#if UNITY_EDITOR
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using UnityEditor;
using UnityEngine;

public class DDSMultiSpriteConverter : EditorWindow
{
    [SerializeField] private List<Texture2D> _ddsTextures = new List<Texture2D>();
    [SerializeField] private bool _autoArrange = true;
    [SerializeField] private int _paddingPixels = 2;
    [SerializeField] private float _pixelsPerUnit = 100f;
    [SerializeField] private string _outputFolder = "Assets/GeneratedSprites";
    [SerializeField] private string _atlasName = "DDSAtlas";
    [SerializeField] private bool _keepOriginalNames = true;
    [SerializeField] private bool _createSpriteAtlas = true;
    
    private Vector2 _scrollPosition;
    private string _status = "";
    private bool _isProcessing = false;

    [MenuItem("Tools/Sprites/Convert DDS Files to Multi-Sprite")]
    private static void Open()
    {
        var window = GetWindow<DDSMultiSpriteConverter>("DDS Multi-Sprite Converter");
        window.minSize = new Vector2(500, 400);
        window.Show();
    }

    private void OnGUI()
    {
        EditorGUILayout.LabelField("DDS Multi-Sprite Converter", EditorStyles.boldLabel);
        EditorGUILayout.Space();

        // Input Section
        EditorGUILayout.LabelField("Input DDS Files", EditorStyles.boldLabel);
        EditorGUILayout.HelpBox("Use 'Add DDS Files' for individual files or 'Add Folder' to process all .dds files in a folder (including subfolders).", MessageType.Info);
        
        EditorGUILayout.BeginHorizontal();
        if (GUILayout.Button("Add DDS Files", GUILayout.Height(25)))
        {
            AddDDSFiles();
        }
        if (GUILayout.Button("Add Folder", GUILayout.Height(25)))
        {
            AddDDSFolder();
        }
        if (GUILayout.Button("Clear All", GUILayout.Height(25)))
        {
            _ddsTextures.Clear();
            _status = "";
        }
        EditorGUILayout.EndHorizontal();

        // Display selected textures
        if (_ddsTextures.Count > 0)
        {
            EditorGUILayout.Space();
            EditorGUILayout.LabelField($"Selected Files ({_ddsTextures.Count}):", EditorStyles.miniLabel);
            
            _scrollPosition = EditorGUILayout.BeginScrollView(_scrollPosition, GUILayout.Height(150));
            for (int i = 0; i < _ddsTextures.Count; i++)
            {
                EditorGUILayout.BeginHorizontal();
                
                var texture = _ddsTextures[i];
                if (texture != null)
                {
                    EditorGUILayout.LabelField($"{i + 1}. {texture.name}", GUILayout.Width(200));
                    EditorGUILayout.LabelField($"{texture.width}x{texture.height}", GUILayout.Width(80));
                    
                    if (GUILayout.Button("Remove", GUILayout.Width(60)))
                    {
                        _ddsTextures.RemoveAt(i);
                        i--;
                    }
                }
                else
                {
                    EditorGUILayout.LabelField($"{i + 1}. <Missing Texture>", GUILayout.Width(200));
                    if (GUILayout.Button("Remove", GUILayout.Width(60)))
                    {
                        _ddsTextures.RemoveAt(i);
                        i--;
                    }
                }
                
                EditorGUILayout.EndHorizontal();
            }
            EditorGUILayout.EndScrollView();
        }

        EditorGUILayout.Space();

        // Settings Section
        EditorGUILayout.LabelField("Settings", EditorStyles.boldLabel);
        
        _autoArrange = EditorGUILayout.ToggleLeft("Auto-arrange sprites in atlas", _autoArrange);
        _paddingPixels = EditorGUILayout.IntField("Padding (pixels)", _paddingPixels);
        _pixelsPerUnit = EditorGUILayout.FloatField("Pixels Per Unit", _pixelsPerUnit);
        _keepOriginalNames = EditorGUILayout.ToggleLeft("Keep original DDS names", _keepOriginalNames);
        _createSpriteAtlas = EditorGUILayout.ToggleLeft("Create Sprite Atlas asset", _createSpriteAtlas);
        
