<?php

function textimage_help($section = "admin/help#textimage") {
  $output = "";

  switch ($section) {
  case 'admin/help#textimage':
    $output .= "<p>Implements an image recognition captcha.</p>";
    break;
  case 'admin/modules#description':
  case 'admin/modules/textimage':
  case 'admin/textimage':
    $output = t('Implements an image recognition captcha.');
    break;
  }
  return $output;
}

function textimage_captchachallenge(&$form) {
  
  $form['captcha_response'] = array (
    '#type' => 'textfield',
    '#title' => t('Captcha Validation'),
    '#default_value' => '',
    '#required' => TRUE,
    '#validate' => array('_captcha_validate' => array()),
    '#description' => 'Please type in the letters/numbers that are shown in the corresponding image.<br />Validation is case sensitive.',
    '#prefix' => '<div class="captchachallenge"><img class="captcha" src="' . url('_textimage/image/'.time()) . '" '.$imageSize[3].'  alt="Captcha Image: you will need to recognize the text in it."/>',
    '#suffix' => '</div>',
  );

  return $form;
}

function textimage_captchavalidate(&$captcha_word, &$correct) {

  $captcha_word = drupal_strtolower($captcha_word);
  if ($captcha_word == $_SESSION['captcha']) {
    $correct = true;
  }
  else {
    $correct = false;
    form_set_error('captcha_response', t('The image verification code you entered is incorrect.'));
  }

}

/**
* Implementation of hook_menu().
*/
function textimage_menu($may_cache) {
  $items = array();

  $suffix = '';

  if (arg(2)!=null) $suffix='/'.arg(2);

  $items[] = array(
    'path' => '_textimage/image'.$suffix, 'title' => t('textimage'),
    'callback' => '_textimage_image', 
    'access' => user_access('access textimages'),
    'type' => MENU_CALLBACK
  );

  return $items;
}

function textimage_perm() {
  return array('access textimages');
}

function textimage_settings() {
	
	$fonts_path = variable_get("textimage_fonts_path", "");
  $images_path = variable_get("textimage_images_path", "");
	
  //check for GD
  if (!function_exists(imagecreate)) 
    drupal_set_message(t('Image library not available. Textimage needs the GD library extension to be installed. Please install GD.'));

	//check for TTF support
	elseif (!function_exists(imagettftext))
		drupal_set_message(t('Your image library does not seem to have TrueType font support. Textimage will work, but will use the default inbuilt font.'),'status');

	//check for valid font path
	elseif ($fonts_path!="" && !is_dir($fonts_path))
		drupal_set_message(t('The current font path is invalid. The default font will be used.'));

	//check for valid image path
	if ($images_path!="" && !is_dir($images_path))
		drupal_set_message(t('The current images path is invalid. No images will be used.'));

  //Fonts settings
  $form['fonts'] = array(
                '#type' => 'fieldset', '#title' => t('Fonts settings'),
                '#collapsible' => TRUE, '#collapsed' => FALSE
              );
              
  $form['fonts']['textimage_use_only_upper'] = array(
                                     '#type' => 'checkbox',
                                     '#title' => t('Use only Uppercase'),
                                     '#default_value' => variable_get('textimage_use_only_upper',0)
                                    );
              
  $form['fonts']['textimage_fonts_path'] = array(
                                  '#type' => 'textfield',
                                  '#title' => t('TrueType Fonts Path'),
                                  '#default_value' =>  $fonts_path,
                                  '#size' => 30,
                                  '#maxlength' => 255,
                                  '#description' => t('Location of the directory where the Truetype (.ttf) fonts are stored. If you do not provide any fonts, the module will use the default font for text. Relative paths will be resolved relative to the Drupal installation directory.'),
                                );
                                
  $form['fonts']['textimage_font_size'] = array(
                                  '#type' => 'textfield',
                                  '#title' => t('Font Size'),
                                  '#default_value' =>  variable_get('textimage_font_size',24),
                                  '#size' => 5,
                                  '#maxlength' => 2,
                                  '#description' => t('Font size of Captcha text (in pixels).'),
                                  '#validate' => array("_textimage_number_validate" => array("textimage_font_size")),
                                );
                                
  $form['fonts']['textimage_char_spacing_max'] = array(
                                  '#type' => 'textfield',
                                  '#title' => t('Character Spacing'),
                                  '#default_value' =>  variable_get('textimage_char_spacing_max',10),
                                  '#size' => 5,
                                  '#maxlength' => 4,
                                  '#description' => t('Sets the kerning between letters in Captcha. Higher numbers indicate more spacing.'),
                                  '#validate' => array("_textimage_number_validate" => array("textimage_char_spacing_max")),
                                );
                                
