using System.Collections.Generic;
using System.Text;
using System.Security.Cryptography;
using System.Web;

namespace Jd.ACES.Utils
{
    public class WebUtils
    {
        /// <summary>
        /// 给Jd请求签名。
        /// </summary>
        /// <param name="parameters">所有字符型的Jd请求参数</param>
        /// <param name="secret">签名密钥</param>
        /// <param name="qhs">是否前后都加密钥进行签名</param>
        /// <returns>签名</returns>
        public static string SignJdRequest(IDictionary<string, string> parameters, string secret, bool qhs)
        {
            // 第一步：把字典按Key的字母顺序排序
            IDictionary<string, string> sortedParams = new SortedDictionary<string, string>(parameters);
            IEnumerator<KeyValuePair<string, string>> dem = sortedParams.GetEnumerator();

            // 第二步：把所有参数名和参数值串在一起
            StringBuilder query = new StringBuilder(secret);
            while (dem.MoveNext())
            {
                string key = dem.Current.Key;
                string value = dem.Current.Value;
                if (!string.IsNullOrEmpty(key) && !string.IsNullOrEmpty(value))
                {
                    query.Append(key).Append(value);
                }
            }
            if (qhs)
            {
                query.Append(secret);
            }
            // 第三步：使用MD5加密
            MD5 md5 = MD5.Create();
            byte[] bytes = md5.ComputeHash(Encoding.UTF8.GetBytes(query.ToString()));

            // 第四步：把二进制转化为大写的十六进制
            StringBuilder result = new StringBuilder();
            for (int i = 0; i < bytes.Length; i++)
            {
                result.Append(bytes[i].ToString("X2"));
            }

            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)
        {
            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();
        }
    }
}