<?php

/**
 * Part of the Joomla Framework Database Package
 *
 * @copyright  Copyright (C) 2005 - 2021 Open Source Matters, Inc. All rights reserved.
 * @license    GNU General Public License version 2 or later; see LICENSE
 */

namespace Joomla\Database\Mysql;

use Joomla\Database\Exception\ConnectionFailureException;
use Joomla\Database\Pdo\PdoDriver;
use Joomla\Database\UTF8MB4SupportInterface;

/**
 * MySQL database driver supporting PDO based connections
 *
 * @link   https://www.php.net/manual/en/ref.pdo-mysql.php
 * @since  1.0
 */
class MysqlDriver extends PdoDriver implements UTF8MB4SupportInterface
{
    /**
     * The name of the database driver.
     *
     * @var    string
     * @since  1.0
     */
    public $name = 'mysql';

    /**
     * The character(s) used to quote SQL statement names such as table names or field names, etc.
     *
     * If a single character string the same character is used for both sides of the quoted name, else the first character will be used for the
     * opening quote and the second for the closing quote.
     *
     * @var    string
     * @since  1.0
     */
    protected $nameQuote = '`';

    /**
     * The null or zero representation of a timestamp for the database driver.
     *
     * @var    string
     * @since  1.0
     */
    protected $nullDate = '0000-00-00 00:00:00';

    /**
     * True if the database engine supports UTF-8 Multibyte (utf8mb4) character encoding.
     *
     * @var    boolean
     * @since  1.4.0
     */
    protected $utf8mb4 = false;

    /**
     * True if the database engine is MariaDB.
     *
     * @var    boolean
     * @since  2.0.0
     */
    protected $mariadb = false;

    /**
     * The minimum supported database version.
     *
     * @var    string
     * @since  1.0
     */
    protected static $dbMinimum = '5.6';

    /**
     * The minimum supported MariaDB database version.
     *
     * @var    string
     * @since  2.0.0
     */
    protected static $dbMinMariadb = '10.0';

    /**
     * The default cipher suite for TLS connections.
     *
     * @var    array
     * @since  2.0.0
     */
    protected static $defaultCipherSuite = [
        'AES128-GCM-SHA256',
        'AES256-GCM-SHA384',
        'AES128-CBC-SHA256',
        'AES256-CBC-SHA384',
        'DES-CBC3-SHA',
    ];

    /**
     * The default charset.
     *
     * @var    string
     * @since  2.0.0
     */
    public $charset = 'utf8';

    /**
     * Constructor.
     *
     * @param   array  $options  Array of database options with keys: host, user, password, database, select.
     *
     * @since   1.0
     */
    public function __construct(array $options)
    {
        /**
         * sql_mode to MySql 5.7.8+ default strict mode minus ONLY_FULL_GROUP_BY
         *
         * @link https://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-8.html#mysqld-5-7-8-sql-mode
         */
        $sqlModes = [
            'STRICT_TRANS_TABLES',
            'ERROR_FOR_DIVISION_BY_ZERO',
            'NO_ENGINE_SUBSTITUTION',
        ];

        // Get some basic values from the options.
        $options['driver']   = 'mysql';
        $options['charset']  = $options['charset'] ?? 'utf8';
        $options['sqlModes'] = isset($options['sqlModes']) ? (array) $options['sqlModes'] : $sqlModes;

        $this->charset = $options['charset'];

        /*
         * Pre-populate the UTF-8 Multibyte compatibility flag. Unfortunately PDO won't report the server version unless we're connected to it,
         * and we cannot connect to it unless we know if it supports utf8mb4, which requires us knowing the server version. Because of this
         * chicken and egg issue, we _assume_ it's supported and we'll just catch any problems at connection time.
         */
        $this->utf8mb4 = $options['charset'] === 'utf8mb4';

        // Finalize initialisation.
        parent::__construct($options);
    }

    /**
     * Connects to the database if needed.
     *
     * @return  void  Returns void if the database connected successfully.
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function connect()
    {
        if ($this->getConnection()) {
            return;
        }

        // For SSL/TLS connection encryption.
        if ($this->options['ssl'] !== [] && $this->options['ssl']['enable'] === true) {
            $sslContextIsNull = true;

