Contract Name:
YieldFarmXfund3
Contract Source Code:
// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.6.0;
import "@openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "./interfaces/IStaking.sol";
contract YieldFarmXfund3 {
// lib
using SafeMath for uint;
using SafeMath for uint128;
// constants
uint public constant TOTAL_DISTRIBUTED_AMOUNT = 50;
uint public constant NR_OF_EPOCHS = 10;
uint128 public constant EPOCHS_DELAYED_FROM_STAKING_CONTRACT = 22; // start Staking epoch 23
// state variables
// addreses
address private _poolTokenAddress;
address private _communityVault;
// contracts
IERC20 private _xfund;
IStaking private _staking;
uint[] private epochs = new uint[](NR_OF_EPOCHS + 1);
uint private _totalAmountPerEpoch;
uint128 public lastInitializedEpoch;
mapping(address => uint128) private lastEpochIdHarvested;
uint public epochDuration; // init from staking contract
uint public epochStart; // init from staking contract
// events
event MassHarvest(address indexed user, uint256 epochsHarvested, uint256 totalValue);
event Harvest(address indexed user, uint128 indexed epochId, uint256 amount);
// constructor
constructor(address xfundTokenAddress, address stakeContract, address communityVault) public {
_xfund = IERC20(xfundTokenAddress);
_poolTokenAddress = xfundTokenAddress;
_staking = IStaking(stakeContract);
_communityVault = communityVault;
epochDuration = _staking.epochDuration();
epochStart = _staking.epoch1Start() + epochDuration.mul(EPOCHS_DELAYED_FROM_STAKING_CONTRACT);
// xFUND has 9 decimals
_totalAmountPerEpoch = TOTAL_DISTRIBUTED_AMOUNT.mul(10**9).div(NR_OF_EPOCHS);
}
// public methods
// public method to harvest all the unharvested epochs until current epoch - 1
function massHarvest() external returns (uint){
uint totalDistributedValue;
uint epochId = _getEpochId().sub(1); // fails in epoch 0
// force max number of epochs
if (epochId > NR_OF_EPOCHS) {
epochId = NR_OF_EPOCHS;
}
for (uint128 i = lastEpochIdHarvested[msg.sender] + 1; i <= epochId; i++) {
// i = epochId
// compute distributed Value and do one single transfer at the end
totalDistributedValue += _harvest(i);
}
emit MassHarvest(msg.sender, epochId - lastEpochIdHarvested[msg.sender], totalDistributedValue);
if (totalDistributedValue > 0) {
_xfund.transferFrom(_communityVault, msg.sender, totalDistributedValue);
}
return totalDistributedValue;
}
function harvest (uint128 epochId) external returns (uint){
// checks for requested epoch
require (_getEpochId() > epochId, "This epoch is in the future");
require(epochId <= NR_OF_EPOCHS, "Maximum number of epochs is 10");
require (lastEpochIdHarvested[msg.sender].add(1) == epochId, "Harvest in order");
uint userReward = _harvest(epochId);
if (userReward > 0) {
_xfund.transferFrom(_communityVault, msg.sender, userReward);
}
emit Harvest(msg.sender, epochId, userReward);
return userReward;
}
// views
// calls to the staking smart contract to retrieve the epoch total pool size
function getPoolSize(uint128 epochId) external view returns (uint) {
return _getPoolSize(epochId);
}
function getCurrentEpoch() external view returns (uint) {
return _getEpochId();
}
// calls to the staking smart contract to retrieve user balance for an epoch
function getEpochStake(address userAddress, uint128 epochId) external view returns (uint) {
return _getUserBalancePerEpoch(userAddress, epochId);
}
function userLastEpochIdHarvested() external view returns (uint){
return lastEpochIdHarvested[msg.sender];
}
// internal methods
function _initEpoch(uint128 epochId) internal {
require(lastInitializedEpoch.add(1) == epochId, "Epoch can be init only in order");
lastInitializedEpoch = epochId;
// call the staking smart contract to init the epoch
epochs[epochId] = _getPoolSize(epochId);
}
function _harvest (uint128 epochId) internal returns (uint) {
// try to initialize an epoch. if it can't it fails
// if it fails either user either a BarnBridge account will init not init epochs
if (lastInitializedEpoch < epochId) {
_initEpoch(epochId);
}
// Set user state for last harvested
lastEpochIdHarvested[msg.sender] = epochId;
// compute and return user total reward. For optimization reasons the transfer have been moved to an upper layer (i.e. massHarvest needs to do a single transfer)
// exit if there is no stake on the epoch
if (epochs[epochId] == 0) {
return 0;
}
return _totalAmountPerEpoch
.mul(_getUserBalancePerEpoch(msg.sender, epochId))
.div(epochs[epochId]);
}
// retrieve _poolTokenAddress token balance
function _getPoolSize(uint128 epochId) internal view returns (uint) {
return _staking.getEpochPoolSize(_poolTokenAddress, _stakingEpochId(epochId));
}
// retrieve _poolTokenAddress token balance per user per epoch
function _getUserBalancePerEpoch(address userAddress, uint128 epochId) internal view returns (uint){
return _staking.getEpochUserBalance(userAddress, _poolTokenAddress, _stakingEpochId(epochId));
}
// compute epoch id from block.timestamp and epochStart date
function _getEpochId() internal view returns (uint128 epochId) {
if (block.timestamp < epochStart) {
return 0;
}
epochId = uint128(block.timestamp.sub(epochStart).div(epochDuration).add(1));
}
// get the staking epoch
function _stakingEpochId(uint128 epochId) pure internal returns (uint128) {
return epochId + EPOCHS_DELAYED_FROM_STAKING_CONTRACT;
}
}
pragma solidity ^0.6.0;
/**
* @dev Wrappers over Solidity's arithmetic operations with added overflow
* checks.