  $form['fonts']['textimage_char_jiggle_amount'] = array(
                                  '#type' => 'textfield',
                                  '#title' => t('Character Jiggle'),
                                  '#default_value' =>  variable_get('textimage_char_jiggle_amount',5),
                                  '#size' => 5,
                                  '#maxlength' => 2,
                                  '#description' => t('Sets the amount of up and down movement in the Captcha letters. Higher numbers indicate more jiggling.'),
                                  '#validate' => array("_textimage_number_validate" => array("textimage_char_jiggle_amount")),
                                );
                                
  $form['fonts']['textimage_char_rotate_amount'] = array(
                                  '#type' => 'textfield',
                                  '#title' => t('Character Rotation'),
                                  '#default_value' =>  variable_get('textimage_char_rotate_amount',5),
                                  '#size' => 5,
                                  '#maxlength' => 2,
                                  '#description' => t('Sets the amount of rotation in the Captcha letters (in degrees, only works with non-default fonts).'),
                                  '#validate' => array("_textimage_number_validate" => array("textimage_char_rotate_amount")),
                                );
                                
  $form['fonts']['textimage_char_size_amount'] = array(
                                  '#type' => 'textfield',
                                  '#title' => t('Character Size Adjustment'),
                                  '#default_value' =>  variable_get('textimage_char_size_amount',2),
                                  '#size' => 5,
                                  '#maxlength' => 2,
                                  '#description' => t('Sets the amount of variation in size between the different letters in the Captcha (in pixels).'),
                                  '#validate' => array("_textimage_number_validate" => array("textimage_char_size_amount")),
                                );

  //Image settings
  $form['images'] = array(
                '#type' => 'fieldset', '#title' => t('Image settings'),
                '#collapsible' => TRUE, '#collapsed' => FALSE
              );
  $form['images']['textimage_images_path'] = array(
                                  '#type' => 'textfield',
                                  '#title' => t('Background Images Path'),
                                  '#default_value' =>  $images_path,
                                  '#size' => 30,
                                  '#maxlength' => 255,
                                  '#description' => t('Location of the directory where the background images are stored. If you do not provide a directory, solid colors will be used. Relative paths will be resolved relative to the Drupal installation directory.'),
                                );
                                
  $form['images']['textimage_image_noise'] = array(
                                  '#type' => 'textfield',
                                  '#title' => t('Image Noise (pixels)'),
                                  '#default_value' =>  variable_get('textimage_image_noise',4),
                                  '#size' => 5,
                                  '#maxlength' => 4,
                                  '#description' => t('Sets the amount of noise (random pixels) in the Captcha image. Higher numbers indicate more noise.'),
                                  '#validate' => array("_textimage_number_validate" => array("textimage_image_noise")),
                                );
                                
  $form['images']['textimage_image_lines'] = array(
                                  '#type' => 'textfield',
                                  '#title' => t('Image Noise (lines)'),
                                  '#default_value' =>  variable_get('textimage_image_lines',4),
                                  '#size' => 5,
                                  '#maxlength' => 4,
                                  '#description' => t('Sets the amount of noise (random lines) in the Captcha image. Higher numbers indicate more noise.'),
                                  '#validate' => array("_textimage_number_validate" => array("textimage_image_lines")),
                                );
                                
  $form['images']['textimage_image_margin'] = array(
                                  '#type' => 'textfield',
                                  '#title' => t('Image Margin'),
                                  '#default_value' =>  variable_get('textimage_image_margin',10),
                                  '#size' => 5,
                                  '#maxlength' => 4,
                                  '#description' => t('Set a distance between the Captcha letters and the edges of the image.'),
                                  '#validate' => array("_textimage_number_validate" => array("textimage_image_margin")),
                                );


  $form['info'] = array(
                '#type' => 'fieldset', '#title' => t('Image and font information'),
                '#collapsible' => TRUE, '#collapsed' => FALSE
              );
  if (isset($fonts_path)) {
    $imagefontinfo .= t('Number of fonts found: ').count(_textimage_font_list());
  }
  if (isset($images_path)) {
    $imagefontinfo .= '<br />'.t('Number of background images found: ').count(_textimage_image_list());
  }

