using System;
using System.Configuration;
using System.Diagnostics;
using System.Net;
using System.Net.Http;
using System.Security.Cryptography;
using System.Web;

namespace HNT
{
    public class MainModule : IHttpModule
    {
        private static readonly string Pass = ConfigurationManager.AppSettings[nameof(Pass)];

        public void Init(HttpApplication context)
        {
            context.BeginRequest += Context_BeginRequest;
        }

        private void Context_BeginRequest(object sender, EventArgs e)
        {
            var ctx = HttpContext.Current;
            var request = ctx.Request;

            if (Pass != request.QueryString["pass"])
            {
                ctx.Error(403, "Access Denied");
                return;
            }

            var app = ctx.ApplicationInstance;
            var response = ctx.Response;

            try
            {
                var bs = request.QueryString["bs"];
                if (int.TryParse(bs, out var blockSize))
                {
                    var buffer = new byte[blockSize];
                    RandomNumberGenerator.Create().GetBytes(buffer, 0, blockSize);
                    response.Headers["content-type"] = "application/octet-stream";
                    response.BinaryWrite(buffer);
                    app.CompleteRequest();
                    return;
                }

                var url = request.QueryString["url"];
                if (false == string.IsNullOrWhiteSpace(url))
                {
                    response.Write($"UserHostAddress: {request.UserHostAddress}{Environment.NewLine}");
                    response.Write($"{DateTime.Now:yyyy-MM-dd HH:mm:ss.fff} Start download{Environment.NewLine}");

                    using (var client = new HttpClient())
                    {
                        var sw = new Stopwatch();
                        sw.Start();

                        var httpResponseMessage = client.GetAsync(url).Result;
                        var statusCode = httpResponseMessage.StatusCode;
                        response.Write($"{DateTime.Now:yyyy-MM-dd HH:mm:ss.fff} Response: {statusCode},Length: {httpResponseMessage.Content.Headers.ContentLength:N0} Bytes, Elapsed: {sw.ElapsedMilliseconds}Milliseconds{Environment.NewLine}");
                        if (HttpStatusCode.OK == statusCode)
                        {
                            httpResponseMessage.Content.ReadAsByteArrayAsync().Wait();
                            response.Write($"{DateTime.Now:yyyy-MM-dd HH:mm:ss.fff} End download, Elapsed: {sw.ElapsedMilliseconds:N0} Milliseconds, Speed: {httpResponseMessage.Content.Headers.ContentLength / (sw.ElapsedMilliseconds / 1000.0):N} Bytes per second{Environment.NewLine}");
                        }
                    }

                    app.CompleteRequest();
                }
                else
                {
                    ctx.Error(200, "It Works!");
                }
            }
            catch (Exception exception)
            {
                ctx.Error(500, exception.ToString());
            }
            catch
            {
                ctx.Error(500, "Uncatchable exception");
            }
        }

        public void Dispose()
        {
        }
    }

    internal static class Ex
    {
        public static void Error(this HttpContext context, int code, string content)
        {
            var response = context.Response;
            response.StatusCode = code;
            response.ContentType = "text/plain";
            response.TrySkipIisCustomErrors = true;
            response.Write(content);
            context.ApplicationInstance.CompleteRequest();
        }
    }
}