<?php
/************************************************************************
 * This file is part of EspoCRM.
 *
 * EspoCRM - Open Source CRM application.
 * Copyright (C) 2014-2021 Yurii Kuznietsov, Taras Machyshyn, Oleksii Avramenko
 * Website: https://www.espocrm.com
 *
 * EspoCRM 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.
 *
 * EspoCRM 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 EspoCRM. If not, see http://www.gnu.org/licenses/.
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU General Public License version 3.
 *
 * In accordance with Section 7(b) of the GNU General Public License version 3,
 * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
 ************************************************************************/

namespace Espo\Core\Utils\Database;

use Espo\Core\{
    Exceptions\Error,
    Utils\Config,
};

use Doctrine\DBAL\{
    Connection as DbalConnection,
    Platforms\AbstractPlatform as DbalPlatform,
};

use PDO;
use ReflectionClass;

class Helper
{
    private $config;

    private $dbalConnection;

    private $pdoConnection;

    protected $dbalDrivers = [
        'mysqli' => 'Doctrine\\DBAL\\Driver\\Mysqli\\Driver',
        'pdo_mysql' => 'Espo\\Core\\Utils\\Database\\DBAL\\Driver\\PDO\\MySQL\\Driver',
    ];

    protected $dbalPlatforms = [
        'MariaDb1027Platform' => 'Espo\\Core\\Utils\\Database\\DBAL\\Platforms\\MariaDb1027Platform',
        'MySQL57Platform' => 'Espo\\Core\\Utils\\Database\\DBAL\\Platforms\\MySQL57Platform',
        'MySQL80Platform' => 'Espo\\Core\\Utils\\Database\\DBAL\\Platforms\\MySQL80Platform',
        'MySQLPlatform' => 'Espo\\Core\\Utils\\Database\\DBAL\\Platforms\\MySQLPlatform',
    ];

    public function __construct(Config $config = null)
    {
        $this->config = $config;
    }

    protected function getConfig()
    {
        return $this->config;
    }

    public function getDbalConnection()
    {
        if (!isset($this->dbalConnection)) {
            $this->dbalConnection = $this->createDbalConnection();
        }

        return $this->dbalConnection;
    }

    public function getPdoConnection()
    {
        if (!isset($this->pdoConnection)) {
            $this->pdoConnection = $this->createPdoConnection();
        }

        return $this->pdoConnection;
    }

    public function setDbalConnection(DbalConnection $dbalConnection)
    {
        $this->dbalConnection = $dbalConnection;
    }

    public function setPdoConnection(PDO $pdoConnection)
    {
        $this->pdoConnection = $pdoConnection;
    }

    public function createDbalConnection(array $params = null)
    {
        if (!isset($params)) {
            $config = $this->getConfig();

            if ($config) {
                $params = $config->get('database');
            }
        }

        if (empty($params['dbname']) || empty($params['user'])) {
            return null;
        }

        $driverName = isset($params['driver']) ? $params['driver'] : 'pdo_mysql';

        unset($params['driver']);

        if (!isset($this->dbalDrivers[$driverName])) {
            throw new Error('Unknown database driver.');
        }

        $driverClass = $this->dbalDrivers[$driverName];

        if (!class_exists($driverClass)) {
            throw new Error('Unknown database class.');
        }

        $driver = new $driverClass();

        $version = $this->getFullDatabaseVersion();

        $platform = $driver->createDatabasePlatformForVersion($version);

        $params['platform'] = $this->createDbalPlatform($platform);

        return new DbalConnection($params, $driver);
    }

    protected function createDbalPlatform(DbalPlatform $platform)
    {
        $reflect = new ReflectionClass($platform);

        $platformClass = $reflect->getShortName();

        if (isset($this->dbalPlatforms[$platformClass])) {
            $class = $this->dbalPlatforms[$platformClass];

            return new $class();
        }

        return $platform;
    }

    /**
     * Create PDO connection.
     *
     * @param array $params
     * @return PDO|\PDOException
     */
    public function createPdoConnection(array $params = null)
    {
        if (!isset($params)) {
            $config = $this->getConfig();

            if ($config) {
                $params = $config->get('database');
            }
        }

        if (empty($params)) {
            return null;
        }

        $platform = !empty($params['platform']) ? strtolower($params['platform']) : 'mysql';
        $port = empty($params['port']) ? '' : ';port=' . $params['port'];
        $dbname = empty($params['dbname']) ? '' : ';dbname=' . $params['dbname'];

