<?php
App::uses('AppHelper', 'View/Helper');
App::uses('CaptchaLib', 'Tools.Lib');

if (!defined('BR')) {
	define('BR', '<br />');
}

/**
 * PHP5 / CakePHP2
 *
 * @author Mark Scherer
 * @link http://www.dereuromark.de
 * @license MIT License (http://www.opensource.org/licenses/mit-license.php)
 */

/**
 * Works togehter with captcha behaviour/component
 */
class CaptchaHelper extends AppHelper {

	public $helpers = array('Form');

	protected $_defaults = array(
		'difficulty' => 1, # initial diff. level (@see operator: + = 0, +- = 1, +-* = 2)
		'raiseDifficulty' => 2, # number of failed trails, after the x. one the following one it will be more difficult
	);

	protected $numberConvert = null;

	protected $operatorConvert = null;

	public function __construct($View = null, $settings = array()) {
		parent::__construct($View, $settings);

		// First of all we are going to set up an array with the text equivalents of all the numbers we will be using.
		$this->numberConvert = array(0 => 'zero', 1 => 'one', 2 => 'two', 3 => 'three', 4 => 'four', 5 => 'five', 6 => 'six', 7 => 'seven', 8 => 'eight', 9 => 'nine', 10 => 'ten');

		// Set up an array with the operators that we want to use. With difficulty=1 it is only subtraction and addition.
		$this->operatorConvert = array(0 => array('+', __('calcPlus')), 1 => array('-', __('calcMinus')), 2 => '*', __('calcTimes'));

		$this->settings = array_merge(CaptchaLib::$defaults, $this->_defaults);
		$settings = (array)Configure::read('Captcha');
		if (!empty($settings)) {
			$this->settings = array_merge($this->settings, $settings);
		}
	}

	/**
	 * //TODO: move to Lib
	 * shows the statusText of Relations
	 *
	 * @param int $difficulty: not build in yet
	 * @return array
	 */
	protected function _generate($difficulty = null) {
		// Choose the first number randomly between 6 and 10. This is to stop the answer being negative.
		$numberOne = mt_rand(6, 10);
		// Choose the second number randomly between 0 and 5.
		$numberTwo = mt_rand(0, 5);
		// Choose the operator randomly from the array.
		$captchaOperatorSelection = $this->operatorConvert[mt_rand(0, 1)];
		$captchaOperator = $captchaOperatorSelection[mt_rand(0, 1)];

		// Get the equation in textual form to show to the user.
		$code = (mt_rand(0, 1) == 1 ? __($this->numberConvert[$numberOne]) : $numberOne) . ' ' . $captchaOperator . ' ' . (mt_rand(0, 1) == 1 ? __($this->numberConvert[$numberTwo]) : $numberTwo);

		// Evaluate the equation and get the result.
		eval('$result = ' . $numberOne . ' ' . $captchaOperatorSelection[0] . ' ' . $numberTwo . ';');

		return array('code' => $code, 'result' => $result);
	}

	/**
	 * Main captcha output (usually called from $this->input() automatically)
	 * - hash-based
	 * - session-based (not impl.)
	 * - db-based (not impl.)
	 *
	 * @return string HTML
	 */
	public function captcha($modelName = null) {
		$captchaCode = $this->_generate();

		// Session-Way (only one form at a time) - must be a component then
	//$this->Session->write('Captcha.result', $result);

	// DB-Way (several forms possible, high security via IP-Based max limits)
	// the following should be done in a component and passed to the view/helper
	// $Captcha = ClassRegistry::init('Captcha');
	// $this->Captcha->new(); $this->Captcha->update(); etc

		// Timestamp-SessionID-Hash-Way (several forms possible, not as secure)
		$hash = $this->_buildHash($captchaCode);

		$return = '';

		if (in_array($this->settings['type'], array('active', 'both'))) {
			// //todo obscure html here?
			$fill = ''; //'<span></span>';
			$return .= '<span id="captchaCode">' . $fill . '' . $captchaCode['code'] . '</span>';
		}

		$field = $this->_fieldName($modelName);

		// add passive part on active forms as well
		$return .= '<div style="display:none">' .
			$this->Form->input($field . '_hash', array('value' => $hash)) .
			$this->Form->input($field . '_time', array('value' => time())) .
			$this->Form->input((!empty($modelName) ? $modelName . '.' : '') . $this->settings['dummyField'], array('value' => '')) .
		'</div>';
		return $return;
	}

	/**
	 * Active math captcha
	 * either combined with between=true (all in this one funtion)
	 * or seperated by =false (needs input(false) and captcha() calls then)
	 *
	 * @param bool between: [default: true]
	 * @return string HTML
	 */
	public function input($modelName = null, $options = array()) {
		$defaultOptions = array(
			'type' => 'text',
			'class' => 'captcha',
			'value' => '',
			'maxlength' => 3,
			'label' => __('Captcha') . BR . __('captchaExplained'),
			'combined' => true,
			'autocomplete' => 'off',
			'after' => __('captchaTip'),
		);
		$options = array_merge($defaultOptions, $options);

		if ($options['combined'] === true) {
			$options['between'] = $this->captcha($modelName);
			if (in_array($this->settings['type'], array('active', 'both'))) {
				$options['between'] .= ' = ';
			}
		}
		unset($options['combined']);

		$field = $this->_fieldName($modelName);
		return $this->Form->input($field . '', $options); // TODO: rename: _code
	}

	/**
	 * Passive captcha
	 *
	 * @return string HTML
	 */
	public function passive($modelName = null, $options = array()) {
		$tmp = $this->settings['type'];
		$this->settings['type'] = 'passive';
		$res = $this->captcha($modelName);
		$this->settings['type'] = $tmp;
		return $res;
	}

	/**
	 * Active captcha
	 * (+ passive captcha right now)
	 *
	 * @return string Form input
	 */
	public function active($modelName = null, $options = array()) {
		return $this->input($modelName, $options);
	}

	/**
	 * @param array $captchaCode
	 * @return string Hash
	 */
	protected function _buildHash($data) {
		return CaptchaLib::buildHash($data, $this->settings, true);
	}

	/**
	 * @return string Field name
	 */
	protected function _fieldName($modelName = null) {
		$fieldName = 'captcha';
		if (isSet($modelName)) {
			$fieldName = $modelName . '.' . $fieldName;
		}
		return $fieldName;
	}

}