using System;
using System.IO;
using System.Text;

namespace AllBase
{

    /// <summary>
    /// 实现Base64加密解密
    /// 作者：周公
    /// 时间：2007
    /// </summary>
    public static class Base64Encode
    {
        /// <summary>
        /// Base64加密
        /// </summary>
        /// <param name="codeName">加密采用的编码方式</param>
        /// <param name="source">待加密的明文</param>
        /// <returns></returns>
        public static string EncodeBase64(Encoding encode, string source)
        {
            byte[] bytes = encode.GetBytes(source);
            try
            {
                string code = Convert.ToBase64String(bytes);
                return code;
            }
            catch
            {
                return source;
            }
            
        }

        /// <summary>
        /// Base64加密，采用utf8编码方式加密
        /// </summary>
        /// <param name="source">待加密的明文</param>
        /// <returns>加密后的字符串</returns>
        public static string EncodeBase64(string source)
        {
            return EncodeBase64(Encoding.UTF8, source);
        }

        /// <summary>
        /// Base64解密
        /// </summary>
        /// <param name="codeName">解密采用的编码方式，注意和加密时采用的方式一致</param>
        /// <param name="result">待解密的密文</param>
        /// <returns>解密后的字符串</returns>
        public static string DecodeBase64(Encoding encode, string result)
        {
            string decode = "";
            byte[] bytes = Convert.FromBase64String(result);
            try
            {
                decode = encode.GetString(bytes);
            }
            catch
            {
                decode = result;
            }
            return decode;
        }

        /// <summary>
        /// Base64解密，采用utf8编码方式解密
        /// </summary>
        /// <param name="result">待解密的密文</param>
        /// <returns>解密后的字符串</returns>
        public static string DecodeBase64(string result)
        {
            return DecodeBase64(Encoding.UTF8, result);
        }

        /// <summary>
        /// 文件转Base64编码
        /// </summary>
        /// <param name="fileName">文件全路径</param>
        /// <returns></returns>
        public static string DocumentToBase64Str(string fileName)
        {
            FileStream filestream = new FileStream(fileName, FileMode.Open);

            byte[] bt = new byte[filestream.Length];
            //调用read读取方法
            filestream.Read(bt, 0, bt.Length);
            string base64Str = Convert.ToBase64String(bt);
            filestream.Close();
            return base64Str;
        }

        /// <summary>
        /// Base64字符串转文件并保存
        /// </summary>
        /// <param name="base64String">base64字符串</param>
        /// /// <param name="fileFullPath">保存的文件路径 </param>
        /// <param name="fileName">保存的文件名</param>
        /// <returns>是否转换并保存成功</returns>
        public static bool Base64StringToFile(string base64String, string fileFullPath, string fileName)
        {
            bool opResult = false;
            try
            {

                if (!Directory.Exists(fileFullPath))
                {
                    Directory.CreateDirectory(fileFullPath);
                }
                MemoryStream stream = new MemoryStream(Convert.FromBase64String(base64String));
                FileStream fs = new FileStream(fileFullPath + "\\" + fileName, FileMode.OpenOrCreate, FileAccess.Write);
                byte[] b = stream.ToArray();
                fs.Write(b, 0, b.Length);
                fs.Close();

                opResult = true;
            }
            catch (Exception e)
            {

            }
            return opResult;
        }
    }
}