//  OpenVPN 3 Linux client -- Next generation OpenVPN client
//
//  SPDX-License-Identifier: AGPL-3.0-only
//
//  Copyright (C)  OpenVPN Inc <sales@openvpn.net>
//  Copyright (C)  David Sommerseth <davids@openvpn.net>
//

/**
 * @file   settings-manager.hpp
 *
 * @brief  Main manager object for all DNS resolver settings (declaration)
 */

#pragma once

#include <map>
#include <memory>
#include <vector>

#include "netcfg/netcfg-signals.hpp"
#include "netcfg/dns/resolver-settings.hpp"
#include "netcfg/dns/resolver-backend-interface.hpp"

using namespace NetCfg::DNS;

namespace NetCfg {
namespace DNS {

/**
 *  Manager object for all DNS settings on the system
 *
 *  This depends on a backend handler object (ResolverBackendInterface)
 *  which will perform the changes on the system.
 */
class SettingsManager
{
  public:
    using Ptr = std::shared_ptr<SettingsManager>;

    [[nodiscard]] static SettingsManager::Ptr Create(ResolverBackendInterface::Ptr be)
    {
        return SettingsManager::Ptr(new SettingsManager(be));
    }
    ~SettingsManager();

    /**
     *  Retrieve information about the configured DNS Settings backend
     *
     * @return  Returns a std::string containing the details
     */
    const std::string GetBackendInfo() const;

    const ApplySettingsMode GetApplyMode() const;


    /**
     *  Allocate a new set of DNS settings for the DNS resolver.
     *
     *  This operation is transaction oriented and will not be applied
     *  until the ApplySettings() method has been called.   The order
     *  of execution will be the reverse order of the
     *  NewResolverSettings() calls.  The latest call gets precedence
     *  over the other calls.
     *
     * @return  Returns a ResolverSettings::Ptr to an object which
     *          need to be configured with the DNS settings for the
     *          VPN session it is associated with
     */
    ResolverSettings::Ptr NewResolverSettings();


    /**
     *   Apply all configured DNS settings
     */
    void ApplySettings(NetCfgSignals::Ptr signals);


    /**
     *  Retrieve the full list of all configured DNS servers
     *  for all VPN sessions
     *
     * @return  Returns a std::vector<std::string> with all DNS
     *          servers.  They are ordered according to the reverse
     *          order the VPN sessions were started.  The last entries
     *          will be the system configured DNS servers.
     */
    std::vector<std::string> GetDNSservers() const;


    /**
     *  Retrieve the full list of all search domains
     *
     * @return  Returns a std::vector<std::string> with all DNS
     *          search domains for both VPN sessions and the
     *          configured system search domains.
     */
    std::vector<std::string> GetSearchDomains() const;


  private:
    ResolverBackendInterface::Ptr backend;
    ssize_t resolver_idx = -1;
    std::map<size_t, ResolverSettings::Ptr> resolvers{};

    SettingsManager(ResolverBackendInterface::Ptr be);
};

} // namespace DNS
} // namespace NetCfg