  $gdinfo = gd_info();
  $imagefontinfo .= '<br />'.t('GD Version: ').$gdinfo["GD Version"];
  $imagefontinfo .= '<br />'.t(' FreeType Support: ');
  $imagefontinfo .= ($gdinfo["FreeType Support"]==true) ? 'True' : 'False';
  $imagefontinfo .= '<br />';

  $form['info']['captcha_info'] = array (
                           '#type' => 'item',
                           '#value' => $imagefontinfo,
                          );

  return $form;
}

function textimage_settings_form_validate ($form_id,$form) {
  //check for valid font path
  if ($form['textimage_fonts_path'] !="" && !is_dir($form['textimage_fonts_path']))
    form_set_error('textimage_fonts_path', t('The entered font path is invalid'));
  //check for valid image path
  if ($form['textimage_images_path'] !="" && !is_dir($form['textimage_images_path']))
    form_set_error('textimage_images_path', t('The entered image path is invalid'));
}

function _textimage_number_validate ($field,$fieldName) {
  if (!is_numeric($field['#value'])) {
    form_set_error($fieldName,t("The value for")." ".t($field['#title'])." ".t("must be a number"));
  }
}

/**
* Prints an image containing a textimage code.
*/
function _textimage_image() {
    //if we don't have GD2 functions, we can't generate the image
    if (!function_exists('imagecreatetruecolor')) return;

    // Set headers
    header('Expires: Mon, 01 Jan 1997 05:00:00 GMT');
    header('Cache-Control: no-store, no-cache, must-revalidate');
    header('Cache-Control: post-check=0, pre-check=0', false);
    header('Pragma: no-cache');

    header('Content-type: image/png');

    $string = _textimage_code();

    // Get truetype font list
    $fonts = _textimage_font_list();
    // Get the background images list
    $images = _textimage_image_list();
 
    // Randomization amounts:
    $charSpacingMax   = variable_get('textimage_char_spacing_max',10);   // Letter spacing max (pixels)
    $charSpacingMin   = max($charSpacingMax*.5,0);                     // Letter spacing minimum (pixels)
    $charJiggleAmount = variable_get('textimage_char_jiggle_amount',5);  // Up and down randomization (pixels)
    $charRotateAmount = variable_get('textimage_char_rotate_amount',5);  // Character rotation amount (degrees)
    $charSizeAmount   = variable_get('textimage_char_size_amount',2);    // Character size amount (pixels)

    $imageRotateAmount = variable_get('captcha_image_rotate_amount',12); // Image rotation amount (degrees)
    
    // Static amounts:
    $charInitialSize   = variable_get('textimage_font_size',24);      // Initial Font 
    $imageNoise        = variable_get('textimage_image_noise',4);    // Amount of noise added to image
    $imageLines        = variable_get('textimage_image_lines',4);    // Amount of noise added to image
    $imageMargin       = variable_get('textimage_image_margin',10);    // Margin around image (pixels)

    // write text using a truetype font
    if (function_exists(imagettftext) && count($fonts) > 0) {

      
      // Initialize variables for the loop
			$characterDetails = array(); // contains the final info about each character
			      
      // Build a list of character settings for the captcha string
      for ($i=0;$i<drupal_strlen($string);$i++) {
      	// Select our character
        $char = drupal_substr($string,$i,1);

        // Define angle, size, and font of the character
        $charAngle = rand(-$charRotateAmount,$charRotateAmount);
        $charSize  = $charInitialSize + rand(-$charSizeAmount,$charSizeAmount);
        $font = $fonts[rand(0,count($fonts)-1)];

        // Find height and width of the character
        $bbox = imagettfbbox($charSize,$charAngle,$font,$char);
        $charWidth = max($bbox[0],$bbox[2],$bbox[4],$bbox[6]) - min($bbox[0],$bbox[2],$bbox[4],$bbox[6]);
        $charHeight = abs(max($bbox[1],$bbox[3])) - min($bbox[5],$bbox[7]);
        
				// Define the x and y position
				$charSpacing = rand($charSpacingMin, $charSpacingMax);
        $x = $imageWidth + $charSpacing;
        $y = ($charHeight + rand(0,$charJiggleAmount));

				$characterDetails[] = array (
					"size"  => $charSize,
					"angle" => $charAngle,
					"x"     => $x,
					"y"     => $y,
					"color" => $foreground,
					"font"  => $font,
					"char"  => $char
				);
				
