<?php
/**
 * Script for generation of CAPTCHAs
 *
 * @author  Jose Rodriguez <jose.rodriguez@exec.cl>
 * @license GPLv3
 * @link    http://code.google.com/p/cool-php-captcha
 * @version 0.3
 *
 */

session_start();
putenv('GDFONTPATH=' . realpath(dirname(__FILE__)) . '/fonts/');
$captcha = new SimpleCaptcha();
$captcha->CreateImage();

/**
 * SimpleCaptcha class
 *
 */
class SimpleCaptcha {
	/** Width of the image */
	public $width = 175;

	/** Height of the image */
	public $height = 55;

	/** Dictionary word file (empty for random text) */
	public $wordsFile = '';

	/**
	 * Path for resource files (fonts, words, etc.)
	 *
	 * "resources" by default. For security reasons, is better move this
	 * directory to another location outside the web server
	 *
	 */
	public $resourcesPath = './fonts';

	/** Min word length (for non-dictionary random text generation) */
	public $minWordLength = 4;

	/**
	 * Max word length (for non-dictionary random text generation)
	 *
	 * Used for dictionary words indicating the word-length
	 * for font-size modification purposes
	 */
	public $maxWordLength = 6;

	/** Sessionname to store the original text */
	public $session_var = 'tinyibcaptcha';

	/** Background color in RGB-array */
	public $backgroundColor = array(254, 254, 254);

	/** Foreground colors in RGB-array */
	public $colors = array(
		array(27, 78, 181), // blue
		array(22, 163, 35), // green
		array(214, 36, 7),  // red
	);

	/** Shadow color in RGB-array or null */
	public $shadowColor = array(0, 0, 0);

	/** Horizontal line through the text */
	public $lineWidth = 3;

	/**
	 * Font configuration
	 *
	 * - font: TTF file
	 * - spacing: relative pixel space between character
	 * - minSize: min font size
	 * - maxSize: max font size
	 */
	public $fonts = array(
		'Roboto-Regular' => array('spacing' => 0, 'minSize' => 27, 'maxSize' => 27, 'font' => 'roboto_regular.ttf'),
		'Roboto-Bold' => array('spacing' => 0, 'minSize' => 27, 'maxSize' => 27, 'font' => 'roboto_bold.ttf')
	);

	/** Wave configuration in X and Y axes */
	public $Yperiod = 12;
	public $Yamplitude = 14;
	public $Xperiod = 11;
	public $Xamplitude = 5;

	/** letter rotation clockwise */
	public $maxRotation = 8;

	/**
	 * Internal image size factor (for better image quality)
	 * 1: low, 2: medium, 3: high
	 */
	public $scale = 3;

	/**
	 * Blur effect for better image quality (but slower image processing).
	 * Better image results with scale=3
	 */
	public $blur = true;

	/** Debug? */
	public $debug = false;

	/** Image format: jpeg or png */
	public $imageFormat = 'png';

	/** GD image */
	public $im;

	public function __construct($config = array()) {
	}

	public function CreateImage() {
		$ini = microtime(true);

		/** Initialization */
		$this->ImageAllocate();

		/** Text insertion */
		$text = $this->GetCaptchaText();
		$fontcfg = $this->fonts[array_rand($this->fonts)];
		$this->WriteText($text, $fontcfg);

		$_SESSION[$this->session_var] = $text;

		/** Transformations */
		if (!empty($this->lineWidth)) {
			$this->WriteLine();
		}
		$this->WaveImage();
		if ($this->blur && function_exists('imagefilter')) {
			imagefilter($this->im, IMG_FILTER_GAUSSIAN_BLUR);
		}
		$this->ReduceImage();

		if ($this->debug) {
			imagestring($this->im, 1, 1, $this->height - 8,
				"$text {$fontcfg['font']} " . round((microtime(true) - $ini) * 1000) . "ms",
				$this->GdFgColor
			);
		}

		/** Output */
		$this->WriteImage();
		$this->Cleanup();
	}

	/**
	 * Creates the image resources
	 */
	protected function ImageAllocate() {
		// Cleanup
		if (!empty($this->im)) {
			imagedestroy($this->im);
		}

		$this->im = imagecreatetruecolor($this->width * $this->scale, $this->height * $this->scale);

		// Background color
		$this->GdBgColor = imagecolorallocate($this->im,
			$this->backgroundColor[0],
			$this->backgroundColor[1],
			$this->backgroundColor[2]
		);
		imagefilledrectangle($this->im, 0, 0, $this->width * $this->scale, $this->height * $this->scale, $this->GdBgColor);

		// Foreground color
		$color = $this->colors[mt_rand(0, sizeof($this->colors) - 1)];
		$this->GdFgColor = imagecolorallocate($this->im, $color[0], $color[1], $color[2]);

		// Shadow color
		if (!empty($this->shadowColor) && is_array($this->shadowColor) && sizeof($this->shadowColor) >= 3) {
			$this->GdShadowColor = imagecolorallocate($this->im,
				$this->shadowColor[0],
				$this->shadowColor[1],
				$this->shadowColor[2]
			);
		}
	}

	/**
	 * Text generation
	 *
	 * @return string Text
	 */
	protected function GetCaptchaText() {
		$text = $this->GetDictionaryCaptchaText();
		if (!$text) {
			$text = $this->GetRandomCaptchaText();
		}
		return $text;
	}

	/**
	 * Random text generation
	 *
	 * @return string Text
	 */
	protected function GetRandomCaptchaText($length = null) {
		if (empty($length)) {
			$length = rand($this->minWordLength, $this->maxWordLength);
		}

		$words = "abcdefghijlmnopqrstvwyz";
		$vocals = "aeiou";

