willy.club/app/App/Controller/ChatController.php

<?php

namespace App\Controller;

use App\Model\ChatModel;

abstract class ChatController
{
    static function index()
    {
        if (empty($_POST)) {
            return view('pages/chat/index', [
                'nick' => 'Willy',
                'just_sent_message' => false,
                'errmsg' => false
            ]); 
        }

        $nick = filter_input(INPUT_POST, 'nick');
        $text = filter_input(INPUT_POST, 'text');
        $errmsg = (function() use (&$text, &$nick): string {
            if (empty(trim($nick, ' '))) {
                return 'You must choose a nickname.';
            }

            $nick_max_chars = 128;
            if (strlen($nick) > $nick_max_chars) {
                return 'Your nickname is TOO LONG! ' . strlen($nick) . ' out of ' . $nick_max_chars. ' characters.';
            }

            $text_max_chars = 4096;
            if (strlen($text) > $text_max_chars) {
                return 'Your message is TOO LONG!!!! ' . strlen($text) . ' out of ' . $text_max_chars . ' characters.';
            }

            if (empty(trim($text, ' '))) {
                return 'Message body cannot be empty.';
            }

            return '';
        })();

        if (empty($errmsg)) {
            ChatModel::save_message(
                $nick,
                $text
            );
        }

        view('pages/chat/index', [
            'nick' => $nick,
            'just_sent_message' => true,
            'errmsg' => $errmsg
        ]);
    }

    static function messages()
    {
        view('pages/chat/messages',
            ['messages' => ChatModel::get_messages()]);
    }

    static function sync()
    {
        json_response(hash('crc32', serialize(
            ChatModel::get_messages()
        )));
    }
}