Skip to content

fix: correct fee calculation for exactOut swaps in afterSwap example #1109

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
Kropiunig wants to merge 1 commit into
base: main
Choose a base branch
from
Open

fix: correct fee calculation for exactOut swaps in afterSwap example #1109

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
64 changes: 37 additions & 27 deletions docs/contracts/v4/guides/custom-accounting.mdx
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -314,26 +314,31 @@ function _afterSwap(
BalanceDelta delta,
bytes calldata
) internal override returns (bytes4, int128) {
bool outputIsToken0 = params.zeroForOne ? false : true;
bool isExactIn = (params.amountSpecified < 0);

// Determine the unspecified currency and amount
// exactIn: unspecified is output; exactOut: unspecified is input
bool unspecifiedIsToken0;
if (isExactIn) {
unspecifiedIsToken0 = params.zeroForOne ? false : true; // output token
} else {
unspecifiedIsToken0 = params.zeroForOne ? true : false; // input token
}

int256 unspecifiedAmount = unspecifiedIsToken0 ? delta.amount0() : delta.amount1();

int256 outputAmount = outputIsToken0 ? delta.amount0() : delta.amount1();
if (outputAmount <= 0) {
// For exactIn, unspecifiedAmount (output) is positive
// For exactOut, unspecifiedAmount (input) is negative, so we negate it
int256 amountForFee = isExactIn ? unspecifiedAmount : -unspecifiedAmount;
if (amountForFee <= 0) {
return (BaseHook.afterSwap.selector, 0);
}

uint256 feeAmount = (uint256(outputAmount) * HOOK_FEE_PERCENTAGE) / FEE_DENOMINATOR;
uint256 feeAmount = (uint256(amountForFee) * HOOK_FEE_PERCENTAGE) / FEE_DENOMINATOR;

require(feeAmount <= ((uint256(1) << 127) - 1), "fee too large");

bool isExactIn = (params.amountSpecified < 0);

Currency feeCurrency;
if (isExactIn) {
feeCurrency = outputIsToken0 ? key.currency0 : key.currency1;
} else {
bool inputIsToken0 = params.zeroForOne ? true : false;
feeCurrency = inputIsToken0 ? key.currency0 : key.currency1;
}
Currency feeCurrency = unspecifiedIsToken0 ? key.currency0 : key.currency1;

poolManager.take(feeCurrency, address(this), feeAmount);

Expand Down Expand Up @@ -380,32 +385,37 @@ contract HookFeeAfterSwap is BaseHook {
}

function _afterSwap(
address ,
address,
PoolKey calldata key,
SwapParams calldata params,
BalanceDelta delta,
bytes calldata
) internal override returns (bytes4, int128) {
bool outputIsToken0 = params.zeroForOne ? false : true;
bool isExactIn = (params.amountSpecified < 0);

// Determine the unspecified currency and amount
// exactIn: unspecified is output; exactOut: unspecified is input
bool unspecifiedIsToken0;
if (isExactIn) {
unspecifiedIsToken0 = params.zeroForOne ? false : true; // output token
} else {
unspecifiedIsToken0 = params.zeroForOne ? true : false; // input token
}

int256 unspecifiedAmount = unspecifiedIsToken0 ? delta.amount0() : delta.amount1();

int256 outputAmount = outputIsToken0 ? delta.amount0() : delta.amount1();
if (outputAmount <= 0) {
// For exactIn, unspecifiedAmount (output) is positive
// For exactOut, unspecifiedAmount (input) is negative, so we negate it
int256 amountForFee = isExactIn ? unspecifiedAmount : -unspecifiedAmount;
if (amountForFee <= 0) {
return (BaseHook.afterSwap.selector, 0);
}

uint256 feeAmount = (uint256(outputAmount) * HOOK_FEE_PERCENTAGE) / FEE_DENOMINATOR;
uint256 feeAmount = (uint256(amountForFee) * HOOK_FEE_PERCENTAGE) / FEE_DENOMINATOR;

require(feeAmount <= ((uint256(1) << 127) - 1), "fee too large");

bool isExactIn = (params.amountSpecified < 0);

Currency feeCurrency;
if (isExactIn) {
feeCurrency = outputIsToken0 ? key.currency0 : key.currency1;
} else {
bool inputIsToken0 = params.zeroForOne ? true : false;
feeCurrency = inputIsToken0 ? key.currency0 : key.currency1;
}
Currency feeCurrency = unspecifiedIsToken0 ? key.currency0 : key.currency1;

poolManager.take(feeCurrency, address(this), feeAmount);

Expand Down