using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Text;
using System.Web;
using System.Net.Security;
using System.Security.Authentication;
using System.Security.Cryptography.X509Certificates;

namespace cuidian.OpenApi.Http
{
    public sealed class WebUtils
    {
        private int _timeout = 100000;

        /// <summary>
        /// 请求与响应的超时时间
        /// </summary>
        public int Timeout
        {
            get { return this._timeout; }
            set { this._timeout = value; }
        }

        /// <summary>
        /// 执行HTTP POST请求。
        /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="parameters">请求参数</param>
        /// <returns>HTTP响应</returns>
        public HttpWebResponse Post(string url, IDictionary<string, string> parameters, string data)
        {
            if (parameters != null && parameters.Count > 0)
            {
                if (url.Contains("?"))
                {
                    url = url + "&" + BuildQuery(parameters);
                }
                else
                {
                    url = url + "?" + BuildQuery(parameters);
                }
            }

            HttpWebRequest req = GetWebRequest(url, "POST");
            req.ContentType = "application/json;charset=utf-8";

            byte[] postData = Encoding.UTF8.GetBytes(data);
            System.IO.Stream reqStream = req.GetRequestStream();
            reqStream.Write(postData, 0, postData.Length);
            reqStream.Close();

            return (HttpWebResponse)req.GetResponse();
        }

        /// <summary>
        /// 执行HTTP GET请求。
        /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="parameters">请求参数</param>
        /// <returns>HTTP响应</returns>
        public HttpWebResponse Get(string url, IDictionary<string, string> parameters)
        {
            if (parameters != null && parameters.Count > 0)
            {
                if (url.Contains("?"))
                {
                    url = url + "&" + BuildQuery(parameters);
                }
                else
                {
                    url = url + "?" + BuildQuery(parameters);
                }
            }

            Console.WriteLine("url:" + url);
            HttpWebRequest req = GetWebRequest(url, "GET");
            req.ContentType = "application/json;charset=utf-8";

            return (HttpWebResponse)req.GetResponse();
        }

        public bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
        { //直接确认，否则打不开
            return true;
        }

        public HttpWebRequest GetWebRequest(string url, string method)
        {
            HttpWebRequest req = null;
            if (url.Contains("https"))
            {
                ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
                req = (HttpWebRequest)WebRequest.CreateDefault(new Uri(url));
            }
            else
            {
                req = (HttpWebRequest)WebRequest.Create(url);
            }

            req.ServicePoint.Expect100Continue = false;
            req.Method = method;
            req.KeepAlive = true;
            req.UserAgent = "openapi4net:open.yonyouup.com";
            req.Timeout = this._timeout;

            return req;
        }

        /// <summary>
        /// 把响应流转换为文本。
        /// </summary>
        /// <param name="rsp">响应流对象</param>
        /// <param name="encoding">编码方式</param>
        /// <returns>响应文本</returns>
        public string GetResponseAsString(HttpWebResponse rsp, Encoding encoding)
        {
            System.IO.Stream stream = null;
            StreamReader reader = null;

            try
            {
                // 以字符流的方式读取HTTP响应
                stream = rsp.GetResponseStream();
                reader = new StreamReader(stream, encoding);
                return reader.ReadToEnd();
            }
            finally
            {
                // 释放资源
                if (reader != null) reader.Close();
                if (stream != null) stream.Close();
                if (rsp != null) rsp.Close();
            }
        }

        /// <summary>
        /// 组装GET请求URL。
        /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="parameters">请求参数</param>
        /// <returns>带参数的GET请求URL</returns>
        public string BuildGetUrl(string url, IDictionary<string, string> parameters)
        {
            if (parameters != null && parameters.Count > 0)
            {
                if (url.Contains("?"))
                {
                    url = url + "&" + BuildQuery(parameters);
                }
                else
                {
                    url = url + "?" + BuildQuery(parameters);
                }
            }
            return url;
        }

        /// <summary>
        /// 组装普通文本请求参数。
        /// </summary>
        /// <param name="parameters">Key-Value形式请求参数字典</param>
        /// <returns>URL编码后的请求数据</returns>
        public static string BuildQuery(IDictionary<string, string> parameters)
        {
            StringBuilder postData = new StringBuilder();
            bool hasParam = false;

            IEnumerator<KeyValuePair<string, string>> dem = parameters.GetEnumerator();
            while (dem.MoveNext())
            {
                string name = dem.Current.Key;
                string value = dem.Current.Value;
                // 忽略参数名或参数值为空的参数
                if (!string.IsNullOrEmpty(name) && !string.IsNullOrEmpty(value))
                {
                    if (hasParam)
                    {
                        postData.Append("&");
                    }

                    postData.Append(name);
                    postData.Append("=");
                    postData.Append(HttpUtility.UrlEncode(value, Encoding.UTF8));
                    hasParam = true;
                }
            }

            return postData.ToString();
        }
    }
}