/**
 * hermes antispam proxy
 * Copyright (C) 2006, 2007 Juan José Gutiérrez de Quevedo <juanjo@gutierrezdequevedo.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * @author Juan José Gutiérrez de Quevedo <juanjo@gutierrezdequevedo.com>
 */

#include "Spf.h"
#include <stdexcept>    
#include <string>
#include <mutex>

SPF_server_t *Spf::spfserver = nullptr;

/**
 * Constructor
 * 
 * Initializes the SPF server if this is the first created object of the class.
 */
Spf::Spf() {
    static std::once_flag initFlag; // To ensure thread-safe initialization
    std::call_once(initFlag, []() {
        spfserver = SPF_server_new(SPF_DNS_CACHE, 0);
        if (!spfserver) {
            throw std::runtime_error("Can't initialize SPF library");
        }
    });
}

/**
 * Destructor
 * 
 * Frees the memory of the SPF server.
 */
Spf::~Spf() {
    deinitialize(); // Clean up resources
}

/**
 * Frees all memory related to the SPF class.
 *
 * This is needed because common resources are only initialized once (and are static).
 */
void Spf::deinitialize() {
    if (spfserver) {
        SPF_server_free(spfserver);
        spfserver = nullptr; // Optional: Avoid dangling pointer
    }
}

/**
 * Makes a query to the DNS system for an SPF record.
 *
 * @param ip    The IP of the remote server
 * @param helo  The HELO string of the remote server
 * @param from  The envelope from address
 *
 * @returns true if the query is not incorrect
 */
bool Spf::query(const std::string& ip, const std::string& helo, const std::string& from) {
    SPF_request_t* spfrequest = SPF_request_new(spfserver); // Create request here
    if (!spfrequest) {
        throw std::runtime_error("Can't initialize SPF request");
    }

    // Set the values for the SPF request
    if (SPF_request_set_ipv4_str(spfrequest, ip.c_str())) {
        SPF_request_free(spfrequest); // Clean up on failure
        throw std::runtime_error("Error configuring IP for SPF request");
    }
    if (SPF_request_set_helo_dom(spfrequest, helo.c_str())) {
        SPF_request_free(spfrequest); // Clean up on failure
        throw std::runtime_error("Error configuring HELO for SPF request");
    }
    if (SPF_request_set_env_from(spfrequest, from.c_str())) {
        SPF_request_free(spfrequest); // Clean up on failure
        throw std::runtime_error("Error configuring FROM for SPF request");
    }

    // Make the actual query
    SPF_response_t* spfresponse = nullptr; // Local response variable
    SPF_request_query_mailfrom(spfrequest, &spfresponse);

    bool retval = false;
    if (spfresponse) {
        retval = !(SPF_response_result(spfresponse) == SPF_RESULT_FAIL ||
                    SPF_response_result(spfresponse) == SPF_RESULT_SOFTFAIL);
        SPF_response_free(spfresponse); // Free the response
    }

    SPF_request_free(spfrequest); // Free the request
    return retval;
}