// Copyright (c) 2024-2026 Tarik Moussa.
// SPDX-License-Identifier: MIT

// Port of de.varylab.discreteconformal.util.DiscreteEllipticUtilityTest (Java/JUnit).
// Tests the normalizeModulus function that moves a complex number tau into the
// fundamental domain of the modular group SL(2,Z).

#include "discrete_elliptic_utility.hpp"
#include <gtest/gtest.h>
#include <complex>
#include <cmath>

using namespace conformallab;

// Corresponds to Java testNormalizeModulus()
TEST(DiscreteEllipticUtilityTest, NormalizeModulus) {
    // tau already in fundamental domain → should be returned unchanged
    std::complex<double> tau(0.45, 1.1);
    auto tauNorm = normalizeModulus(tau);
    EXPECT_NEAR(0.45, tauNorm.real(), 1E-12);
    EXPECT_NEAR(1.1,  tauNorm.imag(), 1E-12);

    // tau = i/3  (|tau| < 1) → inversion gives 3i
    tau = std::complex<double>(0.0, 1.0 / 3.0);
    tauNorm = normalizeModulus(tau);
    EXPECT_NEAR(3.0, tauNorm.imag(), 1E-12);
    EXPECT_NEAR(0.0, tauNorm.real(), 1E-12);
}

// Corresponds to Java testNormalizeModulusPeriodShift()
// Two tau values that differ by a T-shift (integer shift of Re) must normalize
// to the same point in the fundamental domain.
TEST(DiscreteEllipticUtilityTest, NormalizeModulusPeriodShift) {
    std::complex<double> tau1(0.3,  1.0);
    std::complex<double> tau2(-0.7, 1.0);   // tau2 = tau1 - 1

    auto n1 = normalizeModulus(tau1);
    auto n2 = normalizeModulus(tau2);

    EXPECT_NEAR(n1.real(), n2.real(), 1E-12) << "real parts should be equal";
    EXPECT_NEAR(n1.imag(), n2.imag(), 1E-12) << "imag parts should be equal";
}