using System;

using System.Collections.Generic;

using System.IO;

using System.Net;

using System.Text;

using System.Web;

namespace ICE.Common

{

    /// <summary>

    /// 网络工具类。

    /// </summary>

    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>

        /// <param name="charset">编码字符集</param>

        /// <returns>HTTP响应</returns>

        public string DoPost(string url, IDictionary<string, string> parameters, string charset)

        {

            HttpWebRequest req = GetWebRequest(url, "POST");

            req.ContentType = "application/x-www-form-urlencoded;charset=" + charset;

            byte[] postData = Encoding.GetEncoding(charset).GetBytes(BuildQuery(parameters, charset));

            Stream reqStream = req.GetRequestStream();

            reqStream.Write(postData, 0, postData.Length);

            reqStream.Close();

            HttpWebResponse rsp = (HttpWebResponse)req.GetResponse();

            Encoding encoding = Encoding.GetEncoding(rsp.CharacterSet);

            return GetResponseAsString(rsp, encoding);

        }

        public string DoPost(string url, string requestBody, string charset)

        {

            HttpWebRequest req = GetWebRequest(url, "POST");

            req.ContentType = "application/x-www-form-urlencoded;charset=" + charset;

            byte[] postData = Encoding.GetEncoding(charset).GetBytes(requestBody);

            Stream reqStream = req.GetRequestStream();

            reqStream.Write(postData, 0, postData.Length);

            reqStream.Close();

            HttpWebResponse rsp = (HttpWebResponse)req.GetResponse();

            Encoding encoding = Encoding.GetEncoding(rsp.CharacterSet);

            return GetResponseAsString(rsp, encoding);

        }

        /// <summary>

        /// 执行HTTP GET请求。

        /// </summary>

        /// <param name="url">请求地址</param>

        /// <param name="parameters">请求参数</param>

        /// <param name="charset">编码字符集</param>

        /// <returns>HTTP响应</returns>

        public string DoGet(string url, IDictionary<string, string> parameters, string charset)

        {

            if (parameters != null && parameters.Count > 0)

            {

                if (url.Contains("?"))

                {

                    url = url + "&" + BuildQuery(parameters,charset);

                }

                else

                {

                    url = url + "?" + BuildQuery(parameters, charset);

                }

            }

            HttpWebRequest req = GetWebRequest(url, "GET");

            req.ContentType = "application/x-www-form-urlencoded;charset=" + charset;

            HttpWebResponse rsp = (HttpWebResponse)req.GetResponse();

            Encoding encoding = Encoding.GetEncoding(rsp.CharacterSet);

            return GetResponseAsString(rsp, encoding);

        }         

        public HttpWebRequest GetWebRequest(string url, string method)

        {

            HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);

            req.ServicePoint.Expect100Continue = false;

            req.Method = method;

            req.KeepAlive = true;

            req.UserAgent = "Aop4Net";

            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)

        {

            StringBuilder result = new StringBuilder();

            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);

                // 按字符读取并写入字符串缓冲

                int ch = -1;

                while ((ch = reader.Read()) > -1)

                {

                    // 过滤结束符

                    char c = (char)ch;

                    if (c != '\0')

                    {

                        result.Append(c);

                    }

                }

            }

            finally

            {

                // 释放资源

                if (reader != null) reader.Close();

                if (stream != null) stream.Close();

                if (rsp != null) rsp.Close();

            }

            return result.ToString();

        }

        /// <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, string charset)

        {

            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("=");

                    string encodedValue = HttpUtility.UrlEncode(value, Encoding.GetEncoding(charset));

                    postData.Append(encodedValue);

                    hasParam = true;

                }

            }

            return postData.ToString();

        }

    }

}