//
// AssetBrowserPanel.cpp：项目资产浏览器实现。
//
// 条目视觉/拖拽/tooltip 单元住 AssetItemView（列表行与网格瓦片共用同一
// 套类别色 + 缩略图）；本文件只负责：根切换 / 过滤 / 目录树 / 内容区
// 铺排 / 选中态 / 双击分派（打开或实例化）。
//

#include "AssetBrowserPanel.h"

#include "AssetItemView.h"          // 列表行 / 网格瓦片 / 目录条目
#include "AssetKind.h"              // EditorAsset::AssetKind / KindOfPath
#include "MaterialEditorPanel.h"    // kMaterialDragPayload + 双击打开材质编辑器
#include "ControllerEditorPanel.h"  // kControllerDragPayload + 双击打开控制器编辑器

#include <Engine/Core/Log.h>
#include <Engine/Serialization/SceneSerializer.h>

#include <imgui.h>

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

namespace {

    // 固定根：下标与 Editor 无耦合，仅面板内部使用
    constexpr const char* kRootNames[] = {"Assets", "Scenes"};
    constexpr const char* kRootPaths[] = {"assets", "scenes"};

    // 类型过滤（下标即身份）：0 = All；其余对齐 AssetKind 顺序
    constexpr const char* kTypeNames[] = {"All",       "Models",
                                          "Textures",  "Scenes",
                                          "Materials", "Controllers",
                                          "Prefabs"};

    bool PassFilter(int typeFilter, EditorAsset::AssetKind kind)
    {
        switch (typeFilter)
        {
            case 1: return kind == EditorAsset::AssetKind::Model;
            case 2: return kind == EditorAsset::AssetKind::Texture;
            case 3: return kind == EditorAsset::AssetKind::Scene;
            case 4: return kind == EditorAsset::AssetKind::Material;
            case 5: return kind == EditorAsset::AssetKind::AnimClip;
            case 6: return kind == EditorAsset::AssetKind::Prefab;
            default: return true;
        }
    }

    // 相对路径规范化为正斜杠（AssetManager 键与场景文件统一 POSIX 风格）
    std::string ToAssetPath(const std::filesystem::path& p)
    {
        std::string s = p.generic_string();
        std::replace(s.begin(), s.end(), '\\', '/');
        return s;
    }

    // 双击分派：材质/控制器 → 打开编辑器；模型/环境 → 缓存预热；
    // 场景 → 提示走 File 菜单；预制体 → 快捷实例化（授权位姿落点）
    void DispatchOpen(const EditorContext& ctx,
                      const std::filesystem::path& path,
                      EditorAsset::AssetKind kind)
    {
        const std::string assetPath = path.generic_string();
        if (kind == EditorAsset::AssetKind::Material && ctx.materialEditor)
        {
            ctx.materialEditor->OpenAsset(assetPath);
        }
        else if (kind == EditorAsset::AssetKind::AnimClip && ctx.controllerEditor)
        {
            ctx.controllerEditor->Open(assetPath);
        }
        else if (kind == EditorAsset::AssetKind::Model && ctx.assets)
        {
            const auto ref = ctx.assets->LoadModel(assetPath);
            ENGINE_INFO("AssetBrowser: model '{}' loaded (valid={})",
                        assetPath, ref.Valid());
        }
        else if (kind == EditorAsset::AssetKind::Texture && ctx.assets)
        {
            const auto ref = ctx.assets->LoadEnvironment(assetPath);
            ENGINE_INFO("AssetBrowser: env '{}' loaded (valid={})",
                        assetPath, ref.Valid());
        }
        else if (kind == EditorAsset::AssetKind::Scene)
        {
            ENGINE_INFO("AssetBrowser: load scenes via File menu ({})",
                        assetPath);
        }
        else if (kind == EditorAsset::AssetKind::Prefab && ctx.scene && ctx.assets)
        {
            // 双击 = 快捷实例化（授权位姿落点，选中交给 Outliner 手动改）；
            // 拖拽实例化见 Outliner 落点
            const auto root = Engine::Serialization::SceneSerializer::
                InstantiatePrefab(*ctx.scene, *ctx.assets, assetPath);
            ENGINE_INFO("AssetBrowser: prefab '{}' instantiated (valid={})",
                        assetPath, root != entt::null);
        }
    }

} // namespace

void AssetBrowserPanel::Draw(const EditorContext& ctx)
{
    if (!ImGui::Begin("Content Browser"))
    {
        ImGui::End();
        return;
    }

