<?php
/*
Plugin Name: Anti-Captcha
Plugin URI: http://blog.fili.nl/articles/wordpress-plugin-anti-captcha/
Description: Anti-Captcha is a transparent captcha solution which does not require any end-user interaction
Version: 20090821
Author: Fili Wiese
Author URI: http://www.fili.nl/
*/

define("ANTI_CAPTCHA_ERROR", __("Error, please enable javascript and try again...", 'anti_captcha'));

if(!isset($_SESSION)) {
	session_start();
}

add_action('wp_head', 'anti_captcha_head');
add_action('login_head', 'anti_captcha_head');
add_filter('preprocess_comment', 'anti_captcha_process_comment');
add_action('wp_authenticate', 'anti_captcha_process_login');
add_action('register_post','anti_captcha_process_registration',10,3);
add_action('lostpassword_post','anti_captcha_process_lostpassword',10,3);

function anti_captcha_head()
{
	if (is_user_logged_in()) return;
	
	wp_enqueue_script('anti-captcha', '/wp-content/plugins/anti-captcha/anti-captcha-0.1.js.php', array('jquery'), '0.1');
	wp_print_scripts(array('anti-captcha'));
}

function anti_captcha_verify_token($token)
{
	if (sha1($token) == $_SESSION['anti-captcha-checksum']) {
		unset($_SESSION['anti-captcha-checksum']);
		return true;
	}
	
	return false;
}

function anti_captcha_process_comment($incoming_comment)
{
	if (is_user_logged_in()) return $incoming_comment;
	
	if (!anti_captcha_verify_token($_POST['anti-captcha-token'])) {
		add_filter('pre_comment_approved', create_function('$a', 'return \'spam\';'));
	}
	
	return $incoming_comment;
}

function anti_captcha_process_login()
{
	if (count($_POST)) {
		if (!anti_captcha_verify_token($_POST['anti-captcha-token'])) {
			wp_die(ANTI_CAPTCHA_ERROR);
		}
	}
}

function anti_captcha_process_registration($login,$email,$errors)
{
	if (!anti_captcha_verify_token($_POST['anti-captcha-token'])) {
		$errors->add('anti_captcha_error', ANTI_CAPTCHA_ERROR);
	}
}

function anti_captcha_process_lostpassword()
{
	if (!anti_captcha_verify_token($_POST['anti-captcha-token'])) {
		wp_die(ANTI_CAPTCHA_ERROR);
	}
}