<?php
/**
 * Captcha
 *
 * $Id$
 *
 * @author gERD Schaufelberger <gerd@php-tools.net>
 * @license PHP License
 * @package WB
 * @subpackage base
 */

WBClass::load('WBService');

/**
 * Captcha
 *
 * Display captcha challenge and keep answer in session
 *
 * @version 0.3.2
 * @package WB
 * @subpackage base
 */
class WBService_Captcha extends WBService
{
    /**
     * decide whether to start locale tools
     * @var bool
     */
    protected $useI18n = false;

    /**
     * decide whether to start WBConfig
     * @var bool
     */
    protected $useConfig = false;

    /**
     * amount of random chars
     * @var int
     */
    protected $length = 5;

    /**
     * font dir folder
     * @var unknown_type
     */
    protected $fontDir = 'resource/font';

    /**
     * current font to use
     * @var string
     */
    protected $font = 'dustismo.ttf';

    /**
     * font size
     * @var int
     */
    protected $fontSize =   25;

    /**
     * text spacing factor realitve to font-size
     * @var float
     */
    protected $fontSpace  =   0.8;

    /**
     * maximum rotation angle of chars
     * @var int
     */
    protected $fontAngle  =   30;

    /**
     * amount of disturbing lines
     * @var int
     */
    protected $lines = 0;

    /**
     * amount of disturbing ghost strings
     * @var int
     */
    protected $ghosts = 5;

    /**
     * Use Alpha Channel
     * @var int 0 or 1
     */
    protected $bgAlpha = 0;

    /**
     * current image
     * @var resource
     */
    protected $img        =   null;

    /**
     * list of RGB color codes
     *
     * RGB colors for foreground, background, lines and ghosts
     *
     * @var array
     */
    protected $colorCodes   =   array(
                                        'fg'    =>  array(0, 0, 0),
                                        'bg'    =>  array(0xFF, 0xFF, 0xFF),
                                        'line'  =>  array(0x99, 0x99, 0x99),
                                        'ghost' =>  array(0x77, 0x77, 0x77)
                                    );

    /**
     * color: foreground
     * @var resource
     */
    protected $colorFg;

    /**
     * color: bacground
     * @var resource
     */
    protected $colorBg;

    /**
     * color: lines
     * @var resource
     */
    protected $colorLine;

    /**
     * color: ghosts
     * @var resource
     */
    protected $colorGhost;

   /**
    * Constructor
    *
    * Call parent constructor and load config
    */
    public function __construct($params)
    {
        parent::__construct($params);

        $config =   WBClass::create('WBConfig');
        if (!$config->load('captcha', true)) {
            return;
        }

        $length =   intval($config->get('image/length', $this->length));
        if ($length > 2) {
            $this->length   =   $length;
        }

        // use alpha channel
        $this->bgAlpha  =   intval($config->get('image/color/alpha', 0));

        // set color
        $fg =   $config->get('image/color/foreground');
        if (!empty($fg)) {
            $this->saveColorCode('fg', $fg);
        }
        $bg =   $config->get('image/color/background');
        if (!empty($bg)) {
            $this->saveColorCode('bg', $bg);
        }

        // set font
        $f  =   $config->get('image/font');
        if (isset($f['name']) && !empty($f['name'])) {
            $this->setFont($f['name']);
        }
        if (isset($f['size']) && 0 < $f['size']) {
            $this->fontSize =   max(14, intval($f['size']));
        }
        if (isset($f['spacing']) && 0 < $f['spacing']) {
            $this->fontSpace =   max(0.5, floatval($f['spacing']));
        }
        if (isset($f['angle']) && -1 < $f['angle']) {
            $this->fontAngle =   $f['angle'];
        }

        // obstacles

        // lines
        $o  =   $config->get('image/obstacles/lines');
        if (isset($o['number'])) {
            $this->lines    =   intval($o['number']);
        }
        if (isset($o['color']) && !empty($o['color'])) {
            $this->saveColorCode('line', $o['color']);
        }

        // ghosts
        $o  =   $config->get('image/obstacles/ghosts');
        if (isset($o['number'])) {
            $this->ghosts   =   intval($o['number']);
        }
        if (isset($o['color']) && !empty($o['color'])) {
            $this->saveColorCode('ghost', $o['color']);
        }
    }

