pricing

schema.graphql

@@ -7,6 +7,9 @@ type Token @entity {
   decimals: BigInt!
 
   totalLiquidity: BigDecimal!
+  stablecoinPairs: [Pair!]!
+  primaryUsdPrice: BigDecimal!
+  primaryUsdLiquidity: BigDecimal!
 
   pairsAsToken0: [Pair!]! @derivedFrom(field: "token0")
   pairsAsToken1: [Pair!]! @derivedFrom(field: "token1")
@@ -28,6 +31,8 @@ type Pair @entity {
   reserve0: BigDecimal!
   reserve1: BigDecimal!
 
+  primaryUsdLiquidity: BigDecimal!
+
   mints: [Mint!]! @derivedFrom(field: "pair")
   burns: [Burn!]! @derivedFrom(field: "pair")
   swaps: [Swap!]! @derivedFrom(field: "pair")

src/mappings/factory.ts

@@ -5,14 +5,18 @@ import { PairCreated } from '../types/Factory/Factory'
 import { Pair, Token, UniswapFactory } from '../types/schema'
 import { Pair as PairTemplate } from '../types/templates'
 import { FACTORY_ADDRESS, fetchTokenDecimals, ONE_BI, ZERO_BD } from './helpers'
+import { getBestPrimaryUsdPrice, isStablecoin } from './pricing'
 
 export function handleNewPair(event: PairCreated): void {
   if (event.params.param3.equals(ONE_BI)) {
     const factory = new UniswapFactory(FACTORY_ADDRESS)
     factory.save()
   }
 
-  if (Token.load(event.params.token0.toHexString()) === null) {
+  let token0 = Token.load(event.params.token0.toHexString())
+  let token1 = Token.load(event.params.token1.toHexString())
+
+  if (token0 === null) {
     const decimals = fetchTokenDecimals(event.params.token0)
     if (decimals === null) {
       log.warning('Could not fetch decimals for token {}, skipping creation of pair {}.', [
@@ -22,13 +26,16 @@ export function handleNewPair(event: PairCreated): void {
       return
     }
 
-    const token0 = new Token(event.params.token0.toHexString())
+    token0 = new Token(event.params.token0.toHexString())
     token0.decimals = decimals
     token0.totalLiquidity = ZERO_BD
+    token0.stablecoinPairs = []
+    token0.primaryUsdPrice = ZERO_BD
+    token0.primaryUsdLiquidity = ZERO_BD
     token0.save()
   }
 
-  if (Token.load(event.params.token1.toHexString()) === null) {
+  if (token1 === null) {
     const decimals = fetchTokenDecimals(event.params.token1)
     if (decimals === null) {
       log.warning('Could not fetch decimals for token {}, skipping creation of pair {}.', [
@@ -37,10 +44,12 @@ export function handleNewPair(event: PairCreated): void {
       ])
       return
     }
-
-    const token1 = new Token(event.params.token1.toHexString())
+    token1 = new Token(event.params.token1.toHexString())
     token1.decimals = decimals
     token1.totalLiquidity = ZERO_BD
+    token1.stablecoinPairs = []
+    token1.primaryUsdPrice = ZERO_BD
+    token1.primaryUsdLiquidity = ZERO_BD
     token1.save()
   }
 
@@ -51,7 +60,23 @@ export function handleNewPair(event: PairCreated): void {
   pair.createdAtBlockNumber = event.block.number
   pair.reserve0 = ZERO_BD
   pair.reserve1 = ZERO_BD
+  pair.primaryUsdLiquidity = ZERO_BD
   pair.save()
 
