Sats per Big Mac

api/resolvers/price.js

@@ -18,10 +18,42 @@ const getPrice = cachedFetcher(async function fetchPrice (fiat = 'USD') {
   keyGenerator: (fiat = 'USD') => fiat
 })
 
+const getBigMacPrice = cachedFetcher(async function fetchBigMacPrice () {
+  const csvUrl = 'https://raw.githubusercontent.com/TheEconomist/big-mac-data/master/output-data/big-mac-raw-index.csv'
+  try {
+    const res = await fetch(csvUrl)
+    const csvText = await res.text()
+    const lines = csvText.split('\n')
+    const usaEntries = lines
+      .filter(line => line.includes(',USA,USD,'))
+      .map(line => {
+        const cols = line.split(',')
+        return {
+          date: cols[0],
+          price: parseFloat(cols[4])
+        }
+      })
+      .filter(entry => !isNaN(entry.price))
+      .sort((a, b) => new Date(b.date) - new Date(a.date))
+    return usaEntries[0]?.price || 5.79
+  } catch (err) {
+    console.error('Big Mac price fetch error:', err)
+    return 5.79
+  }
+}, {
+  maxSize: 1,
+  cacheExpiry: 24 * 60 * 60 * 1000,
+  forceRefreshThreshold: 0,
+  keyGenerator: () => 'bigmac-usd'
+})
+
 export default {
   Query: {
     price: async (parent, { fiatCurrency }, ctx) => {
       return await getPrice(fiatCurrency) || -1
+    },
+    bigMacPrice: async () => {
+      return await getBigMacPrice() || 5.79
     }
   }
 }

api/typeDefs/price.js

@@ -3,5 +3,6 @@ import { gql } from 'graphql-tag'
 export default gql`
   extend type Query {
     price(fiatCurrency: String): Float
+    bigMacPrice: Float
   }
 `

components/nav/price-carousel.js

@@ -9,7 +9,8 @@ const carousel = [
   '1btc',
   'blockHeight',
   'chainFee',
-  'halving'
+  'halving',
+  'bigmac'
 ]
 
 export const PriceCarouselContext = createContext({

components/price.js

@@ -12,7 +12,8 @@ import { usePriceCarousel } from './nav/price-carousel'
 
 export const PriceContext = React.createContext({
   price: null,
-  fiatSymbol: null
+  fiatSymbol: null,
+  bigMacPrice: null
 })
 
 export function usePrice () {
@@ -34,8 +35,9 @@ export function PriceProvider ({ price, children }) {
 
   const contextValue = useMemo(() => ({
     price: data?.price || price,
-    fiatSymbol: CURRENCY_SYMBOLS[fiatCurrency] || '$'
-  }), [data?.price, price, me?.privates?.fiatCurrency])
+    fiatSymbol: CURRENCY_SYMBOLS[fiatCurrency] || '$',
+    bigMacPrice: data?.bigMacPrice || 5.79
+  }), [data?.price, data?.bigMacPrice, price, me?.privates?.fiatCurrency])
 
   return (
     <PriceContext.Provider value={contextValue}>
@@ -56,7 +58,7 @@ function AccessibleButton ({ id, description, children, ...props }) {
 export default function Price ({ className }) {
   const [selection, handleClick] = usePriceCarousel()
 
-  const { price, fiatSymbol } = usePrice()
+  const { price, fiatSymbol, bigMacPrice } = usePrice()
   const { height: blockHeight, halving } = useBlockHeight()
   const { fee: chainFee } = useChainFee()
 
@@ -106,6 +108,15 @@ export default function Price ({ className }) {
     )
   }
 
+  if (selection === 'bigmac') {
+    if (!price || price < 0 || !bigMacPrice) return null
+    return (
+      <AccessibleButton id='bigmac-hint' description='Show satoshis per Big Mac' className={compClassName} onClick={handleClick} variant='link'>
+        {fixedDecimal(Math.round((bigMacPrice / price) * 100000000), 0)} sats/Big Mac
+      </AccessibleButton>
+    )
+  }
+
   if (selection === 'fiat') {
     if (!price || price < 0) return null
     return (

fragments/price.js

@@ -3,4 +3,5 @@ import { gql } from '@apollo/client'
 export const PRICE = gql`
   query price($fiatCurrency: String) {
     price(fiatCurrency: $fiatCurrency)
+    bigMacPrice
   }`