Contract Source Code:
pragma solidity ^0.6.0;
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
contract CommunityVault is Ownable {
IERC20 private _bond;
constructor (address bond) public {
_bond = IERC20(bond);
}
event SetAllowance(address indexed caller, address indexed spender, uint256 amount);
function setAllowance(address spender, uint amount) public onlyOwner {
_bond.approve(spender, amount);
emit SetAllowance(msg.sender, spender, amount);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import "../GSN/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.
*/
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 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;
/*
* @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;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
* @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: Apache-2.0
pragma solidity ^0.6.0;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
contract ERC20Mock is ERC20("ERC20Mock", "MCK") {
bool public transferFromCalled = false;
bool public transferCalled = false;
address public transferRecipient = address(0);
uint256 public transferAmount = 0;
function mint(address user, uint256 amount) public {
_mint(user, amount);
}
function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
transferFromCalled = true;
return super.transferFrom(sender, recipient, amount);
}
function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
transferCalled = true;
transferRecipient = recipient;
transferAmount = amount;
return super.transfer(recipient, amount);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import "../../GSN/Context.sol";
import "./IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";
/**
* @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 {ERC20PresetMinterPauser}.
*
* TIP: For a detailed writeup see our guide
* https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
* to implement supply mechanisms].
*
* 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 Context, IERC20 {
using SafeMath for uint256;
using Address for address;
mapping (address => uint256) private _balances;
mapping (address => mapping (address => uint256)) private _allowances;
uint256 private _totalSupply;
string private _name;
string private _symbol;
uint8 private _decimals;
/**
* @dev Sets the values for {name} and {symbol}, initializes {decimals} with
* a default value of 18.
*
* To select a different value for {decimals}, use {_setupDecimals}.
*
* All three of these values are immutable: they can only be set once during
* construction.
*/
constructor (string memory name, string memory symbol) public {
_name = name;
_symbol = symbol;
_decimals = 18;
}
/**
* @dev Returns the name of the token.
*/
function name() public view returns (string memory) {
return _name;
}
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
function symbol() public view returns (string memory) {
return _symbol;
}
/**
* @dev Returns the number of decimals used to get its user representation.
* For example, if `decimals` equals `2`, a balance of `505` tokens should
* be displayed to a user as `5,05` (`505 / 10 ** 2`).
*
* Tokens usually opt for a value of 18, imitating the relationship between
* Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
* called.
*
* NOTE: This information is only used for _display_ purposes: it in
* no way affects any of the arithmetic of the contract, including
* {IERC20-balanceOf} and {IERC20-transfer}.
*/
function decimals() public view returns (uint8) {
return _decimals;
}
/**
* @dev See {IERC20-totalSupply}.
*/
function totalSupply() public view override returns (uint256) {
return _totalSupply;
}
/**
* @dev See {IERC20-balanceOf}.
*/
function balanceOf(address account) public view override 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 virtual override returns (bool) {
_transfer(_msgSender(), recipient, amount);
return true;
}
/**
* @dev See {IERC20-allowance}.
*/
function allowance(address owner, address spender) public view virtual override returns (uint256) {
return _allowances[owner][spender];
}
/**
* @dev See {IERC20-approve}.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 amount) public virtual override returns (bool) {
_approve(_msgSender(), spender, amount);
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 `amount`.
* - the caller must have allowance for ``sender``'s tokens of at least
* `amount`.
*/
function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
_transfer(sender, recipient, amount);
_approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
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 virtual returns (bool) {
_approve(_msgSender(), spender, _allowances[_msgSender()][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 virtual returns (bool) {
_approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
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 virtual {
require(sender != address(0), "ERC20: transfer from the zero address");
require(recipient != address(0), "ERC20: transfer to the zero address");
_beforeTokenTransfer(sender, recipient, amount);
_balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
_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 virtual {
require(account != address(0), "ERC20: mint to the zero address");
_beforeTokenTransfer(address(0), account, amount);
_totalSupply = _totalSupply.add(amount);
_balances[account] = _balances[account].add(amount);
emit Transfer(address(0), account, amount);
}
/**
* @dev Destroys `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 amount) internal virtual {
require(account != address(0), "ERC20: burn from the zero address");
_beforeTokenTransfer(account, address(0), amount);
_balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
_totalSupply = _totalSupply.sub(amount);
emit Transfer(account, address(0), amount);
}
/**
* @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 amount) internal virtual {
require(owner != address(0), "ERC20: approve from the zero address");
require(spender != address(0), "ERC20: approve to the zero address");
_allowances[owner][spender] = amount;
emit Approval(owner, spender, amount);
}
/**
* @dev Sets {decimals} to a value other than the default one of 18.
