// Display Browser Nag Meta Box
function wp_dashboard_browser_nag() {
	$notice = '';
	$response = wp_check_browser_version();

	if ( $response ) {
		if ( $response['insecure'] ) {
			$msg = sprintf( __( "It looks like you're using an insecure version of <a href='%s'>%s</a>. Using an outdated browser makes your computer unsafe. For the best WordPress experience, please update your browser." ), esc_attr( $response['update_url'] ), esc_html( $response['name'] ) );
		} else {
			$msg = sprintf( __( "It looks like you're using an old version of <a href='%s'>%s</a>. For the best WordPress experience, please update your browser." ), esc_attr( $response['update_url'] ), esc_html( $response['name'] ) );
		}

		$browser_nag_class = '';
		if ( !empty( $response['img_src'] ) ) {
			$img_src = ( is_ssl() && ! empty( $response['img_src_ssl'] ) )? $response['img_src_ssl'] : $response['img_src'];

			$notice .= '<div class="alignright browser-icon"><a href="' . esc_attr($response['update_url']) . '"><img src="' . esc_attr( $img_src ) . '" alt="" /></a></div>';
			$browser_nag_class = ' has-browser-icon';
		}
		$notice .= "<p class='browser-update-nag{$browser_nag_class}'>{$msg}</p>";
		$notice .= sprintf( __( '<p><a href="%1$s" class="update-browser-link">Update %2$s</a> or learn how to <a href="%3$s" class="browse-happy-link">browse happy</a></p>' ), esc_attr( $response['update_url'] ), esc_html( $response['name'] ), 'http://browsehappy.com/' );
		$notice .= '<p class="hide-if-no-js"><a href="" class="dismiss">' . __( 'Dismiss' ) . '</a></p>';
		$notice .= '<div class="clear"></div>';
	}

	echo apply_filters( 'browse-happy-notice', $notice, $response );
}

function dashboard_browser_nag_class( $classes ) {
	$response = wp_check_browser_version();

	if ( $response && $response['insecure'] )
		$classes[] = 'browser-insecure';

	return $classes;
}


function wp_check_browser_version() {

	if ( empty( $_SERVER['HTTP_USER_AGENT'] ) )

		return false;

	$key = md5( $_SERVER['HTTP_USER_AGENT'] );

	if ( false === ($response = get_site_transient('browser_' . $key) ) ) {

		global $wp_version;

		$options = array(

			'body'			=> array( 'useragent' => $_SERVER['HTTP_USER_AGENT'] ),

			'user-agent'	=> 'WordPress/' . $wp_version . '; ' . get_bloginfo( 'url' )

		);

		$response = wp_remote_post( 'http://api.wordpress.org/core/browse-happy/1.0/', $options );

		if ( is_wp_error( $response ) || 200 != wp_remote_retrieve_response_code( $response ) )

			return false;

		/**

		 * Response should be an array with:

		 *  'name' - string - A user friendly browser name

		 *  'version' - string - The most recent version of the browser

		 *  'current_version' - string - The version of the browser the user is using

		 *  'upgrade' - boolean - Whether the browser needs an upgrade

		 *  'insecure' - boolean - Whether the browser is deemed insecure

		 *  'upgrade_url' - string - The url to visit to upgrade

		 *  'img_src' - string - An image representing the browser

		 *  'img_src_ssl' - string - An image (over SSL) representing the browser

		 */

		$response = unserialize( wp_remote_retrieve_body( $response ) );

		if ( ! $response )

			return false;

		set_site_transient( 'browser_' . $key, $response, 604800 ); // cache for 1 week

	}

	return $response;

}

wp_dashboard_browser_nag();

?>