using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Net;

namespace DotNet.Utilities
{

    #region 调用试例
    //    static void Main(string[] args)  
    //    {  
    //        string url = "www.baidu.com";  
    //        string param = "<request><param1></param1></request>";  
    //        string method="GET";  
     
    //        for (int i = 0; i < 1; i++)//发送多条请求看看会不会有问题。  
    //        {  
    //            var result = HttpUtility.Request(method, url, param, onComplete);  
    //            Console.WriteLine("-------------Result----------------");  
    //            Console.WriteLine(result);  
    //            Console.WriteLine("-------------End----------------");  
     
    //        }  
     
    //      Console.ReadLine();  
    //    }  
     
    //    /// <summary>  
    //    /// 请求完成后要执行的操作  
    //    /// </summary>  
    //    /// <param name="code">Http状态码</param>  
    //    /// <param name="result">返回结果</param>  
    //    public static void onComplete(HttpStatusCode code, string result)  
    //    {  
    //        Console.WriteLine("HttpRequest complete! as follow:");  
    //        Console.WriteLine("HttpStatusCode:" + code);  
    //        Console.WriteLine("HttpRequestResult:" + result);  
    //    }  
    #endregion

    /// <summary>  
    /// Http请求  
    /// </summary>  
    public class HttpUtility
    {
        /// <summary>  
        ///通用HttpWebRequest  
        /// </summary>  
        /// <param name="method">请求方式（POST/GET）</param>  
        /// <param name="url">请求地址</param>  
        /// <param name="param">请求参数</param>  
        /// <param name="onComplete">完成后执行的操作(可选参数，通过此方法可以获取到HTTP状态码)</param>  
        /// <returns>请求返回的结果</returns>  
        public static string Request(string method, string url, string param, Action<HttpStatusCode, string> onComplete = null)
        {
            if (string.IsNullOrEmpty(url))
                throw new ArgumentNullException("URL");

            switch (method.ToUpper())
            {
                case "POST":
                    return Post(url, param, onComplete);
                case "GET":
                    return Get(url, param, onComplete);
                default:
                    throw new EntryPointNotFoundException("method:" + method);
            }
        }

        /// <summary>  
        /// Post请求  
        /// </summary>  
        /// <param name="url">请求地址</param>  
        /// <param name="param">参数</param>  
        /// <param name="onComplete">完成后执行的操作(可选参数，通过此方法可以获取到HTTP状态码)</param>  
        /// <returns>请求返回的结果</returns>  
        public static string Post(string url, string param, Action<HttpStatusCode, string> onComplete = null)
        {
            UrlCheck(ref url);

            byte[] bufferBytes = Encoding.UTF8.GetBytes(param);

            var request = WebRequest.Create(url) as HttpWebRequest;//HttpWebRequest方法继承自WebRequest, Create方法在WebRequest中定义，因此此处要显示的转换  
            request.Method = "POST";
            request.ContentLength = bufferBytes.Length;
            request.ContentType = "application/x-www-form-urlencoded";

            try
            {
                using (var requestStream = request.GetRequestStream())
                {
                    requestStream.Write(bufferBytes, 0, bufferBytes.Length);
                }
            }
            catch (WebException ex)
            {

                return ex.Message;
            }

            return HttpRequest(request, onComplete);
        }

        /// <summary>  
        /// GET请求  
        /// </summary>  
        /// <param name="url">请求地址</param>  
        /// <param name="param">参数</param>  
        /// <param name="onComplete">完成后执行的操作(可选参数，通过此方法可以获取到HTTP状态码)</param>  
        /// <returns>请求返回结果</returns>  
        public static string Get(string url, string param, Action<HttpStatusCode, string> onComplete = null)
        {
            UrlCheck(ref url);

            if (!string.IsNullOrEmpty(param))
                if (!param.StartsWith("?"))
                    param += "?" + param;
                else
                    param += param;

            var request = WebRequest.Create(url) as HttpWebRequest;
            request.Method = "GET";
            request.ContentType = "application/x-www-form-urlencoded";

            return HttpRequest(request, onComplete);
        }

        /// <summary>  
        /// 请求的主体部分（由此完成请求并返回请求结果）  
        /// </summary>  
        /// <param name="request">请求的对象</param>  
        /// <param name="onComplete">完成后执行的操作(可选参数，通过此方法可以获取到HTTP状态码)</param>  
        /// <returns>请求返回结果</returns>  
        private static string HttpRequest(HttpWebRequest request, Action<HttpStatusCode, string> onComplete = null)
        {
            HttpWebResponse response = null;

            try
            {
                response = request.GetResponse() as HttpWebResponse;
            }
            catch (WebException ex)
            {
                response = ex.Response as HttpWebResponse;
            }

            if (response == null)
            {
                if (onComplete != null)
                    onComplete(HttpStatusCode.NotFound, "请求远程返回为空");
                return null;
            }

            string result = string.Empty;
            using (StreamReader reader = new StreamReader(response.GetResponseStream()))
            {
                result = reader.ReadToEnd();
            }

            if (onComplete != null)
                onComplete(response.StatusCode, result);

            return result;

        }

        /// <summary>  
        /// URL拼写完整性检查  
        /// </summary>  
        /// <param name="url">待检查的URL</param>  
        private static void UrlCheck(ref string url)
        {
            if (!url.StartsWith("http://") && !url.StartsWith("https://"))
                url = "http://" + url;
        }
    }  

}