using System;
using System.Security.Cryptography;
using System.Text;

namespace OS.Common.Encrypt
{
    /// <summary>
    /// MD5加密类
    /// </summary>
    public static class Md5
    {
        /// <summary>
        /// 获取16位MD5值
        /// </summary>
        /// <param name="input"></param>
        /// <returns></returns>
        public static string HalfEncryptHexString(string input)
        {
            string result = EncryptHexString(input);

            if (!string.IsNullOrEmpty(result))
            {
                return result.Substring(0, 16);
            }
            return result;
        }


        /// <summary>
        /// 获取MD5加密值
        /// </summary>
        /// <param name="input"></param>
        /// <param name="encoding"></param>
        /// <returns></returns>
        public static string EncryptHexString(string input, Encoding encoding = null)
        {
            if (string.IsNullOrEmpty(input))
                throw new ArgumentNullException("input", "MD5加密的字符串不能为空！");

            if (encoding == null)
                encoding = Encoding.UTF8;

            var data = encoding.GetBytes(input);
            var encryData = Encrypt(data);

            StringBuilder sBuilder = new StringBuilder();
            for (int i = 0; i < encryData.Length; i++)
            {
                sBuilder.Append(encryData[i].ToString("x2"));
            }

            // Return the hexadecimal string.
            return sBuilder.ToString();

        }


        /// <summary>
        /// 获取MD5加密值
        /// </summary>
        /// <param name="bytes"></param>
        /// <returns></returns>
        public static byte[] Encrypt(byte[] bytes)
        {
            if (bytes == null || bytes.Length == 0)
                throw new ArgumentNullException("bytes","MD5加密的字节不能为空！");
            
            using (MD5 md5Hash = MD5.Create())
            {
                return md5Hash.ComputeHash(bytes);
            }
        }




    }
}