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

namespace EC.Utils.Security
{
	/// <summary>
	/// md5加密
	/// </summary>
	public class Md5Helper
	{
		/// <summary>
		/// MD5加密
		/// </summary>
		/// <param name="str">加密字符</param>
		/// <param name="len">加密位数16/32</param>
		/// <returns></returns>
		public static string Encrypt(string str, int len)
		{
			string encryptStr;
			switch (len)
			{
				case 16:
					encryptStr = Hash(str).Substring(8, 16);
					break;

				case 32:
					encryptStr = Hash(str);
					break;

				default:
					encryptStr = Hash(str);
					break;
			}
			return encryptStr;
		}

		/// <summary>
		/// 32位MD5加密（小写）
		/// </summary>
		/// <param name="str">输入字段</param>
		/// <returns></returns>
		public static string Hash(string str)
		{
			var md5Hasher = new MD5CryptoServiceProvider();
			var byteArray = md5Hasher.ComputeHash(Encoding.Default.GetBytes(str));
			var builder = new StringBuilder();
			foreach (var b in byteArray)
			{
				builder.Append(b.ToString("x2"));
			}
			return builder.ToString();
		}

		/// <summary>
		/// 生成编号，形如201008251145409865
		/// </summary>
		/// <returns></returns>
		public static string CreateNo()
		{
			var randomStr = new Random().Next(1000, 10000).ToString(); //生成编号
			var number = DateTime.Now.ToString("yyyyMMddHHmmss") + randomStr;
			return number;
		}
	}
}