<?php

/*
 * Enano - an open-source CMS capable of wiki functions, Drupal-like sidebar blocks, and everything in between
 * Copyright (C) 2006-2009 Dan Fuhry
 * captcha.php - visual confirmation system used during registration
 *
 * This program is Free Software; you can redistribute and/or modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for details.
 */

/**
 * The base class for CAPTCHA engines.
 * @package Enano
 * @subpackage User management
 * @copyright 2008 Dan Fuhry
 */
 
class captcha_base
{
	
	/**
 	* Our session ID
 	* @var string
 	*/
	
	private $session_id;
	
	/**
 	* Our saved session data
 	* @var array
 	*/
	
	private $session_data;
	
	/**
 	* The confirmation code we're generating.
 	* @var string
 	*/
	
	private $code = '';
	
	/**
 	* Numerical ID (primary key) for our session
 	* @var int
 	*/
	
	private $id = 0;
	
	/**
 	* Constructor.
 	* @param string Session ID for captcha
 	*/
	
	function __construct($session_id, $row = false)
	{
		global $db, $session, $paths, $template, $plugins; // Common objects
		if ( !preg_match('/^[a-f0-9]{32}([a-z0-9]{8})?$/', $session_id) )
		{
			throw new Exception('Invalid session ID');
		}
		$this->session_id = $session_id;
		// If we weren't supplied with session info, retreive it
		if ( !is_array($row) )
		{
			$q = $db->sql_query('SELECT code_id, code, session_data FROM ' . table_prefix . "captcha WHERE session_id = '$session_id';");
			if ( !$q )
				$db->_die();
			$row = $db->fetchrow();
			$row['code_id'] = intval($row['code_id']);
			$db->free_result();
		}
		if ( !isset($row['code']) || !isset($row['session_data']) || !is_int(@$row['code_id']) )
		{
			throw new Exception('Row doesn\'t contain what we need (code and session_data)');
		}
		$this->session_data = ( is_array($x = @unserialize($row['session_data'])) ) ? $x : array();
		$this->code = $row['code'];
		$this->id = $row['code_id'];
		
		// run any custom init functions
		if ( method_exists($this, 'construct_hook') )
			$this->construct_hook();
	}
	
	/**
 	* Retrieves a key from the session data set
 	* @param int|string Key to fetch
 	* @param mixed Default value for key
 	* @return mixed
 	*/
 	
	function session_fetch($key, $default = false)
	{
		return ( isset($this->session_data[$key]) ) ? $this->session_data[$key] : $default;
	}
	
	/**
 	* Stores a value in the session's data set. Change must be committed using $captcha->session_commit()
 	* @param int|string Name of key
 	* @param mixed Value - can be an array, string, int, or double, but probably not objects :-)
 	*/
	
	function session_store($key, $value)
	{
		$this->session_data[$key] = $value;
	}
	
	/**
 	* Commits changes to the session data set to the database.
 	*/
	
	function session_commit()
	{
		global $db, $session, $paths, $template, $plugins; // Common objects
		$session_data = serialize($this->session_data);
		$session_data = $db->escape($session_data);
		$code = $db->escape($this->code);
		
		$q = $db->sql_query('UPDATE ' . table_prefix . "captcha SET code = '$code', session_data = '$session_data' WHERE code_id = {$this->id};");
		if ( !$q )
			$db->_die();
	}
	
	/**
 	* Changes the confirmation code
 	* @param string New string
 	*/
	
	function set_code($code)
	{
		if ( !is_string($code) )
			return false;
		
		$this->code = $code;
	}
	
	/**
 	* Returns the confirmation code
 	* @return string
 	*/
	
	function get_code()
	{
		return $this->code;
	}
	
}

/**
 * Returns a new captcha object
 * @param string Session ID
 * @param string Optional - engine to load
 * @param array Optional row to send to the captcha engine
 */

function captcha_object($session_id, $engine = false, $row = false)
{
	static $singletons = array();
	if ( !$engine )
	{
		$engine = getConfig('captcha_engine');
		if ( !$engine )
		{
			$engine = 'freecap';
		}
	}
	if( !extension_loaded("gd") || !function_exists("gd_info") || !function_exists('imagettftext') || !function_exists('imagepng') || !function_exists('imagecreatefromjpeg') )
	{
		$engine = 'failsafe';
	}
	if ( !class_exists("captcha_engine_$engine") )
	{
		require_once ENANO_ROOT . "/includes/captcha/engine_{$engine}.php";
	}
	if ( !class_exists("captcha_engine_$engine") )
	{
		throw new Exception("Expected but couldn't find class for captcha engine: captcha_engine_$engine");
	}
	$class = "captcha_engine_$engine";
	return new $class($session_id, $row);
}

?>