@winstrike/next-i18next-koa/dist/es/utils/lng-path-corrector.js

The easiest way to translate your NextJs apps. With Koa support only. Forked from 'next-i18next'.

import { format as formatUrl, parse as parseUrl } from 'url';
import { localeSubpathOptions } from '../config/default-config';

const parseAs = (originalAs, href) => {
  const asType = typeof originalAs;
  let as;

  if (asType === 'undefined') {
    as = formatUrl(href, {
      unicode: true
    });
  } else if (asType === 'string') {
    as = originalAs;
  } else {
    throw new Error(`'as' type must be 'string', but it is ${asType}`);
  }

  return as;
};

const parseHref = originalHref => {
  const hrefType = typeof originalHref;
  let href;

  if (hrefType === 'string') {
    href = parseUrl(originalHref, true
    /* parseQueryString */
    );
  } else if (hrefType === 'object') {
    href = { ...originalHref
    };
    href.query = originalHref.query ? { ...originalHref.query
    } : {};
  } else {
    throw new Error(`'href' type must be either 'string' or 'object', but it is ${hrefType}`);
  }

  return href;
};

export default ((config, currentRoute, currentLanguage) => {
  const {
    defaultLanguage,
    allLanguages,
    localeSubpaths
  } = config;
  const {
    as: originalAs,
    href: originalHref
  } = currentRoute;

  if (!allLanguages.includes(currentLanguage)) {
    throw new Error('Invalid configuration: Current language is not included in all languages array');
  }

  const href = parseHref(originalHref);
  let as = parseAs(originalAs, href); // url.format prefers the 'url.search' string over the 'url.query' object,
  // so remove the search string to ensure the query object is used

  delete href.search;

  for (const lng of allLanguages) {
    if (as.startsWith(`/${lng}/`)) {
      as = as.replace(`/${lng}/`, '/');
      break;
    }
  }

  if (currentLanguage !== defaultLanguage || localeSubpaths === localeSubpathOptions.ALL) {
    const basePath = `${href.protocol}//${href.host}`;
    const currentAs = as.replace(basePath, '');
    as = `/${currentLanguage}${currentAs}`;
    href.query.lng = currentLanguage;
  }

  return {
    as,
    href
  };
});