+  if (isStablecoin(event.params.token1.toHexString())) {
+    const stablecoinPairs = token0.stablecoinPairs
+    stablecoinPairs.push(event.params.pair.toHexString())
+    token0.stablecoinPairs = stablecoinPairs
+    token0.primaryUsdPrice = getBestPrimaryUsdPrice(stablecoinPairs, token0.id)
+    token0.save()
+  }
+  if (isStablecoin(event.params.token0.toHexString())) {
+    const stablecoinPairs = token1.stablecoinPairs
+    stablecoinPairs.push(event.params.pair.toHexString())
+    token1.stablecoinPairs = stablecoinPairs
+    token1.primaryUsdPrice = getBestPrimaryUsdPrice(stablecoinPairs, token1.id)
+    token1.save()
+  }
+
   PairTemplate.create(event.params.pair)
 }

src/mappings/pair.ts

@@ -4,6 +4,7 @@ import { log } from '@graphprotocol/graph-ts'
 import { Burn as BurnEntity, Mint as MintEntity, Pair, Swap as SwapEntity, Token } from '../types/schema'
 import { Burn, Mint, Swap } from '../types/templates/Pair/Pair'
 import { convertTokenToDecimal } from './helpers'
+import { getBestPrimaryUsdPrice } from './pricing'
 
 export function handleMint(event: Mint): void {
   const block = event.block
@@ -36,10 +37,21 @@ export function handleMint(event: Mint): void {
   mint.amount1 = token1Amount as BigDecimal
   mint.save()
 
+  token0.primaryUsdPrice = getBestPrimaryUsdPrice(token0.stablecoinPairs, token0.id)
+  token1.primaryUsdPrice = getBestPrimaryUsdPrice(token1.stablecoinPairs, token1.id)
   token0.totalLiquidity = token0.totalLiquidity.plus(token0Amount)
   token1.totalLiquidity = token1.totalLiquidity.plus(token1Amount)
+  token0.primaryUsdLiquidity = token0.primaryUsdPrice.times(token0.totalLiquidity)
+  token1.primaryUsdLiquidity = token1.primaryUsdPrice.times(token1.totalLiquidity)
   token0.save()
   token1.save()
+
+  pair.reserve0 = pair.reserve0.plus(token0Amount)
+  pair.reserve1 = pair.reserve1.plus(token1Amount)
+  pair.primaryUsdLiquidity = pair.reserve0
+    .times(token0.primaryUsdPrice)
+    .plus(pair.reserve1.times(token1.primaryUsdPrice))
+  pair.save()
 }
 
 export function handleBurn(event: Burn): void {
@@ -66,10 +78,22 @@ export function handleBurn(event: Burn): void {
   burn.to = event.params.to
   burn.save()
 
+
+  token0.primaryUsdPrice = getBestPrimaryUsdPrice(token0.stablecoinPairs, token0.id)
+  token1.primaryUsdPrice = getBestPrimaryUsdPrice(token1.stablecoinPairs, token1.id)
   token0.totalLiquidity = token0.totalLiquidity.minus(token0Amount)
   token1.totalLiquidity = token1.totalLiquidity.minus(token1Amount)
+  token0.primaryUsdLiquidity = token0.primaryUsdPrice.times(token0.totalLiquidity)
+  token1.primaryUsdLiquidity = token1.primaryUsdPrice.times(token1.totalLiquidity)
   token0.save()
   token1.save()
+
+  pair.reserve0 = pair.reserve0.minus(token0Amount)
+  pair.reserve1 = pair.reserve1.minus(token1Amount)
+  pair.primaryUsdLiquidity = pair.reserve0
+    .times(token0.primaryUsdPrice)
+    .plus(pair.reserve1.times(token1.primaryUsdPrice))
+  pair.save()
 }
 
 export function handleSwap(event: Swap): void {
@@ -100,8 +124,19 @@ export function handleSwap(event: Swap): void {
   swap.to = event.params.to
   swap.save()
 
