using UnityEngine;
using System.IO;
using BitMiracle.LibTiff.Classic;

public class TiffFileConverterWithLibrary : MonoBehaviour
{
    public string pngPath;
    public string tiffPath;

    [ContextMenu("ConvertPngFileToTiff")]
    void PNG()
    {
        ConvertPngFileToTiff(pngPath, tiffPath);
    }

    /// <summary>
    /// 从文件路径加载 PNG，并使用 LibTiff.Net 将其转换为 TIFF 文件。
    /// </summary>
    /// <param name="pngFilePath">源 PNG 文件的完整路径。</param>
    /// <param name="outputTiffPath">目标 TIFF 文件的输出路径。</param>
    public static void ConvertPngFileToTiff(string pngFilePath, string outputTiffPath)
    {
        if (!File.Exists(pngFilePath))
        {
            Debug.LogError($"Source PNG file not found at: {pngFilePath}");
            return;
        }

        // 步骤 1: 读取 PNG 文件数据并加载到 Texture2D
        byte[] fileData = File.ReadAllBytes(pngFilePath);
        // 创建一个临时的 Texture2D。尺寸无关紧要，LoadImage 会自动调整。
        Texture2D pngTexture = new Texture2D(2, 2); 
        
        // LoadImage 会自动解码 PNG 数据并填充 Texture2D
        if (!pngTexture.LoadImage(fileData))
        {
            Debug.LogError("Failed to load PNG data into Texture2D.");
            return;
        }

        // 步骤 2: 从 Texture2D 提取像素数据并使用 LibTiff.Net 写入 TIFF 文件
        int width = pngTexture.width;
        int height = pngTexture.height;

        try
        {
            using (Tiff tiff = Tiff.Open(outputTiffPath, "w"))
            {
                if (tiff == null)
                {
                    Debug.LogError("Could not open TIFF file for writing.");
                    return;
                }

                tiff.SetField(TiffTag.IMAGEWIDTH, width);
                tiff.SetField(TiffTag.IMAGELENGTH, height);
                tiff.SetField(TiffTag.SAMPLESPERPIXEL, 4); // RGBA
                tiff.SetField(TiffTag.BITSPERSAMPLE, 8);
                tiff.SetField(TiffTag.ORIENTATION, Orientation.TOPLEFT);
                tiff.SetField(TiffTag.ROWSPERSTRIP, height);
                tiff.SetField(TiffTag.XRESOLUTION, 88.0);
                tiff.SetField(TiffTag.YRESOLUTION, 88.0);
                tiff.SetField(TiffTag.RESOLUTIONUNIT, ResUnit.INCH);
                tiff.SetField(TiffTag.PLANARCONFIG, PlanarConfig.CONTIG);
                tiff.SetField(TiffTag.PHOTOMETRIC, Photometric.RGB);
                tiff.SetField(TiffTag.COMPRESSION, Compression.LZW);

                Color32[] pixels = pngTexture.GetPixels32();
                byte[] raster = new byte[width * height * 4];
                
                // LibTiff 需要的像素顺序可能与 Unity 不同，需要垂直翻转
                for (int y = 0; y < height; y++)
                {
                    for (int x = 0; x < width; x++)
                    {
                        Color32 pixel = pixels[(height - 1 - y) * width + x];
                        int index = (y * width + x) * 4;
                        raster[index] = pixel.r;
                        raster[index + 1] = pixel.g;
                        raster[index + 2] = pixel.b;
                        raster[index + 3] = pixel.a;
                    }
                }
                
                tiff.WriteEncodedStrip(0, raster, raster.Length);
                tiff.Close();

                Debug.Log($"Successfully converted file '{pngFilePath}' to '{outputTiffPath}' using LibTiff.Net");
            }
        }
        catch (System.Exception ex)
        {
            Debug.LogError($"Failed to convert PNG file to TIFF using LibTiff.Net: {ex.Message}");
        }
        finally
        {
            // 销毁临时的 Texture2D 对象以释放内存
            Object.Destroy(pngTexture);
        }
    }

    // 示例用法
    void Start()
    {
        return;
        string sourcePngPath = Path.Combine(Application.streamingAssetsPath, "YourImage.png");
        string destinationTiffPath = Path.Combine(Application.persistentDataPath, "output_from_file_libtiff.tif");

        #if UNITY_EDITOR || UNITY_STANDALONE
        ConvertPngFileToTiff(sourcePngPath, destinationTiffPath);
        #else
        Debug.LogWarning("Direct file access to StreamingAssets might not work on this platform.");
        #endif
    }
}