text: import { decimalToHex } from '../../helpers/utils/conversions.util'
  import { calcTokenValue } from '../../helpers/utils/token-util.js'
  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
  }
  