers sorted list of current signers
     * @param _powers powers of current signers
     */
    function verifySigs(
        bytes memory _msg,
        bytes[] calldata _sigs,
        address[] calldata _signers,
        uint256[] calldata _powers
    ) external view;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) private pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// SPDX-License-Identifier: MIT

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;
    }
}

// SPDX-License-Identifier: MIT

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() {
        _setOwner(_msgSender());
    }

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

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

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT

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

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

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

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

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

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

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

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}