Contract Source Code:
File 1 of 1 : Festaking
// File: openzeppelin-solidity/contracts/token/ERC20/IERC20.sol
pragma solidity ^0.5.0;
/**
* @dev Interface of the ERC20 standard as defined in the EIP. Does not include
* the optional functions; to access them see `ERC20Detailed`.
*/
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.
*
* > 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);
}
// File: openzeppelin-solidity/contracts/math/SafeMath.sol
pragma solidity ^0.5.0;
/**
* @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) {
require(b <= a, "SafeMath: subtraction overflow");
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-solidity/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) {
// Solidity only automatically asserts when dividing by 0
require(b > 0, "SafeMath: division by zero");
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) {
require(b != 0, "SafeMath: modulo by zero");
return a % b;
}
}
// File: openzeppelin-solidity/contracts/token/ERC20/ERC20.sol
pragma solidity ^0.5.0;
/**
* @dev Implementation of the `IERC20` interface.
*
* This implementation is agnostic to the way tokens are created. This means
* that a supply mechanism has to be added in a derived contract using `_mint`.
* For a generic mechanism see `ERC20Mintable`.
*
* *For a detailed writeup see our guide [How to implement supply
* mechanisms](https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226).*
*
* We have followed general OpenZeppelin guidelines: functions revert instead
* of returning `false` on failure. This behavior is nonetheless conventional
* and does not conflict with the expectations of ERC20 applications.
*
* Additionally, an `Approval` event is emitted on calls to `transferFrom`.
* This allows applications to reconstruct the allowance for all accounts just
* by listening to said events. Other implementations of the EIP may not emit
* these events, as it isn't required by the specification.
*
* Finally, the non-standard `decreaseAllowance` and `increaseAllowance`
* functions have been added to mitigate the well-known issues around setting
* allowances. See `IERC20.approve`.
*/
contract ERC20 is IERC20 {
using SafeMath for uint256;
mapping (address => uint256) private _balances;
mapping (address => mapping (address => uint256)) private _allowances;
uint256 private _totalSupply;
/**
* @dev See `IERC20.totalSupply`.
*/
function totalSupply() public view returns (uint256) {
return _totalSupply;
}
/**
* @dev See `IERC20.balanceOf`.
*/
function balanceOf(address account) public view returns (uint256) {
return _balances[account];
}
/**
* @dev See `IERC20.transfer`.
*
* Requirements:
*
* - `recipient` cannot be the zero address.
* - the caller must have a balance of at least `amount`.
*/
function transfer(address recipient, uint256 amount) public returns (bool) {
_transfer(msg.sender, recipient, amount);
return true;
}
/**
* @dev See `IERC20.allowance`.
*/
function allowance(address owner, address spender) public view returns (uint256) {
return _allowances[owner][spender];
}
/**
* @dev See `IERC20.approve`.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 value) public returns (bool) {
_approve(msg.sender, spender, value);
return true;
}
/**
* @dev See `IERC20.transferFrom`.
*
* Emits an `Approval` event indicating the updated allowance. This is not
* required by the EIP. See the note at the beginning of `ERC20`;
*
* Requirements:
* - `sender` and `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `value`.
* - the caller must have allowance for `sender`'s tokens of at least
* `amount`.
*/
function transferFrom(address sender, address recipient, uint256 amount) public returns (bool) {
_transfer(sender, recipient, amount);
_approve(sender, msg.sender, _allowances[sender][msg.sender].sub(amount));
return true;
}
/**
* @dev Atomically increases the allowance granted to `spender` by the caller.
*
* This is an alternative to `approve` that can be used as a mitigation for
* problems described in `IERC20.approve`.
*
* Emits an `Approval` event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
_approve(msg.sender, spender, _allowances[msg.sender][spender].add(addedValue));
return true;
}
/**
* @dev Atomically decreases the allowance granted to `spender` by the caller.
*
* This is an alternative to `approve` that can be used as a mitigation for
* problems described in `IERC20.approve`.
*
* Emits an `Approval` event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
* - `spender` must have allowance for the caller of at least
* `subtractedValue`.
*/
function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
_approve(msg.sender, spender, _allowances[msg.sender][spender].sub(subtractedValue));
return true;
}
/**
* @dev Moves tokens `amount` from `sender` to `recipient`.
*
* This is internal function is equivalent to `transfer`, and can be used to
* e.g. implement automatic token fees, slashing mechanisms, etc.
*
* Emits a `Transfer` event.
*
* Requirements:
*
* - `sender` cannot be the zero address.
* - `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `amount`.