   /**
    * Display/Play Captcha
    *
    * @param int $status
    * @param mixed $data to be send
    * @param string $checksum string, if any
    * @return bool true on success
    */
    public function run(&$status, &$data, &$checksum = null)
    {
        // make sure session is active
        if (patSession::STATE_ACTIVE != $this->sess->state) {
            $this->sess->restart();
        }

        $chars  =   $this->getRandChars($this->length);
        $this->sess->set('wb.service.captcha.txt', implode('', $chars));

        $this->paintCaptchaImage($chars);

        $this->res->addHeader('Content-type', 'image/png');
        ob_start();
        imagepng($this->img);
        $data       =   ob_get_contents();
        $checksum   =   md5($data);
        ob_end_clean();
        imagedestroy($this->img);

        // avoid browser caches
        WBParam::set('wb/cache/use', 0);
        return true;
    }

    /**
     * set main colors
     *
     * Set foreground and background color
     *
     * @param string $fg
     * @param string $bg
     */
    public function setColor($fg = '#000000', $bg = '#ffffff')
    {
        $this->saveColorCode('fg', $fg);
        $this->saveColorCode('bg', $bg);
    }

    /**
     * Configure font
     *
     * Set one, more or all of font name, font size, font spacing and maximum letter angle
     *
     * @param string $name
     * @param int $size
     * @param int $spacing
     * @param int $angle
     */
    public function setFont($name = null, $size = null, $spacing = null, $angle = null)
    {
        if (!is_null($size)) {
            $this->fontSize =   $size;
        }
        if (!is_null($spacing)) {
            $this->fontSpace =   $spacing;
        }
        if (!is_null($angle)) {
            $this->fontAngle =   $angle;
        }

        if (is_null($name)) {
            return;
        }
        if ($name != '__random') {
            $this->font =   $name;
            return;
        }

        $fonts  =   array();
        foreach (new DirectoryIterator(WBParam::get('wb/dir/system') . '/' . $this->fontDir) as $file) {
            if ($file->isDot()) {
                continue;
            }
            $ext    =   array_pop( explode('.', $file->getFilename()));
            if (strtolower($ext) != 'ttf') {
                continue;
            }
            array_push($fonts, $file->getFilename());
        }
        $this->font    =   $fonts[rand(0, count($fonts) - 1)];
    }

    /**
     * set number of disturbing lines
     *
     * @param int $lines
     * @param string $color code
     */
    public function setLines($lines = 15, $color = '#999999')
    {
        $this->lines    =   $lines;
        $this->saveColorCode('line', $color);
    }

    /**
     * set number of disturbing ghost images
     * @param int $ghosts
     * @param string $color
     */
    public function setGhosts($ghosts = 5, $color = '#999999')
    {
        $this->ghosts   =   $ghosts;
        $this->saveColorCode('ghost', $color);
    }

    /**
     * Create list of random characters
     *
     * Use alphabet 2-9 and a-z and select some letters
     *
     * @param int $count
     * @return array
     */
    public function getRandChars($count = 5)
    {
        $chars      =   array_merge(range(2, 9), range('a', 'z'));
        $charMax    =   count($chars) - 1;

        $word       =   array();
        for ($i = 0; $i < $count; ++$i) {
            $word[] =   $chars[ rand(0, $charMax) ];
        }
        return $word;
    }


    /**
     * Paint a picture with random text
     *
     * @param int $length how many letters should be painted
     * @param int $lines number of distrubing lines to draw
     * @return bool true on success
     */
    public function paintCaptchaImage($chars, $lines = 15)
    {
        $width      =   ((count($chars) + 1) * $this->fontSize * $this->fontSpace);
        $height     =   $this->fontSize * 1.8;

        $this->drawImage($width, $height);
        $this->drawLines($width, $height);
        $this->drawGhosts($chars, $width, $height);
        $this->drawLetters($chars, $width, $height);
        return true;
    }