        EditorGUILayout.Space();
        
        EditorGUILayout.LabelField("Output", EditorStyles.boldLabel);
        
        EditorGUILayout.BeginHorizontal();
        EditorGUILayout.LabelField("Output Folder:", GUILayout.Width(100));
        EditorGUILayout.SelectableLabel(_outputFolder, GUILayout.Height(16));
        if (GUILayout.Button("Browse", GUILayout.Width(60)))
        {
            string selectedPath = EditorUtility.OpenFolderPanel("Select Output Folder", _outputFolder, "");
            if (!string.IsNullOrEmpty(selectedPath))
            {
                string projectPath = AbsoluteToProjectPath(selectedPath);
                if (!string.IsNullOrEmpty(projectPath))
                {
                    _outputFolder = projectPath;
                }
                else
                {
                    EditorUtility.DisplayDialog("Invalid Path", "Please select a folder inside the Assets directory.", "OK");
                }
            }
        }
        EditorGUILayout.EndHorizontal();
        
        _atlasName = EditorGUILayout.TextField("Atlas Name", _atlasName);

        EditorGUILayout.Space();

        // Convert Button
        EditorGUI.BeginDisabledGroup(_ddsTextures.Count == 0 || _isProcessing);
        if (GUILayout.Button(_isProcessing ? "Processing..." : "Convert to Multi-Sprite", GUILayout.Height(35)))
        {
            ConvertToMultiSprite();
        }
        EditorGUI.EndDisabledGroup();

        // Status
        if (!string.IsNullOrEmpty(_status))
        {
            EditorGUILayout.Space();
            EditorGUILayout.HelpBox(_status, MessageType.Info);
        }
    }

    private void AddDDSFiles()
    {
        string path = EditorUtility.OpenFilePanelWithFilters(
            "Select DDS Files",
            "Assets",
            new string[] { "DDS files", "dds" }
        );

        if (!string.IsNullOrEmpty(path))
        {
            string projectPath = AbsoluteToProjectPath(path);
            if (!string.IsNullOrEmpty(projectPath))
            {
                Texture2D texture = AssetDatabase.LoadAssetAtPath<Texture2D>(projectPath);
                if (texture != null && !_ddsTextures.Contains(texture))
                {
                    _ddsTextures.Add(texture);
                    _status = $"Added {texture.name}";
                }
            }
        }
    }

    private void AddDDSFolder()
    {
        string folderPath = EditorUtility.OpenFolderPanel(
            "Select Folder Containing DDS Files",
            "Assets",
            ""
        );

        if (!string.IsNullOrEmpty(folderPath))
        {
            string projectPath = AbsoluteToProjectPath(folderPath);
            if (!string.IsNullOrEmpty(projectPath))
            {
                // Find all .dds files in the folder and subfolders
                string[] ddsFiles = Directory.GetFiles(folderPath, "*.dds", SearchOption.AllDirectories);
                int addedCount = 0;
                
                foreach (string ddsFile in ddsFiles)
                {
                    string relativePath = AbsoluteToProjectPath(ddsFile);
                    if (!string.IsNullOrEmpty(relativePath))
                    {
                        Texture2D texture = AssetDatabase.LoadAssetAtPath<Texture2D>(relativePath);
                        if (texture != null && !_ddsTextures.Contains(texture))
                        {
                            _ddsTextures.Add(texture);
                            addedCount++;
                        }
                    }
                }
                
                _status = $"Added {addedCount} DDS files from folder";
            }
            else
            {
                EditorUtility.DisplayDialog("Invalid Path", "Please select a folder inside the Assets directory.", "OK");
            }
        }
    }

    private void ConvertToMultiSprite()
    {
        if (_ddsTextures.Count == 0)
        {
            _status = "No DDS files selected";
            return;
        }

        _isProcessing = true;
        _status = "Processing...";

        try
        {
            // Ensure output folder exists
            EnsureFolderExists(_outputFolder);

            // Calculate atlas size
            var atlasSize = CalculateAtlasSize();
            
            // Create atlas texture
            var atlasTexture = CreateAtlasTexture(atlasSize);
            
