using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Collections;

using System.IO;

using System.Net;

using System.Net.Security;

using System.Security.Cryptography.X509Certificates;

using System.Text.RegularExpressions;

using System.Web;

using System.IO.Compression;

using System.Collections.Specialized;

namespace Application.Study

{

    public class HttpHelper

    {

        /// <summary>

        /// 发起http请求（POST）

        /// </summary>

        /// <param name="Url"></param>

        /// <param name="Data"></param>

        /// <returns></returns>

        public static string SendPost(string Url, string Data)

        {

            return Send(Url, "POST", Data);

        }

        /// <summary>

        /// 发起http请求（GET）

        /// </summary>

        /// <param name="Url"></param>

        /// <returns></returns>

        public static string SendGet(string Url)

        {

            return Send(Url, "GET");

        }

        /// <summary>

        /// 发起请求

        /// </summary>

        /// <param name="url">目标地址</param>

        /// <param name="method">发起方式：GET/POST</param>

        /// <param name="data">发起时：附带数据</param>

        /// <param name="config">配置信息为空则默认配置</param>

        /// <returns>返回string</returns>

        public static string Send(string Url, string Method, string Data = null, HttpConfig Config = null)

        {

            if (Config == null)

            {

                Config = new HttpConfig();

            }

            string result;

            using (HttpWebResponse response = GetResponse(Url, Method, Data, Config))

            {

                Stream stream = response.GetResponseStream();

                if (!String.IsNullOrEmpty(response.ContentEncoding))

                {

                    if (response.ContentEncoding.Contains("gzip"))

                    {

                        stream = new GZipStream(stream, CompressionMode.Decompress);

                    }

                    else if (response.ContentEncoding.Contains("deflate"))

                    {

                        stream = new DeflateStream(stream, CompressionMode.Decompress);

                    }

                }

                byte[] bytes = null;

                using (MemoryStream ms = new MemoryStream())

                {

                    int count;

                    byte[] buffer = new byte[];

                    while ((count = stream.Read(buffer, , buffer.Length)) > )

                    {

                        ms.Write(buffer, , count);

                    }

                    bytes = ms.ToArray();

                }

                #region 检测流编码

                Encoding encoding;

                //检测响应头是否返回了编码类型,若返回了编码类型则使用返回的编码

                //注：有时响应头没有编码类型，CharacterSet经常设置为ISO-8859-1

                if (!string.IsNullOrEmpty(response.CharacterSet) && response.CharacterSet.ToUpper() != "ISO-8859-1")

                {

                    encoding = Encoding.GetEncoding(response.CharacterSet == "utf8" ? "utf-8" : response.CharacterSet);

                }

                else

                {

                    //若没有在响应头找到编码，则去html找meta头的charset

                    result = Encoding.Default.GetString(bytes);

                    //在返回的html里使用正则匹配页面编码

                    Match match = Regex.Match(result, @"<meta.*charset=""?([\w-]+)""?.*>", RegexOptions.IgnoreCase);

                    if (match.Success)

                    {

                        encoding = Encoding.GetEncoding(match.Groups[].Value);

                    }

                    else

                    {

                        //若html里面也找不到编码，默认使用utf-8

                        encoding = Encoding.GetEncoding(Config.CharacterSet);

                    }

                }

                #endregion

                result = encoding.GetString(bytes);

            }

            return result;

        }

        /// <summary>

        /// 获取目标网址的返回数据

        /// </summary>

        /// <param name="Url"></param>

        /// <param name="Method"></param>

        /// <param name="Data"></param>

        /// <param name="Config"></param>

        /// <returns></returns>

        private static HttpWebResponse GetResponse(string Url, string Method, string Data, HttpConfig Config)

        {

            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);

            request.Method = Method;

            request.Referer = Config.Referer;

            //有些页面不设置用户代理信息则会抓取不到内容

            request.UserAgent = Config.UserAgent;

            request.Timeout = Config.Timeout;

            request.Accept = Config.Accept;

            request.Headers.Set("Accept-Encoding", Config.AcceptEncoding);

            request.ContentType = Config.ContentType;

            request.KeepAlive = Config.KeepAlive;

            if (Url.ToLower().StartsWith("https"))

            {

                //这里加入解决生产环境访问https的问题--Could not establish trust relationship for the SSL/TLS secure channel

                ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(RemoteCertificateValidate);

            }

            if (Method.ToUpper() == "POST")

            {

                if (!string.IsNullOrEmpty(Data))

                {

                    byte[] DateBytes = Encoding.UTF8.GetBytes(Data);

                    if (Config.GZipCompress)

                    {

                        using (MemoryStream MRStream = new MemoryStream())

                        {

                            using (GZipStream gZipStream = new GZipStream(MRStream, CompressionMode.Compress))

                            {

                                gZipStream.Write(DateBytes, , DateBytes.Length);

                            }

                            DateBytes = MRStream.ToArray();

                        }

                    }

                    request.ContentLength = DateBytes.Length;

                    request.GetRequestStream().Write(DateBytes, , DateBytes.Length);

                }

                else

                {

                    request.ContentLength = ;

                }

            }

            return (HttpWebResponse)request.GetResponse();

        }

        /// <summary>

        /// 解决https 生产环境无法为SSL/TLS安全信道建立信任关系

        /// </summary>

        /// <param name="sender"></param>

        /// <param name="certificate"></param>

        /// <param name="chain"></param>

        /// <param name="errors"></param>

        /// <returns></returns>

        private static bool RemoteCertificateValidate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)

        {

            //用户https请求

            return true; //总是接受

        }

    }

    /// <summary>

    /// http配置信息

    /// </summary>

    public class HttpConfig

    {

        /// <summary>

        /// Referer http 表头值设置或获取

        /// </summary>

        public string Referer { get; set; }

        /// <summary>

        /// 默认(text/html)

        /// </summary>

        public string ContentType { get; set; }

        /// <summary>

        /// 配置值：Accept HTTP 标头的值。

        /// </summary>

        public string Accept { get; set; }

        /// <summary>

        /// 指定构成 HTTP 标头的名称/值对的集合。

        /// </summary>

        public string AcceptEncoding { get; set; }

        /// <summary>

        /// 超时时间(毫秒)默认60000

        /// </summary>

        public int Timeout { get; set; }

        /// <summary>

        /// User-Agent http表头值设置或获取

        /// </summary>

        public string UserAgent { get; set; }

        /// <summary>

        /// POST请求时，数据是否进行gzip压缩

        /// </summary>

        public bool GZipCompress { get; set; }

        /// <summary>

        /// 持久连接

        /// </summary>

        public bool KeepAlive { get; set; }

        public string CharacterSet { get; set; }

        public HttpConfig()

        {

            this.Timeout = ;

            this.ContentType = "text/html; charset=" + Encoding.UTF8.WebName;

            this.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.117 Safari/537.36";

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

            this.AcceptEncoding = "gzip,deflate";

            this.GZipCompress = false;

            this.KeepAlive = true;

            this.CharacterSet = "UTF-8";

        }

    }

}