            // If customised, add cipher suite, ca file path, ca path, private key file path and certificate file path to PDO driver options.
            foreach (['cipher', 'ca', 'capath', 'key', 'cert'] as $key => $value) {
                if ($this->options['ssl'][$value] !== null) {
                    $this->options['driverOptions'][constant('\PDO::MYSQL_ATTR_SSL_' . strtoupper($value))] = $this->options['ssl'][$value];
                    $sslContextIsNull                                                                       = false;
                }
            }

            // PDO, if no cipher, ca, capath, cert and key are set, can't start TLS one-way connection, set a common ciphers suite to force it.
            if ($sslContextIsNull === true) {
                $this->options['driverOptions'][\PDO::MYSQL_ATTR_SSL_CIPHER] = implode(':', static::$defaultCipherSuite);
            }

            // If customised, for capable systems (PHP 7.0.14+ and 7.1.4+) verify certificate chain and Common Name to driver options.
            if ($this->options['ssl']['verify_server_cert'] !== null && defined('\PDO::MYSQL_ATTR_SSL_VERIFY_SERVER_CERT')) {
                $this->options['driverOptions'][\PDO::MYSQL_ATTR_SSL_VERIFY_SERVER_CERT] = $this->options['ssl']['verify_server_cert'];
            }
        }

        try {
            // Try to connect to MySQL
            parent::connect();
        } catch (ConnectionFailureException $e) {
            // If the connection failed, but not because of the wrong character set, then bubble up the exception.
            if (!$this->utf8mb4) {
                throw $e;
            }

            /*
             * Otherwise, try connecting again without using utf8mb4 and see if maybe that was the problem. If the connection succeeds, then we
             * will have learned that the client end of the connection does not support utf8mb4.
               */
            $this->utf8mb4            = false;
            $this->options['charset'] = 'utf8';

            parent::connect();
        }

        $serverVersion = $this->getVersion();

        $this->mariadb = stripos($serverVersion, 'mariadb') !== false;

        if ($this->utf8mb4) {
            // At this point we know the client supports utf8mb4.  Now we must check if the server supports utf8mb4 as well.
            $this->utf8mb4 = version_compare($serverVersion, '5.5.3', '>=');

            if ($this->mariadb && version_compare($serverVersion, '10.0.0', '<')) {
                $this->utf8mb4 = false;
            }

            if (!$this->utf8mb4) {
                // Reconnect with the utf8 character set.
                parent::disconnect();
                $this->options['charset'] = 'utf8';
                parent::connect();
            }
        }

        // If needed, set the sql modes.
        if ($this->options['sqlModes'] !== []) {
            $this->connection->query('SET @@SESSION.sql_mode = \'' . implode(',', $this->options['sqlModes']) . '\';');
        }

        $this->setOption(\PDO::ATTR_EMULATE_PREPARES, true);
    }

    /**
     * Automatically downgrade a CREATE TABLE or ALTER TABLE query from utf8mb4 (UTF-8 Multibyte) to plain utf8.
     *
     * Used when the server doesn't support UTF-8 Multibyte.
     *
     * @param   string  $query  The query to convert
     *
     * @return  string  The converted query
     *
     * @since   1.4.0
     */
    public function convertUtf8mb4QueryToUtf8($query)
    {
        if ($this->hasUTF8mb4Support()) {
            return $query;
        }

        // If it's not an ALTER TABLE or CREATE TABLE command there's nothing to convert
        $beginningOfQuery = substr($query, 0, 12);
        $beginningOfQuery = strtoupper($beginningOfQuery);

        if (!\in_array($beginningOfQuery, ['ALTER TABLE ', 'CREATE TABLE'], true)) {
            return $query;
        }

        // Replace utf8mb4 with utf8
        return str_replace('utf8mb4', 'utf8', $query);
    }

    /**
     * Test to see if the MySQL connector is available.
     *
     * @return  boolean  True on success, false otherwise.
     *
     * @since   1.0
     */
    public static function isSupported()
    {
        return class_exists('\\PDO') && \in_array('mysql', \PDO::getAvailableDrivers(), true);
    }

    /**
     * Select a database for use.
     *
     * @param   string  $database  The name of the database to select for use.
     *
     * @return  boolean
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function select($database)
    {
        $this->connect();