*
* WARNING: This function should only be called from the constructor. Most
* applications that interact with token contracts will not expect
* {decimals} to ever change, and may work incorrectly if it does.
*/
function _setupDecimals(uint8 decimals_) internal {
_decimals = decimals_;
}
/**
* @dev Hook that is called before any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* will be to transferred to `to`.
* - when `from` is zero, `amount` tokens will be minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens will be burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}
// SPDX-License-Identifier: MIT
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) {
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 ^0.6.2;
/**
* @dev Collection of functions related to the address type
*/
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* [IMPORTANT]
* ====
* It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*
* Among others, `isContract` will return false for the following
* types of addresses:
*
* - an externally-owned account
* - a contract in construction
* - an address where a contract will be created
* - an address where a contract lived, but was destroyed
* ====
*/
function isContract(address account) internal view returns (bool) {
// According to EIP-1052, 0x0 is the value returned for not-yet created accounts
// and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
// for accounts without code, i.e. `keccak256('')`
bytes32 codehash;
bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
// solhint-disable-next-line no-inline-assembly
assembly { codehash := extcodehash(account) }
return (codehash != accountHash && codehash != 0x0);
}
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
*
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* imposed by `transfer`, making them unable to receive funds via
* `transfer`. {sendValue} removes this limitation.
*
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
// solhint-disable-next-line avoid-low-level-calls, avoid-call-value
(bool success, ) = recipient.call{ value: amount }("");
require(success, "Address: unable to send value, recipient may have reverted");
}
/**
* @dev Performs a Solidity function call using a low level `call`. A
* plain`call` is an unsafe replacement for a function call: use this
* function instead.
*
* If `target` reverts with a revert reason, it is bubbled up by this
* function (like regular Solidity function calls).
*
* Returns the raw returned data. To convert to the expected return value,
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
*
* Requirements:
*
* - `target` must be a contract.
* - calling `target` with `data` must not revert.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
return _functionCallWithValue(target, data, 0, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but also transferring `value` wei to `target`.
*
* Requirements:
*
* - the calling contract must have an ETH balance of at least `value`.
* - the called Solidity function must be `payable`.
*
* _Available since v3.1._
*/
function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
/**
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* with `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
return _functionCallWithValue(target, data, value, errorMessage);
}
function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
require(isContract(target), "Address: call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
if (success) {
return returndata;
} else {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
// solhint-disable-next-line no-inline-assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}
// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.6.0;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
contract ERC20Mock6Decimals is ERC20("ERC20Mock6decimals", "MCK") {
bool public transferFromCalled = false;
bool public transferCalled = false;
address public transferRecipient = address(0);
uint256 public transferAmount = 0;
uint8 private _decimals;
constructor () public {
_decimals = 6;
}
function mint(address user, uint256 amount) public {
_mint(user, amount);
}
function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
transferFromCalled = true;
return super.transferFrom(sender, recipient, amount);
}
