using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace HttpUpload.Core
{
    class ImgExt
    {
        public static FileExtension CheckImgFile(string fileName)
        {
            FileStream fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
            System.IO.BinaryReader br = new System.IO.BinaryReader(fs);
            string fileType = string.Empty;
            FileExtension extension;
            try
            {
                byte data = br.ReadByte();
                fileType += data.ToString();
                data = br.ReadByte();
                fileType += data.ToString();
                try
                {
                    extension = (FileExtension)Enum.Parse(typeof(FileExtension), fileType);
                }
                catch
                {

                    extension = FileExtension.VALIDFILE;
                }
            }
            catch
            {
                extension = FileExtension.VALIDFILE;
            }
            finally
            {
                if (fs != null)
                {
                    fs.Close();
                    br.Close();
                }
            }
            return extension;
        }
        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;
        }
        public static FileExtension CheckImgFile(byte[] bytes)
        {
            string fileType = string.Empty;
            FileExtension extension;
            try
            {
                if (bytes.Length <= 2) { return FileExtension.VALIDFILE; }
                byte data = bytes[0];
                fileType += data.ToString();
                data = bytes[1];
                fileType += data.ToString();
                try
                {
                    extension = (FileExtension)Enum.Parse(typeof(FileExtension), fileType);
                }
                catch
                {

                    extension = FileExtension.VALIDFILE;
                }
            }
            catch
            {
                extension = FileExtension.VALIDFILE;
            }
            finally
            {
            }
            return extension;
        }
    }
    public enum FileExtension
    {
        JPG = 255216,
        GIF = 7173,
        PNG = 13780,
        SWF = 6787,
        RAR = 8297,
        ZIP = 8075,
        _7Z = 55122,
        WebP = 8273,
        BMP = 6677,
        VALIDFILE = 9999999
        // 255216 jpg;  

        // 7173 gif;  

        // 6677 bmp,  

        // 13780 png;  

        // 6787 swf  

        // 7790 exe dll,  

        // 8297 rar  

        // 8075 zip  

        // 55122 7z  

        // 6063 xml  

        // 6033 html  

        // 239187 aspx  

        // 117115 cs  

        // 119105 js  

        // 102100 txt  

        // 255254 sql   
    }
}