        $this->setQuery('USE ' . $this->quoteName($database))
            ->execute();

        return true;
    }

    /**
     * Return the query string to alter the database character set.
     *
     * @param   string  $dbName  The database name
     *
     * @return  string  The query that alter the database query string
     *
     * @since   2.0.0
     */
    public function getAlterDbCharacterSet($dbName)
    {
        $charset   = $this->utf8mb4 ? 'utf8mb4' : 'utf8';
        $collation = $charset . '_unicode_ci';

        return 'ALTER DATABASE ' . $this->quoteName($dbName) . ' CHARACTER SET `' . $charset . '` COLLATE `' . $collation . '`';
    }

    /**
     * Method to get the database collation in use by sampling a text field of a table in the database.
     *
     * @return  string|boolean  The collation in use by the database (string) or boolean false if not supported.
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function getCollation()
    {
        $this->connect();

        return $this->setQuery('SELECT @@collation_database;')->loadResult();
    }

    /**
     * Method to get the database connection collation in use by sampling a text field of a table in the database.
     *
     * @return  string|boolean  The collation in use by the database connection (string) or boolean false if not supported.
     *
     * @since   1.6.0
     * @throws  \RuntimeException
     */
    public function getConnectionCollation()
    {
        $this->connect();

        return $this->setQuery('SELECT @@collation_connection;')->loadResult();
    }

    /**
     * Method to get the database encryption details (cipher and protocol) in use.
     *
     * @return  string  The database encryption details.
     *
     * @since   2.0.0
     * @throws  \RuntimeException
     */
    public function getConnectionEncryption(): string
    {
        $this->connect();

        $variables = $this->setQuery('SHOW SESSION STATUS WHERE `Variable_name` IN (\'Ssl_version\', \'Ssl_cipher\')')
            ->loadObjectList('Variable_name');

        if (!empty($variables['Ssl_cipher']->Value)) {
            return $variables['Ssl_version']->Value . ' (' . $variables['Ssl_cipher']->Value . ')';
        }

        return '';
    }

    /**
     * Method to test if the database TLS connections encryption are supported.
     *
     * @return  boolean  Whether the database supports TLS connections encryption.
     *
     * @since   2.0.0
     */
    public function isConnectionEncryptionSupported(): bool
    {
        $this->connect();

        $variables = $this->setQuery('SHOW SESSION VARIABLES WHERE `Variable_name` IN (\'have_ssl\')')->loadObjectList('Variable_name');

        return !empty($variables['have_ssl']->Value) && $variables['have_ssl']->Value === 'YES';
    }

    /**
     * Return the query string to create new Database.
     *
     * @param   \stdClass  $options  Object used to pass user and database name to database driver. This object must have "db_name" and "db_user" set.
     * @param   boolean    $utf      True if the database supports the UTF-8 character set.
     *
     * @return  string  The query that creates database
     *
     * @since   2.0.0
     */
    protected function getCreateDatabaseQuery($options, $utf)
    {
        if ($utf) {
            $charset   = $this->utf8mb4 ? 'utf8mb4' : 'utf8';
            $collation = $charset . '_unicode_ci';

            return 'CREATE DATABASE ' . $this->quoteName($options->db_name) . ' CHARACTER SET `' . $charset . '` COLLATE `' . $collation . '`';
        }

        return 'CREATE DATABASE ' . $this->quoteName($options->db_name);
    }

    /**
     * Shows the table CREATE statement that creates the given tables.
     *
     * @param   array|string  $tables  A table name or a list of table names.
     *
     * @return  array  A list of the create SQL for the tables.
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function getTableCreate($tables)
    {
        $this->connect();

        // Initialise variables.
        $result = [];

        // Sanitize input to an array and iterate over the list.
        $tables = (array) $tables;

        foreach ($tables as $table) {
            $row = $this->setQuery('SHOW CREATE TABLE ' . $this->quoteName($table))->loadRow();

            // Populate the result array based on the create statements.
            $result[$table] = $row[1];
        }

        return $result;
    }

    /**
     * Retrieves field information about a given table.
     *
     * @param   string   $table     The name of the database table.
     * @param   boolean  $typeOnly  True to only return field types.
     *
     * @return  array  An array of fields for the database table.
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function getTableColumns($table, $typeOnly = true)
    {
        $this->connect();

        $result = [];

