<?php
// $Id: image_captcha.admin.inc,v 1.7.2.6 2009-04-10 21:35:29 soxofaan Exp $

/**
 * @file
 * Implementation of the administration UI of the image CAPTCHA module.
 */

/**
 * function to get a list of available fonts
 */
function _image_captcha_available_fonts() {
  $available_fonts = array('BUILTIN' => t('Built-in font'));
  $fontsdirectories = array(
    drupal_get_path('module', 'image_captcha') .'/fonts',
    file_directory_path(),
  );
  foreach ($fontsdirectories as $fontsdirectory) {
    foreach (file_scan_directory($fontsdirectory, '\.[tT][tT][fF]$') as $filename => $font) {
      $available_fonts[$filename] = "{$font->basename} ($filename)";
    }
  }
  return $available_fonts;
}


/**
 * Helper function for the configuration form for image_captcha
 * Called by image_captcha_settings_form() (which determines the real form_id
 * 'image_captcha_settings_form')
 */
function _image_captcha_settings_form() {
  if (!function_exists('imagejpeg')) {
    drupal_set_message(t('Images cannot be generated, because your PHP installation\'s GD library has no JPEG support.'), 'error');
  }
  $form = array();
  $form['image_captcha_code_settings'] = array(
    '#type' => 'fieldset',
    '#title' => t('Code settings'),
  );
  $form['image_captcha_code_settings']['image_captcha_image_allowed_chars'] = array(
    '#type' => 'textfield',
    '#title' => t('Characters to use in the code'),
    '#default_value' => variable_get('image_captcha_image_allowed_chars', IMAGE_CAPTCHA_ALLOWED_CHARACTERS),
  );
  $form['image_captcha_code_settings']['image_captcha_code_length'] = array(
    '#type' => 'select',
    '#title' => t('Code length'),
    '#options' => array(2 => 2, 3, 4, 5, 6, 7, 8, 9, 10),
    '#default_value' => (int) variable_get('image_captcha_code_length', 5),
    '#description' => t('The code length influences the size of the image. Note that larger values make the image generation more CPU intensive.'),
  );

  // Option fo case insensitive validation
  $form['image_captcha_code_settings']['image_captcha_case_insensitive'] = array(
    '#type' => 'checkbox',
    '#title' => t('Case insensitive validation'),
    '#description' => t('Enable this option to ignore uppercase/lowercase errors in the response. This can be usefull for adapting the challenge to your audience or for certain fonts where the differences between upper and lower case are too small.'),
    '#default_value' => variable_get('image_captcha_case_insensitive', FALSE),
  );

  // font related stuff
  $form['image_captcha_font_settings'] = array(
    '#type' => 'fieldset',
    '#title' => t('Font settings'),
  );
  $available_fonts = _image_captcha_available_fonts();
  list($default_font, $errmsg) = _image_captcha_get_font();
  $form['image_captcha_font_settings']['image_captcha_font'] = array(
    '#type' => 'select',
    '#title' => t('Font'),
    '#default_value' => $default_font,
    '#description' => t('The TrueType font (.ttf) to use for the text in the image CAPTCHA.'),
    '#options' => $available_fonts,
  );
  // add a prerender procedure for checking that a font should be set.
  $form['#pre_render'] = array('image_captcha_settings_form_pre_render');
  // font size
  if ($default_font != 'BUILTIN') {
    $form['image_captcha_font_settings']['image_captcha_font_size'] = array(
      '#type' => 'select',
      '#title' => t('Font size'),
      '#options' => array(
        12 => t('tiny'),
        20 => t('small'),
        30 => t('normal'),
        40 => t('large'),
      ),
      '#default_value' => (int) variable_get('image_captcha_font_size', 30),
      '#description' => t('The font size influences the size of the image. Note that larger values make the image generation more CPU intensive.'),
    );
  }
  // character spacing
  $form['image_captcha_font_settings']['image_captcha_character_spacing'] = array(
    '#type' => 'select',
    '#title' => t('Character spacing'),
    '#description' => t('Define the average spacing between characters. Note that larger values make the image generation more CPU intensive.'),
    '#default_value' => variable_get('image_captcha_character_spacing', '1.2'),
    '#options' => array(
      '1' => t('small'),
      '1.2' => t('normal'),
      '1.5' => t('large'),
    ),
  );

  // color settings
  $form['image_captcha_color_settings'] = array(
    '#type' => 'fieldset',
    '#title' => t('Color settings'),
    '#description' => t('Configuration of the background and text colors in the image CAPTCHA.'),
  );
  $form['image_captcha_color_settings']['image_captcha_background_color'] = array(
    '#type' => 'textfield',
    '#title' => t('Background color'),
    '#description' => t('Enter the hexadecimal code for the background color (e.g. #FFF or #FFCE90).'),
    '#default_value' => variable_get('image_captcha_background_color', '#ffffff'),
    '#maxlength' => 7,
    '#size' => 8,
  );
  $form['image_captcha_color_settings']['image_captcha_foreground_color'] = array(
    '#type' => 'textfield',
    '#title' => t('Text color'),
    '#description' => t('Enter the hexadecimal code for the text color (e.g. #000 or #004283).'),
    '#default_value' => variable_get('image_captcha_foreground_color', '#000000'),
    '#maxlength' => 7,
    '#size' => 8,
  );
  $form['image_captcha_color_settings']['image_captcha_foreground_color_randomness'] = array(
    '#type' => 'select',
    '#title' => t('Additional variation of text color'),
    '#options' => array(
      0 => t('none'),
      50 => t('small'),
      100 => t('moderate'),
      150 => t('high'),
      200 => t('very high'),
    ),
    '#default_value' => (int) variable_get('image_captcha_foreground_color_randomness', 100),
    '#description' => t('The different characters will have randomized colors in the specified range around the text color.'),
  );

