<?php
/**
 * wallabag, self hostable application allowing you to not miss any content anymore
 *
 * @category   wallabag
 * @author     Nicolas Lœuillet <nicolas@loeuillet.org>
 * @copyright  2013
 * @license    http://opensource.org/licenses/MIT see COPYING file
 */


final class Picture
{
    private function __construct()
    {

    }

    /**
     * Changing pictures URL in article content
     */
    public static function filterPicture($content, $url, $id)
    {
        $matches = array();
        $processing_pictures = array(); // list of processing image to avoid processing the same pictures twice
        preg_match_all('#<\s*(img)[^>]+src="([^"]*)"[^>]*>#Si', $content, $matches, PREG_SET_ORDER);
        foreach($matches as $i => $link) {
            $link[1] = trim($link[1]);
            if (!preg_match('#^(([a-z]+://)|(\#))#', $link[1])) {
                $absolute_path = self::_getAbsoluteLink($link[2], $url);
                $filename = basename(parse_url($absolute_path, PHP_URL_PATH));
                $directory = self::_createAssetsDirectory($id);
                $fullpath = $directory . '/' . $filename;

                if (in_array($absolute_path, $processing_pictures) === true) {
                    // replace picture's URL only if processing is OK : already processing -> go to next picture
                    continue;
                }

                if (self::_downloadPictures($absolute_path, $fullpath) === true) {
                    $content = str_replace($matches[$i][2], $fullpath, $content);
                }

                $processing_pictures[] = $absolute_path;
            }
        }

        return $content;
    }

    /**
     * Get absolute URL
     */
    private static function _getAbsoluteLink($relativeLink, $url)
    {
        /* return if already absolute URL */
        if (parse_url($relativeLink, PHP_URL_SCHEME) != '') return $relativeLink;

        /* queries and anchors */
        if ($relativeLink[0]=='#' || $relativeLink[0]=='?') return $url . $relativeLink;

        /* parse base URL and convert to local variables:
           $scheme, $host, $path */
        extract(parse_url($url));

        /* remove non-directory element from path */
        $path = preg_replace('#/[^/]*$#', '', $path);

        /* destroy path if relative url points to root */
        if ($relativeLink[0] == '/') $path = '';

        /* dirty absolute URL */
        $abs = $host . $path . '/' . $relativeLink;

        /* replace '//' or '/./' or '/foo/../' with '/' */
        $re = array('#(/\.?/)#', '#/(?!\.\.)[^/]+/\.\./#');
        for($n=1; $n>0; $abs=preg_replace($re, '/', $abs, -1, $n)) {}

        /* absolute URL is ready! */
        return $scheme.'://'.$abs;
    }

    /**
     * Downloading pictures
     *
     * @return bool true if the download and processing is OK, false else
     */
    private static function _downloadPictures($absolute_path, $fullpath)
    {
        $rawdata = Tools::getFile($absolute_path);
        $fullpath = urldecode($fullpath);

        if(file_exists($fullpath)) {
            unlink($fullpath);
        }

        // check extension
        $file_ext = strrchr($fullpath, '.');
        $whitelist = array(".jpg",".jpeg",".gif",".png");
        if (!(in_array($file_ext, $whitelist))) {
            Tools::logm('processed image with not allowed extension. Skipping ' . $fullpath);
            return false;
        }

        // check headers
        $imageinfo = getimagesize($absolute_path);
        if ($imageinfo['mime'] != 'image/gif' && $imageinfo['mime'] != 'image/jpeg'&& $imageinfo['mime'] != 'image/jpg'&& $imageinfo['mime'] != 'image/png') {
            Tools::logm('processed image with bad header. Skipping ' . $fullpath);
            return false;
        }

        // regenerate image
        $im = imagecreatefromstring($rawdata);
        if ($im === false) {
            Tools::logm('error while regenerating image ' . $fullpath);
            return false;
        }

        switch ($imageinfo['mime']) {
            case 'image/gif':
                $result = imagegif($im, $fullpath);
                break;
            case 'image/jpeg':
            case 'image/jpg':
                $result = imagejpeg($im, $fullpath, REGENERATE_PICTURES_QUALITY);
                break;
            case 'image/png':
                $result = imagepng($im, $fullpath, ceil(REGENERATE_PICTURES_QUALITY / 100 * 9));
                break;
        }
        imagedestroy($im);

        return $result;
    }

    /**
     * Create a directory for an article
     *
     * @param $id ID of the article
     * @return string
     */
    private static function _createAssetsDirectory($id)
    {
        $assets_path = ABS_PATH;
        if (!is_dir($assets_path)) {
            mkdir($assets_path, 0715);
        }

        $article_directory = $assets_path . $id;
        if (!is_dir($article_directory)) {
            mkdir($article_directory, 0715);
        }

        return $article_directory;
    }

    /**
     * Remove the directory
     *
     * @param $directory
     * @return bool
     */
    public static function removeDirectory($directory)
    {
        if (is_dir($directory)) {
            $files = array_diff(scandir($directory), array('.','..'));
            foreach ($files as $file) {
                (is_dir("$directory/$file")) ? self::removeDirectory("$directory/$file") : unlink("$directory/$file");
            }
            return rmdir($directory);
        }
    }
}