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dynamic fees initial implementation
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@khlrst
khlrst committed Sep 7, 2024
1 parent c852804 commit b65503a
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Showing 3 changed files with 102 additions and 30 deletions.
2 changes: 1 addition & 1 deletion packages/masp-anchor-contracts/contracts/tokens/omnipool/ERC20.sol
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Expand Up @@ -3,7 +3,7 @@ pragma solidity ^0.8.24;

import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";

contract ERC20 is IERC20 {
abstract contract ERC20 is IERC20 {

error TransferAmountExceedsBalance();
error TransferAmountExceedsAllowance();
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39 changes: 39 additions & 0 deletions packages/masp-anchor-contracts/contracts/tokens/omnipool/OmniLib.sol
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Expand Up @@ -3,10 +3,49 @@ pragma solidity ^0.8.24;

type TokenInfo is uint256;

struct WhitelistedTokens {
address[] array;
mapping(address => uint256) idx;
}

using OmniLib for WhitelistedTokens global;
using OmniLib for TokenInfo global;

library OmniLib {

function exists(WhitelistedTokens storage _whitelisted, address _token) internal view returns (bool) {
return _whitelisted.idx[_token] != 0;
}

function add(WhitelistedTokens storage _whitelisted, address _token) internal {
if (exists(_whitelisted, _token)) {
return;
}

_whitelisted.array.push(_token);
_whitelisted.idx[_token] = _whitelisted.array.length;
}

function remove(WhitelistedTokens storage _whitelisted, address _token) internal {
uint256 tokenIdx = _whitelisted.idx[_token];

if (tokenIdx == 0) {
return;
}

uint256 arrayIdx = tokenIdx - 1;
uint256 lastIdx = _whitelisted.array.length - 1;

if (arrayIdx != lastIdx) {
address lastElement = _whitelisted.array[lastIdx];
_whitelisted.array[arrayIdx] = lastElement;
_whitelisted.idx[lastElement] = tokenIdx;
}

_whitelisted.array.pop();
delete _whitelisted.idx[_token];
}

function isWhitelisted(TokenInfo _info) internal pure returns (bool) {
return uint128(TokenInfo.unwrap(_info)) == WHITELISTED;
}
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91 changes: 62 additions & 29 deletions packages/masp-anchor-contracts/contracts/tokens/omnipool/OmniPool.sol
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Expand Up @@ -5,7 +5,7 @@ import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

import { TokenInfo, PRECISION, FEE_BASIS_POINTS } from "./OmniLib.sol";
import { WhitelistedTokens, PRECISION, FEE_BASIS_POINTS } from "./OmniLib.sol";
import { IOmniPool } from "../../interfaces/IOmniPool.sol";
import { IOracle} from "../../interfaces/IOracle.sol";
import { ERC20 } from "./ERC20.sol";
Expand All @@ -16,21 +16,24 @@ contract OmniPool is IOmniPool, ERC20, ReentrancyGuard, Ownable {
address public immutable anchor;
address public immutable treasury;
IOracle public oracle;
uint256 public feeCap;

mapping(address => TokenInfo) private _tokenInfo;
address[] private _whitelistedTokens;
//mapping(address => TokenInfo) private _tokenInfo; this mapping used with manually managed fees.
WhitelistedTokens private _whitelist;


constructor(
string memory _name,
string memory _symbol,
address _anchor,
address _oracle,
address _treasury
address _treasury,
uint256 _feeCap
) ERC20(_name, _symbol) {
anchor = _anchor;
treasury = _treasury;
oracle = IOracle(_oracle);
feeCap = _feeCap;
}

function changeOracle(
Expand Down Expand Up @@ -76,11 +79,9 @@ contract OmniPool is IOmniPool, ERC20, ReentrancyGuard, Ownable {
address _token,
uint256 _shares
) external nonReentrant returns (uint256 amount) {
// read token info
TokenInfo info = _tokenInfo[_token];

// validate token whitelists and shares are not zero
if(!info.isWhitelisted()) revert TokenIsNotWhitelisted(_token);
if(!_whitelist.exists(_token)) revert TokenIsNotWhitelisted(_token);
if(_shares == 0) revert WithdrawAmountIsZero();

// get total pool value
Expand All @@ -98,55 +99,48 @@ contract OmniPool is IOmniPool, ERC20, ReentrancyGuard, Ownable {
}

function swap(
address _from,
address _to,
address _in,
address _out,
uint256 _amountIn
) external nonReentrant returns (uint256 amountOut) {
// read tokens info
TokenInfo tokenIn = _tokenInfo[_from];
TokenInfo tokenOut = _tokenInfo[_to];

