using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;
using System.Text;

namespace RunUpdater.Lib
{
    public class HttpHelper
    {
        #region 方法 -> 检查网站是否可以访问
        /// <summary>
        /// 检查网站是否可以访问
        /// </summary>
        /// <param name="ConnectUrl"></param>
        /// <returns></returns>
        public static bool UrlIsExist(string ConnectUrl)
        {
            try
            {
                // Creates an HttpWebRequest for the specified URL.
                HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(ConnectUrl);
                myHttpWebRequest.Timeout = 3 * 1000;
                // 有些网站会阻止程序访问，需要加入下面这句
                myHttpWebRequest.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko";
                myHttpWebRequest.Method = "GET";
                // Sends the HttpWebRequest and waits for a response.
                HttpWebResponse myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse();
                if (myHttpWebResponse.StatusCode == HttpStatusCode.OK)
                {
                    myHttpWebResponse.Close();
                    return true;
                }
                else
                {
                    myHttpWebResponse.Close();
                    return false;
                }
                // Releases the resources of the response.
            }
            catch
            {
                return false;
            }
        }
        #endregion

        ///<summary>
        /// 获取标准北京时间
        ///</summary>
        ///<returns>
        ///<para>成功：返回服务器当前时间</para>
        ///<para>失败：返回DateTime.MinValue</para>
        ///</returns>
        public static DateTime GetBeijingTime(string timeServerURL, DateTime localDate)
        {
            DateTime date_Server = localDate;
            try
            {
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(timeServerURL);
                request.Timeout = 3 * 1000;
                request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko";
                request.Method = "HEAD";
                request.AllowAutoRedirect = false;
                using (HttpWebResponse reponse = (HttpWebResponse)request.GetResponse())
                {
                    if (DateTime.TryParseExact(reponse.GetResponseHeader("date"), "r", new CultureInfo("en-US"),
                        DateTimeStyles.None, out DateTime gmtTime))
                    {
                        date_Server = gmtTime.ToLocalTime(); //GMT要加8个小时才是北京时间
                    }
                    reponse.Close();
                }
            }
            catch (WebException ex)
            {
                if (DateTime.TryParseExact(ex.Response.Headers.Get("Date"), "r", new CultureInfo("en-US"),
                    DateTimeStyles.None, out DateTime gmtTime))
                {
                    date_Server = gmtTime.ToLocalTime(); //GMT要加8个小时才是北京时间
                }
            }
            return date_Server;
        }
        #region 方法 -> HttpPost

        /// <summary>
        /// Post请求方法
        /// </summary>
        /// <param name="postData"></param>
        /// <param name="requestURL"></param>
        /// <param name="contentType"></param>
        /// <param name="timeOut"></param>
        /// <returns></returns>
        public static string HttpPost(string postData, string requestURL, string contentType = "application/x-www-form-urlencoded", int timeOut = 0)
        {
            try
            {
                CookieContainer cookieContainer = new CookieContainer();
                byte[] postBytes = Encoding.UTF8.GetBytes(postData);
                // 设置提交的相关参数
                ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(requestURL);
                if (timeOut == 0)
                {
                    timeOut = 5;
                }
                request.Timeout = timeOut * 1000;
                request.Method = "POST";
                request.KeepAlive = false;
                request.ContentType = contentType;
                request.CookieContainer = cookieContainer;
                request.ContentLength = postBytes.Length;

                using (Stream reqStream = request.GetRequestStream())
                {
                    //LogHelper.WriteSendLog("==开始写数据==");
                    reqStream.Write(postBytes, 0, postBytes.Length);
                    //LogHelper.WriteSendLog("==写入完成==");
                }
                using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
                {
                    //在这里对接收到的页面内容进行处理
                    //直到request.GetResponse()程序才开始向目标网页发送post请求
                    Stream responseStream = response.GetResponseStream();
                    using (StreamReader reader = new StreamReader(responseStream, Encoding.UTF8))
                    {
                        return reader.ReadToEnd();
                    }
                }
            }
            catch (WebException wex)
            {
                return wex.ToString();
            }
            catch (Exception ex)
            {
                return ex.Message;
            }
        }

        private static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
        {
            return true;
        }
        #endregion

    }
}