using System;
using System.Net;
using System.Net.Http;
using System.Net.Http.Formatting;
using System.Threading;
using System.Threading.Tasks;
using System.Web.Http;
using System.Web.Http.ExceptionHandling;

namespace Step
{
    public class WebApiUnhandledExceptionHandler : ExceptionHandler
    {
        public override void Handle(ExceptionHandlerContext context)
        {
            context.Result = new TextPlainErrorResult
            {
                Request = context.ExceptionContext.Request,
                Exception = context.Exception,
                HttpStatusCode = HttpStatusCode.InternalServerError
            };
        }

        private class TextPlainErrorResult : IHttpActionResult
        {
            public HttpRequestMessage Request { get; set; }

            public Exception Exception { get; set; }

            public HttpStatusCode HttpStatusCode { get; set; }

            public Task<HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken)
            {
                HttpError error = new HttpError(Exception, true);
                HttpResponseMessage response = new HttpResponseMessage()
                {
                    Content = new ObjectContent<HttpError>(error, new JsonMediaTypeFormatter()),
                    StatusCode = HttpStatusCode,
                    RequestMessage = Request
                };

                return Task.FromResult(response);
            }
        }
    }
}