        // Set the query to get the table fields statement.
        $fields = $this->setQuery('SHOW FULL COLUMNS FROM ' . $this->quoteName($table))->loadObjectList();

        // If we only want the type as the value add just that to the list.
        if ($typeOnly) {
            foreach ($fields as $field) {
                $result[$field->Field] = preg_replace('/[(0-9)]/', '', $field->Type);
            }
        } else {
            // If we want the whole field data object add that to the list.
            foreach ($fields as $field) {
                $result[$field->Field] = $field;
            }
        }

        return $result;
    }

    /**
     * Get the details list of keys for a table.
     *
     * @param   string  $table  The name of the table.
     *
     * @return  array  An array of the column specification for the table.
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function getTableKeys($table)
    {
        $this->connect();

        // Get the details columns information.
        return $this->setQuery('SHOW KEYS FROM ' . $this->quoteName($table))->loadObjectList();
    }

    /**
     * Method to get an array of all tables in the database.
     *
     * @return  array  An array of all the tables in the database.
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function getTableList()
    {
        $this->connect();

        // Set the query to get the tables statement and not the views.
        return $this->setQuery('SHOW FULL TABLES WHERE table_type="BASE TABLE"')->loadColumn();
    }

    /**
     * Get the version of the database connector.
     *
     * @return  string  The database connector version.
     *
     * @since   2.0.0
     */
    public function getVersion()
    {
        $this->connect();

        $version = $this->getOption(\PDO::ATTR_SERVER_VERSION);

        if (stripos($version, 'mariadb') !== false) {
            // MariaDB: Strip off any leading '5.5.5-', if present
            return preg_replace('/^5\.5\.5-/', '', $version);
        }

        return $version;
    }

    /**
     * Get the minimum supported database version.
     *
     * @return  string
     *
     * @since   2.0.0
     */
    public function getMinimum()
    {
        return $this->mariadb ? static::$dbMinMariadb : static::$dbMinimum;
    }

    /**
     * Get the null or zero representation of a timestamp for the database driver.
     *
     * @return  string
     *
     * @since   2.0.0
     */
    public function getNullDate()
    {
        // Check the session sql mode;
        if (\in_array('NO_ZERO_DATE', $this->options['sqlModes']) !== false) {
            $this->nullDate = '1000-01-01 00:00:00';
        }

        return $this->nullDate;
    }

    /**
     * Determine whether the database engine support the UTF-8 Multibyte (utf8mb4) character encoding.
     *
     * @return  boolean  True if the database engine supports UTF-8 Multibyte.
     *
     * @since   2.0.0
     */
    public function hasUTF8mb4Support()
    {
        return $this->utf8mb4;
    }

    /**
     * Determine if the database engine is MariaDB.
     *
     * @return  boolean
     *
     * @since   2.0.0
     */
    public function isMariaDb(): bool
    {
        $this->connect();

        return $this->mariadb;
    }

    /**
     * Locks a table in the database.
     *
     * @param   string  $table  The name of the table to unlock.
     *
     * @return  $this
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function lockTable($table)
    {
        $this->setQuery('LOCK TABLES ' . $this->quoteName($table) . ' WRITE')
            ->execute();

        return $this;
    }

    /**
     * Renames a table in the database.
     *
     * @param   string  $oldTable  The name of the table to be renamed
     * @param   string  $newTable  The new name for the table.
     * @param   string  $backup    Not used by MySQL.
     * @param   string  $prefix    Not used by MySQL.
     *
     * @return  $this
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function renameTable($oldTable, $newTable, $backup = null, $prefix = null)
    {
        $this->setQuery('RENAME TABLE ' . $this->quoteName($oldTable) . ' TO ' . $this->quoteName($newTable))
            ->execute();

        return $this;
    }

    /**
     * Inserts a row into a table based on an object's properties.
     *
     * @param   string  $table   The name of the database table to insert into.
     * @param   object  $object  A reference to an object whose public properties match the table fields.
     * @param   string  $key     The name of the primary key. If provided the object property is updated.
     *
     * @return  boolean
     *
     * @since   2.0.0
     * @throws  \RuntimeException
     */
    public function insertObject($table, &$object, $key = null)
    {
        $fields       = [];
        $values       = [];
        $tableColumns = $this->getTableColumns($table);