            // Pack sprites into atlas
            var spriteData = PackSpritesIntoAtlas(atlasTexture, atlasSize);
            
            // Save atlas texture
            string atlasPath = SaveAtlasTexture(atlasTexture, atlasSize);
            
            // Create sprite metadata and import
            CreateSpriteMetadata(atlasPath, spriteData);
            
            // Create Sprite Atlas asset if requested
            if (_createSpriteAtlas)
            {
                CreateSpriteAtlasAsset(atlasPath, spriteData);
            }

            _status = $"Successfully converted {_ddsTextures.Count} DDS files to multi-sprite atlas!";
            
            // Clean up
            DestroyImmediate(atlasTexture);
        }
        catch (Exception ex)
        {
            Debug.LogError($"[DDSMultiSpriteConverter] Error: {ex}");
            _status = $"Error: {ex.Message}";
        }
        finally
        {
            _isProcessing = false;
            Repaint();
        }
    }

    private Vector2Int CalculateAtlasSize()
    {
        if (_autoArrange)
        {
            // Calculate optimal atlas size based on sprite count and sizes
            int totalPixels = 0;
            int maxWidth = 0;
            int maxHeight = 0;
            
            foreach (var texture in _ddsTextures)
            {
                if (texture != null)
                {
                    totalPixels += texture.width * texture.height;
                    maxWidth = Mathf.Max(maxWidth, texture.width);
                    maxHeight = Mathf.Max(maxHeight, texture.height);
                }
            }
            
            // Estimate atlas size (square-ish)
            int atlasSize = Mathf.CeilToInt(Mathf.Sqrt(totalPixels * 1.5f)); // 1.5x for padding
            
            // Round up to nearest power of 2
            atlasSize = Mathf.NextPowerOfTwo(atlasSize);
            
            // Ensure minimum size
            atlasSize = Mathf.Max(atlasSize, 512);
            
            return new Vector2Int(atlasSize, atlasSize);
        }
        else
        {
            // Use fixed size
            return new Vector2Int(2048, 2048);
        }
    }

    private Texture2D CreateAtlasTexture(Vector2Int size)
    {
        var atlasTexture = new Texture2D(size.x, size.y, TextureFormat.RGBA32, false);
        
        // Fill with transparent
        Color[] clearPixels = new Color[size.x * size.y];
        for (int i = 0; i < clearPixels.Length; i++)
        {
            clearPixels[i] = Color.clear;
        }
        atlasTexture.SetPixels(clearPixels);
        
        return atlasTexture;
    }

    private List<SpriteData> PackSpritesIntoAtlas(Texture2D atlasTexture, Vector2Int atlasSize)
    {
        var spriteData = new List<SpriteData>();
        var currentX = _paddingPixels;
        var currentY = _paddingPixels;
        var rowHeight = 0;
        
        foreach (var texture in _ddsTextures)
        {
            if (texture == null) continue;
            
            // Check if sprite fits in current row
            if (currentX + texture.width + _paddingPixels > atlasSize.x)
            {
                // Move to next row
                currentY += rowHeight + _paddingPixels;
                currentX = _paddingPixels;
                rowHeight = 0;
            }
            
            // Check if sprite fits in atlas
            if (currentY + texture.height + _paddingPixels > atlasSize.y)
            {
                Debug.LogWarning($"Sprite {texture.name} doesn't fit in atlas, skipping...");
                continue;
            }
            
            // Copy texture to atlas
            CopyTextureToAtlas(texture, atlasTexture, currentX, currentY);
            
            // Store sprite data
            spriteData.Add(new SpriteData
            {
                name = _keepOriginalNames ? texture.name : Path.GetFileNameWithoutExtension(texture.name),
                rect = new Rect(currentX, currentY, texture.width, texture.height),
                originalTexture = texture
            });
            
