DevmindUSDTVault

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.30;

// ============================================================================
// FLATTENED CONTRACT FOR ETHERSCAN VERIFICATION
// This file combines all OpenZeppelin dependencies into a single file
// Use this for "Solidity (Single File)" verification on Etherscan/PolygonScan/BscScan
// ============================================================================

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev The ETH balance of the account is not enough to perform the operation.
     */
    error AddressInsufficientBalance(address account);

    /**
     * @dev There's no code at `target` (it is not a contract).
     */
    error AddressEmptyCode(address target);

    /**
     * @dev A call to an address target failed. The target may have reverted.
     */
    error FailedInnerCall();

    /**
     * @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://consensys.net/diligence/blog/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/v0.8.20/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        if (address(this).balance < amount) {
            revert AddressInsufficientBalance(address(this));
        }

        (bool success, ) = recipient.call{value: amount}("");
        if (!success) {
            revert FailedInnerCall();
        }
    }

    /**
     * @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 or custom error, it is bubbled
     * up by this function (like regular Solidity function calls). However, if
     * the call reverted with no returned reason, this function reverts with a
     * {FailedInnerCall} error.
     *
     * 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.
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0);
    }

    /**
     * @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`.
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        if (address(this).balance < value) {
            revert AddressInsufficientBalance(address(this));
        }
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and reverts if the target
     * was not a contract or bubbling up the revert reason (falling back to {FailedInnerCall}) in case of an
     * unsuccessful call.
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata
    ) internal view returns (bytes memory) {
        if (!success) {
            _revert(returndata);
        } else {
            // only check if target is a contract if the call was successful and the return data is empty
            // otherwise we already know that it was a contract
            if (returndata.length == 0 && target.code.length == 0) {
                revert AddressEmptyCode(target);
            }
            return returndata;
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and reverts if it wasn't, either by bubbling the
     * revert reason or with a default {FailedInnerCall} error.
     */
    function verifyCallResult(bool success, bytes memory returndata) internal pure returns (bytes memory) {
        if (!success) {
            _revert(returndata);
        } else {
            return returndata;
        }
    }

    /**
     * @dev Reverts with returndata if present. Otherwise reverts with {FailedInnerCall}.
     */
    function _revert(bytes memory returndata) private pure {
        // 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
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert FailedInnerCall();
        }
    }
}

/**
 * @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 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);
}

/**
 * @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;

    /**
     * @dev An operation with an ERC20 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 Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    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.
     */
    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.
     */
    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 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);
        if (returndata.length != 0 && !abi.decode(returndata, (bool))) {
            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 silents catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
        // 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 cannot use {Address-functionCall} here since this should return false
        // and not revert is the subcall reverts.

        (bool success, bytes memory returndata) = address(token).call(data);
        return success && (returndata.length == 0 || abi.decode(returndata, (bool))) && address(token).code.length > 0;
    }
}

/**
 * @title DevmindUSDTVault
 * @dev Time-locked USDT vault with emergency withdrawal capabilities
 * @notice This vault allows deposits anytime but withdrawals only after lock period
 *         Emergency wallet can withdraw during lock period with daily/monthly caps
 * @notice Uses SafeERC20 to handle USDT's non-standard ERC20 implementation
 */
contract DevmindUSDTVault {
    using SafeERC20 for IERC20;
    
    // State variables
    address public owner;
    address public emergencyWallet;
    IERC20 public usdt;
    
    uint256 public lockStart;
    uint256 public lockEnd;
    uint256 public dailyCap;
    uint256 public monthlyCap;
    
    uint256 public dailyUsed;
    uint256 public monthlyUsed;
    uint256 public lastDailyReset;
    uint256 public lastMonthlyReset;
    
    bool public unlocked;
    
    // Constants
    uint256 private constant DAY = 1 days;
    uint256 private constant MONTH = 30 days;
    