function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
transferCalled = true;
transferRecipient = recipient;
transferAmount = amount;
return super.transfer(recipient, amount);
}
}
// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.6.0;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
contract Staking is ReentrancyGuard {
using SafeMath for uint256;
uint128 constant private BASE_MULTIPLIER = uint128(1 * 10 ** 18);
// timestamp for the epoch 1
// everything before that is considered epoch 0 which won't have a reward but allows for the initial stake
uint256 public epoch1Start;
// duration of each epoch
uint256 public epochDuration;
// holds the current balance of the user for each token
mapping(address => mapping(address => uint256)) private balances;
struct Pool {
uint256 size;
bool set;
}
// for each token, we store the total pool size
mapping(address => mapping(uint256 => Pool)) private poolSize;
// a checkpoint of the valid balance of a user for an epoch
struct Checkpoint {
uint128 epochId;
uint128 multiplier;
uint256 startBalance;
uint256 newDeposits;
}
// balanceCheckpoints[user][token][]
mapping(address => mapping(address => Checkpoint[])) private balanceCheckpoints;
mapping(address => uint128) private lastWithdrawEpochId;
event Deposit(address indexed user, address indexed tokenAddress, uint256 amount);
event Withdraw(address indexed user, address indexed tokenAddress, uint256 amount);
event ManualEpochInit(address indexed caller, uint128 indexed epochId, address[] tokens);
event EmergencyWithdraw(address indexed user, address indexed tokenAddress, uint256 amount);
constructor (uint256 _epoch1Start, uint256 _epochDuration) public {
epoch1Start = _epoch1Start;
epochDuration = _epochDuration;
}
/*
* Stores `amount` of `tokenAddress` tokens for the `user` into the vault
*/
function deposit(address tokenAddress, uint256 amount) public nonReentrant {
require(amount > 0, "Staking: Amount must be > 0");
IERC20 token = IERC20(tokenAddress);
uint256 allowance = token.allowance(msg.sender, address(this));
require(allowance >= amount, "Staking: Token allowance too small");
balances[msg.sender][tokenAddress] = balances[msg.sender][tokenAddress].add(amount);
token.transferFrom(msg.sender, address(this), amount);
// epoch logic
uint128 currentEpoch = getCurrentEpoch();
uint128 currentMultiplier = currentEpochMultiplier();
if (!epochIsInitialized(tokenAddress, currentEpoch)) {
address[] memory tokens = new address[](1);
tokens[0] = tokenAddress;
manualEpochInit(tokens, currentEpoch);
}
// update the next epoch pool size
Pool storage pNextEpoch = poolSize[tokenAddress][currentEpoch + 1];
pNextEpoch.size = token.balanceOf(address(this));
pNextEpoch.set = true;
Checkpoint[] storage checkpoints = balanceCheckpoints[msg.sender][tokenAddress];
uint256 balanceBefore = getEpochUserBalance(msg.sender, tokenAddress, currentEpoch);
// if there's no checkpoint yet, it means the user didn't have any activity
// we want to store checkpoints both for the current epoch and next epoch because
// if a user does a withdraw, the current epoch can also be modified and
// we don't want to insert another checkpoint in the middle of the array as that could be expensive
if (checkpoints.length == 0) {
checkpoints.push(Checkpoint(currentEpoch, currentMultiplier, 0, amount));
// next epoch => multiplier is 1, epoch deposits is 0
checkpoints.push(Checkpoint(currentEpoch + 1, BASE_MULTIPLIER, amount, 0));
} else {
uint256 last = checkpoints.length - 1;
// the last action happened in an older epoch (e.g. a deposit in epoch 3, current epoch is >=5)
if (checkpoints[last].epochId < currentEpoch) {
uint128 multiplier = computeNewMultiplier(
getCheckpointBalance(checkpoints[last]),
BASE_MULTIPLIER,
amount,
currentMultiplier
);
checkpoints.push(Checkpoint(currentEpoch, multiplier, getCheckpointBalance(checkpoints[last]), amount));
checkpoints.push(Checkpoint(currentEpoch + 1, BASE_MULTIPLIER, balances[msg.sender][tokenAddress], 0));
}
// the last action happened in the previous epoch
else if (checkpoints[last].epochId == currentEpoch) {
checkpoints[last].multiplier = computeNewMultiplier(
getCheckpointBalance(checkpoints[last]),
checkpoints[last].multiplier,
amount,
currentMultiplier
);
checkpoints[last].newDeposits = checkpoints[last].newDeposits.add(amount);
