// SPDX-FileCopyrightText: 2025 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only

#include <catch2/catch_all.hpp>
#include <cmath>
#include <limits>
#include "../common/ResolutionShells.h"

TEST_CASE("ResolutionShells_WrongInput") {
    REQUIRE_THROWS(ResolutionShells(-1,5,10));
    REQUIRE_THROWS(ResolutionShells(7,5,10));
    REQUIRE_THROWS(ResolutionShells(5,6,0));
    REQUIRE_THROWS(ResolutionShells(5,6,-10));
}

TEST_CASE("ResolutionShells") {
    ResolutionShells shells(1,50, 20);
    REQUIRE(!shells.GetShell(50.0111));
    REQUIRE(shells.GetShell(50.0) == 0);
    REQUIRE(shells.GetShell(49.555) == 0);
    REQUIRE(shells.GetShell(1.001) == 19);
    REQUIRE(!shells.GetShell(1.0));

    float one_over_d_sq = 1/(50. * 50.) + 10.2 * (1/(1 * 1) - 1/(50 * 50)) / 20;

    REQUIRE(shells.GetShell(1/sqrtf(one_over_d_sq)) == 10);
}
// An infinite d_max is "no low-resolution bound": the shells start at 1/d^2 = 0, so every finite
// resolution coarser than d_min falls in shell 0 and the shell boundaries stay finite.
TEST_CASE("ResolutionShells_NoLowBound") {
    const ResolutionShells shells(1, std::numeric_limits<float>::infinity(), 20);
    REQUIRE(shells.GetShell(1e6f) == 0);
    REQUIRE(shells.GetShell(50.0) == 0);
    REQUIRE(shells.GetShell(1.001) == 19);
    REQUIRE(!shells.GetShell(1.0));
    REQUIRE(!shells.GetShell(std::numeric_limits<float>::infinity()));

    const auto min_res = shells.GetShellMinRes();
    REQUIRE(min_res.size() == 20);
    for (const auto d: min_res)
        REQUIRE(std::isfinite(d));
    // With the low bound at 1/d^2 = 0 the first boundary is at 1/20th of the sphere.
    REQUIRE(min_res.front() == Catch::Approx(std::sqrt(20.0)));
}