/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Copyright:
 *      2018, Danny Robson <danny@nerdcruft.net>
 */

#pragma once

#include <functional>


namespace cruft::search {
    /// Performs a linear search to discover the iterator corresponding to
    /// the value which minimises a function.
    ///
    /// Useful as a mechanism to avoid possibly expensive comparison
    /// calculations; eg recomputing path distances when testing a series of
    /// possible routes.
    ///
    /// The provided function will be invoked with the supplied argument pack
    /// as the first arguments and the dereferenced iterator as the final
    /// argument.
    template <typename InputT, typename FunctionT, typename ...Args>
    InputT
    minimises (InputT first, InputT last, FunctionT &&func, Args &&...args)
    {
        auto best_score = std::invoke (func, args..., *first);
        auto best_item = first;

        for (++first; first != last; ++first) {
            auto this_score = std::invoke (func, args..., *first);
            if (this_score < best_score) {
                best_score = this_score;
                best_item = first;
            }
        }

        return best_item;
    }
}