<?php namespace CodeIgniter\Database\MySQLi;

/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2016, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package	CodeIgniter
 * @author	CodeIgniter Dev Team
 * @copyright	Copyright (c) 2014 - 2016, British Columbia Institute of Technology (http://bcit.ca/)
 * @license	http://opensource.org/licenses/MIT	MIT License
 * @link	http://codeigniter.com
 * @since	Version 3.0.0
 * @filesource
 */

use CodeIgniter\Database\BaseConnection;
use CodeIgniter\Database\ConnectionInterface;
use CodeIgniter\DatabaseException;

/**
 * Connection for MySQLi
 */
class Connection extends BaseConnection implements ConnectionInterface
{
	/**
	 * Database driver
	 *
	 * @var    string
	 */
	public $DBDriver = 'MySQLi';

	/**
	 * DELETE hack flag
	 *
	 * Whether to use the MySQL "delete hack" which allows the number
	 * of affected rows to be shown. Uses a preg_replace when enabled,
	 * adding a bit more processing to all queries.
	 *
	 * @var    bool
	 */
	public $deleteHack = true;

	// --------------------------------------------------------------------

	/**
	 * Identifier escape character
	 *
	 * @var    string
	 */
	public $escapeChar = '`';

	// --------------------------------------------------------------------

	/**
	 * MySQLi object
	 *
	 * Has to be preserved without being assigned to $conn_id.
	 *
	 * @var    MySQLi
	 */
	public $mysqli;

	//--------------------------------------------------------------------

	/**
	 * Connect to the database.
	 *
	 * @param bool $persistent
	 *
	 * @return mixed
	 * @throws \CodeIgniter\DatabaseException
	 */
	public function connect($persistent = false)
	{
		// Do we have a socket path?
		if ($this->hostname[0] === '/')
		{
			$hostname = null;
			$port     = null;
			$socket   = $this->hostname;
		}
		else
		{
			$hostname = ($persistent === true)
				? 'p:'.$this->hostname
				: $this->hostname;
			$port     = empty($this->port) ? null : $this->port;
			$socket   = null;
		}

		$client_flags = ($this->compress === true) ? MYSQLI_CLIENT_COMPRESS : 0;
		$this->mysqli = mysqli_init();

		$this->mysqli->options(MYSQLI_OPT_CONNECT_TIMEOUT, 10);

		if (isset($this->strictOn))
		{
			if ($this->strictOn)
			{
				$this->mysqli->options(MYSQLI_INIT_COMMAND,
					'SET SESSION sql_mode = CONCAT(@@sql_mode, ",", "STRICT_ALL_TABLES")');
			}
			else
			{
				$this->mysqli->options(MYSQLI_INIT_COMMAND,
					'SET SESSION sql_mode =
					REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(
					@@sql_mode,
					"STRICT_ALL_TABLES,", ""),
					",STRICT_ALL_TABLES", ""),
					"STRICT_ALL_TABLES", ""),
					"STRICT_TRANS_TABLES,", ""),
					",STRICT_TRANS_TABLES", ""),
					"STRICT_TRANS_TABLES", "")'
				);
			}
		}

		if (is_array($this->encrypt))
		{
			$ssl = [];
			empty($this->encrypt['ssl_key']) OR $ssl['key'] = $this->encrypt['ssl_key'];
			empty($this->encrypt['ssl_cert']) OR $ssl['cert'] = $this->encrypt['ssl_cert'];
			empty($this->encrypt['ssl_ca']) OR $ssl['ca'] = $this->encrypt['ssl_ca'];
			empty($this->encrypt['ssl_capath']) OR $ssl['capath'] = $this->encrypt['ssl_capath'];
			empty($this->encrypt['ssl_cipher']) OR $ssl['cipher'] = $this->encrypt['ssl_cipher'];

			if ( ! empty($ssl))
			{
				if (isset($this->encrypt['ssl_verify']))
				{
					if ($this->encrypt['ssl_verify'])
					{
						defined('MYSQLI_OPT_SSL_VERIFY_SERVER_CERT') &&
						$this->mysqli->options(MYSQLI_OPT_SSL_VERIFY_SERVER_CERT, true);
					}
					// Apparently (when it exists), setting MYSQLI_OPT_SSL_VERIFY_SERVER_CERT
					// to FALSE didn't do anything, so PHP 5.6.16 introduced yet another
					// constant ...
					//
					// https://secure.php.net/ChangeLog-5.php#5.6.16
					// https://bugs.php.net/bug.php?id=68344
					elseif (defined('MYSQLI_CLIENT_SSL_DONT_VERIFY_SERVER_CERT'))
					{
						$this->mysqli->options(MYSQLI_CLIENT_SSL_DONT_VERIFY_SERVER_CERT, true);
					}
				}

