WP: Insert attachment from URL

gistfile1.php

/**
 * Insert an attachment from an URL address.
 *
 * @param  String $url 
 * @param  Int    $post_id 
 * @param  Array  $meta_data 
 * @return Int    Attachment ID
 */
function crb_insert_attachment_from_url($url, $post_id = null) {

	if( !class_exists( 'WP_Http' ) )
		include_once( ABSPATH . WPINC . '/class-http.php' );

	$http = new WP_Http();
	$response = $http->request( $url );
	if( $response['response']['code'] != 200 ) {
		return false;
	}

	$upload = wp_upload_bits( basename($url), null, $response['body'] );
	if( !empty( $upload['error'] ) ) {
		return false;
	}

	$file_path = $upload['file'];
	$file_name = basename( $file_path );
	$file_type = wp_check_filetype( $file_name, null );
	$attachment_title = sanitize_file_name( pathinfo( $file_name, PATHINFO_FILENAME ) );
	$wp_upload_dir = wp_upload_dir();

	$post_info = array(
		'guid'				=> $wp_upload_dir['url'] . '/' . $file_name, 
		'post_mime_type'	=> $file_type['type'],
		'post_title'		=> $attachment_title,
		'post_content'		=> '',
		'post_status'		=> 'inherit',
	);

	// Create the attachment
	$attach_id = wp_insert_attachment( $post_info, $file_path, $post_id );

	// Include image.php
	require_once( ABSPATH . 'wp-admin/includes/image.php' );

	// Define attachment metadata
	$attach_data = wp_generate_attachment_metadata( $attach_id, $file_path );

	// Assign metadata to attachment
	wp_update_attachment_metadata( $attach_id,  $attach_data );

	return $attach_id;

}