<?php
/**
 * Implementation of conversion service exec class
 *
 * @category   DMS
 * @package    SeedDMS
 * @license    GPL 2
 * @version    @version@
 * @author     Uwe Steinmann <uwe@steinmann.cx>
 * @copyright  Copyright (C) 2021 Uwe Steinmann
 * @version    Release: @package_version@
 */

require_once("inc/inc.ClassConversionServiceBase.php");

/**
 * Implementation of conversion service exec class
 *
 * @category   DMS
 * @package    SeedDMS
 * @author     Uwe Steinmann <uwe@steinmann.cx>
 * @copyright  Copyright (C) 2021 Uwe Steinmann
 * @version    Release: @package_version@
 */
class SeedDMS_ConversionServiceExec extends SeedDMS_ConversionServiceBase {
	/**
	 * shell cmd
	 */
	public $cmd;

	/**
	 * timeout
	 */
	public $timeout;

	/**
	 * Run a shell command
	 *
	 * @param $cmd
	 * @param int $timeout
	 * @return array
	 * @throws Exception
	 */
	static function execWithTimeout($cmd, $timeout=5) { /* {{{ */
		$descriptorspec = array(
			0 => array("pipe", "r"),
			1 => array("pipe", "w"),
			2 => array("pipe", "w")
		);
		$pipes = array();

		$timeout += time();
		// Putting an 'exec' before the command will not fork the command
		// and therefore not create any child process. proc_terminate will
		// then reliably terminate the cmd and not just shell. See notes of
		// https://www.php.net/manual/de/function.proc-terminate.php
		$process = proc_open('exec '.$cmd, $descriptorspec, $pipes);
		if (!is_resource($process)) {
			throw new Exception("proc_open failed on: " . $cmd);
		}
		stream_set_blocking($pipes[1], 0);
		stream_set_blocking($pipes[2], 0);

		$output = $error = '';
		$timeleft = $timeout - time();
		$read = array($pipes[1], $pipes[2]);
		$write = NULL;
		$exeptions = NULL;
		do {
			$num_changed_streams = stream_select($read, $write, $exeptions, $timeleft, 200000);

			if ($num_changed_streams === false) {
				proc_terminate($process);
				throw new Exception("stream select failed on: " . $cmd);
			} elseif ($num_changed_streams > 0) {
				$output .= fread($pipes[1], 8192);
				$error .= fread($pipes[2], 8192);
			}
			$timeleft = $timeout - time();
		} while (!feof($pipes[1]) && $timeleft > 0);

		fclose($pipes[0]);
		fclose($pipes[1]);
		fclose($pipes[2]);
		if ($timeleft <= 0) {
			proc_terminate($process);
			throw new Exception("command timeout on: " . $cmd);
		} else {
			$return_value = proc_close($process);
			return array('stdout'=>$output, 'stderr'=>$error, 'return'=>$return_value);
		}
	} /* }}} */

	public function __construct($from, $to, $cmd) {
		$this->from = $from;
		$this->to = $to;
		$this->cmd = $cmd;
		$this->timeout = 5;
	}

	public function convert($infile, $target = null, $params = array()) {
		$start = microtime(true);
		if(!$target)
			$tmpfile = tempnam(sys_get_temp_dir(), 'convert');
		else
			$tmpfile = $target;
		$cmd = str_replace(array('%w', '%f', '%o', '%m'), array(isset($params['width']) ? $params['width'] : '', $infile, $tmpfile, $this->from), $this->cmd);
		try {
			self::execWithTimeout($cmd, $this->timeout);
		} catch(Exception $e) {
			return false;
		}
		$end = microtime(true);
		if($this->logger) {
			$this->logger->log('Conversion from '.$this->from.' to '.$this->to.' with cmd "'.$this->cmd.'" took '.($end-$start).' sec.', PEAR_LOG_INFO);
		}
		if(!$target) {
			$content = file_get_contents($tmpfile);
			unlink($tmpfile);
			return $content;
		} else {
			return true;
		}
	}
}