				$client_flags |= MYSQLI_CLIENT_SSL;
				$this->mysqli->ssl_set(
					isset($ssl['key']) ? $ssl['key'] : null,
					isset($ssl['cert']) ? $ssl['cert'] : null,
					isset($ssl['ca']) ? $ssl['ca'] : null,
					isset($ssl['capath']) ? $ssl['capath'] : null,
					isset($ssl['cipher']) ? $ssl['cipher'] : null
				);
			}
		}

		if ($this->mysqli->real_connect($hostname, $this->username, $this->password, $this->database, $port, $socket,
			$client_flags)
		)
		{
			// Prior to version 5.7.3, MySQL silently downgrades to an unencrypted connection if SSL setup fails
			if (
				($client_flags & MYSQLI_CLIENT_SSL)
				&& version_compare($this->mysqli->client_info, '5.7.3', '<=')
				&& empty($this->mysqli->query("SHOW STATUS LIKE 'ssl_cipher'")
				                      ->fetch_object()->Value)
			)
			{
				$this->mysqli->close();
				$message = 'MySQLi was configured for an SSL connection, but got an unencrypted connection instead!';
				log_message('error', $message);

				if ($this->DBDebug)
				{
					throw new DatabaseException($message);
				}
				return false;
			}

			if ( ! $this->mysqli->set_charset($this->charset))
			{
				log_message('error', "Database: Unable to set the configured connection charset ('{$this->charset}').");
				$this->mysqli->close();

				if ($this->db->debug)
				{
					throw new DatabaseException('Unable to set client connection character set: '.$this->charset);
				}
				return false;
			}

			return $this->mysqli;
		}

		return false;
	}

	//--------------------------------------------------------------------

	/**
	 * Keep or establish the connection if no queries have been sent for
	 * a length of time exceeding the server's idle timeout.
	 *
	 * @return mixed
	 */
	public function reconnect()
	{
		if ($this->connID !== false && $this->connID->ping() === false)
		{
			$this->connID = false;
		}
	}

	//--------------------------------------------------------------------

    /**
     * Close the database connection.
     */
    protected function _close()
    {
        $this->connID->close();
    }

    //--------------------------------------------------------------------

	/**
	 * Select a specific database table to use.
	 *
	 * @param string $databaseName
	 *
	 * @return mixed
	 */
	public function setDatabase(string $databaseName)
	{
		if ($databaseName === '')
		{
			$databaseName = $this->database;
		}

		if ($this->connID->select_db($databaseName))
		{
			$this->database = $databaseName;

			return true;
		}

		return false;
	}

	//--------------------------------------------------------------------

	/**
	 * Returns a string containing the version of the database being used.
	 *
	 * @return mixed
	 */
	public function getVersion()
	{
		if (isset($this->dataCache['version']))
		{
			return $this->dataCache['version'];
		}

		if (empty($this->mysqli))
        {
            $this->initialize();
        }

		return $this->dataCache['version'] = $this->mysqli->server_info;
	}

	//--------------------------------------------------------------------

	/**
	 * Executes the query against the database.
	 *
	 * @param $sql
	 *
	 * @return mixed
	 */
	public function execute($sql)
	{
		return $this->connID->query($this->prepQuery($sql));
	}

