core/app/Console/Commands/TranslateDirectory.php

<?php

namespace App\Console\Commands;

use Illuminate\Console\Command;
use Illuminate\Support\Facades\File;
use Illuminate\Support\Str;

class TranslateDirectory extends Command
{
    /**
     * The name and signature of the console command.
     * @var string
     */
    protected $signature = 'translate:dir {dir}';
    /**
     * The console command description.
     * @var string
     */
    protected $description = 'Checks for missing translations in given directory.';
    /**
     * @var array All translations
     */
    protected $translations = [];

    /**
     * Execute the console command.
     */
    public function handle()
    {
        $dir = rtrim($this->argument('dir'), '/');
        $defaultLocales = config('app.fallback_locale');
        $currentLocales = config('app.locale');

        $defaultLocalesDir = base_path($dir . '/' . $defaultLocales);
        $currentLocalesDir = base_path($dir . '/' . $currentLocales);

        if (!is_dir($defaultLocalesDir)) {
            // this is the place for checking for submodules

            $modulePath = dirname(dirname($dir));

            // does exist directory with translations?
            if (is_dir(base_path($modulePath . '/Resources/lang')) || file_exists(base_path($modulePath.DIRECTORY_SEPARATOR.'info.php'))) {
                $modules = File::directories($modulePath);
                foreach ($modules as $module) {
                    $this->call('translate:dir', ['dir' => $module . '/Resources/lang']);
                }
            }
            return;
        }

        if (!is_dir($currentLocalesDir)) {
            File::makeDirectory($currentLocalesDir);
        }

        $this->compareTranslationsInDirectory($defaultLocalesDir, $currentLocalesDir);
    }

    /**
     * Crawl given defaul directory and compare all files in default and current directory.
     *
     * @param $defaultDir string path to directory with default (fallback) locales
     * @param $currentDir string path to directory with currently selected localse
     */
    private function compareTranslationsInDirectory($defaultDir, $currentDir)
    {
        $files = File::files($defaultDir);
        foreach ($files as $file) {
            if (!Str::endsWith($file, '.php')) {
                continue;
            }

            $fileName = basename($file);
            $default = include($file);
            $checked = file_exists($currentDir . '/' . $fileName) ? include $currentDir . '/' . $fileName : [];
            $this->translations = &$checked;

            $this->checkForMissingTranslations($default, $checked, $currentDir, $fileName);
        }

        // iterate over directories
        $this->crawlSubdirectories($defaultDir, $currentDir);
    }

    /**
     * Check translations and ask for missing ones.
     *
     * @param $default
     * @param $checked
     * @param $currentLocalesDir
     * @param $fileName
     */
    private function checkForMissingTranslations($default, &$checked, $currentLocalesDir, $fileName)
    {
        foreach ($default as $key => $translation) {
            if (!isset($checked[$key])) {
                // translate only plain text fields
                if (is_array($default[$key])) {

                    if (!isset($checked[$key])) {
                        $checked[$key] = [];
                    }

                    $this->checkForMissingTranslations($default[$key], $checked[$key], $currentLocalesDir, $fileName);
                    continue;
                }

                $this->info($fileName . ':' . $key);
                $this->line($translation);
                $newTranslation = $this->ask('Translate');

                $checked[$key] = $newTranslation;
                $this->saveTranslation($currentLocalesDir, $fileName);
            }
        }
    }

    /**
     * Create new/reset file and fill it with translations
     *
     * @param $checked
     * @param $dir
     * @param $fileName
     */
    private function saveTranslation($dir, $fileName)
    {
        $file = $dir . '/' . $fileName;

        $this->resetFile($file);
        $this->writeRow('<?php', null, $file, false);
        $this->writeRow('return [', null, $file, false);

        // write real translation data
        $this->writeTranslations($this->translations, $dir, $fileName);

        $this->writeRow('];', '', $file, false);
    }

    /**
     * Write translation as PHP array
     *
     * @param $checked
     * @param $dir
     * @param $fileName
     */
    private function writeTranslations($checked, $dir, $fileName)
    {
        $file = $dir . '/' . $fileName;

        ksort($checked);

        foreach ($checked as $key => $value) {
            if (is_array($value)) {
                $this->writeRow($key, '[', $file, false);
                $this->writeTranslations($value, $dir, $fileName);
                $this->writeRow('],', null, $file, false);
            } else {
                $this->writeRow($key, $value, $file);
            }
        }
    }

    /**
     * Resets content of given file
     *
     * @param $file
     */
    private function resetFile($file)
    {
        file_put_contents($file, '');
    }

    /**
     * Write row with translations
     *
     * @param      $key
     * @param      $value
     * @param      $file
     * @param bool $arrayItem
     */
    private function writeRow($key, $value, $file, $arrayItem = true)
    {
        if ($value != null) {
            if ($arrayItem) {
                $value = strpos($value, '"') !== false ? '\'' . $value . '\'' : '"' . $value . '"';
                $value .= ",\n";
            }

            file_put_contents($file, '"' . $key . '" => ' . $value, FILE_APPEND);
        } else {
            file_put_contents($file, $key . "\n", FILE_APPEND);
        }
    }

    /**
     * Crawl subdirectories and compare translations there
     *
     * @param $defaultDir
     * @param $currentDir
     */
    private function crawlSubdirectories($defaultDir, $currentDir)
    {
        $directories = File::directories($defaultDir);

        foreach ($directories as $directory) {
            $dirname = basename($directory);

            if (!is_dir($currentDir . '/' . $dirname)) {
                File::makeDirectory($currentDir . '/' . $dirname);
            }

            $this->compareTranslationsInDirectory($directory, $currentDir . '/' . $dirname);
        }
    }
}