Stacks Forum

Hey Can someone explain something about this Smart contract to me

hey so i was looking through github for a LP staking smart contract and i came across this

// SPDX-License-Identifier: MIT
pragma solidity 0.7.6;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";

contract StakingV2 is Ownable {
    using SafeMath for uint;
    using SafeERC20 for IERC20;

    struct Stake {
        uint amount;
        uint stakeTime;
        uint fraction;
        uint rewardOut;

    mapping(uint => mapping(address => Stake)) public stakes;

    // Info of each pool.
    struct Pool {
        uint rewardAmount; // Pool reward tokens limit
        uint startTime;
        uint endTime;
        uint total;
        uint freezeTime;
        uint freezePercent;

    Pool[] public pools;

    address public stakeToken; // Uniswap LP token from pool MRCH/USDT
    address public rewardToken; // MRCH token

    event AddPool(uint pid, uint reward, uint startTime, uint endTime, uint freezeTime, uint percent);
    event PoolTotal(uint pid, uint oldTotal, uint newTotal);
    event StakerFraction(uint pid, address staker, uint oldFraction, uint newFraction);
    event Staked(uint pid, address staker, uint amount);
    event RewardOut(uint pid, address staker, address token, uint amount);

        address stakeToken_,
        address rewardToken_
    ) {
        require(stakeToken_ != address(0), "MRCHStaking::constructor: stake token address is 0x0");
        stakeToken = stakeToken_;

        require(rewardToken_ != address(0), "MRCHStaking::constructor: reward token address is 0x0");
        rewardToken = rewardToken_;

    function addPool(uint rewardAmount_, uint startTime_, uint endTime_, uint freezeTime_, uint freezePercent_) public onlyOwner {
        require(getTimeStamp() <= startTime_, "MRCHStaking::addPool: bad timing for the request");
        require(startTime_ < endTime_, "MRCHStaking::addPool: endTime > startTime");

        doTransferIn(msg.sender, rewardToken, rewardAmount_);

                rewardAmount: rewardAmount_,
                startTime: startTime_,
                endTime: endTime_,
                total: 0,
                freezeTime: freezeTime_,
                freezePercent: freezePercent_ // scaled by 1e18, for example 5% = 5e18, 0.01% = 1e16

        emit AddPool(pools.length - 1, rewardAmount_, startTime_, endTime_, freezeTime_, freezePercent_);

    function stake(uint pid, uint amount) public returns (bool) {
        require(amount > 0, "MRCHStaking::stake: amount must be positive");

        uint timeStamp = getTimeStamp();
        require(timeStamp < pools[pid].endTime, "MRCHStaking::stake: bad timing for the request");

        address staker = msg.sender;

        doTransferIn(staker, stakeToken, amount);

        // Transfer is completed
        stakes[pid][staker].amount = stakes[pid][staker].amount.add(amount);

        uint addition;

        if (timeStamp < pools[pid].startTime) {
            stakes[pid][staker].stakeTime = pools[pid].startTime;
            addition = (pools[pid].endTime.sub(pools[pid].startTime)).mul(amount);
        } else {
            stakes[pid][staker].stakeTime = timeStamp;
            addition = (pools[pid].endTime.sub(timeStamp)).mul(amount);

        uint oldFraction = stakes[pid][staker].fraction;
        stakes[pid][staker].fraction = stakes[pid][staker].fraction.add(addition);

        uint oldTotal = pools[pid].total;
        pools[pid].total = pools[pid].total.add(addition);

        emit Staked(pid, staker, amount);
        emit StakerFraction(pid, staker, oldFraction, stakes[pid][staker].fraction);
        emit PoolTotal(pid, oldTotal, pools[pid].total);

        return true;

    function withdraw(uint pid) public returns (bool) {
        require(claim(pid), "MRCHStaking::withdraw: claim error");

        uint amount = stakes[pid][msg.sender].amount;

        return withdrawWithoutReward(pid, amount);

    function withdrawWithoutReward(uint pid, uint amount) public returns (bool) {
        return withdrawInternal(pid, msg.sender, amount);

    function withdrawInternal(uint pid, address staker, uint amount) internal returns (bool) {
        require(amount > 0, "MRCHStaking::withdrawInternal: amount must be positive");
        require(amount <= stakes[pid][msg.sender].amount, "MRCHStaking::withdrawInternal: not enough balance");

        stakes[pid][staker].amount = stakes[pid][staker].amount.sub(amount);

        uint freezeTime = stakes[pid][staker].stakeTime.add(pools[pid].freezeTime);

        if (getTimeStamp() < freezeTime) {
            uint freezeAmount = amount.mul(pools[pid].freezePercent).div(100);
            amount = amount.sub(freezeAmount);

        doTransferOut(stakeToken, staker, amount);

        return true;

    function claim(uint pid) public returns (bool) {
        require(getTimeStamp() > pools[pid].endTime, "MRCHStaking::claim: bad timing for the request");

        address staker = msg.sender;

        uint rewardAmount = currentTotalReward(pid, staker);

        if (rewardAmount == 0) {
            return true;

        doTransferOut(rewardToken, staker, rewardAmount);

        stakes[pid][staker].rewardOut = stakes[pid][staker].rewardOut.add(rewardAmount);

        emit RewardOut(pid, staker, rewardToken, rewardAmount);

        return true;

    function currentTotalReward(uint pid, address staker) public view returns (uint) {
        uint totalRewardAmount = pools[pid].rewardAmount;
        uint total = pools[pid].total;

        if (total == 0) {
            return 0;

        uint fraction = stakes[pid][staker].fraction;
        uint rewardOut = stakes[pid][staker].rewardOut;

        uint rewardAmount = totalRewardAmount.mul(fraction).div(total);

        return rewardAmount.sub(rewardOut);

    function doTransferOut(address token, address to, uint amount) internal {
        if (amount == 0) {

        IERC20 ERC20Interface = IERC20(token);
        ERC20Interface.safeTransfer(to, amount);

    function doTransferIn(address from, address token, uint amount) internal {
        IERC20 ERC20Interface = IERC20(token);
        ERC20Interface.safeTransferFrom(from, address(this), amount);

    function transferTokens(address token, address to, uint amount) public onlyOwner {
        doTransferOut(token, to, amount);

    function getTimeStamp() public view virtual returns (uint) {
        return block.timestamp;

    function getPoolLength() public view returns(uint) {
        return pools.length;

so after successfully deploying to the rinkeby testnet am not sure what this means ( some of them).


so i know for a fact the rewardAmount_ - is how much reward will be distributed per block.

The startTime_ is when the pool should start ( like the daye and time which you can use for that.

The startTime_is when the contract will stop distributing the rewards.

The freeze time is like locking the token so when users try to take out before the freeze time they wont be able to.

The freeze percentage is Apy which reduces over time.

i dont really understand it very well so if am wrong please correct. and the reason why am here is that ; if my understanding about the freezetime and freezepercentage are correct how how i do that or enter it in the field.

i know that the freezePercentage can be entered like this 5% = 5e18.

but what of the freezeTime?.

and if anyone has a better understanding please share with me