old/application/controllers/Tools/Twitch.php

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Twitch extends MY_Controller {

    public function __construct() {
        parent::__construct('tools');
    }

    public function index($channel = 'kingofdog') {
        if(isset($_GET['twitch-channel']) && !empty($_GET['twitch-channel'])) {
            header("Location: /tools/twitch/" . $_GET['twitch-channel']);
        }
        $this->load->view('header', ['active' => 'twitch-tools', 'title' => lang('twitch_site_title')]);
		$this->load->model('TwitchModel');

//	    $data =

        $result = $this->load->view('tools/twitch_result', ['json' => $this->TwitchModel->getTwitchInfos($channel), 'stream' => $this->TwitchModel->getTwitchStream($channel), 'videos' => $this->TwitchModel->getTwitchVideos($channel)], true);
		$this->load->view('tools/twitch', ['result' => $result]);
        $this->load->view('footer');
    }

    public function sudoku() {
        if(isset($_POST['sudoku'])) {
            $sudoku = [];
            $rows = [];
            $cols = [];
            $fields = [];
            for ($i=0; $i < 9; $i++) {
                for ($j=0; $j < 9; $j++) {
                    if(isset($_POST['field-' . $i . '-' . $j])) {
                        $sudoku[$i][$j] = $_POST['field-' . $i . '-' . $j];
                    } else {
                        $sudoku[$i][$j] = '_';
                    }
                }
            }

            for ($i=0; $i < 9; $i++) {
                for ($j=0; $j < 9; $j++) {
                    $rows[$i] .= $sudoku[$i][$j] . "|";
                    $cols[$i] .= $sudoku[$j][$i] . "|";
                }
            }

            for ($i=0; $i < 3; $i++) {
                for ($j=0; $j < 3; $j++) {
                    for ($k=0; $k < 3; $k++) {
                        for ($l=0; $l < 3; $l++) {
                            $fields[$i][$j] .= $sudoku[$i * $k][$j * $l] . "|";
                        }
                    }
                }
            }

            var_dump($fields);
            var_dump($rows);
            var_dump($cols);
        }

        $this->load->view('header', ['active' => 'sudoku', 'title' => 'Sudoku-Löser']);
        $this->load->view('sudoku');
        $this->load->view('footer');
    }
}