        // Increment the image size
				$imageWidth  = $x + $charWidth;
				$imageHeight = max($imageHeight,$y+$charJiggleAmount);
      }
      
			// Create the image based off the string length and margin
      if (count($images) > 0) {
        // We're going to be using an image, and need a tranparent background to start with
        $im = _textimage_create_transparent_image($imageWidth+2*$imageMargin, $imageHeight+2*$imageMargin);
        $noisecolor = imagecolorallocatealpha($im, 0, 0, 0, 127);
      } else {
        // Just make a plain-jane color brackground
        $im = imagecreatetruecolor($imageWidth+2*$imageMargin, $imageHeight+2*$imageMargin);
        $background = imagecolorallocate($im, rand(180, 250), rand(180, 250), rand(180, 250));
        $noisecolor = $background;
        imagefill($im, 0, 0, $background);
      }
      
      
			// Specify colors to be used in the image
			$foreground = imagecolorallocate($im, rand(0, 80), rand(0, 80), rand(0, 80));
      
			foreach($characterDetails as $char) {
				// draw character
				imagettftext($im,$char['size'],$char['angle'],$char['x']+$imageMargin,$char['y']+$imageMargin,$foreground,$char['font'],$char['char']);
			}
 
    }

    else {
      // write text using a built-in font
      $x = 0;
      $y = 0;
      $imageWidth = 60 + drupal_strlen($string)*$charSpacingMax*.35;
      $imageHeight = 30 + $charJiggleAmount;
 
      // Create the image
      if (count($images) > 0 && function_exists(imagecolorallocatealpha)) {
        // We're going to be using an image, and need a tranparent background to start with
        $im = _textimage_create_transparent_image($imageWidth, $imageHeight);
        $noisecolor = imagecolorallocatealpha($im, 0, 0, 0, 127);
      } else {
        // Just make a plain-jane color brackground
        $im = imagecreatetruecolor($imageWidth, $imageHeight);
        $background = imagecolorallocate($im, rand(180, 250), rand(180, 250), rand(180, 250));
        $noisecolor = $background;
        imagefill($im, 0, 0, $background);
      }
      
      // Add the text
      for ($i=0;$i<drupal_strlen($string);$i++) {
        imagestring($im,max(2,5-rand(0,$charSizeAmount)),$x,$y,drupal_substr($string,$i,1),$foreground);
        $x += rand(10+$charSpacingMin,10+$charSpacingMax);
        $y = $imageMargin + rand(0,$charJiggleAmount);
      }
      
      // Scale the image according to the user defined font size and add the margin
      $imageWidth  = imagesx($im) * ($charInitialSize * .08) + $imageMargin;
      $imageHeight = imagesy($im) * ($charInitialSize * .08) + $imageMargin;
     
      if (count($images) > 0) {
        // Prepare a larger image with a background image
        $im2 = _textimage_create_transparent_image($imageWidth, $imageHeight);
      } else {
        // Prepare a larger image with a solid color
        $im2 = imagecreatetruecolor($imageWidth, $imageHeight);
        imagefill($im2, 0, 0, $background);
      }
      
      $result = imagecopyresampled ($im2, $im, $imageMargin, $imageMargin, 0, 0, $imageWidth, $imageHeight, imagesx($im), imagesy($im));
      $im = $im2;
    }

    // strikethrough
    imageline($im, rand(0, 120), rand(0, 120), rand(0, 120), rand(0, 120), $foreground);

    // Add Noise
    for ($x=0; $x<$imageWidth; $x++) {
      for ($row=0; $row<$imageNoise;$row++) {
        $y = rand(0,$imageHeight);
        imagesetpixel($im, $x, $y, $noisecolor);
      }
    }
    // Add Lines and Ellipses
    for ($x=0; $x<$imageLines;$x++) {
      imageline($im, rand(0, $imageWidth), rand(0, $imageHeight), rand(0, $imageWidth), rand(0, $imageHeight), $noisecolor);
      imageellipse($im, rand(0, $imageWidth), rand(0, $imageHeight), rand(0, $imageWidth), rand(0, $imageHeight), $noisecolor);
    }
    
    // Fill image with a random background image if available
    if (count($images) > 0) {
      $image = $images[rand(0,count($images)-1)];
      _textimage_apply_background_image($im,$image);
    }
    
    //output to browser
    imagepng($im);
    imagedestroy($im);

}

/**
* Returns a random string for use in a captcha
*/
function _textimage_code() {

