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

#include <cmath>

#include "HKLKey.h"
#include "gemmi/symmetry.hpp"

uint64_t HKLKey::pack() const {
    constexpr int bits = 21;
    constexpr int bias = 1 << (bits - 1); // 1,048,576
    constexpr int max_value = bias - 1;
    constexpr int min_value = -bias;
    constexpr std::uint64_t mask = (1ULL << bits) - 1ULL;

    if (h < min_value || h > max_value ||
        k < min_value || k > max_value ||
        l < min_value || l > max_value) {
        throw std::out_of_range("HKL index outside packable range");
        }

    const std::uint64_t hh = static_cast<std::uint64_t>(h + bias) & mask;
    const std::uint64_t kk = static_cast<std::uint64_t>(k + bias) & mask;
    const std::uint64_t ll = static_cast<std::uint64_t>(l + bias) & mask;

    return (hh << 1) | (kk << (bits + 1)) | (ll << (2 * bits + 1)) | (plus ? 1ULL : 0ULL);
}

HKLKeyGenerator::HKLKeyGenerator(bool merge_friedel, int32_t space_group_number)
    : HKLKeyGenerator(merge_friedel, *gemmi::find_spacegroup_by_number(space_group_number)) {
}

HKLKeyGenerator::HKLKeyGenerator(bool merge_friedel, const gemmi::SpaceGroup &sg)
    : merge_friedel(merge_friedel),
      sg(sg),
      ops(sg.operations()),
      asu(&sg) {
}

HKLKey HKLKeyGenerator::operator()(const MergedReflection &r) const {
    return operator()(r.h, r.k, r.l);
}

HKLKey HKLKeyGenerator::operator()(const Reflection &r) const {
    return operator()(r.h, r.k, r.l);
}

HKLKey HKLKeyGenerator::operator()(int32_t h, int32_t k, int32_t l) const {
    HKLKey key{h, k, l, true};

    if (sg.number == 1) {
        const HKLKey neg{-h, -k, -l, true};
        if (std::tie(key.h, key.k, key.l) < std::tie(neg.h, neg.k, neg.l)) {
            key.h = -key.h;
            key.k = -key.k;
            key.l = -key.l;
            key.plus = merge_friedel;
        }
    } else {
        const gemmi::Op::Miller in{h, k, l};
        const auto [hkl, sign_plus] = asu.to_asu_sign(in, ops);

        key.h = hkl[0];
        key.k = hkl[1];
        key.l = hkl[2];
        key.plus = merge_friedel ? true : sign_plus;
    }
    return key;
}

bool HKLKeyGenerator::IsSystematicallyAbsent(int32_t h, int32_t k, int32_t l) const {
    return ops.is_systematically_absent(gemmi::Op::Miller{h, k, l});
}

bool HKLKeyGenerator::IsSystematicallyAbsent(const Reflection &r) const {
    return IsSystematicallyAbsent(r.h, r.k, r.l);
}

bool AcceptReflection(const Reflection &r, std::optional<double> d_min_limit) {
    if (!std::isfinite(r.I))
        return false;
    if (!std::isfinite(r.d) || r.d <= 0.0f)
        return false;
    if (d_min_limit && r.d < d_min_limit)
        return false;
    if (!std::isfinite(r.rlp) || r.rlp == 0.0f)
        return false;
    if (!std::isfinite(r.sigma) || r.sigma <= 0.0)
        return false;
    return true;
}

bool AcceptReflection(const Reflection &r, double d_min_limit) {
    if (!std::isfinite(r.I))
        return false;
    if (!std::isfinite(r.d) || r.d <= 0.0f)
        return false;
    if (d_min_limit > 0.0 && r.d < d_min_limit)
        return false;
    if (!std::isfinite(r.rlp) || r.rlp == 0.0f)
        return false;
    if (!std::isfinite(r.sigma) || r.sigma <= 0.0)
        return false;
    return true;
}