using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace System
{
    /// <summary>
    /// 封装的一些通用方法
    /// </summary>
    public class RSA_Unit
    {
        static public string Base64EncodeBytes(byte[] byts)
        {
            return Convert.ToBase64String(byts);
        }
        static public byte[] Base64DecodeBytes(string str)
        {
            try
            {
                return Convert.FromBase64String(str);
            }
            catch
            {
                return null;
            }
        }
        /// <summary>
        /// 把字符串按每行多少个字断行
        /// </summary>
        static public string TextBreak(string text, int line)
        {
            var idx = 0;
            var len = text.Length;
            var str = new StringBuilder();
            while (idx < len)
            {
                if (idx > 0)
                {
                    str.Append('\n');
                }
                if (idx + line >= len)
                {
                    str.Append(text.Substring(idx));
                }
                else
                {
                    str.Append(text.Substring(idx, line));
                }
                idx += line;
            }
            return str.ToString();
        }
    }

    static public class Extensions
    {
        /// <summary>
        /// 从数组start开始到指定长度复制一份
        /// </summary>
        static public T[] sub<T>(this T[] arr, int start, int count)
        {
            T[] val = new T[count];
            for (var i = 0; i < count; i++)
            {
                val[i] = arr[start + i];
            }
            return val;
        }
        static public void writeAll(this Stream stream, byte[] byts)
        {
            stream.Write(byts, 0, byts.Length);
        }
    }
}