/*
Copyright Contributors to the libdnf project.

This file is part of libdnf: https://github.com/rpm-software-management/libdnf/

Libdnf is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 2.1 of the License, or
(at your option) any later version.

Libdnf 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License
along with libdnf.  If not, see <https://www.gnu.org/licenses/>.
*/


#include "string.hpp"


namespace libdnf5::utils::string {


static std::vector<std::string> split_impl(
    const std::string & str, const std::string & delimiter, std::size_t limit, bool from_right) {
    std::vector<std::string> result;

    // For an empty input string, return a vector with one empty token.
    if (str.empty()) {
        result.emplace_back("");
        return result;
    }

    if (limit < 2) {
        result.emplace_back(str);
        return result;
    }

    const auto delim_length = delimiter.size();

    // Count the number of tokens on the input.
    std::size_t tokens_count = 1;
    for (auto pos = str.find(delimiter); pos != std::string::npos; pos = str.find(delimiter, pos + delim_length)) {
        ++tokens_count;
    }

    auto delim_pos = str.find(delimiter);

    // The resulting number of tokens must be less than or equal to the limit.
    if (tokens_count > limit) {
        if (from_right) {
            // For right-split, skip the left excess delimiters.
            for (; tokens_count > limit; --tokens_count) {
                delim_pos = str.find(delimiter, delim_pos + delim_length);
            }
        } else {
            // For left-split, adjust the tokens_count.
            tokens_count = limit;
        }
    }

    // Reserve memory to avoid realocations.
    result.reserve(tokens_count);

    // Split the input string.
    std::size_t token_pos = 0;
    while (--tokens_count != 0) {
        result.emplace_back(str, token_pos, delim_pos - token_pos);
        token_pos = delim_pos + delim_length;
        delim_pos = str.find(delimiter, token_pos);
    }
    // Put the rest as the last token.
    result.emplace_back(str, token_pos);

    return result;
}

std::vector<std::string> rsplit(const std::string & str, const std::string & delimiter, std::size_t limit) {
    return split_impl(str, delimiter, limit, true);
}

std::vector<std::string> split(const std::string & str, const std::string & delimiter, std::size_t limit) {
    return split_impl(str, delimiter, limit, false);
}


}  // namespace libdnf5::utils::string
