Crappy .srt helper

subtitles.php

#!/usr/bin/env php
<?php

date_default_timezone_set('UTC');

$stderr = fopen('php://stderr', 'wb');

$shift = 0.0;
switch( $argv[1] ?? '' ) {
	case 'shift':
		if( $argc !== 4 ) {
			helpExit('invalid argument count');
		}
		if( preg_match('/^(?<time1>[-+]?\d\d:\d\d:\d\d)(?:,(?<frac1>\d\d\d))?$/', $argv[2], $regs) ) {
			$shift = parseTimeString($regs['time1'], $regs['frac1'] ?? '000');
		} else {
			helpExit('invalid shift argument');
		}

		$string = @file_get_contents($argv[3]);
		if( $string === false ) {
			helpExit('failed to read file "' . $argv[3] . '"');
		}

		break;
	case 'reindex':
		$string = '';
		for( $i = 2; $i <= $argc - 1; $i++ ) {
			$string .= @file_get_contents($argv[$i]);
			if( $string === false ) {
				helpExit('failed to read file "' . $argv[$i] . '"');
			}

			$string .= "\n\n";
		}
		break;
	default:
		helpExit();
}

$string = preg_replace('/(?<!\r)\n/s', "\r\n", $string);


preg_match_all('/\d+\r\n
(?<time1>\d\d:\d\d:\d\d),(?<frac1>\d\d\d)\s
-->\s
(?<time2>\d\d:\d\d:\d\d),(?<frac2>\d\d\d)\r\n
(?<text>.+?)(?:\r\n\r|$)/sx', $string, $result, PREG_PATTERN_ORDER);

if(preg_last_error() !== PREG_NO_ERROR) {
	output("regex error\n");
    exit(1);
}

if(empty($result[0])) {
	output("no subtitles found\n");
	exit(2);
}

$subs = [];
foreach( $result['text'] as $i => $text ) {
	$start  = parseTimeString($result['time1'][$i], $result['frac1'][$i]);
	$finish = parseTimeString($result['time2'][$i], $result['frac2'][$i]);

	$start  += $shift;
	$finish += $shift;

	$subs[] = [$start, $finish, trim($result['text'][$i])];
}

usort($subs, function(array $a, array $b) {
	return $a <=> $b;
});

foreach($subs as $i => $sub) {
	echo sprintf("%d\r\n%s --> %s\r\n%s\r\n\r\n",
		$i + 1,
		createTimeString($sub[0]),
		createTimeString($sub[1]),
		$sub[2]
	);
}

if( $shift ) {
	output("\nshifted by " . createTimeString($shift) . "\n");
}


function parseTimeString( string $time, int $frac ) : float {
	$sign = 1;
	if( ($time[0] ?? '') === '-' ) {
		$sign = -1;
	}
	$time = ltrim($time, '-+');

	return $sign * (strtotime("January 1 1970 {$time}") + ($frac / 1000));
}

function createTimeString( float $secs ) : string {
	$pre = '';
	if( $secs < 0 ) {
		$pre = '-';
	}
	$secs = (float)abs($secs);
	$base = (int)$secs;
	$frac = round(($secs - $base) * 1000);

	return sprintf('%s%s,%03d', $pre, gmdate('H:i:s', $base), $frac);
}

function helpExit( string $error = '' ) {
	global $argv;

	if( $error ) {
		output(sprintf("error: %s\n\n", $error));
	}

	output(sprintf(<<<HELP
%s <command> [<args>]

   shift [+-]00:00:00[,000] <file>
      time shift an srt file by the given seconds  

   reindex <file ...>
      reindex one or more srt files


HELP
		, $argv[0]));
	die(1);
}

function output( string $str ) {
	global $stderr;
	fwrite($stderr, $str);
}

function drop( ...$args ) {
	foreach( $args as $arg ) {
		var_export($arg);
		echo "\n===\n";
	}

	exit(3);
}