// validate tokens are whitelisted
if(!tokenIn.isWhitelisted()) revert TokenIsNotWhitelisted(_from);
if(!tokenOut.isWhitelisted()) revert TokenIsNotWhitelisted(_to);
if(!_whitelist.exists(_in)) revert TokenIsNotWhitelisted(_in);
if(!_whitelist.exists(_out)) revert TokenIsNotWhitelisted(_out);
// validate amountIn is non zero
if(_amountIn == 0) revert SwapAmountIsZero();

uint256 swapValueIn = _chargeFees(tokenIn.inputFee(), _amountIn * oracle.getPrice(_from) / PRECISION);
uint256 swapValueOut = _chargeFees(tokenOut.outputFee(), swapValueIn);
amountOut = swapValueOut * PRECISION / oracle.getPrice(_to);
amountOut = _calculateAmountOut(_in, _out, _amountIn);

if (IERC20(_to).balanceOf(address(this)) >= amountOut) revert NotEnoughTokensToWithdraw();
if (IERC20(_out).balanceOf(address(this)) >= amountOut) revert NotEnoughTokensToWithdraw();

IERC20(_to).safeTransferFrom(address(this), msg.sender, amountOut);
IERC20(_out).safeTransferFrom(address(this), msg.sender, amountOut);

emit Swap(msg.sender, _from, _to, _amountIn, amountOut);
emit Swap(msg.sender, _in, _out, _amountIn, amountOut);
}

function totalPoolValue() public view returns (uint256 value) {
uint256 length = _whitelistedTokens.length;
uint256 length = _whitelist.array.length;
for (uint256 i = 0; i < length;) {
(uint256 price, uint256 balance) =oracle.getPriceAndBalance(address(this), _whitelistedTokens[i]);
value += (price * balance) / PRECISION;
(uint256 price, uint256 balance) = oracle.getPriceAndBalance(address(this), _whitelist.array[i]);
unchecked {
value += (price * balance) / PRECISION;
++i;
}
}
}

function getWhitelistedTokens() public view returns (address[] memory whitelisted) {
whitelisted = _whitelistedTokens;
whitelisted = _whitelist.array;
}

function _deposit(
address _token,
uint256 _amount
) private returns (uint256 shares) {
// read token info
TokenInfo info = _tokenInfo[_token];

// validate token whitelists and amount is not zero
if(!info.isWhitelisted()) revert TokenIsNotWhitelisted(_token);
if(!_whitelist.exists(_token)) revert TokenIsNotWhitelisted(_token);
if(_amount == 0) revert DepositAmountIsZero();

// get native value of the deposit
Expand All @@ -160,7 +154,46 @@ contract OmniPool is IOmniPool, ERC20, ReentrancyGuard, Ownable {
emit Deposit(msg.sender, _token, _amount, shares);
}

function _chargeFees(uint256 _fee, uint256 _amount) private pure returns (uint256){
return _amount * _fee / FEE_BASIS_POINTS;
function _calculateAmountOut(
address _in,
address _out,
uint256 _amountIn
) private view returns (uint256 amountOut) {
// read token prices and calculate ideal target value.
uint256 priceIn = oracle.getPrice(_in);
uint256 priceOut = oracle.getPrice(_out);
uint256 targetValue = totalPoolValue() / _whitelist.array.length;

// apply fees
uint256 swapValueIn = _chargeFees(
_calculateInputFee(_in, targetValue, priceIn),
_amountIn * priceIn / PRECISION
);
uint256 swapValueOut = _chargeFees(
_calculateOutputFee(_in, targetValue, priceOut),
swapValueIn
);

// calculate output amount
amountOut = swapValueOut * PRECISION / priceOut;
}

function _calculateInputFee(address _in, uint256 _targetValue, uint256 _priceIn) private view returns (uint256) {
uint256 tokenValue = IERC20(_in).balanceOf(address(this)) * _priceIn / PRECISION;
if (tokenValue <= _targetValue) return 0;
uint256 proficit = tokenValue - _targetValue;
return proficit * FEE_BASIS_POINTS / _targetValue;
}

function _calculateOutputFee(address _out, uint256 _targetValue, uint256 _priceOut) private view returns (uint256) {
uint256 tokenValue = IERC20(_out).balanceOf(address(this)) * _priceOut / PRECISION;
if (tokenValue >= _targetValue) return 0;
uint256 deficit = _targetValue - tokenValue;
return deficit * FEE_BASIS_POINTS / _targetValue;
}

function _chargeFees(uint256 _fee, uint256 _amount) private view returns (uint256){
uint256 fee = _fee > feeCap ? feeCap : _fee;
return _amount * fee / FEE_BASIS_POINTS;
}
}

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