fix: postage stamp price and TTL calculation (#305)

* fix: postage stamp price and TTL calculation

* chore: removed logs and fixed linter issues

src/models/Token.ts

@@ -57,4 +57,25 @@ export class Token {
   toFixedDecimal(digits = 7): string {
     return this.toDecimal.toFixed(digits)
   }
+
+  toSignificantDigits(digits = 4): string {
+    const asString = this.toDecimal.toFixed(16)
+
+    let indexOfSignificantDigit = -1
+    let reachedDecimalPoint = false
+
+    for (let i = 0; i < asString.length; i++) {
+      const char = asString[i]
+
+      if (char === '.') {
+        reachedDecimalPoint = true
+        indexOfSignificantDigit = i + 1
+      } else if (reachedDecimalPoint && char !== '0') {
+        indexOfSignificantDigit = i
+        break
+      }
+    }
+
+    return asString.slice(0, indexOfSignificantDigit + digits)
+  }
 }

src/pages/stamps/PostageStampCreation.tsx

@@ -2,20 +2,14 @@ import { Box, Grid, Typography } from '@material-ui/core'
 import BigNumber from 'bignumber.js'
 import { Form, Formik, FormikHelpers } from 'formik'
 import { useSnackbar } from 'notistack'
-import React, { ReactElement, useContext } from 'react'
+import { ReactElement, useContext } from 'react'
 import { Check } from 'react-feather'
 import { SwarmButton } from '../../components/SwarmButton'
 import { SwarmTextInput } from '../../components/SwarmTextInput'
 import { Context as BeeContext } from '../../providers/Bee'
 import { Context as SettingsContext } from '../../providers/Settings'
 import { Context as StampsContext } from '../../providers/Stamps'
-import {
-  calculateStampPrice,
-  convertAmountToSeconds,
-  convertDepthToBytes,
-  formatBzz,
-  secondsToTimeString,
-} from '../../utils'
+import { calculateStampPrice, convertAmountToSeconds, convertDepthToBytes, secondsToTimeString } from '../../utils'
 import { getHumanReadableFileSize } from '../../utils/file'
 
 interface FormValues {
@@ -50,24 +44,27 @@ export function PostageStampCreation({ onFinished }: Props): ReactElement {
   }
 
   function getTtl(amount: number): string {
-    if (isNaN(amount) || amount <= 0) {
-      return '-'
-    }
-
-    return secondsToTimeString(convertAmountToSeconds(amount))
-  }
-
-  function getPrice(depth: number, amount: number): string {
-    const hasInvalidInput = isNaN(amount) || amount <= 0 || isNaN(depth) || depth < 17 || depth > 255
     const isCurrentPriceAvailable = chainState && chainState.currentPrice
 
-    if (hasInvalidInput || !isCurrentPriceAvailable) {
+    if (amount <= 0 || !isCurrentPriceAvailable) {
       return '-'
     }
 
-    const price = calculateStampPrice(depth, amount, chainState.currentPrice)
+    const pricePerBlock = Number.parseInt(chainState.currentPrice, 10)
 
-    return `${formatBzz(price)} BZZ`
+    return `${secondsToTimeString(convertAmountToSeconds(amount, pricePerBlock))} (with price of 0 per block)`
+  }
+
+  function getPrice(depth: number, amount: bigint): string {
+    const hasInvalidInput = amount <= 0 || isNaN(depth) || depth < 17 || depth > 255
+
+    if (hasInvalidInput) {
+      return '-'
+    }
+
+    const price = calculateStampPrice(depth, amount)
+
+    return `${price.toSignificantDigits()} BZZ`
   }
 
   return (
@@ -136,7 +133,7 @@ export function PostageStampCreation({ onFinished }: Props): ReactElement {
             <Box mt={0.25} sx={{ bgcolor: '#f6f6f6' }} p={2}>
               <Grid container justifyContent="space-between">
                 <Typography>Corresponding TTL (Time to live)</Typography>
-                <Typography>{getTtl(parseInt(values.amount || '0', 10))}</Typography>
+                <Typography>{getTtl(Number.parseInt(values.amount || '0', 10))}</Typography>
               </Grid>
             </Box>
           </Box>
@@ -146,7 +143,7 @@ export function PostageStampCreation({ onFinished }: Props): ReactElement {
           <Box mb={4} sx={{ bgcolor: '#fcf2e8' }} p={2}>
             <Grid container justifyContent="space-between">
               <Typography>Indicative Price</Typography>
-              <Typography>{getPrice(parseInt(values.depth || '0', 10), parseInt(values.amount || '0', 10))}</Typography>
+              <Typography>{getPrice(parseInt(values.depth || '0', 10), BigInt(values.amount || '0'))}</Typography>
             </Grid>
           </Box>
           <SwarmButton

src/utils/index.ts

@@ -1,5 +1,5 @@
-import { NumberString } from '@ethersphere/bee-js'
 import { BigNumber } from 'bignumber.js'
+import { Token } from '../models/Token'
 
 /**
  * Test if value is an integer
@@ -159,38 +159,21 @@ export function secondsToTimeString(seconds: number): string {
   return `${unit.toFixed(1)} years`
 }
 
-export function formatBzz(amount: number): string {
-  const asString = amount.toFixed(16)
-
-  let indexOfSignificantDigit = -1
-  let reachedDecimalPoint = false
-
-  for (let i = 0; i < asString.length; i++) {
-    const char = asString[i]
-
-    if (char === '.') {
-      reachedDecimalPoint = true
-    } else if (reachedDecimalPoint && char !== '0') {
-      indexOfSignificantDigit = i
-      break
-    }
-  }
-
-  return asString.slice(0, indexOfSignificantDigit + 4)
-}
-
 export function convertDepthToBytes(depth: number): number {
   return 2 ** depth * 4096
 }
 
-export function convertAmountToSeconds(amount: number): number {
-  return amount / 10 / 1
+export function convertAmountToSeconds(amount: number, pricePerBlock: number): number {
+  // TODO: blocktime should come directly from the blockchain as it may differ between different networks
+  const blockTime = 5 // On mainnet there is 5 seconds between blocks
+
+  // See https://github.com/ethersphere/bee/blob/66f079930d739182c4c79eb6008784afeeba1096/pkg/debugapi/postage.go#L410-L413
+  return (amount * blockTime) / pricePerBlock
 }
 
-export function calculateStampPrice(depth: number, amount: number, currentPrice: NumberString): number {
-  const price = parseInt(currentPrice, 10)
-
-  return (amount * 2 ** (depth - 16) * price) / 1e16
+export function calculateStampPrice(depth: number, amount: bigint): Token {
+  // See https://github.com/ethersphere/bee/blob/66f079930d739182c4c79eb6008784afeeba1096/pkg/debugapi/postage.go#L410-L413
+  return new Token(amount * BigInt(2 ** depth)) // FIXME: the 2 ** depth should be performed on bigint already
 }
 
 export function shortenText(text: string, length = 20, separator = '[…]'): string {