/// @file fuzz_sdf.cpp
/// @brief SDF 随机CSG树模糊测试 + 持续运行模式
///
/// 测试策略：
///   1. 随机生成深度 CSG 树（最大深度 6）
///   2. 随机选择操作符（union/intersection/difference/smooth variants）
///   3. 随机选择图元（sphere/box/cylinder/torus/capsule）
///   4. 随机应用域变形（translate/rotate/scale/twist/bend）
///   5. 随机采样点评估并验证结果
///   6. 持续运行模式（命令行参数 -1 表示无限循环）

#include <gtest/gtest.h>
#include "vde/sdf/sdf_primitives.h"
#include "vde/sdf/sdf_operations.h"
#include "vde/sdf/sdf_tree.h"
#include <cmath>
#include <random>
#include <vector>
#include <string>
#include <cstdlib>

using namespace vde::sdf;
using namespace vde::core;

// ═══════════════════════════════════════════════
//  SDF 随机种子
// ═══════════════════════════════════════════════

static std::mt19937 s_rng(42);

// ═══════════════════════════════════════════════
//  随机参数生成器
// ═══════════════════════════════════════════════

namespace {

/// 随机双精度 [lo, hi]
double rand_range(double lo, double hi) {
    std::uniform_real_distribution<double> dist(lo, hi);
    return dist(s_rng);
}

/// 随机 Point3D，范围 [lo, hi]
Point3D rand_point(double lo, double hi) {
    return Point3D(rand_range(lo, hi), rand_range(lo, hi), rand_range(lo, hi));
}

/// 随机选择操作类型（CSG 布尔）
SdfOp rand_csg_op() {
    static const SdfOp ops[] = {
        SdfOp::Union, SdfOp::Intersection, SdfOp::Difference,
        SdfOp::SmoothUnion, SdfOp::SmoothIntersection, SdfOp::SmoothDifference
    };
    return ops[std::uniform_int_distribution<int>(0, 5)(s_rng)];
}

/// 随机选择图元类型
SdfOp rand_primitive_op() {
    static const SdfOp ops[] = {
        SdfOp::Sphere, SdfOp::Box, SdfOp::Cylinder,
        SdfOp::Torus, SdfOp::Capsule
    };
    return ops[std::uniform_int_distribution<int>(0, 4)(s_rng)];
}

/// 随机选择域变形类型
SdfOp rand_transform_op() {
    static const SdfOp ops[] = {
        SdfOp::Translate, SdfOp::Rotate, SdfOp::Scale,
        SdfOp::Twist, SdfOp::Bend
    };
    return ops[std::uniform_int_distribution<int>(0, 4)(s_rng)];
}

} // anonymous

// ═══════════════════════════════════════════════
//  随机 CSG 树构造
// ═══════════════════════════════════════════════

/// 创建随机图元节点
SdfNodePtr rand_primitive() {
    SdfOp op = rand_primitive_op();
    auto node = std::make_shared<SdfNode>(op);

    switch (op) {
    case SdfOp::Sphere:
        node->params.radius = rand_range(0.1, 5.0);
        break;
    case SdfOp::Box:
        node->params.extents = rand_point(0.1, 3.0);
        break;
    case SdfOp::Cylinder:
        node->params.radius = rand_range(0.1, 3.0);
        node->params.height = rand_range(0.2, 6.0);
        break;
    case SdfOp::Torus:
        node->params.major_radius = rand_range(0.5, 4.0);
        node->params.minor_radius = rand_range(0.1, 1.5);
        break;
    case SdfOp::Capsule:
        node->params.pt_a = Point3D(0, -rand_range(0.5, 3.0), 0);
        node->params.pt_b = Point3D(0, rand_range(0.5, 3.0), 0);
        node->params.radius = rand_range(0.1, 1.0);
        break;
    default:
        break;
    }
    return node;
}

/// 创建随机 CSG 布尔节点（递归）
SdfNodePtr rand_csg_tree(int depth, int max_depth) {
    if (depth >= max_depth) {
        return rand_primitive();
    }

    SdfOp op = rand_csg_op();
    auto left = rand_csg_tree(depth + 1, max_depth);
    auto right = rand_csg_tree(depth + 1, max_depth);

    auto node = std::make_shared<SdfNode>(op);
    node->children.push_back(left);
    node->children.push_back(right);

    if (op == SdfOp::SmoothUnion || op == SdfOp::SmoothIntersection ||
        op == SdfOp::SmoothDifference) {
        node->params.blend_k = rand_range(0.05, 0.5);
    }

    return node;
}

/// 随机应用域变形包装
SdfNodePtr wrap_transform(SdfNodePtr child) {
    if (rand_range(0.0, 1.0) < 0.3) {
        SdfOp op = rand_transform_op();
        auto node = std::make_shared<SdfNode>(op);
        node->children.push_back(child);

        switch (op) {
        case SdfOp::Translate:
            node->params.translate_offset = rand_point(-2.0, 2.0);
            break;
        case SdfOp::Rotate:
            node->params.amount = rand_range(-M_PI, M_PI);
            break;
        case SdfOp::Scale:
            node->params.scale_factors = rand_point(0.5, 2.0);
            break;
        case SdfOp::Twist:
            node->params.amount = rand_range(-0.5, 0.5);
            break;
        case SdfOp::Bend:
            node->params.amount = rand_range(-0.3, 0.3);
            break;
        default:
            break;
        }
        return node;
    }
    return child;
}

