using System;
using System.Drawing;
using System.IO;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Linq;
 
namespace file2jpg
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
 
        // 按钮1点击事件，选择文件并转换为图片
        private void button1_Click(object sender, EventArgs e)
        {
            using (OpenFileDialog openFileDialog1 = new OpenFileDialog())
            {
                if (openFileDialog1.ShowDialog() == DialogResult.OK)
                {
                    string inputFilePath = openFileDialog1.FileName;
                    ConvertFileToImage(inputFilePath);
                }
            }
        }
 
        // 将文件转换为图片
        private void ConvertFileToImage(string inputFilePath)
        {
            string outputImagePath = Path.Combine(Path.GetDirectoryName(inputFilePath), "output.png");
            byte[] fileBytes = File.ReadAllBytes(inputFilePath);
            int totalPixels = (fileBytes.Length * 8 + 23) / 24; // 计算所需的总像素数
            int width = (int)Math.Ceiling(Math.Sqrt(totalPixels)); // 计算图片宽度
            int height = (int)Math.Ceiling((double)totalPixels / width); // 计算图片高度
 
            using (Bitmap bitmap = new Bitmap(width, height))
            {
                int byteIndex = 0;
                int bitOffset = 0;
 
                for (int y = 0; y < height; y++)
                {
                    for (int x = 0; x < width; x++)
                    {
                        if (byteIndex >= fileBytes.Length)
                        {
                            bitmap.SetPixel(x, y, Color.Black); // 如果文件读取完毕，设置像素为黑色
                            continue;
                        }
 
                        int r = GetNextByte(fileBytes, ref byteIndex, ref bitOffset);
                        int g = GetNextByte(fileBytes, ref byteIndex, ref bitOffset);
                        int b = GetNextByte(fileBytes, ref byteIndex, ref bitOffset);
 
                        Color color = Color.FromArgb(r, g, b);
                        bitmap.SetPixel(x, y, color); // 设置像素颜色
                    }
                }
 
                bitmap.Save(outputImagePath, System.Drawing.Imaging.ImageFormat.Png); // 保存图片
            }
 
            MessageBox.Show("图片已保存为 " + outputImagePath);
        }
 
        // 获取下一个字节
        private int GetNextByte(byte[] bytes, ref int byteIndex, ref int bitOffset)
        {
            int value = 0;
            for (int i = 0; i < 8; i++)
            {
                if (byteIndex >= bytes.Length)
                    break;
 
                int bit = (bytes[byteIndex] >> (7 - bitOffset)) & 1;
                value = (value << 1) | bit;
 
                bitOffset++;
                if (bitOffset == 8)
                {
                    bitOffset = 0;
                    byteIndex++;
                }
            }
            return value;
        }
 
        // 按钮2点击事件，选择图片并恢复为文件
        private void button2_Click(object sender, EventArgs e)
        {
            using (OpenFileDialog openFileDialog2 = new OpenFileDialog())
            {
                openFileDialog2.Filter = "PNG Image|*.png";
                if (openFileDialog2.ShowDialog() == DialogResult.OK)
                {
                    string pngFilePath = openFileDialog2.FileName;
                    RestoreImageToFile(pngFilePath);
                }
            }
        }
 
        // 从图片恢复文件
        private void RestoreImageToFile(string pngFilePath)
        {
            string outputDirectory = Path.GetDirectoryName(pngFilePath);
            string outputFilePath = Path.Combine(outputDirectory, "restored_file");
 
            using (Bitmap bitmap = new Bitmap(pngFilePath))
            {
                int width = bitmap.Width;
                int height = bitmap.Height;
 
                using (MemoryStream memoryStream = new MemoryStream())
                {
                    for (int y = 0; y < height; y++)
                    {
                        for (int x = 0; x < width; x++)
                        {
                            Color color = bitmap.GetPixel(x, y);
                            memoryStream.WriteByte(color.R);
                            memoryStream.WriteByte(color.G);
                            memoryStream.WriteByte(color.B);
                        }
                    }
 
                    byte[] fileBytes = memoryStream.ToArray();
 
                    int index = Array.IndexOf(fileBytes, (byte)'5');
                    if (index != -1 && index <= fileBytes.Length - 4 && fileBytes[index + 1] == (byte)'2' && fileBytes[index + 2] == (byte)'P' && fileBytes[index + 3] == (byte)'J')
                    {
                        string fileNameWithExtension = System.Text.Encoding.Default.GetString(fileBytes, index, fileBytes.Length - index);
                        string originalFileName = fileNameWithExtension.Substring(0, fileNameWithExtension.Length - 4);
                        string originalExtension = Path.GetExtension(originalFileName);
 
                        originalFileName = originalFileName.Substring(0, originalFileName.Length - originalExtension.Length);
                        string restoredFilePath = Path.Combine(outputDirectory, originalFileName + originalExtension);
 
                        int count = 1;
                        while (File.Exists(restoredFilePath))
                        {
                            restoredFilePath = Path.Combine(outputDirectory, $"{originalFileName} ({count++}){originalExtension}");
                        }
 
                        File.WriteAllBytes(restoredFilePath, fileBytes.Take(index).ToArray());
                        MessageBox.Show("文件已恢复为 " + restoredFilePath);
                    }
                    else
                    {
                        File.WriteAllBytes(outputFilePath, fileBytes);
                        MessageBox.Show("未找到加密文件名，文件已恢复为 " + outputFilePath);
                    }
                }
            }
        }
    }
}