Robots Middleware

Middleware

public class RobotsMiddleware
	{
		private readonly RequestDelegate _next;
		private readonly ILogger _logger;

		public RobotsMiddleware(RequestDelegate next, ILoggerFactory loggerFactory)
		{
			_next = next;
			_logger = loggerFactory.CreateLogger<RobotsMiddleware>();
		}

		public Task Invoke(HttpContext context)
			=> Robots(context, () => _next(context), _logger);

		private static Task Robots(HttpContext context, Func<Task> func, ILogger logger)
		{
			if (context.Request.Path.ToString().ToLower() != "/robots.txt")
				return func();
				
			var sb = new StringBuilder();
			sb.AppendLine("User-agent: *");
			sb.AppendLine("Disallow: /");

			context.Response.StatusCode = 200;
			context.Response.ContentType = "text/plain";
			var content = sb.ToString();
			logger.LogDebug($"Serving robots.txt {content}");

			return context.Response.WriteAsync(content);
		}

	}
	public static class RobotsExtensions
	{
		public static IApplicationBuilder UseRobotsDontIndex(this IApplicationBuilder builder)
			=> builder.UseMiddleware<RobotsMiddleware>();
	}