		$text = "";
		$vocal = rand(0, 1);
		for ($i = 0; $i < $length; $i++) {
			if ($vocal) {
				$text .= substr($vocals, mt_rand(0, 4), 1);
			} else {
				$text .= substr($words, mt_rand(0, 22), 1);
			}
			$vocal = !$vocal;
		}
		return $text;
	}

	/**
	 * Random dictionary word generation
	 *
	 * @param boolean $extended Add extended "fake" words
	 * @return string Word
	 */
	function GetDictionaryCaptchaText($extended = false) {
		if (empty($this->wordsFile)) {
			return false;
		}

		// Full path of words file
		if (substr($this->wordsFile, 0, 1) == '/') {
			$wordsfile = $this->wordsFile;
		} else {
			$wordsfile = realpath(dirname(__FILE__)) . '/' . $this->resourcesPath . '/' . $this->wordsFile;
		}

		if (!file_exists($wordsfile)) {
			return false;
		}

		$fp = fopen($wordsfile, "r");
		$length = strlen(fgets($fp));
		if (!$length) {
			return false;
		}
		$line = rand(1, (filesize($wordsfile) / $length) - 2);
		if (fseek($fp, $length * $line) == -1) {
			return false;
		}
		$text = trim(fgets($fp));
		fclose($fp);

		/** Change random volcals */
		if ($extended) {
			$text = preg_split('//', $text, -1, PREG_SPLIT_NO_EMPTY);
			$vocals = array('a', 'e', 'i', 'o', 'u');
			foreach ($text as $i => $char) {
				if (mt_rand(0, 1) && in_array($char, $vocals)) {
					$text[$i] = $vocals[mt_rand(0, 4)];
				}
			}
			$text = implode('', $text);
		}

		return $text;
	}

	/**
	 * Horizontal line insertion
	 */
	protected function WriteLine() {
		$x1 = $this->width * $this->scale * .15;
		$x2 = $this->textFinalX;
		$y1 = rand($this->height * $this->scale * .40, $this->height * $this->scale * .65);
		$y2 = rand($this->height * $this->scale * .40, $this->height * $this->scale * .65);
		$width = $this->lineWidth / 2 * $this->scale;

		for ($i = $width * -1; $i <= $width; $i++) {
			imageline($this->im, $x1, $y1 + $i, $x2, $y2 + $i, $this->GdFgColor);
		}
	}

	/**
	 * Text insertion
	 */
	protected function WriteText($text, $fontcfg = array()) {
		if (empty($fontcfg)) {
			// Select the font configuration
			$fontcfg = $this->fonts[array_rand($this->fonts)];
		}

		$fontfile = realpath(dirname(__FILE__)) . '/' . $this->resourcesPath . '/' . $fontcfg['font'];

		/** Increase font-size for shortest words: 9% for each glyph missing */
		$lettersMissing = $this->maxWordLength - strlen($text);
		$fontSizefactor = 1 + ($lettersMissing * 0.09);

		// Text generation (char by char)
		$x = 20 * $this->scale;
		$y = round(($this->height * 27 / 40) * $this->scale);
		$length = strlen($text);
		for ($i = 0; $i < $length; $i++) {
			$degree = rand($this->maxRotation * -1, $this->maxRotation);
			$fontsize = rand($fontcfg['minSize'], $fontcfg['maxSize']) * $this->scale * $fontSizefactor;
			$letter = substr($text, $i, 1);

			if ($this->shadowColor) {
				$coords = imagettftext($this->im, $fontsize, $degree,
					$x + $this->scale, $y + $this->scale,
					$this->GdShadowColor, $fontfile, $letter);
			}
			$coords = imagettftext($this->im, $fontsize, $degree,
				$x, $y,
				$this->GdFgColor, $fontfile, $letter);
			$x += ($coords[2] - $x) + ($fontcfg['spacing'] * $this->scale);
		}

		$this->textFinalX = $x;
	}

	/**
	 * Wave filter
	 */
	protected function WaveImage() {
		// X-axis wave generation
		$xp = $this->scale * $this->Xperiod * rand(1, 3);
		$k = rand(0, 100);
		for ($i = 0; $i < ($this->width * $this->scale); $i++) {
			imagecopy($this->im, $this->im,
				$i - 1, sin($k + $i / $xp) * ($this->scale * $this->Xamplitude),
				$i, 0, 1, $this->height * $this->scale);
		}

		// Y-axis wave generation
		$k = rand(0, 100);
		$yp = $this->scale * $this->Yperiod * rand(1, 2);
		for ($i = 0; $i < ($this->height * $this->scale); $i++) {
			imagecopy($this->im, $this->im,
				sin($k + $i / $yp) * ($this->scale * $this->Yamplitude), $i - 1,
				0, $i, $this->width * $this->scale, 1);
		}
	}

	/**
	 * Reduce the image to the final size
	 */
	protected function ReduceImage() {
		// Reduzco el tama�o de la imagen
		$imResampled = imagecreatetruecolor($this->width, $this->height);
		imagecopyresampled($imResampled, $this->im,
			0, 0, 0, 0,
			$this->width, $this->height,
			$this->width * $this->scale, $this->height * $this->scale
		);
		imagedestroy($this->im);
		$this->im = $imResampled;
	}

	/**
	 * File generation
	 */
	protected function WriteImage() {
		if ($this->imageFormat == 'png' && function_exists('imagepng')) {
			imagealphablending($this->im, true);
			imagesavealpha($this->im, false);
			imagecolortransparent($this->im, $this->GdBgColor);

			header("Content-type: image/png");
			imagepng($this->im);
		} else {
			header("Content-type: image/jpeg");
			imagejpeg($this->im, null, 80);
		}
	}

	/**
	 * Cleanup
	 */
	protected function Cleanup() {
		imagedestroy($this->im);
	}
}