<?php
/**
 * AlertDB.php
 *
 * Extending the built in logging to add an event logger function
 *
 * 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, either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 *
 *
 * Original code:
 * @author Daniel Preussker <f0o@devilcode.org>
 * @copyright 2014 f0o, LibreNMS
 * @license GPL
 *
 * Modified by:
 * @package    LibreNMS
 * @link       http://librenms.org
 * @copyright  2019 KanREN, Inc.
 * @author     Heath Barnhart <hbarnhart@kanren.net>
 */

namespace LibreNMS\Alert;

use App\Models\Device;
use LibreNMS\Alert\AlertUtil;
use LibreNMS\Alerting\QueryBuilderParser;

class AlertDB
{

    /**
     * @param $rule
     * @param $query_builder
     * @return bool|string
     */
    public static function genSQL($rule, $query_builder = false)
    {
        if ($query_builder) {
            return QueryBuilderParser::fromJson($query_builder)->toSql();
        } else {
            return self::genSQLOld($rule);
        }
    }

    /**
     * Generate SQL from Rule
     * @param string $rule Rule to generate SQL for
     * @return string|boolean
     */
    public static function genSQLOld($rule)
    {
        $rule = AlertUtil::runMacros($rule);
        if (empty($rule)) {
            //Cannot resolve Macros due to recursion. Rule is invalid.
            return false;
        }
        //Pretty-print rule to dissect easier
        $pretty = array('&&' => ' && ', '||' => ' || ');
        $rule = str_replace(array_keys($pretty), $pretty, $rule);
        $tmp = explode(" ", $rule);
        $tables = array();
        foreach ($tmp as $opt) {
            if (strstr($opt, '%') && strstr($opt, '.')) {
                $tmpp = explode(".", $opt, 2);
                $tmpp[0] = str_replace("%", "", $tmpp[0]);
                $tables[] = mres(str_replace("(", "", $tmpp[0]));
                $rule = str_replace($opt, $tmpp[0].'.'.$tmpp[1], $rule);
            }
        }
        $tables = array_keys(array_flip($tables));
        if (dbFetchCell('SELECT 1 FROM information_schema.COLUMNS WHERE TABLE_NAME = ? && COLUMN_NAME = ?', array($tables[0],'device_id')) != 1) {
            //Our first table has no valid glue, append the 'devices' table to it!
            array_unshift($tables, 'devices');
        }
        $x = sizeof($tables)-1;
        $i = 0;
        $join = "";
        while ($i < $x) {
            if (isset($tables[$i+1])) {
                $gtmp = ResolveGlues(array($tables[$i+1]), 'device_id');
                if ($gtmp === false) {
                    //Cannot resolve glue-chain. Rule is invalid.
                    return false;
                }
                $last = "";
                $qry = "";
                foreach ($gtmp as $glue) {
                    if (empty($last)) {
                        list($tmp,$last) = explode('.', $glue);
                        $qry .= $glue.' = ';
                    } else {
                        list($tmp,$new) = explode('.', $glue);
                        $qry .= $tmp.'.'.$last.' && '.$tmp.'.'.$new.' = ';
                        $last = $new;
                    }
                    if (!in_array($tmp, $tables)) {
                        $tables[] = $tmp;
                    }
                }
                $join .= "( ".$qry.$tables[0].".device_id ) && ";
            }
            $i++;
        }
        $sql = "SELECT * FROM ".implode(",", $tables)." WHERE (".$join."".str_replace("(", "", $tables[0]).".device_id = ?) && (".str_replace(array("%","@","!~","~"), array("",".*","NOT REGEXP","REGEXP"), $rule).")";
        return $sql;
    }
}
