// SPDX-FileCopyrightText: 2026 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only

#include <catch2/catch_all.hpp>

#ifdef JFJOCH_USE_CUDA
#include <algorithm>
#include <random>
#include <utility>
#include <vector>

#include "../common/CUDAWrapper.h"
#include "../image_analysis/scale_merge/PairSortGPU.h"

// The device sort against std::sort, with many repeated first and second values (so both keys decide)
// and whole duplicate pairs.
TEST_CASE("SortPairsGPU: the order std::sort leaves", "[PairSortGPU]") {
    if (get_gpu_count() == 0) {
        WARN("No CUDA GPU present. Skipping SortPairsGPU");
        return;
    }
    std::mt19937 rng(5);
    std::uniform_int_distribution<int> coarse(0, 200);
    std::exponential_distribution<double> fine(1.0);
    std::vector<std::pair<double, double>> v(500000);
    for (auto &p : v) p = {coarse(rng) * 0.37, coarse(rng) % 3 ? fine(rng) : 0.5 * coarse(rng)};
    for (size_t i = 0; i < 1000; ++i) v[v.size() - 1 - i] = v[i];
    auto host = v;
    std::sort(host.begin(), host.end());
    SortPairsGPU(v);
    CHECK(v == host);
}
#endif