checkpoints.push(Checkpoint(currentEpoch + 1, BASE_MULTIPLIER, balances[msg.sender][tokenAddress], 0));
}
// the last action happened in the current epoch
else {
if (last >= 1 && checkpoints[last - 1].epochId == currentEpoch) {
checkpoints[last - 1].multiplier = computeNewMultiplier(
getCheckpointBalance(checkpoints[last - 1]),
checkpoints[last - 1].multiplier,
amount,
currentMultiplier
);
checkpoints[last - 1].newDeposits = checkpoints[last - 1].newDeposits.add(amount);
}
checkpoints[last].startBalance = balances[msg.sender][tokenAddress];
}
}
uint256 balanceAfter = getEpochUserBalance(msg.sender, tokenAddress, currentEpoch);
poolSize[tokenAddress][currentEpoch].size = poolSize[tokenAddress][currentEpoch].size.add(balanceAfter.sub(balanceBefore));
emit Deposit(msg.sender, tokenAddress, amount);
}
/*
* Removes the deposit of the user and sends the amount of `tokenAddress` back to the `user`
*/
function withdraw(address tokenAddress, uint256 amount) public nonReentrant {
require(balances[msg.sender][tokenAddress] >= amount, "Staking: balance too small");
balances[msg.sender][tokenAddress] = balances[msg.sender][tokenAddress].sub(amount);
IERC20 token = IERC20(tokenAddress);
token.transfer(msg.sender, amount);
// epoch logic
uint128 currentEpoch = getCurrentEpoch();
lastWithdrawEpochId[tokenAddress] = currentEpoch;
if (!epochIsInitialized(tokenAddress, currentEpoch)) {
address[] memory tokens = new address[](1);
tokens[0] = tokenAddress;
manualEpochInit(tokens, currentEpoch);
}
// update the pool size of the next epoch to its current balance
Pool storage pNextEpoch = poolSize[tokenAddress][currentEpoch + 1];
pNextEpoch.size = token.balanceOf(address(this));
pNextEpoch.set = true;
Checkpoint[] storage checkpoints = balanceCheckpoints[msg.sender][tokenAddress];
uint256 last = checkpoints.length - 1;
// note: it's impossible to have a withdraw and no checkpoints because the balance would be 0 and revert
// there was a deposit in an older epoch (more than 1 behind [eg: previous 0, now 5]) but no other action since then
if (checkpoints[last].epochId < currentEpoch) {
checkpoints.push(Checkpoint(currentEpoch, BASE_MULTIPLIER, balances[msg.sender][tokenAddress], 0));
poolSize[tokenAddress][currentEpoch].size = poolSize[tokenAddress][currentEpoch].size.sub(amount);
}
// there was a deposit in the `epochId - 1` epoch => we have a checkpoint for the current epoch
else if (checkpoints[last].epochId == currentEpoch) {
checkpoints[last].startBalance = balances[msg.sender][tokenAddress];
checkpoints[last].newDeposits = 0;
checkpoints[last].multiplier = BASE_MULTIPLIER;
poolSize[tokenAddress][currentEpoch].size = poolSize[tokenAddress][currentEpoch].size.sub(amount);
}
// there was a deposit in the current epoch
else {
Checkpoint storage currentEpochCheckpoint = checkpoints[last - 1];
uint256 balanceBefore = getCheckpointEffectiveBalance(currentEpochCheckpoint);
// in case of withdraw, we have 2 branches:
// 1. the user withdraws less than he added in the current epoch
// 2. the user withdraws more than he added in the current epoch (including 0)
if (amount < currentEpochCheckpoint.newDeposits) {
uint128 avgDepositMultiplier = uint128(
balanceBefore.sub(currentEpochCheckpoint.startBalance).mul(BASE_MULTIPLIER).div(currentEpochCheckpoint.newDeposits)
);
currentEpochCheckpoint.newDeposits = currentEpochCheckpoint.newDeposits.sub(amount);
currentEpochCheckpoint.multiplier = computeNewMultiplier(
currentEpochCheckpoint.startBalance,
BASE_MULTIPLIER,
currentEpochCheckpoint.newDeposits,
avgDepositMultiplier
);
} else {
currentEpochCheckpoint.startBalance = currentEpochCheckpoint.startBalance.sub(
amount.sub(currentEpochCheckpoint.newDeposits)
);
currentEpochCheckpoint.newDeposits = 0;
currentEpochCheckpoint.multiplier = BASE_MULTIPLIER;
}
uint256 balanceAfter = getCheckpointEffectiveBalance(currentEpochCheckpoint);
poolSize[tokenAddress][currentEpoch].size = poolSize[tokenAddress][currentEpoch].size.sub(balanceBefore.sub(balanceAfter));
checkpoints[last].startBalance = balances[msg.sender][tokenAddress];
}
emit Withdraw(msg.sender, tokenAddress, amount);
}
/*
* manualEpochInit can be used by anyone to initialize an epoch based on the previous one
* This is only applicable if there was no action (deposit/withdraw) in the current epoch.
