// SPDX-FileCopyrightText: © 2024 LEDGER SAS
// SPDX-License-Identifier: Apache-2.0

// Forked from @ledgerhq/live-currency-format/src/BigNumberToLocaleString.ts
import { BigNumber } from 'bignumber.js'
import { getSeparators } from './localeUtility'

export type SupportedOptions = {
  minimumFractionDigits: number
  maximumFractionDigits: number
  useGrouping: boolean
}

const getFormatForLocale = (locale: string) => {
  const { decimal, thousands } = getSeparators(locale)
  const opts = {
    decimalSeparator: '.',
    groupSeparator: ',',
    groupSize: 3,
    secondaryGroupSize: 0,
    fractionGroupSeparator: '\xA0', // non-breaking space
    fractionGroupSize: 0,
  }
  if (typeof decimal === 'string') opts.decimalSeparator = decimal
  if (typeof thousands === 'string') opts.groupSeparator = thousands
  return opts
}

export const toLocaleString = (
  n: BigNumber,
  localeInput?: string,
  options: Partial<SupportedOptions> = {}
): string => {
  let locale = localeInput
  if (!locale) locale = 'en'
  const minimumFractionDigits =
    typeof options.minimumFractionDigits === 'number' ? options.minimumFractionDigits : 0
  const maximumFractionDigits =
    typeof options.maximumFractionDigits === 'number'
      ? options.maximumFractionDigits
      : Math.max(minimumFractionDigits, 3)
  const useGrouping = 'useGrouping' in options ? options.useGrouping : true
  const format = getFormatForLocale(locale)

  if (!useGrouping) {
    format.groupSeparator = ''
  }

  const BN = BigNumber.clone({
    FORMAT: format,
  })
  const bn = new BN(n)
  const maxDecimals = bn.toFormat(maximumFractionDigits, BigNumber.ROUND_FLOOR)

  if (maximumFractionDigits !== minimumFractionDigits) {
    const minDecimals = bn.toFormat(minimumFractionDigits, BigNumber.ROUND_FLOOR)
    let i = maxDecimals.length

    while (i > minDecimals.length) {
      if (maxDecimals[i - 1] !== '0') {
        if (maxDecimals[i - 1] === format.decimalSeparator) {
          i--
        }
        break
      }
      i--
    }

    return maxDecimals.slice(0, i)
  }

  return maxDecimals
}