// ═══════════════════════════════════════════════
//  模糊测试用例
// ═══════════════════════════════════════════════

TEST(FuzzSdf, RandomCSGTree_Evaluate) {
    // 生成多个随机树并在多个点处求值
    for (int i = 0; i < 50; ++i) {
        auto tree = rand_csg_tree(0, 4);
        // 可选变形包装
        tree = wrap_transform(tree);

        for (int j = 0; j < 30; ++j) {
            Point3D p = rand_point(-5.0, 5.0);
            EXPECT_NO_THROW({
                double v = evaluate(tree, p);
                // 求值结果必须是有限数（不应是 NaN 或 Inf）
                EXPECT_TRUE(std::isfinite(v));
            });
        }
    }
}

TEST(FuzzSdf, RandomCSGTree_DeepTree) {
    // 深度 CSG 树（depth 6 → 最多 2^6 = 64 个叶子节点）
    for (int i = 0; i < 20; ++i) {
        auto tree = rand_csg_tree(0, 6);

        EXPECT_NO_THROW({
            auto bbox = estimate_bbox(tree, 0.5);
            EXPECT_TRUE(std::isfinite(bbox.min.x()));
            EXPECT_TRUE(std::isfinite(bbox.max.x()));

            Point3D p = rand_point(-10.0, 10.0);
            double v = evaluate(tree, p);
            EXPECT_TRUE(std::isfinite(v));
        });
    }
}

TEST(FuzzSdf, RandomCSGTree_Bounds) {
    // 验证 estimate_bounds 对所有随机树返回合理的值
    for (int i = 0; i < 30; ++i) {
        auto tree = rand_csg_tree(0, 3);
        tree = wrap_transform(tree);

        EXPECT_NO_THROW({
            auto half = estimate_bounds(tree, 1.0);
            EXPECT_GE(half.x(), 0.0);
            EXPECT_GE(half.y(), 0.0);
            EXPECT_GE(half.z(), 0.0);
            EXPECT_TRUE(std::isfinite(half.x()));
            EXPECT_TRUE(std::isfinite(half.y()));
            EXPECT_TRUE(std::isfinite(half.z()));
        });
    }
}

TEST(FuzzSdf, RandomTree_Visit) {
    // 验证 visit() 对所有随机树都不崩溃
    for (int i = 0; i < 30; ++i) {
        auto tree = rand_csg_tree(0, 4);
        tree = wrap_transform(tree);

        EXPECT_NO_THROW({
            int count = 0;
            tree->visit([&](const SdfNode& /*n*/) { ++count; });
            EXPECT_GT(count, 0);
        });
    }
}

// ═══════════════════════════════════════════════
//  持续运行模式（-1 = 无限循环）
//  用法: ./fuzz_sdf --fuzz_forever
// ═══════════════════════════════════════════════

TEST(FuzzSdf, ContinuousFuzz) {
    // 检查环境变量 VDE_FUZZ_FOREVER=1 启用持续模式
    const char* forever = std::getenv("VDE_FUZZ_FOREVER");
    if (!forever || std::string(forever) != "1") {
        GTEST_SKIP() << "设置 VDE_FUZZ_FOREVER=1 启用持续模糊测试";
    }

    // 持续运行直到手动停止
    int iteration = 0;
    while (true) {
        ++iteration;
        auto tree = rand_csg_tree(0, std::uniform_int_distribution<int>(2, 5)(s_rng));
        tree = wrap_transform(tree);

        Point3D p = rand_point(-10.0, 10.0);
        double v = evaluate(tree, p);

        ASSERT_TRUE(std::isfinite(v))
            << "iteration=" << iteration
            << " 非有限 SDF 值: " << v;

        // 每 10000 次打印一次进度
        if (iteration % 10000 == 0) {
            auto bbox = estimate_bbox(tree, 1.0);
            std::cout << "[FuzzSdf] iteration=" << iteration
                      << " value=" << v
                      << " bbox=[" << bbox.min.x() << "," << bbox.max.x() << "]"
                      << std::endl;
        }
    }
}