Systems, markets
& chains.

1// SPDX-License-Identifier: MIT
2pragma solidity ^0.8.20;
3 
4import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
5import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
6import "@openzeppelin/contracts/access/Ownable.sol";
7 
8/// @title SimpleStaking - stake tokens, earn rewards
9contract SimpleStaking is ReentrancyGuard, Ownable {
10    IERC20 public immutable stakingToken;
11    uint256 public rewardRate = 100; // per block
12 
13    mapping(address => uint256) public stakedBalance;
14    mapping(address => uint256) public lastClaimBlock;
15 
16    event Staked(address indexed user, uint256 amount);
17 
18    constructor(address _token) Ownable(msg.sender) {
19        stakingToken = IERC20(_token);
20    }
21 
22    function stake(uint256 amount) external nonReentrant {
23        require(amount > 0, "Amount must be > 0");
24        _claimRewards();
25        stakingToken.transferFrom(msg.sender, address(this), amount);
26        stakedBalance[msg.sender] += amount;
27        emit Staked(msg.sender, amount);
28    }
29 
30    function pendingRewards(address user) public view returns (uint256) {
31        uint256 blocks = block.number - lastClaimBlock[user];
32        return (stakedBalance[user] * rewardRate * blocks) / 1e18;
33    }
34}