thumbnail Image is not rotating - php

Question

I am creating a thumbnail in php for the uploaded image. The thumbnail is created and saved correctly but it is not rotating when needed. I test my code on many images but it did not work. Here is my code for creating the thumbnail and rotate it based on its exif data.
//thumb image
$maxDim = 300;
$filename = $_FILES['file']['name'];
list($width, $height, $type, $attr) = getimagesize($path.$filename);
if ( $width > $maxDim || $height > $maxDim )
{
$ext = pathinfo($filename, PATHINFO_EXTENSION); //var_dump($ext);
$target_filename = $path.'thumb_'.$filename;
$ratio = $width/$height;
if( $ratio > 1) {
$new_width = $maxDim;
$new_height = $maxDim/$ratio;
} else {
$new_width = $maxDim*$ratio;
$new_height = $maxDim;
}
$contents = file_get_contents($path.$filename);
$src = imagecreatefromstring($contents);
$dst = imagecreatetruecolor( $new_width, $new_height );
imagecopyresampled( $dst, $src, 0, 0, 0, 0, $new_width, $new_height, $width, $height );
imagedestroy( $src );
$exif = exif_read_data($path.$filename);
if (!empty($exif['Orientation'])) {
switch ($exif['Orientation']) {
case 3:
$dst = imagerotate($dst, 180, 0);
break;
case 6:
$dst = imagerotate($dst, 90, 0);
break;
case 8:
$dst = imagerotate($dst, -90, 0);
break;
}
}
//check src image type
if (exif_imagetype($path.$filename ) == IMAGETYPE_JPEG) {
imagejpeg($dst, $target_filename );
}
else if(exif_imagetype($path.$filename ) == IMAGETYPE_PNG){
imagepng($dst, $target_filename );
}
else if(exif_imagetype($path.$filename ) == IMAGETYPE_GIF){
imagegif($dst, $target_filename );
}
imagedestroy( $dst );
}