build-locales.js

#!/usr/bin/env node

/*
 * Process a set of '.po' language files, extracting its keys and messages, and building
 * an object suitable for [i18next](https://www.npmjs.com/package/i18next)
 */

/* global module:true */
const fs = require('fs')
const path = require('path')
const po2json = require('po2json')
const pkg = require('./package.json')

const _LOCALES = path.resolve('locales');
const _GLOBALDATA = path.resolve('src', 'GlobalData.js');

// Check if GlobalData.js doesn't exist or is older than any of the `po` files in `locales`
const newerData = function (locales = _LOCALES, fileName = _GLOBALDATA) {
  if (!fs.existsSync(fileName))
    return true;
  const gTime = fs.statSync(fileName).ctimeMs;
  return fs.statSync(path.resolve('./package.json')).ctimeMs > gTime
    || fs.readdirSync(locales).find(fn => fn.endsWith('.po') && fs.statSync(path.resolve(locales, fn)).ctimeMs > gTime) !== undefined;
}

// Compiles all 'po' language files in ./locales, returning the resulting i18next options object
const getData = function (locales = _LOCALES, verbose = true) {

  // Initialize the i18next options object
  const opt = {
    version: `${pkg.version} (${(new Date()).toISOString().substr(0, 10)})`,
    languages: ['en'],
    messages: {}
  }

  // Process all .po files found in `localesDir`
  fs.readdirSync(locales).forEach(fn => {
    if (fn.endsWith('.po')) {
      // Gent language code from file name, skipping extension
      const lang = fn.substr(0, fn.lastIndexOf('.'))
      const file = path.resolve(locales, fn)
      if (verbose)
        console.log(`Processing language ${lang}`)
      try {
        // Parse file with po2json and store result in `opt.messages`
        opt.messages[lang] = po2json.parseFileSync(file, { format: 'mf' })
        // Add lang to the list of known languages
        opt.languages.push(lang)
      } catch (e) {
        console.error(`Error processing ${file}: ${e}`)
      }
    }
  })
  return opt
}

// Generates the AMD module `GlobalData.js`, containing a single call to `define` with the content of `opt`
const writeDataToJSFile = function (opt, file = _GLOBALDATA, verbose = true) {
  if (verbose)
    console.log(`Generating file ${file}`)

  try {
    fs.writeFileSync(file, `
// WARNING: Auto-generated file, based on "language.po" files stored in "/locales". Do not edit!
// Launch "npm run build-locales" to update this file

/* global define */
define(${JSON.stringify(opt)})`)
  } catch (e) {
    console.error(`Error generating file ${file}: ${e}`)
  }
}

module.exports = function (locales = _LOCALES, file = _GLOBALDATA, verbose = true) {
  // Run only if newer data
  if (newerData(locales, file))
    writeDataToJSFile(getData(locales, verbose), file, verbose)
}

module.exports.getData = getData
module.exports.writeDataToJSFile = writeDataToJSFile

// Allow direct call from nodejs CLI
if (require.main == module)
  module.exports()