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

namespace WebAPIBase.Utils
{
    public class UploadFileHelper
    {
        /// <summary>
        /// 流文件到字节的转变
        /// </summary>
        /// <param name="stream"></param>
        /// <returns></returns>
        public static byte[] StreamToBytes(Stream stream)
        {
            byte[] bytes = new byte[stream.Length];
            stream.Read(bytes, 0, bytes.Length);
            // 设置当前流的位置为流的开始 
            stream.Seek(0, SeekOrigin.Begin);
            return bytes;
        }
        /// <summary>
        /// 字节到流文件的转变
        /// </summary>
        /// <param name="bytes"></param>
        /// <returns></returns>
        public static Stream BytesToStream(byte[] bytes)
        {
            Stream stream = new MemoryStream(bytes);
            return stream;
        }
        /// <summary>
        /// 流文件转换为文件存入磁盘
        /// </summary>
        /// <param name="stream"></param>
        /// <param name="fileName"></param>
        public static void StreamToFile(Stream stream, string fileName)
        {
            // 把 Stream 转换成 byte[] 
            byte[] bytes = new byte[stream.Length];
            stream.Read(bytes, 0, bytes.Length);
            // 设置当前流的位置为流的开始 
            stream.Seek(0, SeekOrigin.Begin);
            // 把 byte[] 写入文件 
            FileStream fs = new FileStream(fileName, FileMode.Create);
            BinaryWriter bw = new BinaryWriter(fs);
            bw.Write(bytes);
            bw.Close();
            fs.Close();
        }

        /// <summary>
        /// 文件读取成stream
        /// </summary>
        /// <param name="fileName"></param>
        /// <returns></returns>
        public static Stream FileToStream(string fileName)
        {
            // 打开文件 
            FileStream fileStream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);
            // 读取文件的 byte[] 
            byte[] bytes = new byte[fileStream.Length];
            fileStream.Read(bytes, 0, bytes.Length);
            fileStream.Close();
            // 把 byte[] 转换成 Stream 
            Stream stream = new MemoryStream(bytes);
            return stream;
        }
    }
}