/// <summary>
/// Adds a middleware to the OWIN pipeline that sets the Strict-Transport-Security header.
/// </summary>
/// <param name="app">The <see cref="IAppBuilder" /> to which the middleware is added.</param>
/// <param name="configurer">An <see cref="Action" /> that configures the options for the middleware.</param>
/// <returns>The <see cref="IAppBuilder" /> supplied in the app parameter.</returns>
public static IAppBuilder UseHsts(this IAppBuilder app, Action<IFluentHstsOptions> configurer)
{
if (app == null) throw new ArgumentNullException("app");
if (configurer == null) throw new ArgumentNullException("configurer");
var options = new HstsOptions();
configurer(options);
new HstsConfigurationValidator().Validate(options);
return app.Use(typeof(HstsMiddleware), options);
}
