<?php
/**
 * Captchar - a simple captcha in PHP
 * By Richard Ye
 * 
 * http://www.yerich.net/projects/captchar/
 *
 * @copyright This file is in the public domain.
 */

//Remove the following line if already done.
session_start();

class Captchar {
	function error($errorText) {
		$image = imagecreate(300, 30);
		$fontSize = 15;
		$code = $this->generateCode();
		$background_color = imagecolorallocate($image, 0, 0, 0);
		$foreground_color = imagecolorallocate($image, 255, 255, 255);
		header('Content-Type: image/jpeg, Expires: Thu, 1 Jan 1990 00:00:00 GMT');
		imagettftext($image, $fontSize, 0, 2, 25, $foreground_color, "font1.ttf", $code);
		imagettftext($image, 6, 0, 2, 8, $foreground_color, "font.ttf", 'Error: '.$errorText);
		imagejpeg($image, null, 75);
		imagedestroy($image);
		die();
	}
	
	function oldGenerateCode($characters) {
		/* list all possible characters, similar looking characters and vowels have been removed */
		$possible = '2345678bcdfghjkmnprsvwyz';
		$code = '';
		$i = 0;
		while ($i < $characters) { 
			$code .= substr($possible, mt_rand(0, strlen($possible)-1), 1);
			$i++;
		}
		return $code;
	}
	
	function generateCode($characters = 10) {
		//Open up the wordlist file
		if (!$wordlist = @file_get_contents("wordlist.txt")) {
			//No wordlist file present
			return $this->oldGenerateCode($characters);
		}
		$wordlist = explode("\n", $wordlist);
		$validWord = false;
		$i = 0;
		while($validWord == false) {
			$word = $wordlist[array_rand($wordlist)];
			$word = trim($word);
			$i++;
			if(substr($word, 0, 1) == "#")
				$validWord = false;
			if((strlen($word) != $characters) && $characters != 0)
				$validWord = false;
			if($i > 200)
				$validWord = true;
		}
		$possible = 'bcdfhkmnprsvwyz';
		//$word .= substr($possible, mt_rand(0, strlen($possible)-1), 1);
		return strtoupper($word);
	}
	
	function generateImage($width='320',$height='75',$characters='10') {
		$code = $this->generateCode($characters);
		/* font size will be 60% of the image height */
		$font_size = $height * 0.60;
		$image = imagecreatetruecolor($width, $height) or $this->error('Cannot initialize new GD image stream');
		imageantialias ($image, true) or $this->error('Cannot turn on anti-ailasing');
		//Generate some random colors!
		$c1 = mt_rand(60, 90);
		$c2 = mt_rand(60, 90);
		$c3 = mt_rand(60, 90);
		
		/* set the colours */
		$background_1_color = array($c1+60, $c2+60, $c3+60);
		$background_2_color = array($c1+160, $c2+160, $c3+160);
		$background_color = imagecolorallocate($image, $c1+150, $c2+150, $c3+150);
		$text_color = imagecolorallocate($image, $c1+40, $c2+40, $c3+40);
		$noise_color = imagecolorallocate($image, $c1+40, $c2+40, $c3+40);
		$highlight_color = imagecolorallocate($image, 255, 0, 0);
		
		//Draw a gradient background fill
		imagefilledrectangle($image, 0, 0, $width, $height, $background_color);
		for($i=1; $i<=$width; $i++) {
			$linecolors[0] = ($background_1_color[0]+(($background_2_color[0] - $background_1_color[0]) / $width * $i));
			$linecolors[1] = ($background_1_color[1]+(($background_2_color[1] - $background_1_color[1]) / $width * $i));
			$linecolors[2] = ($background_1_color[2]+(($background_2_color[2] - $background_1_color[2]) / $width * $i));
			$linecolor = imagecolorallocate($image, $linecolors[0], $linecolors[1], $linecolors[2]);
			imageline($image, $i, 0, $i, $height, $linecolor);
			imagecolordeallocate($image, $linecolor);
		}
		
		//Long thick lines
		for($w=0; $w<2; $w++) {
			$w1 = mt_rand(10,20) + ($w - 1)*50;
			$w2 = mt_rand($width/1.3,$width)+20;
			$h1 = mt_rand(10, $height/2-10) + $w*$height/2;
			$h2 = mt_rand(0, $height) + (1-$w)*$height/2;
			for( $i=0; $i<30; $i++) {
				$j = $i/2;
				imageline($image, $w1+$j, $h1, $w2+$j, $h2, $text_color)
					or $this->error("Error creating think line.");
			}
		}
		//Small thick lines
		for($w=0; $w<3; $w++) {
			$w1 = mt_rand(0, $width);
			$w2 = $w1 + rand(-30, 30);
			$h1 = mt_rand(0, $height);
			$h2 = $h1 + rand(-30, 30);
			for( $i=0; $i<10; $i++) {
				$j = $i/2;
				imageline($image, $w1+$j, $h1, $w2+$j, $h2, $text_color)
					or $this->error("Error creating think line.");
			}
		}
		
		
		/* create textbox and add text */
		$textbox = @imagettfbbox($font_size, 0, "fonta.ttf", $code) 
			or $this->error('Error in imagettfbbox function');
		$y = ($height - $textbox[5])/2.3;
		$x = -10;
		$i = 0;
		
		$xoffset = 0;
		foreach (str_split($code) as $key => $value) {
			//This bit of code draws the letters onto the image at random angles and at distances
			//so that the letters are smothered together (harder for computers to read)
			$letterfont = "font.ttf";
			$prevangle = $angle;
			$angle = $angle + rand(-30, 30);
			if($angle < -30)
				$angle = -20 - rand(-5, 5);
			if($angle > 30)
				$angle = 20 - rand(-5, 5);
			$xoffset += 18*($font_size/35) - ($prevangle - $angle) / 3 + 2;
			for($j = 0; $j<4; $j++) {
				@imagettftext($image, $font_size, $angle, $x + $xoffset + $j, $y, $text_color, 
					$letterfont, $value) or $this->error('Error in imagettftext function');
			}
			$i++;
		}
		//die();
		//Make sure to have the browser not cache the image
		header('Content-Type: image/jpeg, Expires: Thu, 1 Jan 1990 00:00:00 GMT');
		imagejpeg($image, null, 75);
		imagedestroy($image);
		$_SESSION['captcha'] = $code;
	}

}