/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Modified by ScyllaDB
 * Copyright (C) 2015-present ScyllaDB
 */

/*
 * This file is part of Scylla.
 *
 * Scylla is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Scylla 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 Scylla.  If not, see <http://www.gnu.org/licenses/>.
 */
#include "gms/versioned_value.hh"
#include "message/messaging_service.hh"

#include <boost/algorithm/string/split.hpp>
#include <boost/algorithm/string/classification.hpp>
#include <charconv>

namespace gms {

static_assert(std::is_nothrow_default_constructible_v<versioned_value>);
static_assert(std::is_nothrow_move_constructible_v<versioned_value>);

constexpr char versioned_value::DELIMITER;
constexpr const char versioned_value::DELIMITER_STR[];
constexpr const char* versioned_value::STATUS_UNKNOWN;
constexpr const char* versioned_value::STATUS_BOOTSTRAPPING;
constexpr const char* versioned_value::STATUS_NORMAL;
constexpr const char* versioned_value::STATUS_LEAVING;
constexpr const char* versioned_value::STATUS_LEFT;
constexpr const char* versioned_value::STATUS_MOVING;
constexpr const char* versioned_value::REMOVING_TOKEN;
constexpr const char* versioned_value::REMOVED_TOKEN;
constexpr const char* versioned_value::HIBERNATE;
constexpr const char* versioned_value::SHUTDOWN;
constexpr const char* versioned_value::REMOVAL_COORDINATOR;

versioned_value versioned_value::network_version() {
    return versioned_value(format("{}", netw::messaging_service::current_version));
}

sstring versioned_value::make_full_token_string(const std::unordered_set<dht::token>& tokens) {
    return ::join(";", tokens | boost::adaptors::transformed([] (const dht::token& t) {
        return t.to_sstring(); })
    );
}

sstring versioned_value::make_token_string(const std::unordered_set<dht::token>& tokens) {
    if (tokens.empty()) {
        return "";
    }
    return tokens.begin()->to_sstring();
}

sstring versioned_value::make_cdc_generation_id_string(std::optional<cdc::generation_id> gen_id) {
    // We assume that the db_clock epoch is the same on all receiving nodes.
    if (!gen_id) {
        return "";
    }

    return std::visit(make_visitor(
    [] (const cdc::generation_id_v1& id) -> sstring {
        return std::to_string(id.ts.time_since_epoch().count());
    },
    [] (const cdc::generation_id_v2& id) {
        // v2;<timestamp>;<uuid>
        return format("v2;{};{}", id.ts.time_since_epoch().count(), id.id);
    }
    ), *gen_id);
}

std::unordered_set<dht::token> versioned_value::tokens_from_string(const sstring& s) {
    if (s.size() == 0) {
        return {}; // boost::split produces one element for empty string
    }
    std::vector<sstring> tokens;
    boost::split(tokens, s, boost::is_any_of(";"));
    std::unordered_set<dht::token> ret;
    for (auto str : tokens) {
        ret.emplace(dht::token::from_sstring(str));
    }
    return ret;
}

std::optional<cdc::generation_id> versioned_value::cdc_generation_id_from_string(const sstring& s) {
    if (s.empty()) {
        return {};
    }

    if (std::string_view(s).starts_with("v2;")) {
        // v2;<timestamp>;<uuid>
        constexpr auto invalid_format_template = "Invalid value of CDC generation ID string: {}. The format is \"v2;<timestamp>;<uuid>\".";
        const char* const end = s.c_str() + s.size();

        int64_t ts;
        auto r = std::from_chars(s.c_str() + 3, end, ts);
        if (r.ec != std::errc() || r.ptr == end || *r.ptr != ';') {
            throw std::runtime_error(format(invalid_format_template, s));
        }

        ++r.ptr; // r.ptr now points to <uuid>
        if (r.ptr == end) {
            throw std::runtime_error(format(invalid_format_template, s));
        }

        try {
            auto tp = db_clock::time_point{db_clock::duration{ts}};
            auto id = utils::UUID{std::string_view{r.ptr, end}};
            return cdc::generation_id_v2{tp, id};
        } catch (...) {
            throw std::runtime_error(format(invalid_format_template, s));
        }
    }

    try {
        return cdc::generation_id_v1{db_clock::time_point{db_clock::duration(std::stoll(s))}};
    } catch (...) {
        throw std::runtime_error(format("Invalid value of CDC generation ID string: {}. Should be <timestamp> (an unsigned integer).", s));
    }
}

}