// Copyright 2023 PingCAP, Inc.
//
// Licensed 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.

#include <Common/Config/ConfigReloader.h>
#include <Interpreters/Context.h>
#include <Poco/File.h>
#include <Poco/Path.h>
#include <Poco/Util/LayeredConfiguration.h>
#include <Server/UserConfigParser.h>
#include <common/logger_useful.h>

#include <memory>

namespace DB
{
namespace UserConfig
{
static std::string tryGetAbsolutePath(const std::string & config_path, std::string && users_config_path)
{
    if (users_config_path[0] != '/')
    {
        /// If path to users' config isn't absolute, try guess its root (current) dir.
        /// Try to find it in dir of main config dir.
        /// If the config file is not exists, we will return an empty path.
        std::string config_parent_dir = Poco::Path(config_path).parent().toString();
        if (auto f = Poco::File(config_parent_dir + users_config_path); f.exists())
        {
            users_config_path = config_parent_dir + users_config_path;
        }
        else
        {
            users_config_path.clear();
        }
    }
    return std::move(users_config_path);
}

ConfigReloaderPtr parseSettings(
    Poco::Util::LayeredConfiguration & config,
    const std::string & config_path,
    const std::unique_ptr<Context> & global_context,
    const LoggerPtr & log)
{
    std::string users_config_path = config.getString("users_config", String(1, '\0'));
    bool load_from_main_config_path = true;
    if (users_config_path.empty() || users_config_path[0] == '\0')
        load_from_main_config_path = true;
    else
    {
        /// If path to users' config isn't absolute, try guess its root (current) dir.
        users_config_path = tryGetAbsolutePath(config_path, std::move(users_config_path));
        /// If the config file is not exists, we will use `config_path` as the user config file
        load_from_main_config_path = users_config_path.empty();
    }

    if (load_from_main_config_path)
        users_config_path = config_path;

    if (users_config_path.empty())
    {
        global_context->setUsersConfig(new Poco::Util::LayeredConfiguration());
        return nullptr;
    }

    LOG_INFO(log, "Set users config file to: {}", users_config_path);

    return std::make_unique<ConfigReloader>(
        users_config_path, //
        /* updater = */ [&global_context](ConfigurationPtr cfg) { global_context->setUsersConfig(cfg); },
        /* already_loaded = */ false,
        /* name = */ "UserCfgReloader");
}

} // namespace UserConfig
} // namespace DB