Efikcoin mining pool staking

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

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

contract EfikcoinStakingPool is Ownable {
    IERC20 public efikToken;

    uint256 public rewardRate = 10; // 10 EFIK per day per 1000 staked
    uint256 public totalStaked;

    struct StakeInfo {
        uint256 amount;
        uint256 startTime;
        uint256 rewardClaimed;
    }

    mapping(address => StakeInfo) public stakes;

    event Staked(address indexed user, uint256 amount);
    event RewardClaimed(address indexed user, uint256 reward);
    event Withdrawn(address indexed user, uint256 amount);

    constructor(address _efikTokenAddress) {
        efikToken = IERC20(_efikTokenAddress);
    }

    function stake(uint256 _amount) external {
        require(_amount > 0, "Stake amount must be greater than zero");
        efikToken.transferFrom(msg.sender, address(this), _amount);

        StakeInfo storage user = stakes[msg.sender];
        user.amount += _amount;
        user.startTime = block.timestamp;

        totalStaked += _amount;

        emit Staked(msg.sender, _amount);
    }

    function calculateReward(address _user) public view returns (uint256) {
        StakeInfo memory user = stakes[_user];
        uint256 duration = block.timestamp - user.startTime;
        uint256 daysStaked = duration / 1 days;
        return (user.amount * rewardRate * daysStaked) / 1000;
    }

    function claimReward() external {
        uint256 reward = calculateReward(msg.sender);
        require(reward > 0, "No reward available");

        stakes[msg.sender].rewardClaimed += reward;
        stakes[msg.sender].startTime = block.timestamp;

        efikToken.transfer(msg.sender, reward);

        emit RewardClaimed(msg.sender, reward);
    }

    function withdrawStake() external {
        StakeInfo storage user = stakes[msg.sender];
        require(user.amount > 0, "No staked amount");

        uint256 reward = calculateReward(msg.sender);
        uint256 totalAmount = user.amount + reward;

        efikToken.transfer(msg.sender, totalAmount);

        totalStaked -= user.amount;
        delete stakes[msg.sender];

        emit Withdrawn(msg.sender, totalAmount);
    }

    function updateRewardRate(uint256 _newRate) external onlyOwner {
        rewardRate = _newRate;
    }

    function emergencyWithdraw() external onlyOwner {
        uint256 balance = efikToken.balanceOf(address(this));
        efikToken.transfer(owner(), balance);
    }
}