using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Net;

namespace PdfDownload

{

    /// <summary>

    /// PDF 下载工具

    /// </summary>

    public class PDF : IHttpHandler

    {

        public void ProcessRequest(HttpContext context)

        {

            var url = context.Request["url"];

            var title = context.Request["title"];

            var response = context.Response;

            if (!string.IsNullOrEmpty(url) && !string.IsNullOrEmpty(title))

            {

                response.Charset = System.Text.Encoding.UTF8.ToString();

                response.ContentEncoding = System.Text.Encoding.UTF8;

                try

                {

                    HttpWebRequest request = (HttpWebRequest)System.Net.WebRequest.Create(url);

                    request.Timeout = 5000;

                    request.ReadWriteTimeout = 1000;

                    request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36";

                    request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";

                    using (var remoteResponse = request.GetResponse())

                    {

                        var length = remoteResponse.ContentLength;

                        if (length != -1)

                        {

                            response.ContentType = "application/pdf";

                            response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(title));

                            response.AppendHeader("Content-Length", length.ToString());

                            byte[] buffer = new byte[512 * 1024];

                            using (var stream = remoteResponse.GetResponseStream())

                            {

                                var position = 0;

                                while ((position = stream.Read(buffer, 0, buffer.Length)) > 0)

                                {

                                    response.OutputStream.Write(buffer, 0, position);

                                }

                            }

                            response.Flush();

                            return;

                        }

                    }

                }

                catch (Exception ex)

                {

                    response.ContentType = "html/text";

                    System.Text.StringBuilder builder = new System.Text.StringBuilder();

                    builder.Append("URL:");

                    builder.AppendLine(url);

                    builder.AppendLine(ex.ToString());

                    response.Write(builder.ToString());

                }

            }

            else

            {

                context.Response.StatusCode = 404;

            }

        }

        public string GetWindSessionID(HttpContext context)

        {

            string str = context.Request.Headers["wind.sessionid"];

            if (string.IsNullOrEmpty(str))

            {

                str = context.Request.QueryString["wind.sessionid"];

                if (string.IsNullOrEmpty(str) && (context.Request.Cookies["wind.sessionid"] != null))

                {

                    str = context.Request.Cookies["wind.sessionid"].Value;

                }

            }

            return str;

        }

        public bool IsReusable

        {

            get

            {

                return true;

            }

        }

    }

}