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metamask-extension/ui/app/hooks/useTokenDisplayValue.js
2020-11-02 17:41:28 -06:00

57 lines
2.3 KiB
JavaScript

import { useMemo } from 'react'
import {
getTokenValueParam,
calcTokenAmount,
} from '../helpers/utils/token-util'
import { useTokenData } from './useTokenData'
/**
* Defines the shape for the Token input parameter for useTokenDisplayValue
* @typedef {Object} Token
* @property {string} symbol - The string to use as a suffix for the token (eg. DAI)
* @property {number} decimals - The number of decimals to show when displaying this type of token
*/
/**
* useTokenDisplayValue
* Given the data string from txParams and a token object with symbol and decimals, return
* a displayValue that represents a string representing that token amount as a string. Also
* return a tokenData object for downstream usage and the suffix for the token to use as props
* for other hooks and/or components
* @param {string} [transactionData] - Raw data string from token transaction
* @param {Token} [token] - The token associated with this transaction
* @param {boolean} [isTokenTransaction] - Due to the nature of hooks, it isn't possible
* to conditionally call this hook. This flag will
* force this hook to return null if it set as false
* which indicates the transaction is not associated
* with a token.
* @return {string} - The computed displayValue of the provided transactionData and token
*/
export function useTokenDisplayValue(
transactionData,
token,
isTokenTransaction = true,
) {
const tokenData = useTokenData(transactionData, isTokenTransaction)
const shouldCalculateTokenValue = Boolean(
// If we are currently processing a token transaction
isTokenTransaction &&
// and raw transaction data string is provided
transactionData &&
// and a token object has been provided
token &&
// and we are able to parse the token details from the raw data
tokenData?.args?.length,
)
const displayValue = useMemo(() => {
if (!shouldCalculateTokenValue) {
return null
}
const tokenValue = getTokenValueParam(tokenData)
return calcTokenAmount(tokenValue, token.decimals).toString(10)
}, [shouldCalculateTokenValue, tokenData, token])
return displayValue
}