Staking-Contract-with-Rewards

// SPDX-License-Identifier: MIT pragma solidity ^0.8.20;

interface IERC20 { function totalSupply() external view returns (uint); function balanceOf(address account) external view returns (uint); function transfer(address to, uint amount) external returns (bool); function approve(address spender, uint amount) external returns (bool); function transferFrom(address from, address to, uint amount) external returns (bool); }

contract StakingRewards { IERC20 public stakingToken; IERC20 public rewardToken; address public owner;

uint public rewardRate = 100; // reward tokens per day per staked token
uint public constant SECONDS_IN_A_DAY = 86400;

struct Stake {
    uint amount;
    uint timestamp;
    uint rewardClaimed;
}

mapping(address => Stake) public stakes;

modifier onlyOwner() {
    require(msg.sender == owner, "Not the contract owner");
    _;
}

constructor(address _stakingToken, address _rewardToken) {
    stakingToken = IERC20(_stakingToken);
    rewardToken = IERC20(_rewardToken);
    owner = msg.sender;
}

function stake(uint _amount) external {
    require(_amount > 0, "Amount must be greater than zero");

    Stake storage userStake = stakes[msg.sender];
    if (userStake.amount > 0) {
        uint rewards = calculateReward(msg.sender);
        userStake.rewardClaimed += rewards;
    }

    stakingToken.transferFrom(msg.sender, address(this), _amount);
    userStake.amount += _amount;
    userStake.timestamp = block.timestamp;
}

function unstake() external {
    Stake storage userStake = stakes[msg.sender];
    require(userStake.amount > 0, "Nothing to unstake");

    uint rewards = calculateReward(msg.sender);
    uint totalRewards = rewards + userStake.rewardClaimed;

    stakingToken.transfer(msg.sender, userStake.amount);
    rewardToken.transfer(msg.sender, totalRewards);

    delete stakes[msg.sender];
}

function calculateReward(address _user) public view returns (uint) {
    Stake storage userStake = stakes[_user];
    if (userStake.amount == 0) {
        return 0;
    }

    uint timeStaked = block.timestamp - userStake.timestamp;
    uint daysStaked = timeStaked / SECONDS_IN_A_DAY;

    return (userStake.amount * rewardRate * daysStaked) / 1000; // adjust as needed
}

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

function withdrawRewardTokens(uint _amount) external onlyOwner {
    rewardToken.transfer(owner, _amount);
}

}