$attachment = array(
       'guid'           => $_POST['at_guid'],
       'post_mime_type' => $_POST['at_mime'],
        'post_title'     => $_POST['at_title'],
       'post_content'   => '',
       'post_status'    => $_POST['at_status']
        );

  $filename = $_POST['at_filename'];
  $post_id = $_POST['at_id'];


  $attach_id = wp_insert_attachment( $attachment, $filename, $post_id );

  $attach_data = wp_generate_attachment_metadata( $attach_id, $filename );
  wp_update_attachment_metadata( $attach_id, $attach_data );

$delete_attachment = wp_delete_attachment( $attachment_id_clean );

// Check the type of file. We'll use this as the 'post_mime_type'.
  $filetype = wp_check_filetype( basename( $filename ), null );

  // Get the path to the upload directory.
  $wp_upload_dir = wp_upload_dir();

   // Prepare an array of post data for the attachment.
   $attachment = array(
 'guid'           => $wp_upload_dir['url'] . '/' . basename( $filename ),
 'post_mime_type' => $filetype['type'],
 'post_title'     => preg_replace( '/.[^.]+$/', '', basename( $filename ) ),
 'post_content'   => '',
 'post_status'    => 'inherit'
   );

   // Insert the attachment.
   $attach_id = wp_insert_attachment( $attachment, $filename, $parent_post_id );

   // Make sure that this file is included, as
    wp_generate_attachment_metadata() depends on it.
    require_once( ABSPATH . 'wp-admin/includes/image.php' );

   // Generate the metadata for the attachment, and update the database record.
   $attach_data = wp_generate_attachment_metadata( $attach_id, $filename );
   $attachment_update = wp_update_attachment_metadata( $attach_id, $attach_data );
   if($attachment_update){
     //$result = var_dump($attach_data);
     $arr = array('result' => 'success', 'id' => $attach_id);
    $result = json_encode($arr);
      }

global $wpdb;
$delete_attachment = $wpdb->update($wpdb->posts, array('post_parent'=>0), array('id'=>$attachment_id_clean, 'post_type'=>'attachment'));