<?php
// $Id$

function captcharith_help($section = "admin/modules#description") {
  $output = '';
  switch ($section) {
  case 'admin/modules#description':
    $output = t("Provides an arithmetic challenge for the captcha module.");
    break;
  }
  return $output;
}

/**
* Implementation of hook_captcha().
*/
function captcharith_captcha($op, $edit = NULL) {
  switch ($op) {

    case 'description':
      // Brief description of this method; used in the catpcha settings form.
      // In third-party captcha modules, this could test whether the particular
      // captcha method is supported in the current configuration.
      return t('Arithmetic question.');

    case 'settings':
      // Settings for this captcha method.
      // None for this captcha method.
      return NULL;

    case 'form':
      // Return form items for this captcha method.
      $qa = _captcharith_qa(); 
      $_SESSION['captcha'] = $qa['answer'];
      $output = form_item(t('Question'), $qa['question']); 
      $output .= form_textfield(t('Answer'), 'captchaword', NULL, 15, 15,
        t('Please answer the question above. Use digits, not words.'),
        NULL, TRUE); 
      return $output;

    case 'test':
      // Return TRUE or FALSE according to whether the supplied form values
      // satisfy the captcha test.
      return ($edit != NULL) && ($edit['captchaword'] == $_SESSION['captcha']);

  }
}

/** 
* Returns a question and answer. 
*/ 
function _captcharith_qa() {
  $numbers = array( 
    1 => t('one'), 
    2 => t('two'), 
    3 => t('three'), 
    4 => t('four'), 
    5 => t('five'), 
    6 => t('six'), 
    7 => t('seven'), 
    8 => t('eight'), 
    9 => t('nine'), 
    10 => t('ten'), 
    11 => t('eleven'), 
    12 => t('twelve') 
  ); 

  $operators = array( 
    0 => array(name => t('plus'), symbol => '+'), 
    1 => array(name => t('minus'), symbol => '-'), 
    2 => array(name => t('multiplied by'), symbol => '*'), 
    3 => array(name => t('divided by'), symbol => '/') 
  ); 

  $operator = rand(0,count($operators)-1); 

  // choose numbers based on operator to keep the math simple 
  switch($operator) { 
    case 0: 
      // do addition logic 
      $firstNumber = rand(1,count($numbers)-1); 
      $secondNumber = rand(1,count($numbers)-1); 
      $result = $firstNumber + $secondNumber; 
      break; 
    case 1: 
      // do subtraction logic 
      $firstNumber = rand(6,count($numbers)-1); 
      $secondNumber = rand(1,5); 
      $result = $firstNumber - $secondNumber; 
      break; 
    case 2: 
      // do multiplication logic 
      $firstNumber = rand(1,8); 
      $secondNumber = rand(1,8); 
      $result = $firstNumber * $secondNumber; 
      break; 
    case 3: 
      // do division logic 
      $secondNumber = rand(2,4); 
      $firstNumber = $secondNumber * rand(1,4); 
      $result = $firstNumber / $secondNumber; 
      break; 
  } 

  $equation = $numbers[$firstNumber].' '.$operators[$operator]['name'].' '.$numbers[$secondNumber]; 
  $output = array('question' => t('What is ') . $equation . '?', 'answer' => $result); 

  return $output; 
} 


?>