<?php

class ScannerBase implements ScannerInterface {
    public const LEFT = 1;
    public const FLIP = 2;
    public const RIGHT = 3;
    protected static $scanner = false;

    public static function getScanner()
    {
	if (static::$scanner === false) {
	    $ScannerClass = defined('DOCUMENT_FILES_SCANNER_CLASS') ? DOCUMENT_FILES_SCANNER_CLASS : 'ScannerBase';
	    static::$scanner = new $ScannerClass();

	    if (!is_a(static::$scanner, 'ScannerInterface'))
		throw new Exception("DOCUMENT_FILES_SCANNER_CLASS does not implement ScannerInterface");
	}

	return static::$scanner;
    }

    public function hasScanner()
    {
	return false;
    }

    public function getResolutionList()
    {
    }

    public function setResolution($id)
    {
    }

    public function scanIntoPNM($outfile)
    {
	$scanimage = '/usr/bin/scanimage';

	if (!file_exists($scanimage))
	    throw new Exception("Package sane-utils not installed");

	if (!is_executable($scanimage))
	    throw new Exception("$scanimage not executable");

	$cmd = sprintf("%s --format pnm > %s",
		       $scanimage,
		       escapeshellarg($outfile));

	$this->execute($cmd);
    }

    public function convertPNMtoPNG($infile, $outfile)
    {
	$pnmtopng = '/usr/bin/pnmtopng';

	if (!file_exists($pnmtopng))
	    throw new Exception("Package netpbm not installed");

	if (!is_executable($pnmtopng))
	    throw new Exception("$pnmtopng not executable");

	$cmd = sprintf("cat %s | %s > %s",
		       escapeshellarg($infile),
		       $pnmtopng,
		       escapeshellarg($outfile));

	$this->execute($cmd);
    }

    public function rotatePNM($file, $direction)
    {
	$convert = '/usr/bin/convert';

	if (!file_exists($convert))
	    throw new Exception("Package imagemagick not installed");

	if (!is_executable($convert))
	    throw new Exception("$scanimage not executable");

	switch (intval($direction)) {
	case static::RIGHT: $degrees = 90; break;
	case static::FLIP: $degrees = 180; break;
	case static::LEFT: $degrees = 270; break;
	default: throw new Exception("Invalid rotation command");
	}

	$cmd = sprintf("convert -rotate %d %s %s && mv -f %s %s",
		       $degrees,
		       escapeshellarg($file), escapeshellarg($file.'.pnm'),
		       escapeshellarg($file.'.pnm'), escapeshellarg($file));

	$this->execute($cmd);
    }

    public function convertPNMtoPDF($infile, $outfile)
    {
	$pnmtops = '/usr/bin/pnmtops';
	$pstopdf = '/usr/bin/ps2pdf';

	if (!file_exists($pnmtops))
	    throw new Exception("Package netpbm not installed");

	if (!is_executable($pnmtops))
	    throw new Exception("$pnmtops not executable");

	if (!file_exists($pstopdf))
	    throw new Exception("Package ghostscript not installed");

	if (!is_executable($pstopdf))
	    throw new Exception("$pnmtops not executable");

	$cmd = sprintf("cat %s | %s | %s - > %s",
		       escapeshellarg($infile),
		       $pnmtops,
		       $pstopdf,
		       escapeshellarg($outfile));

	$this->execute($cmd);
    }

    public function mergePDF(Array $infiles, $outfile)
    {
	$pdftk = '/usr/bin/pdftk';

	if (!file_exists($pdftk))
	    throw new Exception("Package pdftk not installed");

	if (!is_executable($pdftk))
	    throw new Exception("$pdftk not executable");

	$cmd = $pdftk;
	foreach ($infiles as $infile)
	    $cmd .= ' ' . escapeshellarg($infile);
	$cmd .= ' cat output ' . escapeshellarg($outfile);

	$this->execute($cmd);
    }

    /***********************************************************************/
    protected function execute($cmd)
    {
	if (defined('DEBUG') && DEBUG == true)
	    debug($cmd);

	system($cmd, $ret);

	if ($ret != 0) {
	    $text = sprintf("Program execution resulted in exit code %d", $ret);
	    error_log($text);
	    error_log($cmd);
	    throw new Exception($text);
	}

	return true;
    }

    public function getPDF(Array $infiles)
    {
    }
}