  // distortion and noise settings
  $form['image_captcha_distortion_and_noise'] = array(
    '#type' => 'fieldset',
    '#title' => t('Distortion and noise'),
    '#description' => t('With these settings you can control the degree of obfuscation by distortion and added noise. Do not exaggerate the obfuscation and assure that the code in the image is reasonably readable. For example, do not combine high levels of distortion and noise.'),
  );
  // distortion
  $form['image_captcha_distortion_and_noise']['image_captcha_distortion_amplitude'] = array(
    '#type' => 'select',
    '#title' => t('Distortion level'),
    '#options' => array(
      0 => t('none'),
      2 => t('low'),
      4 => t('moderate'),
      6 => t('normal'),
      8 => t('high'),
      10 => t('severe'),
    ),
    '#default_value' => (int) variable_get('image_captcha_distortion_amplitude', 6),
    '#description' => t('Set the degree of wave distortion in the image.'),
  );
  $form['image_captcha_distortion_and_noise']['image_captcha_bilinair_interpolation'] = array(
    '#type' => 'checkbox',
    '#title' => t('Smooth distortion'),
    '#default_value' => variable_get('image_captcha_bilinair_interpolation', FALSE),
    '#description' => t('This option enables bilinear interpolation of the distortion which makes the image look smoother, but it is more CPU intensive.'),
  );
  //double vision
  $form['image_captcha_distortion_and_noise']['image_captcha_double_vision'] = array(
    '#type' => 'checkbox',
    '#title' => t('Double vision'),
    '#default_value' => variable_get('image_captcha_double_vision', 0),
    '#description' => t('When enabled, characters appear twice in the image, overlaid onto each other.'),
  );
  // noise
  $form['image_captcha_distortion_and_noise']['image_captcha_dot_noise'] = array(
    '#type' => 'checkbox',
    '#title' => t('Add salt and pepper noise'),
    '#default_value' => variable_get('image_captcha_dot_noise', 0),
    '#description' => t('This option adds randomly colored point noise.'),
  );
  $form['image_captcha_distortion_and_noise']['image_captcha_line_noise'] = array(
    '#type' => 'checkbox',
    '#title' => t('Add line noise'),
    '#default_value' => variable_get('image_captcha_line_noise', 0),
    '#description' => t('This option enables lines randomly drawn on top of the text code.'),
  );
  $form['image_captcha_distortion_and_noise']['image_captcha_noise_level'] = array(
    '#type' => 'select',
    '#title' => t('Noise level'),
    '#options' => array(
      2 => t('low'),
      5 => t('normal'),
      7 => t('high'),
      10 => t('severe'),
    ),
    '#default_value' => (int) variable_get('image_captcha_noise_level', 5),
  );
  return system_settings_form($form);
}

/**
 * Pre render function for image_captcha_settings_form
 */
function image_captcha_settings_form_pre_render($form_id, $form) {
  if (count($form['image_captcha_font_settings']['image_captcha_font']['#options']) == 1) {
    drupal_set_message(t('The image CAPTCHA module works best with a TrueType font file (TTF) for generating the images, but because of licencing issues it is not allowed to package fonts with the module. A simple built-in bitmap font is provided as default instead. You can install TrueType fonts yourself by putting them in the fonts directory of the image CAPTCHA module (directory "%fontsdir") or by uploading them to your Drupal file system (directory "%filesdir") with for example the upload module.', array('%fontsdir' => drupal_get_path('module', 'image_captcha') .'/fonts', '%filesdir' => file_directory_path())), 'warning');
  }
  if ($form['image_captcha_font_settings']['image_captcha_font']['#default_value'] == 'BUILTIN') {
    drupal_set_message(t('The usage of the built-in bitmap font it is not recommended because of its small size and missing UTF-8 support.'), 'warning');
  }
}

/**
 * Validation function for image_captcha configuration form
 */
function image_captcha_settings_form_validate($form_id, $form_values) {
  if ($form_id == 'image_captcha_settings_form') {
    // check image_captcha_image_allowed_chars for spaces
    if (preg_match('/\s/', $form_values['image_captcha_image_allowed_chars'])) {
      form_set_error('image_captcha_image_allowed_chars', t('The list of characters to use should not contain spaces.'));
    }
    // check font
    $font = $form_values['image_captcha_font'];
    if ($font == '0') {
      form_set_error('image_captcha_font', t('You need to select a font'));
    }
    elseif ($font != 'BUILTIN' && (!is_file($font) || !is_readable($font))) {
      form_set_error('image_captcha_font', t('Font does not exist or is not readable.'));
    }
    // check color settings
    if (!preg_match('/^#([0-9a-fA-F]{3}){1,2}$/', $form_values['image_captcha_background_color'])) {
      form_set_error('image_captcha_background_color', t('Background color is not a valid hexadecimal color value.'));
    }
    if (!preg_match('/^#([0-9a-fA-F]{3}){1,2}$/', $form_values['image_captcha_foreground_color'])) {
      form_set_error('image_captcha_foreground_color', t('Text color is not a valid hexadecimal color value.'));
    }
  }
}