	//--------------------------------------------------------------------

	/**
	 * Prep the query
	 *
	 * If needed, each database adapter can prep the query string
	 *
	 * @param    string $sql an SQL query
	 *
	 * @return    string
	 */
	protected function prepQuery($sql)
	{
		// mysqli_affected_rows() returns 0 for "DELETE FROM TABLE" queries. This hack
		// modifies the query so that it a proper number of affected rows is returned.
		if ($this->deleteHack === true && preg_match('/^\s*DELETE\s+FROM\s+(\S+)\s*$/i', $sql))
		{
			return trim($sql).' WHERE 1=1';
		}

		return $sql;
	}

	//--------------------------------------------------------------------

	/**
	 * Returns the total number of rows affected by this query.
	 *
	 * @return mixed
	 */
	public function affectedRows(): int
	{
		return $this->connID->affected_rows;
	}

	//--------------------------------------------------------------------

	/**
	 * Platform-dependant string escape
	 *
	 * @param	string $str
	 * @return	string
	 */
	protected function _escapeString(string $str): string
	{
		if (is_bool($str))
		{
			return $str;
		}

		return $this->connID->real_escape_string($str);
	}

	//--------------------------------------------------------------------

	/**
	 * Generates the SQL for listing tables in a platform-dependent manner.
	 *
	 * @param bool $prefixLimit
	 *
	 * @return string
	 */
	protected function _listTables($prefixLimit = false): string
	{
		$sql = 'SHOW TABLES FROM '.$this->escapeIdentifiers($this->database);

		if ($prefixLimit !== FALSE && $this->DBPrefix !== '')
		{
			return $sql." LIKE '".$this->escapeLikeStr($this->DBPrefix)."%'";
		}

		return $sql;
	}

	//--------------------------------------------------------------------

	/**
	 * Generates a platform-specific query string so that the column names can be fetched.
	 *
	 * @param string $table
	 *
	 * @return string
	 */
	protected function _listColumns(string $table = ''): string
	{
		return 'SHOW COLUMNS FROM '.$this->protectIdentifiers($table, TRUE, NULL, FALSE);
	}

	//--------------------------------------------------------------------

	/**
	 * Returns an object with field data
	 *
	 * @param	string	$table
	 * @return	array
	 */
	public function fieldData(string $table)
	{
		if (($query = $this->query('SHOW COLUMNS FROM '.$this->protectIdentifiers($table, TRUE, NULL, FALSE))) === FALSE)
		{
			return FALSE;
		}
		$query = $query->getResultObject();

		$retval = array();
		for ($i = 0, $c = count($query); $i < $c; $i++)
		{
			$retval[$i]			= new \stdClass();
			$retval[$i]->name		= $query[$i]->Field;

			sscanf($query[$i]->Type, '%[a-z](%d)',
				$retval[$i]->type,
				$retval[$i]->max_length
			);

			$retval[$i]->default		= $query[$i]->Default;
			$retval[$i]->primary_key	= (int) ($query[$i]->Key === 'PRI');
		}

		return $retval;
	}

	//--------------------------------------------------------------------

	/**
	 * Returns the last error code and message.
	 *
	 * Must return an array with keys 'code' and 'message':
	 *
	 *  return ['code' => null, 'message' => null);
	 *
	 * @return	array
	 */
	public function error()
	{
		if ( ! empty($this->mysqli->connect_errno))
		{
			return array(
				'code' => $this->mysqli->connect_errno,
				'message' => $this->_mysqli->connect_error
			);
		}

		return array('code' => $this->connID->errno, 'message' => $this->connID->error);
	}

	//--------------------------------------------------------------------

	/**
	 * Insert ID
	 *
	 * @return	int
	 */
	public function insertID()
	{
		return $this->connID->insert_id;
	}

	//--------------------------------------------------------------------

    /**
     * Begin Transaction
     *
     * @return	bool
     */
    protected function _transBegin():bool
    {
        $this->connID->autocommit(false);

        return $this->connID->begin_transaction();
    }

    //--------------------------------------------------------------------

    /**
     * Commit Transaction
     *
     * @return	bool
     */
    protected function _transCommit(): bool
    {
        if ($this->connID->commit())
        {
            $this->connID->autocommit(true);
            return true;
        }

        return false;
    }

    //--------------------------------------------------------------------

    /**
     * Rollback Transaction
     *
     * @return	bool
     */
    protected function _transRollback(): bool
    {
        if ($this->connID->rollback())
        {
            $this->connID->autocommit(true);
            return true;
        }

        return false;
    }

    //--------------------------------------------------------------------
}
