using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Configuration;
using System.EnterpriseServices;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web;
using System.Web.Services.Configuration;

namespace WebGet
{
    public class WebGetModule : IHttpModule
    {

        private static readonly ConcurrentDictionary<string, DownloadState> Sessions = new ConcurrentDictionary<string, DownloadState>();

        public void Init(HttpApplication context)
        {
            context.PostMapRequestHandler += ContextOnPostMapRequestHandler;
        }

        private void ContextOnPostMapRequestHandler(object sender, EventArgs e)
        {
            var ctx = HttpContext.Current;
            var req = ctx.Request;
            var qs = req.QueryString;

            var rsp = ctx.Response;
            if (qs["pass"] != ConfigurationManager.AppSettings["pass"])
            {
                rsp.StatusCode = 403;
                rsp.Write("403 Access Denied");
                ctx.ApplicationInstance.CompleteRequest();
                return;
            }

            var url = qs["url"];
            if (string.IsNullOrEmpty(url))
            {
                rsp.StatusCode = 400;
                rsp.Write("400 Bad Request: Missing URL param");
                ctx.ApplicationInstance.CompleteRequest();
                return;
            }


            rsp.ContentType = "text/html";
            rsp.Write($"Download it - {url}<br/>");


            try
            {
                var http = new HttpClient();
                var r = http.GetAsync(url).Result;
                if (!r.IsSuccessStatusCode) throw new HttpException((int)r.StatusCode, r.ReasonPhrase);

                var fileName = r.Content.Headers.ContentDisposition?.FileName;
                if (string.IsNullOrWhiteSpace(fileName)) fileName = Path.GetFileName(url);
                if (string.IsNullOrWhiteSpace(fileName)) fileName = $"Download-{DateTime.Now:yyyyMMdd-HHmmssff}.bin";

                var start = DateTime.Now;
                rsp.Write($"Download start at {start}<br/>");

                var buf = r.Content.ReadAsByteArrayAsync().Result;
                var end = DateTime.Now;
                rsp.Write($"Download end at {end}<br/>");

                var len = buf.Length;

                rsp.Write($"Len: {len}<br/>");
                rsp.Write($"FileName: {fileName}<br/>");

                rsp.Write($"Download dur {end - start}<br/>");


                var saveTo = ctx.Server.MapPath("~/" + fileName);
                File.WriteAllBytes(saveTo, buf);

                rsp.Write($"File Saved<br/>");
            }
            catch (Exception exception)
            {
                rsp.StatusCode = 500;
                rsp.Write($"Error: {exception.Message}<br/>");
            }

            ctx.ApplicationInstance.CompleteRequest();
        }


        private class DownloadState
        {

        }

        public void Dispose()
        {

        }
    }
}