*/
function _transfer(address sender, address recipient, uint256 amount) internal {
require(sender != address(0), "ERC20: transfer from the zero address");
require(recipient != address(0), "ERC20: transfer to the zero address");
_balances[sender] = _balances[sender].sub(amount);
_balances[recipient] = _balances[recipient].add(amount);
emit Transfer(sender, recipient, amount);
}
/** @dev Creates `amount` tokens and assigns them to `account`, increasing
* the total supply.
*
* Emits a `Transfer` event with `from` set to the zero address.
*
* Requirements
*
* - `to` cannot be the zero address.
*/
function _mint(address account, uint256 amount) internal {
require(account != address(0), "ERC20: mint to the zero address");
_totalSupply = _totalSupply.add(amount);
_balances[account] = _balances[account].add(amount);
emit Transfer(address(0), account, amount);
}
/**
* @dev Destoys `amount` tokens from `account`, reducing the
* total supply.
*
* Emits a `Transfer` event with `to` set to the zero address.
*
* Requirements
*
* - `account` cannot be the zero address.
* - `account` must have at least `amount` tokens.
*/
function _burn(address account, uint256 value) internal {
require(account != address(0), "ERC20: burn from the zero address");
_totalSupply = _totalSupply.sub(value);
_balances[account] = _balances[account].sub(value);
emit Transfer(account, address(0), value);
}
/**
* @dev Sets `amount` as the allowance of `spender` over the `owner`s tokens.
*
* This is internal function is equivalent to `approve`, and can be used to
* e.g. set automatic allowances for certain subsystems, etc.
*
* Emits an `Approval` event.
*
* Requirements:
*
* - `owner` cannot be the zero address.
* - `spender` cannot be the zero address.
*/
function _approve(address owner, address spender, uint256 value) internal {
require(owner != address(0), "ERC20: approve from the zero address");
require(spender != address(0), "ERC20: approve to the zero address");
_allowances[owner][spender] = value;
emit Approval(owner, spender, value);
}
/**
* @dev Destoys `amount` tokens from `account`.`amount` is then deducted
* from the caller's allowance.
*
* See `_burn` and `_approve`.
*/
function _burnFrom(address account, uint256 amount) internal {
_burn(account, amount);
_approve(account, msg.sender, _allowances[account][msg.sender].sub(amount));
}
}
// File: contracts/Festaking.sol
pragma solidity ^0.5.8;
contract Festaking {
using SafeMath for uint256;
mapping (address => uint256) private _stakes;
string public name;
address public tokenAddress;
uint public stakingStarts;
uint public stakingEnds;
uint public withdrawStarts;
uint public withdrawEnds;
uint256 public stakedTotal;
uint256 public stakingCap;
uint256 public totalReward;
uint256 public earlyWithdrawReward;
uint256 public rewardBalance;
uint256 public stakedBalance;
ERC20 public ERC20Interface;
event Staked(address indexed token, address indexed staker_, uint256 requestedAmount_, uint256 stakedAmount_);
event PaidOut(address indexed token, address indexed staker_, uint256 amount_, uint256 reward_);
event Refunded(address indexed token, address indexed staker_, uint256 amount_);
/**
*/
constructor (string memory name_,
address tokenAddress_,
uint stakingStarts_,
uint stakingEnds_,
uint withdrawStarts_,
uint withdrawEnds_,
uint256 stakingCap_) public {
name = name_;
require(tokenAddress_ != address(0), "Festaking: 0 address");
tokenAddress = tokenAddress_;
require(stakingStarts_ > 0, "Festaking: zero staking start time");
if (stakingStarts_ < now) {
stakingStarts = now;
} else {
stakingStarts = stakingStarts_;
}
require(stakingEnds_ > stakingStarts, "Festaking: staking end must be after staking starts");
stakingEnds = stakingEnds_;
require(withdrawStarts_ >= stakingEnds, "Festaking: withdrawStarts must be after staking ends");
withdrawStarts = withdrawStarts_;
require(withdrawEnds_ > withdrawStarts, "Festaking: withdrawEnds must be after withdraw starts");
withdrawEnds = withdrawEnds_;
require(stakingCap_ > 0, "Festaking: stakingCap must be positive");
stakingCap = stakingCap_;
}
function addReward(uint256 rewardAmount, uint256 withdrawableAmount)
public
_before(withdrawStarts)
_hasAllowance(msg.sender, rewardAmount)
returns (bool) {
require(rewardAmount > 0, "Festaking: reward must be positive");
require(withdrawableAmount >= 0, "Festaking: withdrawable amount cannot be negative");
require(withdrawableAmount <= rewardAmount, "Festaking: withdrawable amount must be less than or equal to the reward amount");
address from = msg.sender;
