<?php

// ---------- ---------- ---------- ---------- ----------
// Automatic test to tell computers and humans apart
// Copyright by Kruglov Sergei, 2006
// www.captcha.ru, www.kruglov.ru
// ---------- ---------- ---------- ---------- ----------

function clean_url ($url) {

  if ($url == '') return;

  $url = str_replace("http://", "", $url);
  if (strtolower(substr($url, 0, 4)) == 'www.')  $url = substr($url, 4);
  $url = explode('/', $url);
  $url = reset($url);
  $url = explode(':', $url);
  $url = reset($url);

  return $url;
}

if (clean_url($_SERVER['HTTP_REFERER']) != clean_url($_SERVER['HTTP_HOST'])) die("Hacking attempt!");

class genrandomimage {
	
	var $alphabet = "0123456789abcdefghijklmnopqrstuvwxyz"; // ÍÅ ÈÇÌÅÍßÉÒÅ, åñëè âû íå èçìåíÿëè ôàéë øðèôòîâ!
	// ïîñëåäîâàòåëüíîñòü áóêâ äîëæíà ÑÎÂÏÀÄÀÒÜ!
	
	// ïàïêà ñ øðèôòàìè
	var $fontsdir = 'fonts';	
	
	// ðàçìåð èçîáðàæåíèÿ CAPTCHA (îïòèìàëüíûå ïàðàìåòðû)
	var $width = 120;
	var $height = 50;
	
	// àìïëèòóäà âåðòèêàëüíîé ôëóêòóàöèè ñèìâîëîâ, äåëåííàÿ íà 2
	var $fluctuation_amplitude = 2;
	
	// äëÿ óâåëè÷åíèÿ áåçîïàñíîñòè ìîæíî óáðàòü ïðîáåëû ìåæäó ñèìâîëàìè
	var $no_spaces = true;
	
	// êà÷åñòâî JPEG-èçîáðàæåíèÿ CAPTCHA (÷åì áîëüøå, òåì âûøå êà÷åñòâî)
	var $jpeg_quality = 90;
	
	var $keystring = ''; // êëþ÷åâàÿ ãåíåðèðóåìàÿ ñòðîêà

	// ñèìâîëû, èñïîëüçóåìûå äëÿ ðèñîâàíèÿ ñãåíåðèðîâàííîãî èçîáðàæåíèÿ CAPTCHA	
	var $allowed_symbols = "023456789"; // àëôàâèò ÁÅÇ ïîõîæèõ ñèìâîëîâ (o=0, 1=l, i=j, t=f)
	
	// êîëè÷åñòâî ñèìâîëîâ â ñòðîêå
	var $length_min = 4; // ìèíèìàëüíîå
	var $length_max = 5; // ìàêñèìàëüíîå
	var $length = 0; // äëèíà áóäåò ñãåíåðèðîâàíà
	
	// ---------- ---------- ---------- ---------- ----------
	
	// Ãåíåðàöèÿ ñòðîêè ---------- ---------- -------
	function genstring() {
		// äëèíà ñòðîêè (êîëè÷åñòâî ñèìâîëîâ) CAPTCHA
		// ñëó÷àéíîå ÷èñëî â ïðåäåëàõ îò $length_min äî $length_max âêëþ÷èòåëüíî
		$length = mt_rand( $this->length_min, $this->length_max );
		$this->length = $length;
		
		while (true) { // áåñêîíå÷íûé öèêë, ïîêà íå ñãåíåðèóåì õîðîøóþ ñòðîêó =)
			$this->keystring = '';
			for ($i = 0; $i < $length ; $i++) {
				// â öèêëå äîáàâëÿåì ê ñòðîêå ïî 1 ñëó÷àéíîìó ñèìâîëó
				$this->keystring .= $this->allowed_symbols{ mt_rand( 0, strlen( $this->allowed_symbols ) -1 ) };
			}
			if (!preg_match( '/cp|cb|ck|c6|c9|rn|rm|co|do/', $this->keystring )) break;
		}
	}
	// ---------- ---------- ---------- ---------- ----------