* Any deposit and withdraw will automatically initialize the current and next epoch.
*/
function manualEpochInit(address[] memory tokens, uint128 epochId) public {
require(epochId <= getCurrentEpoch(), "can't init a future epoch");
for (uint i = 0; i < tokens.length; i++) {
Pool storage p = poolSize[tokens[i]][epochId];
if (epochId == 0) {
p.size = uint256(0);
p.set = true;
} else {
require(!epochIsInitialized(tokens[i], epochId), "Staking: epoch already initialized");
require(epochIsInitialized(tokens[i], epochId - 1), "Staking: previous epoch not initialized");
p.size = poolSize[tokens[i]][epochId - 1].size;
p.set = true;
}
}
emit ManualEpochInit(msg.sender, epochId, tokens);
}
function emergencyWithdraw(address tokenAddress) public {
require((getCurrentEpoch() - lastWithdrawEpochId[tokenAddress]) >= 10, "At least 10 epochs must pass without success");
uint256 totalUserBalance = balances[msg.sender][tokenAddress];
require(totalUserBalance > 0, "Amount must be > 0");
balances[msg.sender][tokenAddress] = 0;
IERC20 token = IERC20(tokenAddress);
token.transfer(msg.sender, totalUserBalance);
emit EmergencyWithdraw(msg.sender, tokenAddress, totalUserBalance);
}
/*
* Returns the valid balance of a user that was taken into consideration in the total pool size for the epoch
* A deposit will only change the next epoch balance.
* A withdraw will decrease the current epoch (and subsequent) balance.
*/
function getEpochUserBalance(address user, address token, uint128 epochId) public view returns (uint256) {
Checkpoint[] storage checkpoints = balanceCheckpoints[user][token];
// if there are no checkpoints, it means the user never deposited any tokens, so the balance is 0
if (checkpoints.length == 0 || epochId < checkpoints[0].epochId) {
return 0;
}
uint min = 0;
uint max = checkpoints.length - 1;
// shortcut for blocks newer than the latest checkpoint == current balance
if (epochId >= checkpoints[max].epochId) {
return getCheckpointEffectiveBalance(checkpoints[max]);
}
// binary search of the value in the array
while (max > min) {
uint mid = (max + min + 1) / 2;
if (checkpoints[mid].epochId <= epochId) {
min = mid;
} else {
max = mid - 1;
}
}
return getCheckpointEffectiveBalance(checkpoints[min]);
}
/*
* Returns the amount of `token` that the `user` has currently staked
*/
function balanceOf(address user, address token) public view returns (uint256) {
return balances[user][token];
}
/*
* Returns the id of the current epoch derived from block.timestamp
*/
function getCurrentEpoch() public view returns (uint128) {
if (block.timestamp < epoch1Start) {
return 0;
}
return uint128((block.timestamp - epoch1Start) / epochDuration + 1);
}
/*
* Returns the total amount of `tokenAddress` that was locked from beginning to end of epoch identified by `epochId`
*/
function getEpochPoolSize(address tokenAddress, uint128 epochId) public view returns (uint256) {
// Premises:
// 1. it's impossible to have gaps of uninitialized epochs
// - any deposit or withdraw initialize the current epoch which requires the previous one to be initialized
if (epochIsInitialized(tokenAddress, epochId)) {
return poolSize[tokenAddress][epochId].size;
}
// epochId not initialized and epoch 0 not initialized => there was never any action on this pool
if (!epochIsInitialized(tokenAddress, 0)) {
return 0;
}
// epoch 0 is initialized => there was an action at some point but none that initialized the epochId
// which means the current pool size is equal to the current balance of token held by the staking contract
IERC20 token = IERC20(tokenAddress);
return token.balanceOf(address(this));
}
/*
* Returns the percentage of time left in the current epoch
*/
function currentEpochMultiplier() public view returns (uint128) {
uint128 currentEpoch = getCurrentEpoch();
uint256 currentEpochEnd = epoch1Start + currentEpoch * epochDuration;
uint256 timeLeft = currentEpochEnd - block.timestamp;
uint128 multiplier = uint128(timeLeft * BASE_MULTIPLIER / epochDuration);
return multiplier;
}
