import CountryData from 'country-data'
import { getCurrencies } from 'react-native-localize'
import { createSelector } from 'reselect'
import { e164NumberSelector } from 'src/account/selectors'
import { isE2EEnv } from 'src/config'
import {
  LOCAL_CURRENCY_CODES,
  LocalCurrencyCode,
  LocalCurrencySymbol,
} from 'src/localCurrency/consts'
import { RootState } from 'src/redux/reducers'
import { getRegionCode } from 'src/utils/phoneNumbers'

function getCountryCurrencies(e164PhoneNumber: string) {
  const regionCode = getRegionCode(e164PhoneNumber)
  const countries = CountryData.lookup.countries({ alpha2: regionCode })
  const country = countries.length > 0 ? countries[0] : undefined

  return country ? country.currencies : []
}

export const getDefaultLocalCurrencyCode = createSelector(
  e164NumberSelector,
  (e164PhoneNumber): LocalCurrencyCode => {
    // Note: we initially tried using the device locale for getting the currencies (`RNLocalize.getCurrencies()`)
    // but the problem is some Android versions don't make it possible to select the appropriate language/country
    // from the device settings.
    // So here we use the country of the phone number
    const countryCurrencies = e164PhoneNumber
      ? getCountryCurrencies(e164PhoneNumber)
      : !isE2EEnv
        ? getCurrencies()
        : [LocalCurrencyCode.USD]
    const supportedCurrenciesSet = new Set(LOCAL_CURRENCY_CODES)

    for (const countryCurrency of countryCurrencies) {
      if (supportedCurrenciesSet.has(countryCurrency as LocalCurrencyCode)) {
        return countryCurrency as LocalCurrencyCode
      }
    }

    return LocalCurrencyCode.USD
  }
)

export function getLocalCurrencyCode(state: RootState): LocalCurrencyCode {
  return state.localCurrency.preferredCurrencyCode || getDefaultLocalCurrencyCode(state)
}

export function getLocalCurrencySymbol(state: RootState): LocalCurrencySymbol | null {
  return LocalCurrencySymbol[getLocalCurrencyCode(state)]
}

export const usdToLocalCurrencyRateSelector = (state: RootState) => {
  const localCurrencyCode = getLocalCurrencyCode(state)
  const { usdToLocalRate, fetchedCurrencyCode } = state.localCurrency
  if (localCurrencyCode !== fetchedCurrencyCode) {
    // This makes sure we don't return a stale exchange rate when the currency code changed
    return null
  }

  return usdToLocalRate
}

export const localCurrencyExchangeRateErrorSelector = (state: RootState) =>
  state.localCurrency.error