+  token0.primaryUsdPrice = getBestPrimaryUsdPrice(token0.stablecoinPairs, token0.id)
+  token1.primaryUsdPrice = getBestPrimaryUsdPrice(token1.stablecoinPairs, token1.id)
   token0.totalLiquidity = token0.totalLiquidity.minus(token0AmountOut).plus(token0AmountIn)
   token1.totalLiquidity = token1.totalLiquidity.minus(token1AmountOut).plus(token1AmountIn)
+  token0.primaryUsdLiquidity = token0.primaryUsdPrice.times(token0.totalLiquidity)
+  token1.primaryUsdLiquidity = token1.primaryUsdPrice.times(token1.totalLiquidity)
   token0.save()
   token1.save()
-}
+
+  pair.reserve0 = pair.reserve0.minus(token0AmountOut).plus(token0AmountIn)
+  pair.reserve1 = pair.reserve1.minus(token1AmountOut).plus(token1AmountIn)
+  pair.primaryUsdLiquidity = pair.reserve0
+    .times(token0.primaryUsdPrice)
+    .plus(pair.reserve1.times(token1.primaryUsdPrice))
+  pair.save()
+}

src/mappings/pricing.ts

@@ -0,0 +1,87 @@
+import { BigDecimal } from '@graphprotocol/graph-ts'
+
+import { Pair, Token } from '../types/schema'
+import { ZERO_BD } from './helpers'
+
+const STABLECOINS: string[] = [
+  '0x6b175474e89094c44da98b954eedeac495271d0f', // DAI
+  '0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48', // USDC
+  '0xdac17f958d2ee523a2206206994597c13d831ec7', // USDT
+]
+
+export function isStablecoin(token: string): boolean {
+  return STABLECOINS.includes(token)
+}
+
+export function updatePrimaryUsdPrices(pair: Pair, token0: Token, token1: Token): void {
+  if (isStablecoin(pair.token0) && isStablecoin(pair.token1)) {
+    return
+  }
+
+  if (isStablecoin(pair.token0)) {
+    token1.primaryUsdPrice = pair.reserve0.div(pair.reserve1)
+  } else if (isStablecoin(pair.token1)) {
+    token0.primaryUsdPrice = pair.reserve1.div(pair.reserve0)
+  }
+}
+
+export function safeDiv(a: BigDecimal, b: BigDecimal): BigDecimal {
+  if (b.equals(ZERO_BD)) {
+    return ZERO_BD
+  }
+
+  return a.div(b)
+}
+
+export function getPrimaryUsdLiquidity(pair: Pair): BigDecimal {
+  if (isStablecoin(pair.token0) && isStablecoin(pair.token1)) {
+    return pair.reserve0.plus(pair.reserve1)
+  }
+
+  if (isStablecoin(pair.token0)) {
+    return pair.reserve0
+  }
+
+  if (isStablecoin(pair.token1)) {
+    return pair.reserve1
+  }
+
+  return ZERO_BD
+}
+
+export function getUsdPrice(pair: Pair, tokenAddress: string): BigDecimal {
+  if (isStablecoin(tokenAddress)) {
+    return BigDecimal.fromString('1.0')
+  }
+
+  if (isStablecoin(pair.token0)) {
+    return safeDiv(pair.reserve0, pair.reserve1)
+  }
+
+  if (isStablecoin(pair.token1)) {
+    return safeDiv(pair.reserve1, pair.reserve0)
+  }
+
+  return ZERO_BD
+}
+
+// returns [maxUsdLiquidity, bestUsdPrice]
+export function getBestPrimaryUsdPrice(stablecoinPairAddresses: string[], tokenAddress: string): [BigDecimal, BigDecimal] {
+  if (isStablecoin(tokenAddress)) {
+    return [ZERO_BD, BigDecimal.fromString('1.0')]
+  }
+
+  let maxUsdLiquidity = ZERO_BD
+  let bestUsdPrice = ZERO_BD
+
+  for (let i = 0; i < stablecoinPairAddresses.length; i++) {
+    const pair = Pair.load(stablecoinPairAddresses[i])!
+    const primaryUsdLiquidity = getPrimaryUsdLiquidity(pair)
+    if (primaryUsdLiquidity.gt(maxUsdLiquidity)) {
+      maxUsdLiquidity = primaryUsdLiquidity
+      bestUsdPrice = getUsdPrice(pair, tokenAddress)
+    }
+  }
+
+  return [maxUsdLiquidity, bestUsdPrice]
+}