    // Events
    event DepositRecorded(address indexed from, uint256 amount, uint256 timestamp);
    event WithdrawalExecuted(address indexed to, uint256 amount, uint256 timestamp);
    event EmergencyWithdrawal(address indexed to, uint256 amount, uint256 timestamp);
    event VaultUnlocked(uint256 timestamp);
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
    event EmergencyWalletUpdated(address indexed previousWallet, address indexed newWallet);
    
    // Custom errors
    error Unauthorized();
    error VaultStillLocked();
    error InsufficientFunds();
    error EmergencyDailyCapExceeded();
    error EmergencyMonthlyCapExceeded();
    error InvalidAddress();
    error InvalidAmount();
    error InvalidLockPeriod();
    
    // Modifiers
    modifier onlyOwner() {
        if (msg.sender != owner) revert Unauthorized();
        _;
    }
    
    modifier onlyEmergencyWallet() {
        if (msg.sender != emergencyWallet) revert Unauthorized();
        _;
    }
    
    modifier onlyAfterUnlock() {
        if (block.timestamp < lockEnd) revert VaultStillLocked();
        _;
        if (!unlocked) {
            unlocked = true;
            emit VaultUnlocked(block.timestamp);
        }
    }
    
    /**
     * @dev Constructor to initialize the vault
     * @param _owner Address of the vault owner
     * @param _emergencyWallet Address of emergency wallet
     * @param _usdtAddress Address of USDT token contract
     * @param _lockDuration Duration of lock period in seconds
     * @param _dailyCap Daily withdrawal cap for emergency wallet
     * @param _monthlyCap Monthly withdrawal cap for emergency wallet
     */
    constructor(
        address _owner,
        address _emergencyWallet,
        address _usdtAddress,
        uint256 _lockDuration,
        uint256 _dailyCap,
        uint256 _monthlyCap
    ) {
        if (_owner == address(0) || _emergencyWallet == address(0) || _usdtAddress == address(0)) {
            revert InvalidAddress();
        }
        if (_lockDuration == 0) revert InvalidLockPeriod();
        if (_dailyCap == 0 || _monthlyCap == 0) revert InvalidAmount();
        if (_dailyCap > _monthlyCap) revert InvalidAmount();
        
        owner = _owner;
        emergencyWallet = _emergencyWallet;
        usdt = IERC20(_usdtAddress);
        
        lockStart = block.timestamp;
        lockEnd = block.timestamp + _lockDuration;
        dailyCap = _dailyCap;
        monthlyCap = _monthlyCap;
        
        lastDailyReset = block.timestamp;
        lastMonthlyReset = block.timestamp;
        unlocked = false;
    }
    
    /**
     * @dev Deposit USDT to vault via pre-approved allowance
     * @param amount Amount of USDT to deposit (in smallest unit, e.g., 1 USDT = 1000000)
     */
    function depositViaApprove(uint256 amount) external {
        if (amount == 0) revert InvalidAmount();
        
        usdt.safeTransferFrom(msg.sender, address(this), amount);
        
        emit DepositRecorded(msg.sender, amount, block.timestamp);
    }
    
    /**
     * @dev Withdraw specific amount after lock period (owner only)
     * @param amount Amount to withdraw
     */
    function withdraw(uint256 amount) external onlyOwner onlyAfterUnlock {
        if (amount == 0) revert InvalidAmount();
        
        uint256 vaultBalance = usdt.balanceOf(address(this));
        if (amount > vaultBalance) revert InsufficientFunds();
        
        usdt.safeTransfer(owner, amount);
        
        emit WithdrawalExecuted(owner, amount, block.timestamp);
    }
    
    /**
     * @dev Withdraw all funds after lock period (owner only)
     */
    function withdrawAll() external onlyOwner onlyAfterUnlock {
        uint256 vaultBalance = usdt.balanceOf(address(this));
        if (vaultBalance == 0) revert InsufficientFunds();
        
        usdt.safeTransfer(owner, vaultBalance);
        
        emit WithdrawalExecuted(owner, vaultBalance, block.timestamp);
    }
    
    /**
     * @dev Emergency withdrawal with daily/monthly caps (emergency wallet only)
     * @param amount Amount to withdraw
     */
    function emergencyWithdraw(uint256 amount) external onlyEmergencyWallet {
        if (amount == 0) revert InvalidAmount();
        
        uint256 vaultBalance = usdt.balanceOf(address(this));
        if (amount > vaultBalance) revert InsufficientFunds();
        