if (!_payMe(from, rewardAmount)) {
return false;
}
totalReward = totalReward.add(rewardAmount);
rewardBalance = totalReward;
earlyWithdrawReward = earlyWithdrawReward.add(withdrawableAmount);
return true;
}
function stakeOf(address account) public view returns (uint256) {
return _stakes[account];
}
/**
* Requirements:
* - `amount` Amount to be staked
*/
function stake(uint256 amount)
public
_positive(amount)
_realAddress(msg.sender)
returns (bool) {
address from = msg.sender;
return _stake(from, amount);
}
function withdraw(uint256 amount)
public
_after(withdrawStarts)
_positive(amount)
_realAddress(msg.sender)
returns (bool) {
address from = msg.sender;
require(amount <= _stakes[from], "Festaking: not enough balance");
if (now < withdrawEnds) {
return _withdrawEarly(from, amount);
} else {
return _withdrawAfterClose(from, amount);
}
}
function _withdrawEarly(address from, uint256 amount)
private
_realAddress(from)
returns (bool) {
// This is the formula to calculate reward:
// r = (earlyWithdrawReward / stakedTotal) * (now - stakingEnds) / (withdrawEnds - stakingEnds)
// w = (1+r) * a
uint256 denom = (withdrawEnds.sub(stakingEnds)).mul(stakedTotal);
uint256 reward = (
( (now.sub(stakingEnds)).mul(earlyWithdrawReward) ).mul(amount)
).div(denom);
uint256 payOut = amount.add(reward);
rewardBalance = rewardBalance.sub(reward);
stakedBalance = stakedBalance.sub(amount);
_stakes[from] = _stakes[from].sub(amount);
if (_payDirect(from, payOut)) {
emit PaidOut(tokenAddress, from, amount, reward);
return true;
}
return false;
}
function _withdrawAfterClose(address from, uint256 amount)
private
_realAddress(from)
returns (bool) {
uint256 reward = (rewardBalance.mul(amount)).div(stakedBalance);
uint256 payOut = amount.add(reward);
_stakes[from] = _stakes[from].sub(amount);
if (_payDirect(from, payOut)) {
emit PaidOut(tokenAddress, from, amount, reward);
return true;
}
return false;
}
function _stake(address staker, uint256 amount)
private
_after(stakingStarts)
_before(stakingEnds)
_positive(amount)
_hasAllowance(staker, amount)
returns (bool) {
// check the remaining amount to be staked
uint256 remaining = amount;
if (remaining > (stakingCap.sub(stakedBalance))) {
remaining = stakingCap.sub(stakedBalance);
}
// These requires are not necessary, because it will never happen, but won't hurt to double check
// this is because stakedTotal and stakedBalance are only modified in this method during the staking period
require(remaining > 0, "Festaking: Staking cap is filled");
require((remaining + stakedTotal) <= stakingCap, "Festaking: this will increase staking amount pass the cap");
if (!_payMe(staker, remaining)) {
return false;
}
emit Staked(tokenAddress, staker, amount, remaining);
if (remaining < amount) {
// Return the unstaked amount to sender (from allowance)
uint256 refund = amount.sub(remaining);
if (_payTo(staker, staker, refund)) {
emit Refunded(tokenAddress, staker, refund);
}
}
// Transfer is completed
stakedBalance = stakedBalance.add(remaining);
stakedTotal = stakedTotal.add(remaining);
_stakes[staker] = _stakes[staker].add(remaining);
return true;
}
function _payMe(address payer, uint256 amount)
private
returns (bool) {
return _payTo(payer, address(this), amount);
}
function _payTo(address allower, address receiver, uint256 amount)
_hasAllowance(allower, amount)
private
returns (bool) {
// Request to transfer amount from the contract to receiver.
// contract does not own the funds, so the allower must have added allowance to the contract
// Allower is the original owner.
ERC20Interface = ERC20(tokenAddress);
return ERC20Interface.transferFrom(allower, receiver, amount);
}
function _payDirect(address to, uint256 amount)
private
_positive(amount)
returns (bool) {
ERC20Interface = ERC20(tokenAddress);
return ERC20Interface.transfer(to, amount);
}
modifier _realAddress(address addr) {
require(addr != address(0), "Festaking: zero address");
_;
}
modifier _positive(uint256 amount) {
require(amount >= 0, "Festaking: negative amount");
_;
}
modifier _after(uint eventTime) {
require(now >= eventTime, "Festaking: bad timing for the request");
_;
}
modifier _before(uint eventTime) {
require(now < eventTime, "Festaking: bad timing for the request");
_;
}
modifier _hasAllowance(address allower, uint256 amount) {
// Make sure the allower has provided the right allowance.
ERC20Interface = ERC20(tokenAddress);
uint256 ourAllowance = ERC20Interface.allowance(allower, address(this));
require(amount <= ourAllowance, "Festaking: Make sure to add enough allowance");
_;
}
}