function computeNewMultiplier(uint256 prevBalance, uint128 prevMultiplier, uint256 amount, uint128 currentMultiplier) public pure returns (uint128) {
uint256 prevAmount = prevBalance.mul(prevMultiplier).div(BASE_MULTIPLIER);
uint256 addAmount = amount.mul(currentMultiplier).div(BASE_MULTIPLIER);
uint128 newMultiplier = uint128(prevAmount.add(addAmount).mul(BASE_MULTIPLIER).div(prevBalance.add(amount)));
return newMultiplier;
}
/*
* Checks if an epoch is initialized, meaning we have a pool size set for it
*/
function epochIsInitialized(address token, uint128 epochId) public view returns (bool) {
return poolSize[token][epochId].set;
}
function getCheckpointBalance(Checkpoint memory c) internal pure returns (uint256) {
return c.startBalance.add(c.newDeposits);
}
function getCheckpointEffectiveBalance(Checkpoint memory c) internal pure returns (uint256) {
return getCheckpointBalance(c).mul(c.multiplier).div(BASE_MULTIPLIER);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
* @dev Contract module that helps prevent reentrant calls to a function.
*
* Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
* available, which can be applied to functions to make sure there are no nested
* (reentrant) calls to them.
*
* Note that because there is a single `nonReentrant` guard, functions marked as
* `nonReentrant` may not call one another. This can be worked around by making
* those functions `private`, and then adding `external` `nonReentrant` entry
* points to them.
*
* TIP: If you would like to learn more about reentrancy and alternative ways
* to protect against it, check out our blog post
* https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
*/
contract ReentrancyGuard {
// Booleans are more expensive than uint256 or any type that takes up a full
// word because each write operation emits an extra SLOAD to first read the
// slot's contents, replace the bits taken up by the boolean, and then write
// back. This is the compiler's defense against contract upgrades and
// pointer aliasing, and it cannot be disabled.
// The values being non-zero value makes deployment a bit more expensive,
// but in exchange the refund on every call to nonReentrant will be lower in
// amount. Since refunds are capped to a percentage of the total
// transaction's gas, it is best to keep them low in cases like this one, to
// increase the likelihood of the full refund coming into effect.
uint256 private constant _NOT_ENTERED = 1;
uint256 private constant _ENTERED = 2;
uint256 private _status;
constructor () internal {
_status = _NOT_ENTERED;
}
/**
* @dev Prevents a contract from calling itself, directly or indirectly.
* Calling a `nonReentrant` function from another `nonReentrant`
* function is not supported. It is possible to prevent this from happening
* by making the `nonReentrant` function external, and make it call a
* `private` function that does the actual work.
*/
modifier nonReentrant() {
// On the first call to nonReentrant, _notEntered will be true
require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
// Any calls to nonReentrant after this point will fail
_status = _ENTERED;
_;
// By storing the original value once again, a refund is triggered (see
// https://eips.ethereum.org/EIPS/eip-2200)
_status = _NOT_ENTERED;
}
}
// 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 YieldFarm {
// lib
using SafeMath for uint;
using SafeMath for uint128;
// constants
uint public constant TOTAL_DISTRIBUTED_AMOUNT = 800000;
uint public constant NR_OF_EPOCHS = 25;
// state variables
// addreses
address private _usdc;
address private _susd;
address private _dai;
address private _communityVault;
// contracts
IERC20 private _bond;
IStaking private _staking;
// fixed size array holdings total number of epochs + 1 (epoch 0 doesn't count)
uint[] private epochs = new uint[](NR_OF_EPOCHS + 1);
// pre-computed variable for optimization. total amount of bond tokens to be distributed on each epoch
uint private _totalAmountPerEpoch;
// id of last init epoch, for optimization purposes moved from struct to a single id.