*
* Arithmetic operations in Solidity wrap on overflow. This can easily result
* in bugs, because programmers usually assume that an overflow raises an
* error, which is the standard behavior in high level programming languages.
* `SafeMath` restores this intuition by reverting the transaction when an
* operation overflows.
*
* Using this library instead of the unchecked operations eliminates an entire
* class of bugs, so it's recommended to use it always.
*/
library SafeMath {
/**
* @dev Returns the addition of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `+` operator.
*
* Requirements:
* - Addition cannot overflow.
*/
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a, "SafeMath: addition overflow");
return c;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
* - Subtraction cannot overflow.
*/
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
return sub(a, b, "SafeMath: subtraction overflow");
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
* - Subtraction cannot overflow.
*/
function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b <= a, errorMessage);
uint256 c = a - b;
return c;
}
/**
* @dev Returns the multiplication of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `*` operator.
*
* Requirements:
* - Multiplication cannot overflow.
*/
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
if (a == 0) {
return 0;
}
uint256 c = a * b;
require(c / a == b, "SafeMath: multiplication overflow");
return c;
}
/**
* @dev Returns the integer division of two unsigned integers. Reverts on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return div(a, b, "SafeMath: division by zero");
}
/**
* @dev Returns the integer division of two unsigned integers. Reverts with custom message on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*/
function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
// Solidity only automatically asserts when dividing by 0
require(b > 0, errorMessage);
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* Reverts when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return mod(a, b, "SafeMath: modulo by zero");
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* Reverts with custom message when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*/
function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b != 0, errorMessage);
return a % b;
}
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
interface IERC20 {
/**
* @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 `recipient`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transfer(address recipient, 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 `sender` to `recipient` 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 sender, address recipient, uint256 amount) external returns (bool);
/**
* @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);
}
// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.6.0;
import "@openzeppelin/contracts/access/Ownable.sol";
interface IStaking {
function getEpochId(uint timestamp) external view returns (uint); // get epoch id
function getEpochUserBalance(address user, address token, uint128 epoch) external view returns(uint);
function getEpochPoolSize(address token, uint128 epoch) external view returns (uint);
function epoch1Start() external view returns (uint);
function epochDuration() external view returns (uint);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "../utils/Context.sol";
/**
* @dev Contract module which provides a basic access control mechanism, where
* there is an account (an owner) that can be granted exclusive access to
* specific functions.
*
* By default, the owner account will be the one that deploys the contract. This
* can later be changed with {transferOwnership}.
*
* This module is used through inheritance. It will make available the modifier
* `onlyOwner`, which can be applied to your functions to restrict their use to
* the owner.
*/
abstract contract Ownable is Context {
address private _owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
/**
* @dev Initializes the contract setting the deployer as the initial owner.
*/
constructor () internal {
address msgSender = _msgSender();
_owner = msgSender;
emit OwnershipTransferred(address(0), msgSender);
}
/**
* @dev Returns the address of the current owner.
*/
function owner() public view virtual returns (address) {
return _owner;
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
require(owner() == _msgSender(), "Ownable: caller is not the owner");
_;
}
/**
* @dev Leaves the contract without owner. It will not be possible to call
* `onlyOwner` functions anymore. Can only be called by the current owner.
*
* NOTE: Renouncing ownership will leave the contract without an owner,
* thereby removing any functionality that is only available to the owner.
*/
function renounceOwnership() public virtual onlyOwner {
emit OwnershipTransferred(_owner, address(0));
_owner = address(0);
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Can only be called by the current owner.
*/
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
emit OwnershipTransferred(_owner, newOwner);
_owner = newOwner;
}
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <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 GSN 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 payable) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes memory) {
this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
return msg.data;
}
}