firefly-iii/app/Http/Controllers/HelpController.php

<?php
/**
 * HelpController.php
 * Copyright (C) 2016 thegrumpydictator@gmail.com
 *
 * This software may be modified and distributed under the terms of the
 * Creative Commons Attribution-ShareAlike 4.0 International License.
 *
 * See the LICENSE file for details.
 */

declare(strict_types = 1);

namespace FireflyIII\Http\Controllers;

use FireflyIII\Helpers\Help\HelpInterface;
use Log;
use Preferences;
use Response;

/**
 * Class HelpController
 *
 * @package FireflyIII\Http\Controllers
 */
class HelpController extends Controller
{
    /**
     * HelpController constructor.
     */
    public function __construct()
    {
        parent::__construct();
    }

    /**
     * @param HelpInterface $help
     * @param               $route
     *
     * @return \Illuminate\Http\JsonResponse
     */
    public function show(HelpInterface $help, string $route)
    {

        $language = Preferences::get('language', config('firefly.default_language', 'en_US'))->data;
        $content  = '<p>' . strval(trans('firefly.route_has_no_help')) . '</p>';

        if (!$help->hasRoute($route)) {
            Log::error('No such route: ' . $route);

            return Response::json($content);
        }

        if ($help->inCache($route, $language)) {
            $content = $help->getFromCache($route, $language);
            Log::debug(sprintf('Help text %s was in cache.', $language));

            return Response::json($content);
        }

        $content = $help->getFromGithub($language, $route);

        // get backup language content (try English):
        if (strlen($content) === 0) {
            $language = 'en_US';
            if ($help->inCache($route, $language)) {
                Log::debug(sprintf('Help text %s was in cache.', $language));
                $content = $help->getFromCache($route, $language);
            }
            if (!$help->inCache($route, $language)) {
                $content = $help->getFromGithub($language, $route);
                $content = '<p><em>' . strval(trans('firefly.help_may_not_be_your_language')) . '</em></p>' . $content;
            }
        }

        if (strlen($content) === 0) {
            $content = '<p>' . strval(trans('firefly.route_has_no_help')) . '</p>';
        }

        $help->putInCache($route, $language, $content);

        return Response::json($content);

    }


}