        $options = [];

        if (isset($params['sslCA'])) {
            $options[PDO::MYSQL_ATTR_SSL_CA] = $params['sslCA'];
        }

        if (isset($params['sslCert'])) {
            $options[PDO::MYSQL_ATTR_SSL_CERT] = $params['sslCert'];
        }

        if (isset($params['sslKey'])) {
            $options[PDO::MYSQL_ATTR_SSL_KEY] = $params['sslKey'];
        }

        if (isset($params['sslCAPath'])) {
            $options[PDO::MYSQL_ATTR_SSL_CAPATH] = $params['sslCAPath'];
        }

        if (isset($params['sslCipher'])) {
            $options[PDO::MYSQL_ATTR_SSL_CIPHER] = $params['sslCipher'];
        }

        $dsn = $platform . ':host='.$params['host'].$port.$dbname;

        $dbh = new PDO($dsn, $params['user'], $params['password'], $options);

        return $dbh;
    }

    /**
     * Get maximum index length. If $tableName is empty get a value for all database tables.
     *
     * @param ?string $tableName
     * @return int
     */
    public function getMaxIndexLength($tableName = null, $default = 1000)
    {
        $tableEngine = $this->getTableEngine($tableName);

        if (!$tableEngine) {
            return $default;
        }

        switch ($tableEngine) {
            case 'InnoDB':
                $databaseType = $this->getDatabaseType();
                $version = $this->getDatabaseVersion();

                switch ($databaseType) {
                    case 'MariaDB':
                        if (version_compare($version, '10.2.2') >= 0) {
                            return 3072; //InnoDB, MariaDB 10.2.2+
                        }

                        break;

                    case 'MySQL':
                        if (version_compare($version, '5.7.0') >= 0) {
                            return 3072; //InnoDB, MySQL 5.7+
                        }

                        break;
                }

                return 767; //InnoDB
        }

        return 1000; //MyISAM
    }

    public function getTableMaxIndexLength($tableName, $default = 1000)
    {
        return $this->getMaxIndexLength($tableName, $default);
    }

    /**
     * Get database type (MySQL, MariaDB)
     * @return string
     */
    public function getDatabaseType($default = 'MySQL')
    {
        $version = $this->getFullDatabaseVersion();

        if (preg_match('/mariadb/i', $version)) {
            return 'MariaDB';
        }

        return $default;
    }

    protected function getFullDatabaseVersion()
    {
        $connection = $this->getPdoConnection();

        if (!$connection) {
            return null;
        }

        $sth = $connection->prepare("select version()");

        $sth->execute();

        return $sth->fetchColumn();
    }

    /**
     * Get Database version.
     *
     * @return ?string
     */
    public function getDatabaseVersion()
    {
        $fullVersion = $this->getFullDatabaseVersion();

        if (preg_match('/[0-9]+\.[0-9]+\.[0-9]+/', $fullVersion, $match)) {
            return $match[0];
        }
    }

    /**
     * Get table/database tables engine. If $tableName is empty get a value for all database tables.
     *
     * @param  string|null $tableName
     *
     * @return string
     */
    protected function getTableEngine($tableName = null, $default = null)
    {
        $connection = $this->getPdoConnection();
        if (!$connection) {
            return $default;
        }

        $query = "SHOW TABLE STATUS WHERE Engine = 'MyISAM'";
        if (!empty($tableName)) {
            $query = "SHOW TABLE STATUS WHERE Engine = 'MyISAM' AND Name = '" . $tableName . "'";
        }

        $sth = $connection->prepare($query);
        $sth->execute();

        $result = $sth->fetchColumn();

        if (!empty($result)) {
            return 'MyISAM';
        }

        return 'InnoDB';
    }

    /**
     * Check if full text is supported. If $tableName is empty get a value for all database tables.
     *
     * @param string $tableName
     *
     * @return boolean
     */
    public function doesSupportFulltext($tableName = null, $default = false)
    {
        $tableEngine = $this->getTableEngine($tableName);

        if (!$tableEngine) {
            return $default;
        }

        switch ($tableEngine) {
            case 'InnoDB':
                $version = $this->getFullDatabaseVersion();

                if (version_compare($version, '5.6.4') >= 0) {
                    return true; //InnoDB, MySQL 5.6.4+
                }

                return false; //InnoDB
        }

        return true; //MyISAM
    }

    public function doesTableSupportFulltext($tableName, $default = false)
    {
        return $this->doesSupportFulltext($tableName, $default);
    }

    public function getPdoDatabaseParam($name, PDO $pdoConnection)
    {
        if (!method_exists($pdoConnection, 'prepare')) {
            return null;
        }

        $sth = $pdoConnection->prepare("SHOW VARIABLES LIKE '" . $name . "'");

        $sth->execute();

        $res = $sth->fetch(PDO::FETCH_NUM);

        $version = empty($res[1]) ? null : $res[1];

        return $version;
    }

    public function getPdoDatabaseVersion(PDO $pdoConnection)
    {
        return $this->getPdoDatabaseParam('version', $pdoConnection);
    }
}