class.ilCountPDFPages.php

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<?php

use ILIAS\ResourceStorage\Services;
use ILIAS\FileUpload\MimeType;
use ILIAS\ResourceStorage\Identification\ResourceIdentification;

class ilCountPDFPages
{
    private Services $irss;
    private bool $postscript_available = false;
    private bool $imagick_available = false;

    public function __construct()
    {
        global $DIC;
        $this->irss = $DIC->resourceStorage();
        $this->postscript_available = (defined('PATH_TO_GHOSTSCRIPT') && PATH_TO_GHOSTSCRIPT !== "");
        $this->imagick_available = class_exists('Imagick');
    }

    public function isAvailable(): bool
    {
        return $this->postscript_available || $this->imagick_available;
    }

    public function extractAmountOfPagesByRID(ResourceIdentification $rid): ?int
    {
        if (!$this->postscript_available) {
            return null;
        }
        $revision = $this->irss->manage()->getCurrentRevision($rid);
        $info = $revision->getInformation();
        if ($info->getMimeType() !== MimeType::APPLICATION__PDF) {
            return null;
        }
        $consumer = $this->irss->consume()->stream($rid);
        $path_to_pdf = $consumer->getStream()->getMetadata('uri');
        return $this->extractAmountOfPagesByPath($path_to_pdf);
    }

    public function extractAmountOfPagesByPath(string $path_to_pdf): ?int
    {
        if (!$this->postscript_available && !$this->imagick_available) {
            return null;
        }

        // first we try using Imagick
        if ($this->imagick_available) {
            $pages = null;
            try {
                $imagick = new Imagick();
                $imagick->pingImage($path_to_pdf);

                return $imagick->getNumberImages();
            } catch (Throwable) {
                // Imagick is not available or another error occured
            }
        }

        if ($this->postscript_available) {
            $arg = "-q -dNODISPLAY -dNOSAFER -c \"($path_to_pdf) (r) file runpdfbegin pdfpagecount = quit\";";
            $return = ilShellUtil::execQuoted(PATH_TO_GHOSTSCRIPT, $arg);
            if (!isset($return[0]) || ($pages = (int) $return[0]) === 0) {
                return null;
            }

            return $pages;
        }

        return null;
    }
}