gistfile1.txt

import { BigNumber } from '@ethersproject/bignumber';
import { ethers } from 'ethers';

type APRType = {
  apr: number
  feesEarned0: BigNumber
  feesEarned1: BigNumber
}

const X96 = BigNumber.from(2).pow(BigNumber.from(96))
const BLOCKS_PER_YEAR = 2102400

const computeAverageReserves = (snapshots: any, firstBlock: number, lastBlock: number) => {
  let cumulativeBlocks = BigNumber.from(0)
  let cumulativeReserves = BigNumber.from(0)
  for (let i=1; i < snapshots.length+1; i++) {
    if (Number(snapshots[i-1].block) < lastBlock) {
      if (i == snapshots.length || Number(snapshots[i].block) >= firstBlock) {
        const reserves0 = BigNumber.from(snapshots[i-1].reserves0)
        const reserves1 = BigNumber.from(snapshots[i-1].reserves1)
        const priceX96X96 = BigNumber.from(snapshots[i-1].sqrtPriceX96).mul(BigNumber.from(snapshots[i-1].sqrtPriceX96))
        const reserves0As1X96 = reserves0.mul(priceX96X96).div(X96)
        const reserves0As1 = reserves0As1X96.div(X96)
        const reserves = reserves1.add(reserves0As1)
        let blockDifferential: BigNumber
        if (i<snapshots.length) {
          blockDifferential = BigNumber.from(snapshots[i].block).sub(BigNumber.from(snapshots[i-1].block))
        } else {
          blockDifferential = BigNumber.from(lastBlock).sub(BigNumber.from(snapshots[i-1].block))
        }
        cumulativeReserves = cumulativeReserves.add(reserves.mul(blockDifferential))
        cumulativeBlocks = cumulativeBlocks.add(blockDifferential)
      }
    }
  }
  if (cumulativeBlocks.gt(ethers.constants.Zero)) {
    return cumulativeReserves.div(cumulativeBlocks)
  } else {
    return ethers.constants.Zero
  }
}

const computeTotalFeesEarned = (snapshots: any, sqrtPriceX96: BigNumber, firstBlock: number): BigNumber[] => {
  let feesEarned0 = BigNumber.from(0)
  let feesEarned1 = BigNumber.from(0)
  let totalFeesEarned0 = BigNumber.from(0)
  let totalFeesEarned1 = BigNumber.from(0)
  for (let i=0; i<snapshots.length; i++) {
    if (Number(snapshots[i].block) >= firstBlock) {
      feesEarned0 = feesEarned0.add(BigNumber.from(snapshots[i].feesEarned0))
      feesEarned1 = feesEarned1.add(BigNumber.from(snapshots[i].feesEarned1))
    }
    totalFeesEarned0 = totalFeesEarned0.add(BigNumber.from(snapshots[i].feesEarned0))
    totalFeesEarned1 = totalFeesEarned1.add(BigNumber.from(snapshots[i].feesEarned1))
  }
  const priceX96X96 = sqrtPriceX96.mul(sqrtPriceX96)
  const fees0As1X96 = feesEarned0.mul(priceX96X96).div(X96)
  const fees0As1 = fees0As1X96.div(X96)
  return [feesEarned1.add(fees0As1), totalFeesEarned0, totalFeesEarned1]
}

export const getAPR = (poolData: any, sqrtPriceX96: BigNumber, currentFees0: BigNumber, currentFees1: BigNumber, lastBlock: number): APRType => {
  if (poolData.supplySnapshots.length == 0) {
    return {
      apr: 0,
      feesEarned0: ethers.constants.Zero,
      feesEarned1: ethers.constants.Zero,
    }
  }
  let snapshots = [];
  if (poolData.feeSnapshots.length != 0) {
    snapshots = [...poolData.feeSnapshots].sort((a: any, b:any) => (a.block > b.block) ? 1: -1)
  }
  const supplySnaps = [...poolData.supplySnapshots].sort((a: any, b: any) => (a.block > b.block) ? 1: -1)
  let firstBlock = (Number(lastBlock) - 40320*4).toString()
  if (Number(firstBlock) < Number(poolData.blockCreated)) {
    firstBlock = poolData.blockCreated
  }
  snapshots.push({
    feesEarned0: currentFees0.toString(),
    feesEarned1: currentFees1.toString(),
    block: lastBlock
  });
  if (snapshots.length == 0 || supplySnaps.length == 0) {
    return {
      apr: 0,
      feesEarned0: ethers.constants.Zero,
      feesEarned1: ethers.constants.Zero,
    }
  }
  const [totalFeeValue, feesTotal0, feesTotal1] = computeTotalFeesEarned(snapshots, sqrtPriceX96, Number(firstBlock))
  const averageReserves = computeAverageReserves(supplySnaps, Number(firstBlock), Number(lastBlock))
  let apr = 0
  if (averageReserves.gt(ethers.constants.Zero)) {
    let averagePrincipal = averageReserves.sub(totalFeeValue)
    if (averagePrincipal.lte(ethers.constants.Zero)) {
      averagePrincipal = averageReserves
    }
    const totalBlocks = Number(lastBlock) - Number(firstBlock)
    apr = (Number(ethers.utils.formatEther(totalFeeValue)) * BLOCKS_PER_YEAR) / (Number(ethers.utils.formatEther(averagePrincipal)) * totalBlocks)
  }
  return {
    apr: apr > 0 ? apr : 0,
    feesEarned0: feesTotal0,
    feesEarned1: feesTotal1
  }
}