crnc/x/currency-converter.js

currency conversion and functionality for the web

import { restricted, snapstate } from "@chasemoskal/snapstate";
import { locale2 } from "./locale2.js";
import { formatCurrency } from "./currency-tools/format-currency.js";
import { isCurrencyAllowed } from "./ecommerce/is-currency-allowed.js";
import { assumeUserCurrency } from "./ecommerce/assume-user-currency.js";
import { currenciesByLocales } from "./ecommerce/currencies-by-locales.js";
import { getDetailsForCurrencies } from "./ecommerce/currencies-to-details.js";
import { validateConverterParams } from "./ecommerce/validate-converter-params.js";
import { convertAndFormatCurrency } from "./currency-tools/convert-and-format-currency.js";
import { currencyLibrary as defaultCurrencyLibrary } from "./ecommerce/currency-library.js";
import { rememberOrDownloadExchangeRates } from "./ecommerce/remember-or-download-exchange-rates.js";
import { defaultListenForStorageChange, defaultPersistence } from "./ecommerce/currency-converter-defaults.js";
import { downloadExchangeRates as defaultDownloadExchangeRates } from "./currency-tools/download-exchange-rates.js";
const currencyLibrary = defaultCurrencyLibrary;
export function makeCurrencyConverter({ baseCurrency, currencies = [baseCurrency], locale = locale2(), persistence = defaultPersistence(), downloadExchangeRates = defaultDownloadExchangeRates, listenForStorageChange = defaultListenForStorageChange(persistence), }) {
    const validated = validateConverterParams({ baseCurrency, currencies, currencyLibrary });
    currencies = validated.currencies;
    baseCurrency = validated.baseCurrency;
    const isOnlyBaseCurrency = currencies.length === 1;
    const snap = snapstate({
        currencyPreference: baseCurrency,
        exchangeRates: undefined,
    });
    let exchangeRatesDownload = Promise.resolve();
    if (!isOnlyBaseCurrency) {
        exchangeRatesDownload = rememberOrDownloadExchangeRates({
            currencies,
            persistence,
            downloadExchangeRates,
        })
            .then(rates => snap.state.exchangeRates = rates)
            .catch(() => { });
    }
    function getAvailableCurrencies() {
        const { exchangeRates } = snap.state;
        return exchangeRates
            ? getDetailsForCurrencies([baseCurrency, ...Object.keys(exchangeRates)], currencyLibrary)
            : getDetailsForCurrencies([baseCurrency], currencyLibrary);
    }
    function getTargetCurrency() {
        const { currencyPreference } = snap.state;
        const preferenceIsAvailable = Object.keys(getAvailableCurrencies())
            .indexOf(currencyPreference) !== -1;
        return preferenceIsAvailable
            ? currencyPreference
            : baseCurrency;
    }
    function updateLocalCurrencyPreference(code) {
        code = code
            ? code.toUpperCase()
            : assumeUserCurrency({
                locale,
                currencies,
                currenciesByLocales,
                fallback: baseCurrency,
            });
        const display = isCurrencyAllowed(code, currencies)
            ? code
            : baseCurrency;
        snap.state.currencyPreference = display;
    }
    const reloadCurrencyPreference = () => updateLocalCurrencyPreference(persistence.storage.getItem(persistence.storageKeys.currencyPreference));
    reloadCurrencyPreference();
    listenForStorageChange({ reloadCurrencyPreference });
    return {
        snap: restricted(snap),
        get exchangeRatesDownload() {
            return exchangeRatesDownload;
        },
        get baseCurrency() {
            return baseCurrency;
        },
        get currencyPreference() {
            return snap.readable.currencyPreference;
        },
        get targetCurrency() {
            return getTargetCurrency();
        },
        get availableCurrencies() {
            return getAvailableCurrencies();
        },
        setCurrencyPreference(currency) {
            currency = currency.toUpperCase();
            updateLocalCurrencyPreference(currency);
            persistence.storage.setItem(persistence.storageKeys.currencyPreference, snap.state.currencyPreference);
        },
        display(valueInBaseCurrency, { currency, precision = 2 } = {}) {
            const { exchangeRates } = snap.state;
            currency = currency
                ? Object.keys(getAvailableCurrencies()).includes(currency)
                    ? currency
                    : getTargetCurrency()
                : getTargetCurrency();
            const conversionMustHappen = baseCurrency !== currency;
            return (conversionMustHappen && exchangeRates)
                ? convertAndFormatCurrency({
                    value: valueInBaseCurrency,
                    locale,
                    precision,
                    exchangeRates,
                    inputCurrency: baseCurrency,
                    outputCurrency: currency,
                })
                : formatCurrency({
                    locale,
                    precision,
                    currencyLibrary,
                    code: baseCurrency,
                    value: valueInBaseCurrency,
                });
        },
    };
}
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