using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using TMPro;
using UnityEditor;
using UnityEngine;
using UnityEngine.TextCore;

namespace Cielonos.Editor
{
    /// <summary>
    /// 一键式 Editor 工具：将 Assets/Sprites/Icon/InputIcons/ 下的所有按键图标
    /// 打包为 atlas 纹理，并自动生成 TMP_SpriteAsset 供 TMP 富文本使用。
    /// 使用方式：Tools → Cielonos → Create InputGlyphs Sprite Asset
    /// </summary>
    public static class InputGlyphsSpriteAssetCreator
    {
        private const string KeyboardFolder = "Assets/Sprites/Icon/InputIcons/keyboard";
        private const string MouseFolder = "Assets/Sprites/Icon/InputIcons/mouse";
        private const string AtlasOutputFolder = "Assets/Scripts/SLSUtilities/UI/SpriteAssets";
        private const string AssetOutputFolder = "Assets/TextMesh Pro/Resources/Sprite Assets";
        private const string AtlasFileName = "InputGlyphs_Atlas.png";
        private const string AssetFileName = "InputGlyphs.asset";

        /// <summary>打包前将每张源图缩放到此尺寸（像素），降低 atlas 体积。</summary>
        private const int SpriteSize = 128;

        /// <summary>Atlas 最大边长。</summary>
        private const int MaxAtlasSize = 2048;

        /// <summary>打包时各图之间的像素间距。</summary>
        private const int Padding = 2;

        /// <summary>鼠标文件名 → Token 名映射表。</summary>
        private static readonly Dictionary<string, string> MouseNameMap = new()
        {
            { "mouse-left", "LMB" },
            { "mouse-right", "RMB" },
            { "mouse-middle", "MMB" },
            { "mouse-g1", "Mouse4" },
            { "mouse-g2", "Mouse5" },
            { "mouse-move-hor", "MouseMoveH" },
            { "mouse-move-vert", "MouseMoveV" },
        };

        private struct SpriteEntry
        {
            public string filePath;
            public string tokenName;
        }

        // ================================================================
        // 入口
        // ================================================================

        [MenuItem("Tools/Cielonos/Create InputGlyphs Sprite Asset")]
        public static void Execute()
        {
            var entries = new List<SpriteEntry>();
            CollectEntries(KeyboardFolder, entries, MapKeyboardName);
            CollectEntries(MouseFolder, entries, MapMouseName);

            if (entries.Count == 0)
            {
                Debug.LogError("[InputGlyphs] InputIcons 文件夹中未找到任何图片。");
                return;
            }

            Debug.Log($"[InputGlyphs] 发现 {entries.Count} 张图标，开始打包...");

            // ── 1. 加载并缩放所有图标 ──
            LoadAndResizeResult loaded = LoadAndResize(entries);

            // ── 2. 打包为 atlas ──
            var atlas = new Texture2D(MaxAtlasSize, MaxAtlasSize, TextureFormat.RGBA32, false);
            Rect[] rects = atlas.PackTextures(loaded.Textures.ToArray(), Padding, MaxAtlasSize, false);

            if (rects == null)
            {
                Debug.LogError("[InputGlyphs] PackTextures 失败，请增大 MaxAtlasSize。");
                CleanupTextures(loaded.Textures);
                return;
            }

            // ── 3. 保存 atlas PNG 到磁盘 ──
            string atlasPath = $"{AtlasOutputFolder}/{AtlasFileName}";
            SaveAtlasToDisk(atlas, atlasPath);

            // ── 4. 配置 atlas 导入器，写入每个子 Sprite 的元数据 ──
            ConfigureAtlasImporter(atlasPath, atlas, rects, loaded.Names);

            // ── 5. 从已导入的 atlas 构建 TMP_SpriteAsset（放入 Resources 以便 TMP 按名查找） ──
            string assetPath = $"{AssetOutputFolder}/{AssetFileName}";
            BuildSpriteAsset(atlasPath, assetPath);

            // ── 6. 清理临时纹理 ──
            CleanupTextures(loaded.Textures);
            UnityEngine.Object.DestroyImmediate(atlas);

            Debug.Log($"[InputGlyphs] SpriteAsset 已创建：{assetPath}（{entries.Count} 个图标）。" +
                      $"\n在 TMP 富文本中使用：<sprite=\"InputGlyphs\" name=\"Q\"> 或 <sprite name=\"Q\">");
        }

        // ================================================================
        // 收集文件
        // ================================================================

        private static void CollectEntries(
            string folder,
            List<SpriteEntry> entries,
            Func<string, string> nameMapper)
        {
            string[] guids = AssetDatabase.FindAssets("t:Texture2D", new[] { folder });
            foreach (string guid in guids)
            {
                string assetPath = AssetDatabase.GUIDToAssetPath(guid);
                string fileName = Path.GetFileNameWithoutExtension(assetPath);
                entries.Add(new SpriteEntry
                {
                    filePath = Path.GetFullPath(assetPath),
                    tokenName = nameMapper(fileName)
                });
            }
        }

