translations.js

'use strict';

var fs = require('fs');
var gulp = require('gulp');
var extend = require('gulp-multi-extend');
var merge = require('merge-stream');
var path = require('path');
var connect = require('gulp-connect');

var localesDir = './app/resources/locales/';
var localesGlob = localesDir + '*.json';

/**
 * Loops through contents of the locales directory and returns the 'base' languages (those with only a language and not a locale.
 * @returns {String[]} An array of base languages found in the locales directory. EX: ['en', 'fr']
 */
function getBaseLangs(){
  return fs.readdirSync(localesDir)
    .filter(function(locale){
      return locale.split('-').length === 1;
    }).map(function(locale){
      return path.basename(locale, '.json');
    });
}


/**
 * Merges locale data files to create "fallbacks" from locales to languages as build time.
 * The following fallback is used.
 *  1. The contents of the full locale EX: 'fr-FR.json'
 *  2. The contents of the language EX: 'fr.json'
 *  3. The contents of 'en.json'
 * @returns {*} A gulp stream.
 */
function translations() {
  var merged = merge();
  getBaseLangs().forEach(function(lang){
    var baseLang = [localesDir, lang, '.json'].join('');
    var globs = [
      [localesDir, lang, '-*.json'].join(''),
      baseLang
    ];

    var stream = gulp.src(globs, {base: './app/'})
      .pipe(extend(baseLang))
      .pipe(extend(localesDir + 'en.json'))
      .pipe(gulp.dest('dist'));

    merged.add(stream);
  });


  return merged.pipe(connect.reload());
}

function watch(tasks){
  return function(){
    return gulp.watch(localesGlob, tasks);
  };
}

exports.translations = translations;
exports.watch = watch;