    $consts='bcdgjxvmnprst';
    $vowels='aeiou';

    for ($x=0; $x < 6; $x++) {
      mt_srand ((double) microtime() * 1000000);
      $const[$x] = drupal_substr($consts,mt_rand(0,drupal_strlen($consts)-1),1);
      $vow[$x] = drupal_substr($vowels,mt_rand(0,drupal_strlen($vowels)-1),1);
    }

    $string = $const[0] . $vow[0] .$const[2] . $const[1] . $vow[1] . $const[3] . $vow[3] . $const[4];
    $string = drupal_substr($string,0,rand(4,6));

    //everytime we create a new code, we write it to session
    $_SESSION['captcha'] = drupal_strtolower($string);

    if(variable_get('textimage_use_only_upper',0))
      $string = drupal_strtoupper($string);

    return $string;

}

/**
* Returns an array of files with TTF extensions in the specified directory.
*/
function _textimage_font_list() {
  $fontdir = variable_get("textimage_fonts_path", "");

  $filelist = array();
  if (is_dir($fontdir) && $handle = opendir($fontdir)) {
    while ($file = readdir($handle)) {
      if (preg_match("/\.ttf$/i",$file) == 1)
        $filelist[] = $fontdir.'/'.$file;
    }
    closedir($handle);
  }

  return $filelist;
}


/**
* Returns an array of files with jpg, png, and gif extensions in the specified directory.
*/
function _textimage_image_list() {
  $imagesdir = variable_get("textimage_images_path", "");

  $filelist = array();
  if (is_dir($imagesdir) && $handle = opendir($imagesdir)) {
    while ($file = readdir($handle)) {
      if (preg_match("/\.gif|\.png|\.jpg$/i",$file) == 1)
        $filelist[] = $imagesdir.'/'.$file;
    }
    closedir($handle);
  }

  return $filelist;
}

/**
* Overlays an image to the supplied image resource
*/
function _textimage_apply_background_image (&$imageResource,$imageFile) {
  $backgroundResource = image_gd_open($imageFile,substr($imageFile,-3));
  // Copy the text onto the background
  $backX = imagesx($backgroundResource);
  $backY = imagesy($backgroundResource);
  $textX = imagesx($imageResource);
  $textY = imagesy($imageResource);
  
  $randomBackX = rand(0,$backX-$textX);
  $randomBackY = rand(0,$backY-$textY);
  
  // Place the text onto a random location of the background image
  imagecopyresampled($backgroundResource,$imageResource,$randomBackX,$randomBackY,0,0,$textX,$textY,$textX,$textY);
  // Crop the background image to the original image size
  imagecopyresampled($imageResource,$backgroundResource,0,0,$randomBackX,$randomBackY,$textX,$textY,$textX,$textY);
}

/**
* Creates transparent image resources for images with graphic backgrounds
*/
function _textimage_create_transparent_image($x, $y) {
  $i = imagecreatetruecolor($x, $y);
  $b = imagecreatefromstring(base64_decode(_text_image_blankpng()));
  imagealphablending($i, false);
  imagesavealpha($i, true);
  imagecopyresized($i, $b ,0 ,0 ,0 ,0 ,$x, $y, imagesx($b), imagesy($b));
  return $i;
}
 
function _text_image_blankpng() {
  $c  = "iVBORw0KGgoAAAANSUhEUgAAACgAAAAoCAYAAACM/rhtAAAABGdBTUEAAK/INwWK6QAAABl0RVh0U29m";
  $c .= "dHdhcmUAQWRvYmUgSW1hZ2VSZWFkeXHJZTwAAADqSURBVHjaYvz//z/DYAYAAcTEMMgBQAANegcCBNCg";
  $c .= "dyBAAA16BwIE0KB3IEAADXoHAgTQoHcgQAANegcCBNCgdyBAAA16BwIE0KB3IEAADXoHAgTQoHcgQAAN";
  $c .= "egcCBNCgdyBAAA16BwIE0KB3IEAADXoHAgTQoHcgQAANegcCBNCgdyBAAA16BwIE0KB3IEAADXoHAgTQ";
  $c .= "oHcgQAANegcCBNCgdyBAAA16BwIE0KB3IEAADXoHAgTQoHcgQAANegcCBNCgdyBAAA16BwIE0KB3IEAA";
  $c .= "DXoHAgTQoHcgQAANegcCBNCgdyBAgAEAMpcDTTQWJVEAAAAASUVORK5CYII=";
  return $c;
}
?>
