Sample staking contract

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

interface IERC20 {
    function transfer(address recipient, uint256 amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    function balanceOf(address account) external view returns (uint256);
}

contract Staking {
    // Token used for staking
    IERC20 public stakingToken;

    // Token used for rewards
    IERC20 public rewardToken;

    // Mapping of user addresses to their stakes
    mapping(address => uint256) public stakes;

    // Mapping of user addresses to their accumulated reward points
    mapping(address => uint256) public rewardPoints;

    // Mapping of user addresses to the last time they staked
    mapping(address => uint256) public lastStakeTime;

    // Reward rate per second (adjustable)
    uint256 public rewardRate = 100; // reward rate per second

    // Total amount of tokens staked in the contract
    uint256 public totalStaked;

    // Events to log staking actions
    event Staked(address indexed user, uint256 amount);
    event Unstaked(address indexed user, uint256 amount);
    event RewardsClaimed(address indexed user, uint256 reward);

    // Constructor to set the staking and reward tokens
    constructor(IERC20 _stakingToken, IERC20 _rewardToken) {
        stakingToken = _stakingToken;
        rewardToken = _rewardToken;
    }

    // Function to stake tokens
    function stake(uint256 amount) external {
        require(amount > 0, "Amount must be greater than zero");
        
        // Update rewards for previous stake before new staking
        _updateRewards(msg.sender);

        // Transfer tokens from the user to the contract
        stakingToken.transferFrom(msg.sender, address(this), amount);
        
        // Increase user's stake and total staked amount
        stakes[msg.sender] += amount;
        totalStaked += amount;

        // Record the current time as the last stake time
        lastStakeTime[msg.sender] = block.timestamp;

        emit Staked(msg.sender, amount);
    }

    // Function to unstake tokens
    function unstake(uint256 amount) external {
        require(amount > 0 && amount <= stakes[msg.sender], "Invalid amount");
        
        // Update rewards before unstaking
        _updateRewards(msg.sender);

        // Decrease user's stake and total staked amount
        stakes[msg.sender] -= amount;
        totalStaked -= amount;

        // Transfer tokens back to the user
        stakingToken.transfer(msg.sender, amount);

        emit Unstaked(msg.sender, amount);
    }

    // Function to claim rewards
    function claimRewards() external {
        _updateRewards(msg.sender);
        uint256 reward = rewardPoints[msg.sender];
        require(reward > 0, "No rewards available");
        
        // Reset reward points after claiming
        rewardPoints[msg.sender] = 0;

        // Transfer reward tokens to the user
        rewardToken.transfer(msg.sender, reward);
        emit RewardsClaimed(msg.sender, reward);
    }

    // Internal function to update rewards for a user
    function _updateRewards(address user) internal {
        // Calculate the time the user has staked
        uint256 stakedTime = block.timestamp - lastStakeTime[user];

        // Calculate rewards based on the staked amount and time
        uint256 rewards = stakedTime * rewardRate * stakes[user] / 1e18;

        // Add calculated rewards to user's reward points
        rewardPoints[user] += rewards;

        // Update the last stake time to the current time
        lastStakeTime[user] = block.timestamp;
    }

    // Function to get the total rewards for a user
    function getRewards(address user) external view returns (uint256) {
        uint256 stakedTime = block.timestamp - lastStakeTime[user];
        uint256 rewards = stakedTime * rewardRate * stakes[user] / 1e18;
        return rewardPoints[user] + rewards;
    }
}

2) Documentation for Staking Contract

Technical Documentation

User Guide

3) Deployment Instructions - Steps for deploying on the blockchain.