using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace DG.Tool
{
    public static class SignHelper
    {
        /// <summary>
        /// 计算签名
        /// </summary>
        /// <param name="param"></param>
        /// <param name="timestamps"></param>
        /// <returns></returns>
        public static string GetSign(string appId, string appSecret, Dictionary<string, object> param, string timestamps)
        {

            //一次排序
            var newP = param.OrderBy(m => m.Key).ToDictionary(m => m.Key, n => n.Value);
            var pJosn = JsonHelper.ToJson(newP);

            //二次排序
            var enStrList = new string[] { appId, pJosn, appSecret, timestamps };
            Array.Sort(enStrList, string.CompareOrdinal);

            //拼接
            var enStr = string.Join("", enStrList);
            //md5 加密
            return GetMd5Hash(enStr);
        }
        /// <summary>
        ///  计算 md5
        /// </summary>
        /// <param name="enCode"></param>
        /// <returns></returns>
        private static string GetMd5Hash(string enCode)
        {
            string res = "";
            byte[] data = Encoding.GetEncoding("utf-8").GetBytes(enCode);
            MD5 md5 = MD5.Create();
            byte[] bytes = md5.ComputeHash(data);
            for (int i = 0; i < bytes.Length; i++)
            {
                res += bytes[i].ToString("x2");
            }
            return res;
        }
        /// <summary>
        /// 获取时间戳
        /// </summary>
        /// <returns></returns>
        public static string GetTimeStamp()
        {
            TimeSpan ts = DateTime.Now - new DateTime(1970, 1, 1, 0, 0, 0, 0);
            return Convert.ToInt64(ts.TotalSeconds).ToString();
        }
    }
}