uint128 public lastInitializedEpoch;
// state of user harvest epoch
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 bondTokenAddress, address usdc, address susd, address dai, address stakeContract, address communityVault) public {
_bond = IERC20(bondTokenAddress);
_usdc = usdc;
_susd = susd;
_dai = dai;
_staking = IStaking(stakeContract);
_communityVault = communityVault;
epochStart = _staking.epoch1Start();
epochDuration = _staking.epochDuration();
_totalAmountPerEpoch = TOTAL_DISTRIBUTED_AMOUNT.mul(10**18).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.sub(lastEpochIdHarvested[msg.sender]), totalDistributedValue);
if (totalDistributedValue > 0) {
_bond.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 25");
require (lastEpochIdHarvested[msg.sender].add(1) == epochId, "Harvest in order");
uint userReward = _harvest(epochId);
if (userReward > 0) {
_bond.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 last harvested epoch
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]);
}
function _getPoolSize(uint128 epochId) internal view returns (uint) {
// retrieve stable coins total staked in epoch
uint valueUsdc = _staking.getEpochPoolSize(_usdc, epochId).mul(10 ** 12); // for usdc which has 6 decimals add a 10**12 to get to a common ground
uint valueSusd = _staking.getEpochPoolSize(_susd, epochId);
uint valueDai = _staking.getEpochPoolSize(_dai, epochId);
return valueUsdc.add(valueSusd).add(valueDai);
}
function _getUserBalancePerEpoch(address userAddress, uint128 epochId) internal view returns (uint){
// retrieve stable coins total staked per user in epoch
uint valueUsdc = _staking.getEpochUserBalance(userAddress, _usdc, epochId).mul(10 ** 12); // for usdc which has 6 decimals add a 10**12 to get to a common ground
uint valueSusd = _staking.getEpochUserBalance(userAddress, _susd, epochId);
uint valueDai = _staking.getEpochUserBalance(userAddress, _dai, epochId);
return valueUsdc.add(valueSusd).add(valueDai);
}
// compute epoch id from blocktimestamp 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));
}
}
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: 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 YieldFarmLP {
// lib
using SafeMath for uint;
using SafeMath for uint128;
// constants
uint public constant TOTAL_DISTRIBUTED_AMOUNT = 2000000;
uint public constant NR_OF_EPOCHS = 100;
// state variables
// addreses
address private _uniLP;
address private _communityVault;
// contracts
IERC20 private _bond;
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 bondTokenAddress, address uniLP, address stakeContract, address communityVault) public {
_bond = IERC20(bondTokenAddress);
_uniLP = uniLP;
_staking = IStaking(stakeContract);
_communityVault = communityVault;
epochDuration = _staking.epochDuration();
epochStart = _staking.epoch1Start() + epochDuration;
_totalAmountPerEpoch = TOTAL_DISTRIBUTED_AMOUNT.mul(10**18).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) {
_bond.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 100");
require (lastEpochIdHarvested[msg.sender].add(1) == epochId, "Harvest in order");
uint userReward = _harvest(epochId);
if (userReward > 0) {
_bond.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]);
}
function _getPoolSize(uint128 epochId) internal view returns (uint) {
// retrieve unilp token balance
return _staking.getEpochPoolSize(_uniLP, _stakingEpochId(epochId));
}
function _getUserBalancePerEpoch(address userAddress, uint128 epochId) internal view returns (uint){
// retrieve unilp token balance per user per epoch
return _staking.getEpochUserBalance(userAddress, _uniLP, _stakingEpochId(epochId));
}
// compute epoch id from blocktimestamp 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 which is 1 epoch more
function _stakingEpochId(uint128 epochId) pure internal returns (uint128) {
return epochId + 1;
}
}