//
// MaterialAssetUtil.h：材质资产编辑共用工具（Inspector / Material Editor
// 面板共享）。
//
// 单一事实来源（原 InspectorPanel.cpp 匿名 ns 实现上提）：
//   - .material 文件枚举缓存（inline 变量跨 TU 唯一——面板各自创建
//     Override 后缓存失效即时可见）
//   - Create Override：内建材质快照 → assets/materials/*.material →
//     GUID 登记 → 同步加载 → 挂实体覆盖表
//

#ifndef HELLOVULKAN_MATERIALASSETUTIL_H
#define HELLOVULKAN_MATERIALASSETUTIL_H

#include "AssetKind.h"   // EditorAsset::IsTexturePath（纹理扩展名单一事实来源）

#include <Engine/Assets/AssetManager.h>
#include <Engine/Core/Log.h>
#include <Engine/ECS/Components.h>
#include <Engine/Renderer/MaterialAsset.h>
#include <Engine/Renderer/Model.h>

#include <algorithm>
#include <cctype>
#include <filesystem>
#include <string>
#include <vector>

namespace EditorMaterialUtil {

    namespace fs = std::filesystem;

    // .material 文件枚举（会话级缓存 + 脏标）。inline 变量 = 所有 TU
    // 共享同一份（Create Override 新建文件后置脏重扫）
    inline std::vector<std::string> s_MaterialFiles;
    inline bool s_MaterialFilesDirty = true;

    inline void InvalidateMaterialFileList() { s_MaterialFilesDirty = true; }

    // 递归收集 assets/ 下纹理文件（材质编辑器纹理槽选择器；纹理文件
    // 不被编辑器创建，无需脏标）。会话级缓存
    inline const std::vector<std::string>& AssetTextureFiles()
    {
        static std::vector<std::string> s_Files;
        static bool s_Cached = false;
        if (!s_Cached)
        {
            s_Cached = true;
            if (fs::exists("assets"))
            {
                for (const auto& entry :
                     fs::recursive_directory_iterator("assets"))
                {
                    if (!entry.is_regular_file())
                    {
                        continue;
                    }
                    if (EditorAsset::IsTexturePath(entry.path()))
                    {
                        s_Files.push_back(entry.path().generic_string());
                    }
                }
                std::sort(s_Files.begin(), s_Files.end());
            }
        }
        return s_Files;
    }

    inline const std::vector<std::string>& AssetMaterialFiles()
    {
        if (s_MaterialFilesDirty)
        {
            s_MaterialFilesDirty = false;
            s_MaterialFiles.clear();
            if (fs::exists("assets"))
            {
                for (const auto& entry :
                     fs::recursive_directory_iterator("assets"))
                {
                    if (!entry.is_regular_file())
                    {
                        continue;
                    }
                    std::string ext = entry.path().extension().string();
                    std::transform(ext.begin(), ext.end(), ext.begin(),
                                   [](unsigned char c)
                                   { return std::tolower(c); });
                    if (ext == ".material")
                    {
                        s_MaterialFiles.push_back(
                            entry.path().generic_string());
                    }
                }
                std::sort(s_MaterialFiles.begin(), s_MaterialFiles.end());
            }
        }
        return s_MaterialFiles;
    }

    // Create Override：内建材质快照 → assets/materials/<model>_<mesh>.material
    // → GUID 登记 → 同步加载 → 挂实体覆盖表。失败返回空串（不挂槽）。
    // 数据段 = 内建材质只读快照（纹理路径 + 因子 + 透明语义），此后
    // 该资产独立演化，内建材质不受影响
    inline std::string CreateMaterialOverride(
        const std::string& modelPath,
        const Engine::MeshMaterialInfo& info,
        Engine::u32 meshIdx,
        Engine::ECS::MeshRendererComponent& mr,
        Engine::Assets::AssetManager& assets)
    {
        // 目标文件名：<modelStem>_<meshName|idx>.material；mesh 名非
        // [A-Za-z0-9] 字符折叠 '_'，空名回退下标；重名追加 _2/_3/...
        std::string stem = fs::path(modelPath).stem().string();
        std::string leaf = info.name;
        if (leaf.empty())
        {
            leaf = std::to_string(meshIdx);
        }
        for (char& c : leaf)
        {
            if (!std::isalnum(static_cast<unsigned char>(c)))
            {
                c = '_';
            }
        }

        const fs::path dir = "assets/materials";
        std::error_code ec;
        fs::create_directories(dir, ec);
        if (ec)
        {
            ENGINE_WARN("MaterialUtil: cannot create {}: {}", dir.string(),
                        ec.message());
            return {};
        }

        std::string base = stem + "_" + leaf;
        std::string rel = (dir / (base + ".material")).generic_string();
        for (int n = 2; fs::exists(rel); ++n)
        {
            rel = (dir / (base + "_" + std::to_string(n) + ".material"))
                      .generic_string();
        }

        Engine::MaterialAssetData data;
        data.texPaths = info.texPaths;
        data.params = info.params;
        data.transparent = info.transparent;
        if (!Engine::MaterialAsset::Save(rel, data))
        {
            ENGINE_WARN("MaterialUtil: failed to save material override '{}'",
                        rel);
            return {};
        }

        assets.GetOrCreateGUID(rel);
        if (!assets.LoadMaterialAsset(rel).Valid())
        {
            ENGINE_WARN("MaterialUtil: override '{}' saved but failed to load",
                        rel);
            return {};
        }
        mr.materialOverrides[meshIdx] = rel;
        InvalidateMaterialFileList();   // 新文件进下拉列表
        return rel;
    }

} // namespace EditorMaterialUtil

#endif //HELLOVULKAN_MATERIALASSETUTIL_H