// sdf_visualizer.cpp
// ──────────────────────────────────────────────────────────────────────────────
// 依赖：
//   prim_gen.hpp          → baked_blobtree_t、aabb_t、primitive_t …
//   base/subface.hpp      → internal::get_eval_sdf_ptr、surface_type
//
// 文件格式（output_path）：
//   行 0 : grid_res  y_slice
//   行 1 : x0 x1 z0 z1        （世界坐标范围）
//   行 2 : num_subfaces
//   然后对每个 subface 重复：
//     行   : surface_type_int
//     N 行 : N 个空格分隔的 float（iz 行，ix 列，N = grid_res+1）
// ──────────────────────────────────────────────────────────────────────────────

#include "sdf_visualizer.hpp"
#include <base/subface.hpp> // internal::get_eval_sdf_ptr, surface_type

#include <Eigen/Dense>
#include <fstream>
#include <functional>
#include <iostream>
#include <limits>
#include <vector>

void dump_sdf_slice(const baked_blobtree_t& tree,
                    const std::string&      output_path,
                    double                  y_slice,
                    int                     grid_res,
                    double                  extra_margin)
{
    // ── 0. 基本校验 ────────────────────────────────────────────────────────
    if (tree.subfaces.empty()) {
        std::cerr << "[SDF_VIZ] No subfaces — nothing to dump.\n";
        return;
    }

    // ── 1. 计算场景 AABB（含边距）──────────────────────────────────────────
    aabb_t scene_aabb{};
    for (const auto& prim : tree.primitives) { scene_aabb.extend(prim->fetch_aabb()); }
    if (scene_aabb.isEmpty()) {
        std::cerr << "[SDF_VIZ] Scene AABB is invalid.\n";
        return;
    }
    const double base_margin  = scene_aabb.sizes().maxCoeff() * extra_margin + 0.05;
    scene_aabb.min().array() -= base_margin;
    scene_aabb.max().array() += base_margin;

    const double x0 = scene_aabb.min().x(), x1 = scene_aabb.max().x();
    const double z0 = scene_aabb.min().z(), z1 = scene_aabb.max().z();
    const int    N = grid_res + 1; // 每轴采样点数

    const uint32_t ns = static_cast<uint32_t>(tree.subfaces.size());
    std::cout << "[SDF_VIZ] Grid " << N << "×" << N << "  |  " << ns << " subface(s)"
              << "  |  Y=" << y_slice << "  |  X[" << x0 << ", " << x1 << "]"
              << "  |  Z[" << z0 << ", " << z1 << "]\n";

    // ── 2. 对每个 subface 在网格上采样 SDF ────────────────────────────────
    //   grids[s][iz * N + ix] = SDF 值（float 节省内存）
    std::vector<std::vector<float>> grids(ns, std::vector<float>(N * N, 0.0f));

for (uint32_t s = 0; s < ns; ++s) {
        // 不再调用 .raw() 获取原始指针，而是直接使用包装器对象
        const auto&  subface_wrapper = tree.subfaces[s]; // 使用引用，避免拷贝
        surface_type subface_type    = tree.subface_types[s];

        auto sdf_fn = internal::get_eval_sdf_ptr(subface_type);
        if (!sdf_fn) {
            std::cout << "[SDF_VIZ]   subface[" << s << "] type=" << static_cast<int>(subface_type)
                      << " → null eval_sdf, skipped.\n";
            continue;
        }

        for (int iz = 0; iz < N; ++iz) {
            const double z = z0 + (z1 - z0) * static_cast<double>(iz) / grid_res;
            for (int ix = 0; ix < N; ++ix) {
                const double          x = x0 + (x1 - x0) * static_cast<double>(ix) / grid_res;
                const Eigen::Vector3d pos(x, y_slice, z);
                // 传递包装器对象，而不是原始指针
                grids[s][iz * N + ix] = static_cast<float>(sdf_fn(subface_wrapper, pos));
            }
        }
        std::cout << "[SDF_VIZ]   subface[" << s << "] type=" << static_cast<int>(subface_type) << " ✓\n";
    }

    // ── 3. 写文件 ──────────────────────────────────────────────────────────
    std::ofstream ofs(output_path);
    if (!ofs) {
        std::cerr << "[SDF_VIZ] Cannot open: " << output_path << "\n";
        return;
    }

    // 文件头
    ofs << grid_res << ' ' << y_slice << '\n';
    ofs << x0 << ' ' << x1 << ' ' << z0 << ' ' << z1 << '\n';
    ofs << ns << '\n';

    // 每个 subface 的数据块
    for (uint32_t s = 0; s < ns; ++s) {
        ofs << static_cast<int>(tree.subface_types[s]) << '\n';
        for (int iz = 0; iz < N; ++iz) {
            for (int ix = 0; ix < N; ++ix) {
                if (ix) ofs << ' ';
                ofs << grids[s][iz * N + ix];
            }
            ofs << '\n';
        }
    }

    std::cout << "[SDF_VIZ] Written → " << output_path << '\n';
}