        /// <summary>
        /// 键盘文件名 → Token 名。
        /// 规则：单字母大写，单数字保留，Fn 键大写，连字符转 PascalCase，其余首字母大写。
        /// </summary>
        private static string MapKeyboardName(string fileName)
        {
            // 单字母 → 大写
            if (fileName.Length == 1 && char.IsLetter(fileName[0]))
                return fileName.ToUpperInvariant();

            // 单数字 → 原样
            if (fileName.Length == 1 && char.IsDigit(fileName[0]))
                return fileName;

            // 功能键 f1-f12 → 全大写
            if (fileName.Length >= 2 && fileName[0] == 'f' &&
                int.TryParse(fileName.Substring(1), out _))
                return fileName.ToUpperInvariant();

            // 含连字符 → PascalCase (arrow-down → ArrowDown)
            if (fileName.Contains('-'))
            {
                string[] parts = fileName.Split('-');
                var sb = new StringBuilder();
                foreach (string part in parts)
                {
                    if (part.Length > 0)
                        sb.Append(char.ToUpperInvariant(part[0]))
                          .Append(part, 1, part.Length - 1);
                }
                return sb.ToString();
            }

            // 其余 → 首字母大写
            return char.ToUpperInvariant(fileName[0]) + fileName.Substring(1);
        }

        /// <summary>
        /// 鼠标文件名 → Token 名。通过静态映射表查找。
        /// </summary>
        private static string MapMouseName(string fileName)
        {
            return MouseNameMap.TryGetValue(fileName, out string mapped) ? mapped : fileName;
        }

        // ================================================================
        // 加载 & 缩放
        // ================================================================

        private struct LoadAndResizeResult
        {
            public List<Texture2D> Textures;
            public List<string> Names;
        }

        private static LoadAndResizeResult LoadAndResize(List<SpriteEntry> entries)
        {
            var textures = new List<Texture2D>(entries.Count);
            var names = new List<string>(entries.Count);

            foreach (SpriteEntry entry in entries)
            {
                byte[] bytes = File.ReadAllBytes(entry.filePath);
                var src = new Texture2D(2, 2, TextureFormat.RGBA32, false);
                ImageConversion.LoadImage(src, bytes);

                Texture2D dst = Resize(src, SpriteSize, SpriteSize);
                UnityEngine.Object.DestroyImmediate(src);

                textures.Add(dst);
                names.Add(entry.tokenName);
            }

            return new LoadAndResizeResult { Textures = textures, Names = names };
        }

        private static Texture2D Resize(Texture2D source, int width, int height)
        {
            RenderTexture rt = RenderTexture.GetTemporary(width, height, 0, RenderTextureFormat.ARGB32);
            rt.filterMode = FilterMode.Bilinear;
            Graphics.Blit(source, rt);

            RenderTexture prev = RenderTexture.active;
            RenderTexture.active = rt;

            var dst = new Texture2D(width, height, TextureFormat.RGBA32, false);
            dst.ReadPixels(new Rect(0, 0, width, height), 0, 0);
            dst.Apply();

            RenderTexture.active = prev;
            RenderTexture.ReleaseTemporary(rt);

            return dst;
        }

        // ================================================================
        // Atlas 保存 & 导入
        // ================================================================

        private static void SaveAtlasToDisk(Texture2D atlas, string atlasPath)
        {
            string dir = Path.GetDirectoryName(atlasPath);
            if (!string.IsNullOrEmpty(dir) && !Directory.Exists(dir))
                Directory.CreateDirectory(dir);

            File.WriteAllBytes(atlasPath, atlas.EncodeToPNG());
            AssetDatabase.ImportAsset(atlasPath, ImportAssetOptions.ForceUpdate);
        }

        private static void ConfigureAtlasImporter(
            string atlasPath,
            Texture2D atlas,
            Rect[] rects,
            List<string> names)
        {
            var importer = AssetImporter.GetAtPath(atlasPath) as TextureImporter;
            if (importer == null)
            {
                Debug.LogError($"[InputGlyphs] 无法获取 TextureImporter：{atlasPath}");
                return;
            }

            importer.textureType = TextureImporterType.Sprite;
            importer.spriteImportMode = SpriteImportMode.Multiple;
            importer.isReadable = false;
            importer.mipmapEnabled = false;
            importer.textureCompression = TextureImporterCompression.Uncompressed;
            importer.maxTextureSize = MaxAtlasSize;

            int atlasW = atlas.width;
            int atlasH = atlas.height;

            var spritesheet = new SpriteMetaData[rects.Length];
            for (int i = 0; i < rects.Length; i++)
            {
                float x = rects[i].x * atlasW;
                float y = rects[i].y * atlasH;
                float w = rects[i].width * atlasW;
                float h = rects[i].height * atlasH;

                spritesheet[i] = new SpriteMetaData
                {
                    name = names[i],
                    rect = new Rect(x, y, w, h),
                    alignment = (int)SpriteAlignment.Center,
                    pivot = new Vector2(0.5f, 0.5f)
                };
            }

            importer.spritesheet = spritesheet;
            importer.SaveAndReimport();
        }

