using System;
using System.Linq;
using System.Net;
using System.Web;
using System.Web.Configuration;
using System.Web.Mvc;
using ApacKernel;
using Newtonsoft.Json;

namespace Now.Web.Modules
{
    /// <summary>
    /// Enables support for CustomErrors ResponseRewrite mode in MVC.
    /// </summary>
    public class ErrorHandlerModule : IHttpModule
    {
        private HttpContext HttpContext { get { return HttpContext.Current; } }
        private CustomErrorsSection CustomErrors { get; set; }
        public void Init(HttpApplication application)
        {
            //System.Configuration.Configuration configuration = WebConfigurationManager.OpenWebConfiguration("~");
            //CustomErrors = (CustomErrorsSection)configuration.GetSection("system.web/customErrors");
            CustomErrors = (CustomErrorsSection)ApacConfig.Sections.GetSection("system.web/customErrors");
            application.EndRequest += Application_EndRequest;
        }
        protected void Application_EndRequest(object sender, EventArgs e)
        {
            // only handle rewrite mode, ignore redirect configuration (if it ain't broke don't re-implement it)
            if (CustomErrors.RedirectMode == CustomErrorsRedirectMode.ResponseRewrite && HttpContext.IsCustomErrorEnabled)
            {
                var statusCode = HttpContext.Response.StatusCode;
                // if this request has thrown an exception then find the real status code
                var exception = HttpContext.Error;
                if (exception != null)
                {
                    // set default error status code for application exceptions
                    statusCode = (int)HttpStatusCode.InternalServerError;
                }
                var httpException = exception as HttpException;
                if (httpException != null)
                {
                    statusCode = httpException.GetHttpCode();
                }
                if ((HttpStatusCode)statusCode != HttpStatusCode.OK)
                {
                    var errorPaths = CustomErrors.Errors.Cast<CustomError>().ToDictionary(error => error.StatusCode, error => error.Redirect);
                    // find a custom error path for this status code
                    if (errorPaths.Keys.Contains(statusCode))
                    {
                        string url = errorPaths[statusCode];
                        // avoid circular redirects
                        if (!HttpContext.Request.Url.AbsolutePath.Equals(VirtualPathUtility.ToAbsolute(url)))
                        {
                            HttpContext.Response.Clear();
                            HttpContext.Response.TrySkipIisCustomErrors = true;
                            HttpContext.Server.ClearError();
                            if (!new HttpRequestWrapper(HttpContext.Current.Request).IsAjaxRequest())
                            {
                                // do the redirect here
                                if (HttpRuntime.UsingIntegratedPipeline)
                                {
                                    HttpContext.Server.TransferRequest(url, true);
                                }
                                else
                                {
                                    HttpContext.RewritePath(url, false);
                                    IHttpHandler httpHandler = new MvcHttpHandler();
                                    httpHandler.ProcessRequest(HttpContext);
                                }
                            }
                            else if (exception != null)
                            {
                                HttpContext.Response.ContentType = "application/json";
                                HttpContext.Response.Write(JsonConvert.SerializeObject(exception));
                            }
                            // return the original status code to the client
                            // (this won't work in integrated pipleline mode)
                            HttpContext.Response.StatusCode = statusCode;
                        }
                    }

                }

            }

        }

        public void Dispose()
        {

        }
    }
}