        // Iterate over the object variables to build the query fields and values.
        foreach (get_object_vars($object) as $k => $v) {
            // Skip columns that don't exist in the table.
            if (!array_key_exists($k, $tableColumns)) {
                continue;
            }

            // Only process non-null scalars.
            if (\is_array($v) || \is_object($v) || $v === null) {
                continue;
            }

            // Ignore any internal fields.
            if ($k[0] === '_') {
                continue;
            }

            // Ignore null datetime fields.
            if ($tableColumns[$k] === 'datetime' && empty($v)) {
                continue;
            }

            // Ignore null integer fields.
            if (stristr($tableColumns[$k], 'int') !== false && $v === '') {
                continue;
            }

            // Prepare and sanitize the fields and values for the database query.
            $fields[] = $this->quoteName($k);
            $values[] = $this->quote($v);
        }

        // Create the base insert statement.
        $query = $this->createQuery()
            ->insert($this->quoteName($table))
            ->columns($fields)
            ->values(implode(',', $values));

        // Set the query and execute the insert.
        $this->setQuery($query)->execute();

        // Update the primary key if it exists.
        $id = $this->insertid();

        if ($key && $id && \is_string($key)) {
            $object->$key = $id;
        }

        return true;
    }

    /**
     * Method to escape a string for usage in an SQL statement.
     *
     * Oracle escaping reference:
     * http://www.orafaq.com/wiki/SQL_FAQ#How_does_one_escape_special_characters_when_writing_SQL_queries.3F
     *
     * SQLite escaping notes:
     * http://www.sqlite.org/faq.html#q14
     *
     * Method body is as implemented by the Zend Framework
     *
     * Note: Using query objects with bound variables is preferable to the below.
     *
     * @param   string   $text   The string to be escaped.
     * @param   boolean  $extra  Unused optional parameter to provide extra escaping.
     *
     * @return  string  The escaped string.
     *
     * @since   1.0
     */
    public function escape($text, $extra = false)
    {
        if (\is_int($text)) {
            return $text;
        }

        if (\is_float($text)) {
            // Force the dot as a decimal point.
            return str_replace(',', '.', (string) $text);
        }

        $this->connect();

        $result = substr($this->connection->quote($text), 1, -1);

        if ($extra) {
            $result = addcslashes($result, '%_');
        }

        return $result;
    }

    /**
     * Unlocks tables in the database.
     *
     * @return  $this
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function unlockTables()
    {
        $this->setQuery('UNLOCK TABLES')
            ->execute();

        return $this;
    }

    /**
     * Method to commit a transaction.
     *
     * @param   boolean  $toSavepoint  If true, commit to the last savepoint.
     *
     * @return  void
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function transactionCommit($toSavepoint = false)
    {
        $this->connect();

        if (!$toSavepoint || $this->transactionDepth <= 1) {
            parent::transactionCommit($toSavepoint);
        } else {
            $this->transactionDepth--;
        }
    }

    /**
     * Method to roll back a transaction.
     *
     * @param   boolean  $toSavepoint  If true, rollback to the last savepoint.
     *
     * @return  void
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function transactionRollback($toSavepoint = false)
    {
        $this->connect();

        if (!$toSavepoint || $this->transactionDepth <= 1) {
            parent::transactionRollback($toSavepoint);
        } else {
            $savepoint = 'SP_' . ($this->transactionDepth - 1);
            $this->setQuery('ROLLBACK TO SAVEPOINT ' . $this->quoteName($savepoint));

            if ($this->execute()) {
                $this->transactionDepth--;
            }
        }
    }

    /**
     * Method to initialize a transaction.
     *
     * @param   boolean  $asSavepoint  If true and a transaction is already active, a savepoint will be created.
     *
     * @return  void
     *
     * @since   1.0
     * @throws  \RuntimeException
     */
    public function transactionStart($asSavepoint = false)
    {
        $this->connect();

        if (!$asSavepoint || !$this->transactionDepth) {
            parent::transactionStart($asSavepoint);
        } else {
            $savepoint = 'SP_' . $this->transactionDepth;
            $this->setQuery('SAVEPOINT ' . $this->quoteName($savepoint));

            if ($this->execute()) {
                $this->transactionDepth++;
            }
        }
    }
}