    // ---- 顶栏：根切换 + 类型过滤 + 名字过滤 ----
    if (ImGui::BeginTabBar("##roots"))
    {
        for (int i = 0; i < 2; ++i)
        {
            if (ImGui::BeginTabItem(kRootNames[i]))
            {
                m_Root = i;
                ImGui::EndTabItem();
            }
        }
        ImGui::EndTabBar();
    }
    ImGui::SameLine();
    ImGui::SetNextItemWidth(110.0f);
    ImGui::Combo("##type", &m_TypeFilter, kTypeNames, 7);
    ImGui::SameLine();
    ImGui::SetNextItemWidth(140.0f);
    ImGui::InputTextWithHint("##name", "filter", m_NameFilter,
                             sizeof(m_NameFilter));
    ImGui::Separator();

    const std::filesystem::path root(kRootPaths[m_Root]);
    // 根切换 / 首帧：当前目录回根。前缀比较手写（path::starts_with
    // 是 libstdc++ 11 才补齐的成员，本机 GCC 没有）；补 '/' 分隔校验
    // 防 "assets_x" 之类误匹配
    const std::string rootStr = root.generic_string();
    const std::string curStr = m_CurrentDir.generic_string();
    const bool under = curStr == rootStr ||
                       (curStr.size() > rootStr.size() &&
                        curStr.compare(0, rootStr.size(), rootStr) == 0 &&
                        curStr[rootStr.size()] == '/');
    if (m_CurrentDir.empty() || !under)
    {
        m_CurrentDir = root;
    }

    // ---- 顶栏下：面包屑（当前目录相对根路径 + 回根按钮）+ 视图切换 ----
    if (ImGui::Button("Root"))
    {
        m_CurrentDir = root;
    }
    ImGui::SameLine();
    std::string rel = std::filesystem::relative(m_CurrentDir, root)
                          .generic_string();
    ImGui::TextDisabled("%s/%s", kRootNames[m_Root],
                        rel.empty() ? "" : rel.c_str());

    // 视图切换（列表 / 网格）+ 网格瓦片尺寸
    ImGui::SameLine();
    const bool listMode = m_ViewMode == ViewMode::List;
    if (ImGui::RadioButton("List", listMode))
    {
        m_ViewMode = ViewMode::List;
    }
    ImGui::SameLine();
    if (ImGui::RadioButton("Grid", !listMode))
    {
        m_ViewMode = ViewMode::Grid;
    }
    if (m_ViewMode == ViewMode::Grid)
    {
        ImGui::SameLine();
        ImGui::SetNextItemWidth(120.0f);
        ImGui::SliderFloat("##tile", &m_TileSize, 48.0f, 160.0f, "%.0f px");
    }
    ImGui::Separator();

    // ---- 左：目录树 | 右：当前目录内容（列表 / 网格）----
    const float treeWidth = 180.0f;
    ImGui::BeginChild("##tree", ImVec2(treeWidth, 0.0f),
                      ImGuiChildFlags_ResizeX | ImGuiChildFlags_Borders);
    if (std::filesystem::exists(root))
    {
        // 根节点也画进树（可点击选中）
        ImGui::SetNextItemOpen(true, ImGuiCond_Once);
        if (ImGui::TreeNodeEx(kRootNames[m_Root],
                              ImGuiTreeNodeFlags_OpenOnArrow))
        {
            if (ImGui::IsItemClicked(ImGuiMouseButton_Left))
            {
                m_CurrentDir = root;
            }
            DrawDirTree(ctx, root);
            ImGui::TreePop();
        }
    }
    else
    {
        ImGui::TextDisabled("(no '%s' dir)", kRootPaths[m_Root]);
    }
    ImGui::EndChild();

    ImGui::SameLine();
    ImGui::BeginChild("##files", ImVec2(0.0f, 0.0f),
                      ImGuiChildFlags_Borders);
    if (std::filesystem::exists(m_CurrentDir))
    {
        DrawContent(ctx, m_CurrentDir);
    }
    ImGui::EndChild();