	// Ãåíåðàöèÿ èçîáðàæåíèÿ
	function genimage() {

		// öâåòà èçîáðàæåíèÿ CAPTCHA (RGB, 0-255)
		$foreground_color = array( mt_rand( 0, 100 ), mt_rand( 0, 100 ), mt_rand( 0, 100 ) );
		$background_color = array( mt_rand( 200, 255 ), mt_rand( 200, 255 ), mt_rand( 200, 255 ) ); // ôîí âñåãäà ñâåòëåå

		$fonts = array();
		$fontsdir_absolute = dirname( __FILE__ ).'/'.$this->fontsdir; // ïóòü ê ïàïêå ñ øðèôòàìè

		if ($handle = opendir( $fontsdir_absolute )) { // ñîçäàåì ìàññèâ ñ ïîëíûìè ïóòÿìè ê èçîáðàæåíèÿì ñ øðèôòàìè
			while (false !== ($file = readdir( $handle ))) {
				if (preg_match( '/\.png$/i', $file )) {
					$fonts[] = $fontsdir_absolute.'/'.$file;
				}
			}
		    closedir( $handle );
		}

		$alphabet_length = strlen( $this->alphabet );
		
		while (true) {
			$font_file = $fonts[mt_rand( 0, count( $fonts ) - 1 )]; // âûáèðàåì ñëó÷àéíûé ôàéë øðèôòà
			$font = imagecreatefrompng( $font_file );
			$black = imagecolorallocate( $font, 0, 0, 0 );
			$fontfile_width = imagesx( $font );
			$fontfile_height = imagesy( $font ) - 1;
			$font_metrics = array();
			$symbol = 0;
			$reading_symbol = false;

			// loading font
			for ($i = 0; $i < $fontfile_width && $symbol < $alphabet_length; $i++) {
				$transparent = (imagecolorat( $font, $i, 0 ) >> 24) == 127;

				if (!$reading_symbol && !$transparent) {
					$font_metrics[$this->alphabet{$symbol}] = array( 'start' => $i );
					$reading_symbol = true;
					continue;
				}

				if ($reading_symbol && $transparent) {
					$font_metrics[$this->alphabet{$symbol}]['end'] = $i;
					$reading_symbol = false;
					$symbol++;
					continue;
				}
			}

			$img = imagecreatetruecolor( $this->width, $this->height );

			$white = imagecolorallocate( $img, 255, 255, 255 );
			$black = imagecolorallocate( $img, 0, 0, 0 );

			imagefilledrectangle( $img, 0, 0, $this->width - 1, $this->height - 1, $white );

			// draw text
			$x = 1;
			$shift = 0;
			
			for ($i = 0; $i < $this->length; $i++) {
				$m = $font_metrics[$this->keystring{$i}];

				$y = mt_rand( -$this->fluctuation_amplitude, $this->fluctuation_amplitude ) + ($this->height - $fontfile_height) / 2 + 2;
				

				if ($this->no_spaces) {
					$shift = 0;
					if ($i > 0) {
						$shift = 1000;
						for ($sy = 1; $sy < $fontfile_height - 15; $sy += 2) {
							for ($sx = $m['start'] - 1; $sx < $m['end']; $sx++) {
								$rgb = imagecolorat( $font, $sx, $sy );
								$opacity = $rgb >> 24;
								if ($opacity < 127) {
									$left = $sx - $m['start'] + $x;
									$py = $sy + $y;
									for ($px = min( $left, $this->width - 1 ); $px > $left - 15 && $px >= 0; $px--) {
										$color = imagecolorat( $img, $px, $py ) & 0xff;
										if ($color + $opacity < 190) {
											if ($shift > $left-$px) {
												$shift = $left - $px;
											}
											break;
										}
									}
									break;
								}
							}
						}
					}
				} else {
					$shift = 1;
				}
				
				imagecopy( $img, $font, $x - $shift, $y, $m['start'], 1, $m['end'] - $m['start'], $fontfile_height );
				
				$x += $m['end'] - $m['start'] - $shift;
			}
			if ($x < $this->width - 10) break; // fit in canvas
		}
		$center = $x/2;
		
