// Copyright (C) 2015 xaizek <xaizek@posteo.net>
//
// This file is part of dit.
//
// dit is free software: you can redistribute it and/or modify
// it under the terms of version 3 of the GNU Affero General Public
// License as published by the Free Software Foundation.
//
// dit is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with dit.  If not, see <http://www.gnu.org/licenses/>.

#ifndef DIT__UTILS__CONTAINERS_HPP__
#define DIT__UTILS__CONTAINERS_HPP__

#include <algorithm>
#include <utility>

namespace detail {

/**
 * @brief Wrapper and storage for sorted container.
 *
 * @tparam C Type of container.
 */
template <class C>
class Sorted
{
public:
    /**
     * @brief Constructs the instance by sorting the container.
     *
     * @param c Container to sort.
     */
    Sorted(C &&c) : c(std::move(c))
    {
        std::sort(this->c.begin(), this->c.end());
    }

public:
    /**
     * @brief Retrieves begin iterator of sorted container.
     *
     * @returns The iterator.
     */
    typename C::iterator begin() { return c.begin(); }

    /**
     * @brief Retrieves end iterator of sorted container.
     *
     * @returns The iterator.
     */
    typename C::iterator end() { return c.end(); }

private:
    /**
     * @brief Sorted container.
     */
    C c;
};

}

/**
 * @brief Adapter for iterating container elements in sorted order.
 *
 * @tparam C Type of container.
 * @param c Container itself.
 *
 * @returns Object suitable to be used in range for loop.
 */
template <typename C>
inline detail::Sorted<C>
sorted(C &&c)
{
    return detail::Sorted<C>(std::move(c));
}

/**
 * @brief Splits container into ("start matching predicate", "the rest").
 *
 * @tparam C Type of container to split.
 * @tparam P Predicate to use for the split.
 * @param c Container instance to split.
 * @param p Splitting predicate.
 *
 * @returns Pair of the split.
 */
template <typename C, typename P>
inline std::pair<C, C>
span(const C &c, P p)
{
    C left, right;

    auto begin = std::begin(c);
    auto end = std::end(c);

    while (begin != end && p(*begin)) {
        left.push_back(*begin);
        ++begin;
    }
    while (begin != end) {
        right.push_back(*begin);
        ++begin;
    }

    return { std::move(left), std::move(right) };
}

#endif // DIT__UTILS__CONTAINERS_HPP__