    ImGui::End();
}

void AssetBrowserPanel::DrawDirTree(const EditorContext& ctx,
                                    const std::filesystem::path& dir)
{
    for (const auto& entry : std::filesystem::directory_iterator(dir))
    {
        if (!entry.is_directory())
        {
            continue;
        }
        const std::string name = entry.path().filename().string();
        // OpenOnArrow：单击行 = 选中（列表切换），箭头 = 折叠
        const bool open = ImGui::TreeNodeEx(
            name.c_str(), ImGuiTreeNodeFlags_OpenOnArrow |
                              ImGuiTreeNodeFlags_SpanFullWidth);
        if (ImGui::IsItemClicked(ImGuiMouseButton_Left))
        {
            m_CurrentDir = entry.path();
        }
        if (open)
        {
            DrawDirTree(ctx, entry.path());
            ImGui::TreePop();
        }
    }
}

void AssetBrowserPanel::DrawContent(const EditorContext& ctx,
                                    const std::filesystem::path& dir)
{
    namespace fs = std::filesystem;

    // 收集：目录（不受类型过滤影响）+ 过滤后的文件；目录迭代序不稳定 → 排序
    std::vector<fs::path> dirs;
    std::vector<std::pair<fs::path, EditorAsset::AssetKind>> files;
    const std::string filter = m_NameFilter;
    std::error_code ec;
    for (const auto& entry : fs::directory_iterator(dir, ec))
    {
        if (entry.is_directory())
        {
            dirs.push_back(entry.path());
            continue;
        }
        const EditorAsset::AssetKind kind =
            EditorAsset::KindOfPath(entry.path());
        if (!PassFilter(m_TypeFilter, kind))
        {
            continue;
        }
        if (!filter.empty())
        {
            const std::string name = entry.path().filename().string();
            if (name.find(filter) == std::string::npos)
            {
                continue;
            }
        }
        files.emplace_back(entry.path(), kind);
    }
    std::sort(dirs.begin(), dirs.end(),
              [](const fs::path& a, const fs::path& b)
              {
                  return a.filename().string() < b.filename().string();
              });
    std::sort(files.begin(), files.end(),
              [](const auto& a, const auto& b)
              {
                  return a.first.filename().string() <
                         b.first.filename().string();
              });

    // 双击打开延迟到循环外：Immediate GUI 语义——绘制循环内不改世界状态
    //（prefab 实例化会改场景，边遍历边打开会让后续条目的项状态错乱）
    bool pendingOpen = false;
    std::filesystem::path pendingOpenPath;
    EditorAsset::AssetKind pendingOpenKind = EditorAsset::AssetKind::Other;

    if (m_ViewMode == ViewMode::List)
    {
        for (const auto& d : dirs)
        {
            if (EditorAssetView::DrawFolderRow(d))
            {
                m_CurrentDir = d;
                m_SelectedPath.clear();
            }
        }
        for (const auto& [path, kind] : files)
        {
            const std::string assetPath = ToAssetPath(path);
            const auto res = EditorAssetView::DrawRow(
                ctx, path, assetPath == m_SelectedPath);
            if (res.clicked)
            {
                m_SelectedPath = assetPath;
            }
            if (res.doubleClicked)
            {
                pendingOpen = true;
                pendingOpenPath = path;
                pendingOpenKind = kind;
            }
        }
    }

    else
    {
        // ---- 网格视图：固定列宽表格铺排（列数按可用宽度自适应）----
        const float tile = m_TileSize;
        const float cellW = tile + ImGui::GetStyle().CellPadding.x * 2.0f;
        int cols = static_cast<int>(ImGui::GetContentRegionAvail().x / cellW);
        if (cols < 1)
        {
            cols = 1;
        }
        if (ImGui::BeginTable("##grid", cols, ImGuiTableFlags_SizingFixedFit))
        {
            for (int i = 0; i < cols; ++i)
            {
                ImGui::TableSetupColumn("##c",
                                        ImGuiTableColumnFlags_WidthFixed,
                                        cellW);
            }
            for (const auto& d : dirs)
            {
                ImGui::TableNextColumn();
                const std::string assetPath = ToAssetPath(d);
                if (EditorAssetView::DrawFolderTile(
                        d, tile, assetPath == m_SelectedPath))
                {
                    m_CurrentDir = d;
                    m_SelectedPath.clear();
                }
            }
            for (const auto& [path, kind] : files)
            {
                ImGui::TableNextColumn();
                const std::string assetPath = ToAssetPath(path);
                const auto res = EditorAssetView::DrawTile(
                    ctx, path, tile, assetPath == m_SelectedPath);
                if (res.clicked)
                {
                    m_SelectedPath = assetPath;
                }
                if (res.doubleClicked)
                {
                    pendingOpen = true;
                    pendingOpenPath = path;
                    pendingOpenKind = kind;
                }
            }
            ImGui::EndTable();
        }
    }

    if (pendingOpen)
    {
        DispatchOpen(ctx, pendingOpenPath, pendingOpenKind);
    }
}