GPT

UUPS Upgradeable Vault Pattern

// SPDX-License-Identifier: MIT pragma solidity ^0.8.24; import {UUPSUpgradeable} from "@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol"; import {OwnableUpgradeable} from "@openzeppelin/contracts-upg

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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import {UUPSUpgradeable} from "@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol";
import {OwnableUpgradeable} from "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import {ReentrancyGuardUpgradeable} from "@openzeppelin/contracts-upgradeable/utils/ReentrancyGuardUpgradeable.sol";
import {PausableUpgradeable} from "@openzeppelin/contracts-upgradeable/utils/PausableUpgradeable.sol";
import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

/// @title StakingVault
/// @notice Upgradeable staking vault with timelock withdrawals
/// @dev UUPS proxy pattern — upgrade logic lives in implementation
contract StakingVault is
 UUPSUpgradeable,
 OwnableUpgradeable,
 ReentrancyGuardUpgradeable,
 PausableUpgradeable
{
 using SafeERC20 for IERC20;

 struct StakeInfo {
 uint128 amount; // Packed: 128 bits
 uint64 stakeTime; // Packed: 64 bits — good until year 584 billion
 uint64 lockEndTime; // Packed: 64 bits — same slot as above
 }

 IERC20 public stakingToken;
 uint256 public lockDuration;
 uint256 public totalStaked;
 mapping(address => StakeInfo) public stakes;

 event Staked(address indexed user, uint256 amount, uint256 lockEndTime);
 event Withdrawn(address indexed user, uint256 amount);
 event LockDurationUpdated(uint256 oldDuration, uint256 newDuration);

 error ZeroAmount();
 error LockNotExpired(uint256 lockEndTime, uint256 currentTime);
 error NoStake();

 /// @custom:oz-upgrades-unsafe-allow constructor
 constructor() {
 _disableInitializers();
 }

 function initialize(
 address stakingToken_,
 uint256 lockDuration_,
 address owner_
 ) external initializer {
 __UUPSUpgradeable_init();
 __Ownable_init(owner_);
 __ReentrancyGuard_init();
 __Pausable_init();

 stakingToken = IERC20(stakingToken_);
 lockDuration = lockDuration_;
 }

 /// @notice Stake tokens into the vault
 /// @param amount Amount of tokens to stake
 function stake(uint256 amount) external nonReentrant whenNotPaused {
 if (amount == 0) revert ZeroAmount();

 // Effects before interactions
 StakeInfo storage info = stakes[msg.sender];
 info.amount += uint128(amount);
 info.stakeTime = uint64(block.timestamp);
 info.lockEndTime = uint64(block.timestamp + lockDuration);
 totalStaked += amount;

 emit Staked(msg.sender, amount, info.lockEndTime);

 // Interaction last — SafeERC20 handles non-standard returns
 stakingToken.safeTransferFrom(msg.sender, address(this), amount);
 }

 /// @notice Withdraw staked tokens after lock period
 function withdraw() external nonReentrant {
 StakeInfo storage info = stakes[msg.sender];
 uint256 amount = info.amount;

 if (amount == 0) revert NoStake();
 if (block.timestamp < info.lockEndTime) {
 revert LockNotExpired(info.lockEndTime, block.timestamp);
 }

 // Effects before interactions
 info.amount = 0;
 info.stakeTime = 0;
 info.lockEndTime = 0;
 totalStaked -= amount;

 emit Withdrawn(msg.sender, amount);

 // Interaction last
 stakingToken.safeTransfer(msg.sender, amount);
 }

 function setLockDuration(uint256 newDuration) external onlyOwner {
 emit LockDurationUpdated(lockDuration, newDuration);
 lockDuration = newDuration;
 }

 function pause() external onlyOwner { _pause(); }
 function unpause() external onlyOwner { _unpause(); }

 /// @dev Only owner can authorize upgrades
 function _authorizeUpgrade(address) internal override onlyOwner {}
}

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