        // ================================================================
        // TMP_SpriteAsset 构建
        // ================================================================

        private static void BuildSpriteAsset(string atlasPath, string assetPath)
        {
            // 加载持久化后的 atlas 纹理
            Texture2D atlasTexture = AssetDatabase.LoadAssetAtPath<Texture2D>(atlasPath);
            if (atlasTexture == null)
            {
                Debug.LogError($"[InputGlyphs] 无法加载 atlas：{atlasPath}");
                return;
            }

            // 从 atlas 加载所有子 Sprite
            Sprite[] sprites = AssetDatabase.LoadAllAssetsAtPath(atlasPath)
                .OfType<Sprite>()
                .OrderByDescending(s => s.rect.y)
                .ThenBy(s => s.rect.x)
                .ToArray();

            if (sprites.Length == 0)
            {
                Debug.LogError("[InputGlyphs] Atlas 中未找到子 Sprite，请检查导入设置。");
                return;
            }

            // 创建 TMP_SpriteAsset 实例
            TMP_SpriteAsset spriteAsset = ScriptableObject.CreateInstance<TMP_SpriteAsset>();

            string dir = Path.GetDirectoryName(assetPath);
            if (!string.IsNullOrEmpty(dir) && !Directory.Exists(dir))
                Directory.CreateDirectory(dir);

            // 如果已存在旧资产则删除
            if (AssetDatabase.LoadAssetAtPath<TMP_SpriteAsset>(assetPath) != null)
                AssetDatabase.DeleteAsset(assetPath);

            AssetDatabase.CreateAsset(spriteAsset, assetPath);

            // 设置 sprite sheet 引用
            spriteAsset.spriteSheet = atlasTexture;

            // 通过反射设置版本号（internal setter）
            SetFieldValue(spriteAsset, "m_Version", "1.1.0");

            // 设置 hash code
            spriteAsset.hashCode = TMP_TextUtilities.GetSimpleHashCode(spriteAsset.name);

            // 构建 Glyph 和 Character 表
            var glyphTable = new List<TMP_SpriteGlyph>(sprites.Length);
            var charTable = new List<TMP_SpriteCharacter>(sprites.Length);

            for (int i = 0; i < sprites.Length; i++)
            {
                Sprite sprite = sprites[i];

                var glyph = new TMP_SpriteGlyph(
                    index: (uint)i,
                    metrics: new GlyphMetrics(
                        sprite.rect.width,
                        sprite.rect.height,
                        0f,
                        sprite.rect.height * 0.8f,
                        sprite.rect.width),
                    glyphRect: new GlyphRect(sprite.rect),
                    scale: 1.0f,
                    atlasIndex: 0,
                    sprite: sprite
                );
                glyphTable.Add(glyph);

                var character = new TMP_SpriteCharacter(0xFFFE, glyph)
                {
                    name = sprite.name,
                    scale = 1.0f
                };
                charTable.Add(character);
            }

            // 通过反射设置内部字段（setter 为 internal）
            SetFieldValue(spriteAsset, "m_GlyphTable", glyphTable);
            SetFieldValue(spriteAsset, "m_SpriteCharacterTable", charTable);

            // 创建并嵌入 Material
            Shader shader = Shader.Find("TextMeshPro/Sprite");
            if (shader == null)
            {
                Debug.LogWarning("[InputGlyphs] Shader 'TextMeshPro/Sprite' 未找到。");
                return;
            }

            var material = new Material(shader);
            material.SetTexture(ShaderUtilities.ID_MainTex, atlasTexture);
            material.name = spriteAsset.name + " Material";
            spriteAsset.material = material;
            AssetDatabase.AddObjectToAsset(material, spriteAsset);

            // 重建查找表并保存
            spriteAsset.UpdateLookupTables();
            EditorUtility.SetDirty(spriteAsset);
            AssetDatabase.SaveAssets();
            AssetDatabase.ImportAsset(assetPath);
        }

        // ================================================================
        // 工具方法
        // ================================================================

        private static void SetFieldValue(object target, string fieldName, object value)
        {
            FieldInfo field = target.GetType().GetField(
                fieldName,
                BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Public);

            if (field != null)
            {
                field.SetValue(target, value);
            }
            else
            {
                Debug.LogWarning($"[InputGlyphs] 反射未找到字段 '{fieldName}'（类型：{target.GetType().Name}）。");
            }
        }

        private static void CleanupTextures(List<Texture2D> textures)
        {
            foreach (Texture2D tex in textures)
            {
                if (tex != null)
                    UnityEngine.Object.DestroyImmediate(tex);
            }
        }
    }
}