mainTokenAddress

rewardTokenAddress

rewardWalletAddress

rewardRate

_daysPerPeriod

constructor

account

available

balanceOf

daysPerPeriod

lastUpdateTime

mainToken

redeem

rewardPerTokenPerPeriod

rewardToken

rewardWallet

amount

stake

withdraw

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

/**
 * @title Token Staking with Infinite Rewards
 * @author Breakthrough Labs Inc.
 * @notice Staking, Token, ERC20
 * @custom:version 1.0.0
 * @custom:address 55
 * @custom:default-precision 0
 * @custom:simple-description Token staking contract that rewards stakers with an exact number of ERC20 tokens per period for every token staked.
 * @dev Token staking contract that rewards stakers with an exact number of ERC20 tokens per period for every token staked. On deployment, the owner specifies a reward rate,
 * and an address that tokens will be pulled from. Neither of these can be changed. The per token rate stays the same even when the total number of staked tokens increases/decreases.
 *
 * A common usecase is for blockchain-based games, where holding tokens rewards a certain number of lives per day.
 *
 */
contract TokenStakingPerToken is Context {
    IERC20 public mainToken;
    IERC20 public rewardToken;
    address public rewardWallet;
    /// @custom:precision 18
    uint256 public rewardPerTokenPerPeriod;
    uint256 public daysPerPeriod;

    /// @custom:precision 18
    mapping(address => uint256) public balanceOf;
    mapping(address => uint256) public lastUpdateTime;
    /// @custom:precision 18
    mapping(address => uint256) private reward;

    /**
     * @param mainTokenAddress  Staked Token Address
     * @param rewardTokenAddress Reward Token Address
     * @param rewardWalletAddress Wallet that holds rewards to be paid out
     * @param rewardRate # of tokens per staked token per period | precision:18
     * @param _daysPerPeriod # of days per period
     */
    constructor(
        address mainTokenAddress,
        address rewardTokenAddress,
        address rewardWalletAddress,
        uint256 rewardRate,
        uint256 _daysPerPeriod
    ) {
        mainToken = IERC20(mainTokenAddress);
        rewardToken = IERC20(rewardTokenAddress);
        rewardWallet = rewardWalletAddress;
        rewardPerTokenPerPeriod = rewardRate;
        daysPerPeriod = _daysPerPeriod;
    }

    modifier update(address account) {
        reward[account] = available(account);
        lastUpdateTime[account] = block.timestamp;
        _;
    }

    /**
     * @dev returns the number of reward tokens available for an address
     * @param account account
     */
    function available(address account) public view returns (uint256) {
        uint256 timeElapsed = block.timestamp - lastUpdateTime[account];
        uint256 earned = (balanceOf[account] *
            timeElapsed *
            rewardPerTokenPerPeriod) / (86400 * daysPerPeriod);
        return reward[account] + earned;
    }

    /**
     * @dev stakes an amount of tokens
     * @param amount amount to stake
     */
    function stake(uint256 amount) external update(_msgSender()) {
        mainToken.transferFrom(_msgSender(), address(this), amount);
        balanceOf[_msgSender()] += amount;
    }

    /**
     * @dev withdraws tokens
     * @param amount amount to withdraw
     */
    function withdraw(uint256 amount) external update(_msgSender()) {
        require(amount <= balanceOf[_msgSender()], "Exceeds balance");
        balanceOf[_msgSender()] -= amount;
        mainToken.transfer(_msgSender(), amount);
    }

    /**
     * @dev redeems all of a user's reward tokens.
     */
    function redeem() external update(_msgSender()) {
        uint256 amount = reward[_msgSender()];
        require(amount > 0, "Nothing to redeem");
        reward[_msgSender()] = 0;
        rewardToken.transferFrom(rewardWallet, _msgSender(), amount);
    }
}



Token staking contract that rewards stakers with an exact number of ERC20 tokens per period for every token staked.

