import { decimalToHex } from '../../helpers/utils/conversions.util' import { calcTokenValue } from '../../helpers/utils/token-util' import { getTokenData } from '../../helpers/utils/transactions.util' export function getCustomTxParamsData (data, { customPermissionAmount, decimals }) { const tokenData = getTokenData(data) if (!tokenData) { throw new Error('Invalid data') } else if (tokenData.name !== 'approve') { throw new Error(`Invalid data; should be 'approve' method, but instead is '${tokenData.name}'`) } let spender = tokenData.params[0].value if (spender.startsWith('0x')) { spender = spender.substring(2) } const [signature, tokenValue] = data.split(spender) if (!signature || !tokenValue) { throw new Error('Invalid data') } else if (tokenValue.length !== 64) { throw new Error('Invalid token value; should be exactly 64 hex digits long (u256)') } let customPermissionValue = decimalToHex(calcTokenValue(customPermissionAmount, decimals)) if (customPermissionValue.length > 64) { throw new Error('Custom value is larger than u256') } customPermissionValue = customPermissionValue.padStart(tokenValue.length, '0') const customTxParamsData = `${signature}${spender}${customPermissionValue}` return customTxParamsData }