Simple Image gallery script

index.php

<?php

$files = array_merge(glob("*.jpg"), glob("*.jpeg"), glob("*.png"), glob("*.gif"), glob("*.bmp"), glob("*.swf"));
sort($files);

$num_files = count($files);

if( ! isset($_GET['curr']))
{
	$curr_num = 0;

	$curr = $files[0];
	$prev = $curr;
	$next = $files[1];
}
else if(in_array($_GET['curr'], $files))
{
	$curr = $_GET['curr'];
	$files_rev =  array_flip($files);
	$curr_num = $files_rev[$curr];
	
	$prev = ($curr_num > 0) ? $files[$curr_num - 1] : $curr;
	$next = (isset($files[$curr_num + 1])) ? $files[$curr_num + 1] : $curr;
}
else
{
	header('HTTP/1.0 404 Not Found', TRUE, 404);
	echo "<h1>404 Not Found</h1>";
	echo "The page that you have requested could not be found.";
}
?>
<a style="position:absolute;top:0;left:0" href="?curr=<?= $prev ?>">Previous</a>
<a style="position:absolute;top:0;right:0"href="?curr=<?= $next ?>">Next</a>
<br />
<?php if(stripos($curr, 'swf') !== FALSE): ?>
	<center><object type="application/x-shockwave-flash" data="<?= $curr ?>" width="100%" height="90%">
		<param name="movie" value="<?= $curr ?>" />
	</object></center>
<?php else: ?>
<a href="?curr=<?= $next ?>">
	<center><img src="<?= $curr ?>" style="max-width:100%" /></center>
</a>
<?php endif ?>
<script type="text/javascript">
	var onkey = function(e){
	
		e.preventDefault();
	
		var left = 37,
			right = 39;
			
		if(e.keyCode === left )
		{
			document.location='?curr=<?= $prev ?>';
		}
		else if(e.keyCode === right || e.keyCode === 32)
		{
			document.location='?curr=<?= $next ?>';
		}
	
	};

	window.addEventListener("keydown", onkey, false);
</script>