Token Staking with Infinite Rewards

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}


owner

spender

value

Approval

from

Transfer

allowance

approve

totalSupply

transfer

transferFrom

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);
}


Token staking contract that rewards stakers with an exact number of ERC20 tokens per period for every token staked. On deployment, the owner specifies a reward rate, and an address that tokens will be pulled from. Neither of these can be changed. The per token rate stays the same even when the total number of staked tokens increases/decreases. A common usecase is for blockchain-based games, where holding tokens rewards a certain number of lives per day.

ERC20 Token Staking with Infinite Rewards

returns the number of reward tokens available for an address

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "Context.sol";
import "IERC20.sol";

/**
 * @title Token Staking with Infinite Rewards
 * @author Breakthrough Labs Inc.
 * @notice Staking, Token, ERC20
 * @custom:version 1.0.0
 * @custom:address 55
 * @custom:default-precision 0
 * @custom:simple-description Token staking contract that rewards stakers with an exact number of ERC20 tokens per period for every token staked.
 * @dev Token staking contract that rewards stakers with an exact number of ERC20 tokens per period for every token staked. On deployment, the owner specifies a reward rate,
 * and an address that tokens will be pulled from. Neither of these can be changed. The per token rate stays the same even when the total number of staked tokens increases/decreases.
 *
 * A common usecase is for blockchain-based games, where holding tokens rewards a certain number of lives per day.
 *
 */
contract TokenStakingPerToken is Context {
    IERC20 public mainToken;
    IERC20 public rewardToken;
    address public rewardWallet;
    /// @custom:precision 18
    uint256 public rewardPerTokenPerPeriod;
    uint256 public daysPerPeriod;

    /// @custom:precision 18
    mapping(address => uint256) public balanceOf;
    mapping(address => uint256) public lastUpdateTime;
    /// @custom:precision 18
    mapping(address => uint256) private reward;

    /**
     * @param mainTokenAddress  Staked Token Address
     * @param rewardTokenAddress Reward Token Address
     * @param rewardWalletAddress Wallet that holds rewards to be paid out
     * @param rewardRate # of tokens per staked token per period | precision:18
     * @param _daysPerPeriod # of days per period
     */
    constructor(
        address mainTokenAddress,
        address rewardTokenAddress,
        address rewardWalletAddress,
        uint256 rewardRate,
        uint256 _daysPerPeriod
    ) {
        mainToken = IERC20(mainTokenAddress);
        rewardToken = IERC20(rewardTokenAddress);
        rewardWallet = rewardWalletAddress;
        rewardPerTokenPerPeriod = rewardRate;
        daysPerPeriod = _daysPerPeriod;
    }

    modifier update(address account) {
        reward[account] = available(account);
        lastUpdateTime[account] = block.timestamp;
        _;
    }

    /**
     * @dev returns the number of reward tokens available for an address
     * @param account account
     */
    function available(address account) public view returns (uint256) {
        uint256 timeElapsed = block.timestamp - lastUpdateTime[account];
        uint256 earned = (balanceOf[account] *
            timeElapsed *
            rewardPerTokenPerPeriod) / (86400 * daysPerPeriod);
        return reward[account] + earned;
    }

    /**
     * @dev stakes an amount of tokens
     * @param amount amount to stake
     */
    function stake(uint256 amount) external update(_msgSender()) {
        mainToken.transferFrom(_msgSender(), address(this), amount);
        balanceOf[_msgSender()] += amount;
    }

    /**
     * @dev withdraws tokens
     * @param amount amount to withdraw
     */
    function withdraw(uint256 amount) external update(_msgSender()) {
        require(amount <= balanceOf[_msgSender()], "Exceeds balance");
        balanceOf[_msgSender()] -= amount;
        mainToken.transfer(_msgSender(), amount);
    }

    /**
     * @dev redeems all of a user's reward tokens.
     */
    function redeem() external update(_msgSender()) {
        uint256 amount = reward[_msgSender()];
        require(amount > 0, "Nothing to redeem");
        reward[_msgSender()] = 0;
        rewardToken.transferFrom(rewardWallet, _msgSender(), amount);
    }
}