            // Update position
            currentX += texture.width + _paddingPixels;
            rowHeight = Mathf.Max(rowHeight, texture.height);
        }
        
        atlasTexture.Apply();
        return spriteData;
    }

    private void CopyTextureToAtlas(Texture2D sourceTexture, Texture2D atlasTexture, int x, int y)
    {
        // Make source texture readable temporarily
        var sourcePath = AssetDatabase.GetAssetPath(sourceTexture);
        var importer = AssetImporter.GetAtPath(sourcePath) as TextureImporter;
        bool wasReadable = false;
        bool wasCompressed = false;
        
        if (importer != null)
        {
            wasReadable = importer.isReadable;
            wasCompressed = importer.textureCompression != TextureImporterCompression.Uncompressed;
            
            if (!wasReadable || wasCompressed)
            {
                importer.isReadable = true;
                importer.textureCompression = TextureImporterCompression.Uncompressed;
                importer.SaveAndReimport();
                
                // Wait for reimport to complete
                AssetDatabase.Refresh();
                EditorUtility.SetDirty(importer);
            }
        }
        
        try
        {
            // Create a readable copy of the texture
            Texture2D readableTexture = CreateReadableTexture(sourceTexture);
            
            if (readableTexture != null)
            {
                // Copy pixels from readable texture
                var pixels = readableTexture.GetPixels();
                atlasTexture.SetPixels(x, y, sourceTexture.width, sourceTexture.height, pixels);
                
                // Clean up
                DestroyImmediate(readableTexture);
            }
            else
            {
                Debug.LogWarning($"Could not create readable copy of texture: {sourceTexture.name}");
            }
        }
        catch (Exception ex)
        {
            Debug.LogError($"Error copying texture {sourceTexture.name}: {ex.Message}");
        }
        finally
        {
            // Restore original settings
            if (importer != null && (!wasReadable || wasCompressed))
            {
                importer.isReadable = wasReadable;
                if (wasCompressed)
                {
                    importer.textureCompression = TextureImporterCompression.Compressed;
                }
                importer.SaveAndReimport();
            }
        }
    }
    
    private Texture2D CreateReadableTexture(Texture2D source)
    {
        try
        {
            // Create a new texture with the same dimensions
            var readableTexture = new Texture2D(source.width, source.height, TextureFormat.RGBA32, false);
            
            // Use RenderTexture to copy the texture data
            RenderTexture renderTexture = RenderTexture.GetTemporary(source.width, source.height, 0, RenderTextureFormat.ARGB32, RenderTextureReadWrite.sRGB);
            Graphics.Blit(source, renderTexture);
            
            RenderTexture.active = renderTexture;
            readableTexture.ReadPixels(new Rect(0, 0, source.width, source.height), 0, 0);
            readableTexture.Apply();
            
            RenderTexture.active = null;
            RenderTexture.ReleaseTemporary(renderTexture);
            
            return readableTexture;
        }
        catch (Exception ex)
        {
            Debug.LogError($"Error creating readable texture: {ex.Message}");
            return null;
        }
    }

    private string SaveAtlasTexture(Texture2D atlasTexture, Vector2Int size)
    {
        string fileName = $"{_atlasName}.png";
        string filePath = Path.Combine(_outputFolder, fileName);
        
        // Ensure unique filename
        filePath = GetUniqueFilePath(filePath);
        
        // Save as PNG
        byte[] pngData = atlasTexture.EncodeToPNG();
        File.WriteAllBytes(filePath, pngData);
        
        // Import to Unity
        AssetDatabase.ImportAsset(filePath);
        
        return filePath;
    }

    private void CreateSpriteMetadata(string atlasPath, List<SpriteData> spriteData)
    {
        var importer = AssetImporter.GetAtPath(atlasPath) as TextureImporter;
        if (importer == null) return;
        
        // Configure importer
        importer.textureType = TextureImporterType.Sprite;
        importer.spriteImportMode = SpriteImportMode.Multiple;
        importer.mipmapEnabled = false;
        importer.alphaIsTransparency = true;
        importer.spritePixelsPerUnit = _pixelsPerUnit;
        
        // Create sprite metadata using SpriteMetaData
        var spriteMetas = new List<SpriteMetaData>();
        
        foreach (var data in spriteData)
        {
            var meta = new SpriteMetaData
            {
                name = SafeSpriteName(data.name),
                rect = data.rect,
                alignment = (int)SpriteAlignment.Center,
                border = Vector4.zero,
                pivot = new Vector2(0.5f, 0.5f)
            };
            spriteMetas.Add(meta);
        }
        