        // Reset counters if needed
        if (block.timestamp >= lastDailyReset + DAY) {
            dailyUsed = 0;
            lastDailyReset = block.timestamp;
        }
        if (block.timestamp >= lastMonthlyReset + MONTH) {
            monthlyUsed = 0;
            lastMonthlyReset = block.timestamp;
        }
        
        // Check caps
        if (dailyUsed + amount > dailyCap) revert EmergencyDailyCapExceeded();
        if (monthlyUsed + amount > monthlyCap) revert EmergencyMonthlyCapExceeded();
        
        // Update usage
        dailyUsed += amount;
        monthlyUsed += amount;
        
        usdt.safeTransfer(emergencyWallet, amount);
        
        emit EmergencyWithdrawal(emergencyWallet, amount, block.timestamp);
    }
    
    /**
     * @dev Get current vault balance
     */
    function balance() external view returns (uint256) {
        return usdt.balanceOf(address(this));
    }
    
    /**
     * @dev Get comprehensive vault information
     */
    function getVaultInfo() external view returns (
        address vaultOwner,
        address tokenAddress,
        address emergencyAddr,
        uint256 currentBalance,
        bool isUnlocked,
        uint256 timeRemaining,
        uint256 emergencyDailyCap,
        uint256 emergencyMonthlyCap
    ) {
        uint256 remaining = 0;
        if (block.timestamp < lockEnd) {
            remaining = lockEnd - block.timestamp;
        }
        
        return (
            owner,
            address(usdt),
            emergencyWallet,
            usdt.balanceOf(address(this)),
            block.timestamp >= lockEnd,
            remaining,
            dailyCap,
            monthlyCap
        );
    }
    
    /**
     * @dev Get emergency withdrawal limits and usage
     */
    function getEmergencyLimits() external view returns (
        uint256 emergencyDailyCap,
        uint256 emergencyMonthlyCap,
        uint256 emergencyDailyUsed,
        uint256 emergencyMonthlyUsed
    ) {
        uint256 currentDailyUsed = dailyUsed;
        uint256 currentMonthlyUsed = monthlyUsed;
        
        // Account for resets that would happen
        if (block.timestamp >= lastDailyReset + DAY) {
            currentDailyUsed = 0;
        }
        if (block.timestamp >= lastMonthlyReset + MONTH) {
            currentMonthlyUsed = 0;
        }
        
        return (dailyCap, monthlyCap, currentDailyUsed, currentMonthlyUsed);
    }
    
    /**
     * @dev Transfer ownership to a new address
     * @param newOwner Address of new owner
     */
    function transferOwnership(address newOwner) external onlyOwner {
        if (newOwner == address(0)) revert InvalidAddress();
        
        address oldOwner = owner;
        owner = newOwner;
        
        emit OwnershipTransferred(oldOwner, newOwner);
    }
    
    /**
     * @dev Update emergency wallet address
     * @param newEmergencyWallet Address of new emergency wallet
     */
    function updateEmergencyWallet(address newEmergencyWallet) external onlyOwner {
        if (newEmergencyWallet == address(0)) revert InvalidAddress();
        
        address oldWallet = emergencyWallet;
        emergencyWallet = newEmergencyWallet;
        
        emit EmergencyWalletUpdated(oldWallet, newEmergencyWallet);
    }
}