<?php
/**
 * Lotus Captcha component is inspired by "cool-php-captcha" project
 * http://code.google.com/p/cool-php-captcha
 */
class LtCaptchaImageEngine
{
	public $conf;

    protected $maxWordLength = 9;

    /**
     * * Background color in RGB-array
     */
    protected $backgroundColor = array(255, 255, 255);

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

    /**
     * * Shadow color in RGB-array or null
     */
    protected $shadowColor = null; //array(0, 0, 0);
    
    /**
     * Font configuration
     * 
     * - font: TTF file
     * - spacing: relative pixel space between character
     * - minSize: min font size
     * - maxSize: max font size
     */
    protected $fonts = array('Antykwa' => array('spacing' => -3, 'minSize' => 27, 'maxSize' => 30, 'font' => 'AntykwaBold.ttf'),
        'Candice' => array('spacing' => -1.5, 'minSize' => 28, 'maxSize' => 31, 'font' => 'Candice.ttf'),
        'DingDong' => array('spacing' => -2, 'minSize' => 24, 'maxSize' => 30, 'font' => 'Ding-DongDaddyO.ttf'),
        'Duality' => array('spacing' => -2, 'minSize' => 30, 'maxSize' => 38, 'font' => 'Duality.ttf'),
        'Jura' => array('spacing' => -2, 'minSize' => 28, 'maxSize' => 32, 'font' => 'Jura.ttf'),
        'StayPuft' => array('spacing' => -1.5, 'minSize' => 28, 'maxSize' => 32, 'font' => 'StayPuft.ttf'),
        'Times' => array('spacing' => -2, 'minSize' => 28, 'maxSize' => 34, 'font' => 'TimesNewRomanBold.ttf'),
        'VeraSans' => array('spacing' => -1, 'minSize' => 20, 'maxSize' => 28, 'font' => 'VeraSansBold.ttf'),
        );

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

    /**
     * * GD image
     */
    protected $im;

    public function drawImage($text)
    {
        /**
         * * Initialization
         */
        $this->ImageAllocate();

        $fontcfg = $this->fonts[array_rand($this->fonts)];
        $this->WriteText($text, $fontcfg);

        /**
         * * Transformations
         */
        $this->WaveImage();
        if ($this->conf['blur'] && function_exists('imagefilter'))
        {
            imagefilter($this->im, IMG_FILTER_GAUSSIAN_BLUR);
        }
        $this->ReduceImage();
        return $this->im;
    }

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

        $this->im = imagecreatetruecolor($this->conf['width'] * $this->conf['scale'], $this->conf['height'] * $this->conf['scale']); 
        // Background color
        $this->GdBgColor = imagecolorallocate($this->im,
            $this->backgroundColor[0],
            $this->backgroundColor[1],
            $this->backgroundColor[2]
            );
        imagefilledrectangle($this->im, 0, 0, $this->conf['width'] * $this->conf['scale'], $this->conf['height'] * $this->conf['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 insertion
     */
    protected function WriteText($text, $fontcfg = array())
    {
        if (empty($fontcfg))
        { 
            // Select the font configuration
            $fontcfg = $this->fonts[array_rand($this->fonts)];
        } 
        // Full path of font file
        $fontfile = dirname(__FILE__) . '/fonts/' . $fontcfg['font'];

        /**
         * * Increase font-size for shortest words: 9% for each glyp missing
         */
        $lettersMissing = $this->maxWordLength - strlen($text);
        $fontSizefactor = 1 + ($lettersMissing * 0.09); 
        // Text generation (char by char)
        $x = 20 * $this->conf['scale'];
        $y = round(($this->conf['height'] * 27 / 40) * $this->conf['scale']);
        $length = strlen($text);
        for ($i = 0; $i < $length; $i++)
        {
            $degree = rand($this->conf['max_rotation'] * -1, $this->conf['max_rotation']);
            $fontsize = rand($fontcfg['minSize'], $fontcfg['maxSize']) * $this->conf['scale'] * $fontSizefactor;
            $letter = substr($text, $i, 1);

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

    /**
     * Wave filter
     */
    protected function WaveImage()
    { 
        // X-axis wave generation
        $xp = $this->conf['scale'] * $this->Xperiod * rand(1, 3);
        $k = rand(0, 100);
        for ($i = 0; $i < ($this->conf['width'] * $this->conf['scale']); $i++)
        {
            imagecopy($this->im, $this->im,
                $i-1, sin($k + $i / $xp) * ($this->conf['scale'] * $this->Xamplitude),
                $i, 0, 1, $this->conf['height'] * $this->conf['scale']);
        } 
        // Y-axis wave generation
        $k = rand(0, 100);
        $yp = $this->conf['scale'] * $this->Yperiod * rand(1, 2);
        for ($i = 0; $i < ($this->conf['height'] * $this->conf['scale']); $i++)
        {
            imagecopy($this->im, $this->im,
                sin($k + $i / $yp) * ($this->conf['scale'] * $this->Yamplitude), $i-1,
                0, $i, $this->conf['width'] * $this->conf['scale'], 1);
        }
    }

    /**
     * Reduce the image to the final size
     */
    protected function ReduceImage()
    {
        $imResampled = imagecreatetruecolor($this->conf['width'], $this->conf['height']);
        imagecopyresampled($imResampled, $this->im,
            0, 0, 0, 0,
            $this->conf['width'], $this->conf['height'],
            $this->conf['width'] * $this->conf['scale'], $this->conf['height'] * $this->conf['scale']
            );
        imagedestroy($this->im);
        $this->im = $imResampled;
    }
}