Swap

Uniswap v4's swap event improves token exchanges with enhanced efficiency and customization, allowing seamless ERC-20 trades with features like concentrated liquidity and adjustable fees, strengthening its DeFi role. The standard event emitted on swap is:

event Swap(
    PoolId indexed id,
    address indexed sender,
    int128 amount0,
    int128 amount1,
    uint160 sqrtPriceX96,
    uint128 liquidity,
    int24 tick,
    uint24 fee
);

Where amount0 and amount1 are amounts of tokens that took part in swap, sqrtPriceX96 is:

$$\text{sqrtPriceX96} = \sqrt{\frac{\text{price of token1}}{\text{price of token0}}} \times 2^{96}$$

liquidity is a liquidity in pool after the swap, tick, fee is a percentage of protocol fee.

To effectively monitor swap events on a pool, HookRank utilizes The Graph to continuously track them on-chain and modify entities provided in Tracked Data.

On every Swap event emitted standard flow is executed in following order:

1. convert each token amount from decimal to integer value using number of decimals specified in Token and revert a sign as specified in official Uniswap article: amountDec = -(amount / decimals);

2. calculate abs()for both amounts to be used in volume calculation further: amountAbs = abs(amountDec);

3. calculate amount of each token in ETH and USD: amountETH = amountAbs * tokenPriceETH; amountUSD = amountETH * ethPriceUSD;

4. calculate the total swap amount in ETH and USD by accounting for only non-zero prices and dividing result by 2 as both input and output can`t be counted as volume:

const totalSwapAmount = 0;

if (price0USD > 0 && price1USD > 0) {
    totalSwapAmount = (price0USD * amount0Abs + price1USD * amount1Abs) / 2;
}

if (price0USD == 0 && price1USD > 0) {
    totalSwapAmount = price1USD * amount1Abs;
}

if (price0USD > 0 && price1USD == 0) {
    totalSwapAmount = price0USD * amount0Abs;
}

1. calculate the fees in ETH and USD by multiplying the fee values from the event with the totalSwapAmount in their respective currencies, then divide the result by 10^6 to with Uniswap percent denominator: fees = totalSwapAmount * fee / 10^6;

2. update values of PoolManager

   • increment txCount by 1;

   • increment totalVolumeETH by totalSwapAmount in ETH;

   • increment totalVolumeUSD by totalSwapAmount in USD;

   • increment totalFeesETH by fees in ETH;

   • increment totalFeesUSD by fees in USD;

3. decrement PoolManager totalValueLockedETH by old Pool totalValueLockedETH (it is needed to add new TVL later);
4. update values of Pool:

   • increment token volumes (volumeToken0, volumeToken1) by amount0Abs, amount1Abs respectively;

   • increment volumeUSD by totalSwapAmountUSD;

   • increment feesUSD by calculated feesUSD;

   • increment txCount by 1;

   • update liquidity with value from event;

   • update tick with value from event;

   • update sqrtPrice with value from event;

   • increment totalValueLocked for both tokens by amount respectively;

5. update for both tokens values of Token

   • increment volume by amountAbs;

   • increment totalValueLocked by amount;

   • increment volumeUSD by totalSwapAmountUSD;

   • increment feesUSD by calculated feesUSD;

   • increment txCount by 1;

6. update Pool rates:

   • update token prices to new prices calculated by standard AMM formula;

   • save lastTx value;

7. update BundleethPriceUSD by new value fetched from native token pool;
8. update TokenderivedETH (token price in native currency) for both tokens;
9. update Pool values affected by new USD rates:

   • totalValueLockedETH: totalValueLockedETH = totalValueLockedToken0 * token0DerivedETH + totalValueLockedToken1 * token1DerivedETH;

   • totalValueLockedUSD: totalValueLockedUSD = totalValueLockedETH * ethPriceUSD;

10. update Pool gas values:

    • increment gasAccumulatedBySwaps by gas value from event;

    • increment gasAccumulatedBySwapsInEth by gas value from event times transaction gas price;

    • increment swapsCount by 1;

11. update Hook values:

    • update totalValueLocked in ETH and USD by subtracting the pool's old totalValueLocked and adding new one (calculated with new prices);

    • increment volumeUSD by totalSwapAmountUSD;

    • increment feesUSD by calculated feesUSD;

    • increment gasAccumulatedBySwaps by gas value from event;

    • increment gasAccumulatedBySwapsInEth by gas value from event times transaction gas price;

    • increment swapsCount by 1;

12. increment PoolManager totalValueLocked by updated pool values;
13. increment Token totalValueLocked by updated pool values;
14. update UniswapDayData, PoolDayData, PoolHourData, TokenDayData TokenHourData with values calculated earlier;