<?php
/**
 * Name: Math-Captcha
 * Description: This addon adds a smal calculation, which needs to be solved correctly before a new registration can be done
 * Version: 0.1
 * Author: Tobias Diekershoff <tobias@social.diekershoff.de>
 * License: MIT style
 **/

use Friendica\App;
use Friendica\Core\Hook;
use Friendica\Core\L10n;
use Friendica\Core\Renderer;
use Friendica\Core\System;

function mathcaptcha_install()
{
    Hook::register('register_form', 'addon/mathcaptcha/mathcaptcha.php', 'mathcaptcha_register_form');
    Hook::register('register_post', 'addon/mathcaptcha/mathcaptcha.php', 'mathcaptcha_register_post');
    Hook::register('template_vars', 'addon/mathcaptcha/mathcaptcha.php', 'mathcaptcha_template_vars');
}

function mathcaptcha_uninstall()
{
    Hook::unregister('register_form', 'addon/mathcaptcha/mathcaptcha.php', 'mathcaptcha_register_form');
    Hook::unregister('register_post', 'addon/mathcaptcha/mathcaptcha.php', 'mathcaptcha_register_post');
    Hook::unregister('template_vars', 'addon/mathcaptcha/mathcaptcha.php', 'mathcaptcha_template_vars');
}

/**
 * Check if the captcha was solved correctly when posting the registration form
 */
function mathcaptcha_register_post(App $a, &$b)
{
    $solution = 0;
    switch ($_SESSION['mathcaptcha_op']){
            case 0:
                $solution = $_SESSION['mathcaptcha_n1'] + $_SESSION['mathcaptcha_n2'];
                break;
            case 1:
                $solution = $_SESSION['mathcaptcha_n1'] - $_SESSION['mathcaptcha_n2'];
                break;
            case 2:
                $solution = $_SESSION['mathcaptcha_n1'] * $_SESSION['mathcaptcha_n2'];
                break;
        }
    unset($_SESSION['mathcaptcha_n1']);
    unset($_SESSION['mathcaptcha_n2']);
    unset($_SESSION['mathcaptcha_op']);
    $post = $b['post'];
    if ($solution == $post['mathcaptcha']) {
        return true;
    } else {
        notice(L10n::t('The solution for the captcha was incorrect'));
        $a->internalRedirect('/register');
    }
}

/**
 * Add the captcha to the register form
 */
function mathcaptcha_register_form(App $a, &$b)
{
    $tpl = $b['template'];
    $oldPath = $tpl->filename;
    $newPath = 'addon/mathcaptcha/templates/register.tpl';
    if (strpos($oldPath, 'theme') == true)
    {
        $theme = explode('/', $oldPath)[2];
        $newThemePath = 'addon/mathcaptcha/templates/theme/'.$theme.'/register.tpl';
        if (file_exists($newThemePath)) {
            $newPath = $newThemePath;
        }
    }
    if (file_exists($newPath)) {
        $b['template'] = Renderer::getMarkupTemplate($newPath);
        $b['template']->filename = $newPath;
    }
}

/**
 * add template variables to the registration template
 */
function mathcaptcha_template_vars(App $a, &$arr)
{
    // if the template currently processed is the register.tpl
    // add some new variables to the list of template variables
    if ($arr['template']=='register.tpl')
    {
        unset($_SESSION['mathcaptcha_n1']);
        unset($_SESSION['mathcaptcha_n2']);
        unset($_SESSION['mathcaptcha_op']);
        $num1 = rand(1, 10);
        $num2 = rand(1, 10);
        $operator = rand(0, 2);
        $_SESSION['mathcaptcha_n1'] = $num1;
        $_SESSION['mathcaptcha_n2'] = $num2;
        $_SESSION['mathcaptcha_op'] = $operator;
        $ops = ['+','-','&times'];
        $task = strval($num1)." ".$ops[$operator]." ".strval($num2);
        $arr['vars'] = array_merge($arr['vars'], [
            '$captchaTitle'=>L10n::t('Captcha'),
            '$captchaDescription'=>L10n::t('In order to continue with the registration, please solve the following calculation.'),
            '$mathcaptcha'=> ['mathcaptcha', $task, '', L10n::t('You have to type in the solution of the calculation'), 'required']
        ]);
    }
}