/*
 * Fixed-size map.
 *
 * Author: Malte J. Ziebarth (malte.ziebarth@tum.de)
 *
 * Copyright (C) 2026 Technische Universität München
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 *
 *    1. Redistributions of source code must retain the above copyright notice, this
 *       list of conditions and the following disclaimer.
 *    2. Redistributions in binary form must reproduce the above copyright notice,
 *       this list of conditions and the following disclaimer in the documentation
 *       and/or other materials provided with the distribution.
 *    3. Neither the name of the copyright holder nor the names of its contributors
 *       may be used to endorse or promote products derived from this software
 *       without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * SPDX-FileCopyrightText: 2026 Technical University of Munich
 * SPDX-License-Identifier: BSD-3-Clause
 * SPDX-FileContributor: Malte J. Ziebarth <malte.ziebarth@tum.de>
 */

#ifndef FUNKTIONSKLEMPNER_FIXEDMAP_HPP
#define FUNKTIONSKLEMPNER_FIXEDMAP_HPP

#include <array>
#include <utility>
#include <optional>
#include <algorithm>

namespace funktionsklempner {

template<typename Key, typename Val, size_t n>
class FixedMap
{
public:
    constexpr FixedMap(std::array<std::pair<Key, Val>, n>&& A)
       : key_val(sorted(std::move(A)))
    {}

    constexpr std::optional<Val> find(const Key& key) const noexcept
    {
        /* Use binary search to find the key: */
        auto it = std::lower_bound(
            key_val.begin(),
            key_val.end(),
            key,
            [](const std::pair<Key, Val>& kv, const Key& k) -> bool
            {
                return kv.first < k;
            }
        );
        if (it == key_val.end() || it->first != key)
            return std::optional<Val>();

        return it->second;
    }


private:
    std::array<std::pair<Key, Val>, n> key_val;

    constexpr static std::array<std::pair<Key, Val>, n>
    sorted(std::array<std::pair<Key, Val>, n>&& A)
    {
        std::sort(
            A.begin(),
            A.end(),
            [](const std::pair<Key, Val>& l, const std::pair<Key, Val>& r) -> bool
            {
                return l.first < r.first;
            }
        );
        return A;
    }
};


} // namespace funktionsklempner

#endif