		$img2=imagecreatetruecolor($this->width, $this->height);
		$foreground=imagecolorallocate($img2, $foreground_color[0], $foreground_color[1], $foreground_color[2]);
		$background=imagecolorallocate($img2, $background_color[0], $background_color[1], $background_color[2]);
		imagefilledrectangle($img2, 0, $this->height, $this->width, $this->height+12, $foreground);


		// periods
		$rand1 = mt_rand( 750000, 1200000 ) / 10000000;
		$rand2 = mt_rand( 750000, 1200000 ) / 10000000;
		$rand3 = mt_rand( 750000, 1200000 ) / 10000000;
		$rand4 = mt_rand( 750000, 1200000 ) / 10000000;
		// phases
		$rand5 = mt_rand( 0, 3141592 ) / 500000;
		$rand6 = mt_rand( 0, 3141592 ) / 500000;
		$rand7 = mt_rand( 0, 3141592 ) / 500000;
		$rand8 = mt_rand( 0, 3141592 ) / 500000;
		// amplitudes
		$rand9 = mt_rand( 330, 420 ) / 110;
		$rand10 = mt_rand(330, 450 ) / 110;

		//wave distortion
		for ($x = 0; $x < $this->width; $x++) {
			for ($y = 0; $y < $this->height; $y++) {
				$sx = $x + (sin( $x * $rand1 + $rand5 ) + sin( $y * $rand3 + $rand6 )) * $rand9 - $this->width / 2 + $center + 1;
				$sy = $y + (sin( $x * $rand2 + $rand7 ) + sin( $y * $rand4 + $rand8 )) * $rand10;

				if ($sx < 0 || $sy < 0 || $sx >= $this->width - 1 || $sy >= $this->height - 1) {
					$color = 255;
					$color_x = 255;
					$color_y = 255;
					$color_xy = 255;
				} else {
					$color = imagecolorat( $img, $sx, $sy ) & 0xFF;
					$color_x = imagecolorat( $img, $sx + 1, $sy ) & 0xFF;
					$color_y = imagecolorat( $img, $sx, $sy + 1 ) & 0xFF;
					$color_xy = imagecolorat( $img, $sx + 1, $sy + 1 ) & 0xFF;
				}

				if ($color == 0 && $color_x == 0 && $color_y == 0 && $color_xy == 0) {
					$newred = $foreground_color[0];
					$newgreen = $foreground_color[1];
					$newblue = $foreground_color[2];
				} else if ($color == 255 && $color_x == 255 && $color_y == 255 && $color_xy == 255) {
					$newred = $background_color[0];
					$newgreen = $background_color[1];
					$newblue = $background_color[2];	
				} else {
					$frsx = $sx - floor( $sx );
					$frsy = $sy - floor( $sy );
					$frsx1 = 1 - $frsx;
					$frsy1 = 1 - $frsy;
					$newcolor = (
						$color    * $frsx1 * $frsy1 +
						$color_x  * $frsx  * $frsy1 +
						$color_y  * $frsx1 * $frsy  +
						$color_xy * $frsx  * $frsy);

					if ($newcolor > 255) $newcolor = 255;
					$newcolor = $newcolor / 255;
					$newcolor0 = 1 - $newcolor;

					$newred	  = $newcolor0 * $foreground_color[0] + $newcolor * $background_color[0];
					$newgreen = $newcolor0 * $foreground_color[1] + $newcolor * $background_color[1];
					$newblue  = $newcolor0 * $foreground_color[2] + $newcolor * $background_color[2];
				}

				imagesetpixel( $img2, $x, $y, imagecolorallocate( $img2, $newred, $newgreen, $newblue ) );
			}
		}

      # Ðàìêà
      imageline( $img2, 0, 0,  $this->width, 0, $foreground );
      imageline( $img2, 0, 0,  0, $this->height, $foreground );

      imageline( $img2, 0, $this->height-1,  $this->width, $this->height-1, $foreground );
      imageline( $img2, $this->width-1, 0,  $this->width-1, $this->height, $foreground);

		header( "Expires: Tue, 11 Jun 1985 05:00:00 GMT" );
		header( "Last-Modified: " . gmdate( "D, d M Y H:i:s" ) . " 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/jpeg" );
		//imagejpeg($img2, null, $this->jpeg_quality);
    header( "Content-Type: image/png" );
    imagePNG($img2);
	}
}