/// bench_curves.cpp — Bezier / BSpline evaluation benchmarks
///
/// Metrics:
///   BezierEval/N{iterations}    — evaluate() throughput on a cubic Bezier
///   BSplineEval/N{iterations}   — evaluate() throughput on a cubic BSpline

#include <benchmark/benchmark.h>
#include <vde/curves/bezier_curve.h>
#include <vde/curves/bspline_curve.h>
#include <vde/core/point.h>
#include <random>
#include <vector>

using namespace vde;

namespace {

/// A cubic Bezier with control points scattered in [-10, 10]³
curves::BezierCurve sample_bezier() {
    static std::vector<core::Point3D> cp = {
        {0.0, 0.0, 0.0}, {3.0, 5.0, -1.0}, {7.0, -2.0, 4.0}, {10.0, 3.0, 2.0}};
    return curves::BezierCurve(cp);
}

/// A cubic uniform BSpline with 7 control points
curves::BSplineCurve sample_bspline() {
    static std::vector<core::Point3D> cp = {
        {0.0, 0.0, 0.0}, {2.0, 4.0, -1.0}, {5.0, 1.0, 3.0},
        {8.0, -1.0, 1.0}, {11.0, 3.0, -2.0}, {13.0, 2.0, 0.0}, {15.0, 0.0, 1.0}};
    static std::vector<double> knots = {0,0,0,0, 0.25, 0.5, 0.75, 1,1,1,1};
    return curves::BSplineCurve(cp, knots, 3);
}

/// N equally spaced t values in [0, 1]
std::vector<double> sample_params(int n) {
    std::vector<double> t;
    t.reserve(n);
    for (int i = 0; i < n; ++i)
        t.push_back(static_cast<double>(i) / (n - 1));
    return t;
}

} // namespace

// ── Bezier ────────────────────────────────────────────────────────────

static void BezierEval(benchmark::State& state) {
    auto curve = sample_bezier();
    auto params = sample_params(state.range(0));
    double sum = 0;
    for (auto _ : state) {
        for (double t : params) {
            auto p = curve.evaluate(t);
            benchmark::DoNotOptimize(sum += p.x());
        }
    }
    benchmark::DoNotOptimize(sum);
    state.SetItemsProcessed(state.iterations() * params.size());
}
BENCHMARK(BezierEval)->Arg(10000)->Arg(100000);

// ── BSpline ───────────────────────────────────────────────────────────

static void BSplineEval(benchmark::State& state) {
    auto curve = sample_bspline();
    auto params = sample_params(state.range(0));
    double sum = 0;
    for (auto _ : state) {
        for (double t : params) {
            auto p = curve.evaluate(t);
            benchmark::DoNotOptimize(sum += p.x());
        }
    }
    benchmark::DoNotOptimize(sum);
    state.SetItemsProcessed(state.iterations() * params.size());
}
BENCHMARK(BSplineEval)->Arg(10000)->Arg(100000);