        // Use the legacy spritesheet property (works in most Unity versions)
        #pragma warning disable CS0618 // Type or member is obsolete
        importer.spritesheet = spriteMetas.ToArray();
        #pragma warning restore CS0618 // Type or member is obsolete
        
        importer.SaveAndReimport();
        AssetDatabase.Refresh();
    }

    private void CreateSpriteAtlasAsset(string atlasPath, List<SpriteData> spriteData)
    {
        try
        {
            // Create Sprite Atlas asset using new keyword
            var spriteAtlas = new UnityEngine.U2D.SpriteAtlas();
            
            // Add atlas texture as packable
            var atlasTexture = AssetDatabase.LoadAssetAtPath<Texture2D>(atlasPath);
            if (atlasTexture != null)
            {
                // Use reflection to add objects to sprite atlas (for compatibility)
                var addMethod = typeof(UnityEngine.U2D.SpriteAtlas).GetMethod("Add", 
                    System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance);
                if (addMethod != null)
                {
                    var packableObjects = new UnityEngine.Object[] { atlasTexture };
                    addMethod.Invoke(spriteAtlas, new object[] { packableObjects });
                }
            }
            
            // Save sprite atlas asset
            string atlasAssetPath = Path.Combine(_outputFolder, $"{_atlasName}_Atlas.spriteatlas");
            AssetDatabase.CreateAsset(spriteAtlas, atlasAssetPath);
            
            AssetDatabase.SaveAssets();
            AssetDatabase.Refresh();
        }
        catch (Exception ex)
        {
            Debug.LogWarning($"[DDSMultiSpriteConverter] Could not create Sprite Atlas asset: {ex.Message}");
            _status += " (Sprite Atlas creation failed, but multi-sprite texture was created successfully)";
        }
    }

    private class SpriteData
    {
        public string name;
        public Rect rect;
        public Texture2D originalTexture;
    }

    // Utility methods
    private static void EnsureFolderExists(string folderPath)
    {
        if (!AssetDatabase.IsValidFolder(folderPath))
        {
            string[] parts = folderPath.Split('/');
            string currentPath = parts[0]; // "Assets"
            
            for (int i = 1; i < parts.Length; i++)
            {
                string nextPath = currentPath + "/" + parts[i];
                if (!AssetDatabase.IsValidFolder(nextPath))
                {
                    AssetDatabase.CreateFolder(currentPath, parts[i]);
                }
                currentPath = nextPath;
            }
        }
    }

    private static string AbsoluteToProjectPath(string absolutePath)
    {
        if (string.IsNullOrEmpty(absolutePath)) return string.Empty;
        
        string abs = absolutePath.Replace('\\', '/');
        string data = Application.dataPath.Replace('\\', '/');
        
        if (abs.StartsWith(data, StringComparison.OrdinalIgnoreCase))
        {
            return "Assets" + abs.Substring(data.Length);
        }
        
        return string.Empty;
    }

    private static string GetUniqueFilePath(string filePath)
    {
        if (!File.Exists(filePath)) return filePath;
        
        string directory = Path.GetDirectoryName(filePath);
        string fileName = Path.GetFileNameWithoutExtension(filePath);
        string extension = Path.GetExtension(filePath);
        
        int counter = 1;
        string newPath;
        
        do
        {
            newPath = Path.Combine(directory, $"{fileName}_{counter}{extension}");
            counter++;
        }
        while (File.Exists(newPath));
        
        return newPath;
    }

    private static string SafeSpriteName(string name)
    {
        if (string.IsNullOrWhiteSpace(name)) return "Sprite";
        
        // Remove invalid characters
        char[] invalidChars = Path.GetInvalidFileNameChars();
        foreach (char c in invalidChars)
        {
            name = name.Replace(c, '_');
        }
        
        // Remove .dds extension if present
        if (name.EndsWith(".dds", StringComparison.OrdinalIgnoreCase))
        {
            name = name.Substring(0, name.Length - 4);
        }
        
        return name;
    }
}
#endif