import { formatUnits } from 'viem'

/**
 * Format token amount to at least 6 decimals.
 * @param amount amount to format.
 * @returns formatted amount.
 */
export function formatTokenAmount(
  amount: bigint | undefined,
  decimals: number
) {
  const formattedAmount = amount ? formatUnits(amount, decimals) : '0'
  const parsedAmount = Number.parseFloat(formattedAmount)
  if (!parsedAmount || Number.isNaN(Number(formattedAmount))) {
    return '0'
  }

  return formattedAmount
}

export function formatSlippage(
  slippage = '',
  defaultValue = '',
  returnInitial = false
): string {
  if (!slippage) {
    return slippage
  }
  const parsedSlippage = Number.parseFloat(slippage)
  if (Number.isNaN(Number(slippage)) && !Number.isNaN(parsedSlippage)) {
    return parsedSlippage.toString()
  }
  if (Number.isNaN(parsedSlippage)) {
    return defaultValue
  }
  if (parsedSlippage > 100) {
    return '100'
  }
  if (parsedSlippage < 0) {
    return Math.abs(parsedSlippage).toString()
  }
  if (returnInitial) {
    return slippage
  }
  return parsedSlippage.toString()
}

export function formatInputAmount(
  amount: string,
  decimals: number | null = null,
  returnInitial = false
) {
  if (!amount) {
    return amount
  }
  let formattedAmount = amount.trim().replaceAll(',', '.')
  if (formattedAmount.startsWith('.')) {
    formattedAmount = `0${formattedAmount}`
  }
  const parsedAmount = Number.parseFloat(formattedAmount)
  if (Number.isNaN(Number(formattedAmount)) && !Number.isNaN(parsedAmount)) {
    return parsedAmount.toString()
  }
  if (Number.isNaN(Math.abs(Number(formattedAmount)))) {
    return ''
  }
  if (returnInitial) {
    return formattedAmount
  }
  let [integer, fraction = ''] = formattedAmount.split('.')
  if (decimals !== null && fraction.length > decimals) {
    fraction = fraction.slice(0, decimals)
  }
  integer = integer.replace(/^0+|-/, '')
  fraction = fraction.replace(/(0+)$/, '')
  return `${integer || (fraction ? '0' : '')}${fraction ? `.${fraction}` : ''}`
}

export function formatTokenPrice(
  amount?: string | bigint,
  price?: string,
  decimals?: number
) {
  if (!amount || !price) {
    return 0
  }

  const formattedAmount =
    typeof amount === 'bigint' && decimals !== undefined
      ? formatUnits(amount, decimals)
      : amount.toString()

  if (Number.isNaN(Number(formattedAmount)) || Number.isNaN(Number(price))) {
    return 0
  }
  return Number.parseFloat(formattedAmount) * Number.parseFloat(price)
}