    /**
     * store color values
     *
     * Store color settings internally. Accept RGB color codes in
     * hex with prefixed '#' symbol
     *
     * @param string $name
     * @param string $code
     */
    protected function saveColorCode($name, $code)
    {
        if (strlen($code) != 7) {
            WBClass::load('WBException_Argument');
            throw new WBException_Argument('Color code must start with # followed by 6 hex digits.', 1, __CLASS__);
            return;
        }
        if ($code[0] != '#') {
            WBClass::load('WBException_Argument');
            throw new WBException_Argument('Color code must start with #', 2, __CLASS__);
            return;
        }

        $code   =   substr($code, 1);
        $code   =   str_split($code, 2);
        foreach ($code as $i => $c) {
            $code[$i]   =   hexdec($c);
        }
        $this->colorCodes[$name]    =   $code;
    }

    /**
     * create basic canvas
     *
     * init true color image and init colors
     *
     * @param int $width
     * @param int $height
     */
    protected function drawImage($width, $height)
    {
        $this->img          =   imagecreatetruecolor($width, $height);

        $this->colorFg      =   imagecolorallocate($this->img, $this->colorCodes['fg'][0], $this->colorCodes['fg'][1], $this->colorCodes['fg'][2]);
        $this->colorBg      =   imagecolorallocate($this->img, $this->colorCodes['bg'][0], $this->colorCodes['bg'][1], $this->colorCodes['bg'][2]);
        $this->colorLine    =   imagecolorallocate($this->img, $this->colorCodes['line'][0], $this->colorCodes['line'][1], $this->colorCodes['line'][2]);
        $this->colorGhost   =   imagecolorallocate($this->img, $this->colorCodes['ghost'][0], $this->colorCodes['ghost'][1], $this->colorCodes['ghost'][2]);

        if ($this->bgAlpha) {
            $bg =   imagecolorallocatealpha($this->img, $this->colorCodes['bg'][0], $this->colorCodes['bg'][1], $this->colorCodes['bg'][2], 127);
            imagesavealpha($this->img, true);
            imagealphablending($this->img, false);
            imagefill($this->img, 0, 0, $bg);
        }
        else {
            imagefill($this->img, 0, 0, $this->colorBg);
        }
    }

    /**
     * Draw disturbing lines
     *
     * Use line color and draw number of lines on canvas
     *
     * @param int $width
     * @param int $height
     */
    protected function drawLines($width, $height)
    {
        if (!$this->lines) {
            return;
        }

        for ($i = 0; $i < $this->lines; ++$i) {
            $x1 =   rand(0, $width * 0.75);
            $y1 =   rand(0, $height);

            $x2 =   rand($width * 0.25, $width);
            $y2 =   rand(0, $height);

            imageline($this->img, $x1, $y1, $x2, $y2, $this->colorLine);
        }
    }

    /**
     * Draw disturbing ghost test
     *
     *
     * @param array $chars
     * @param int $width
     * @param int $height
     */
    protected function drawGhosts($chars, $width, $height)
    {
        if (!$this->ghosts) {
            return;
        }

        $ttf    =   WBParam::get('wb/dir/system') . '/' . $this->fontDir . '/' . $this->font;
        $string =   implode('', $chars);
        $ang    =   $this->fontAngle / 3;
        for ($i = 0; $i < $this->ghosts; ++$i) {
            $a  =   rand(-$ang, $ang);
            $x  =   rand(0, $this->fontSize);
            $y  =   rand(0, $this->fontSize * 2);
            imagettftext($this->img, $this->fontSize, $a, $x, $y, $this->colorGhost, $ttf, $string);
        }
    }

    /**
     * Draw actual payload
     *
     *
     *
     * @param array $chars
     * @param int $width
     * @param int $height
     */
    protected function drawLetters($chars, $width, $height)
    {
        $ttf    =   WBParam::get('wb/dir/system') . '/' . $this->fontDir . '/' . $this->font;
        $x      =   $this->fontSize / 4;
        $y      =   $this->fontSize * 1.25;
        foreach ($chars as $char) {
            $a  =   rand(-$this->fontAngle, $this->fontAngle);
            imagettftext($this->img, $this->fontSize, $a, $x, $y, $this->colorFg, $ttf, $char);
            $x   +=  $this->fontSize * $this->fontSpace;
        }
    }
}