<?php

/**
 * dibi - tiny'n'smart database abstraction layer
 * ----------------------------------------------
 *
 * Copyright (c) 2005, 2008 David Grudl (http://davidgrudl.com)
 *
 * This source file is subject to the "dibi license" that is bundled
 * with this package in the file license.txt.
 *
 * For more information please see http://dibiphp.com/
 *
 * @copyright  Copyright (c) 2005, 2008 David Grudl
 * @license    http://dibiphp.com/license  dibi license
 * @link       http://dibiphp.com/
 * @package    dibi
 */


/**
 * The dibi driver for MySQL database.
 *
 * Connection options:
 *   - 'host' - the MySQL server host name
 *   - 'port' - the port number to attempt to connect to the MySQL server
 *   - 'socket' - the socket or named pipe
 *   - 'username' (or 'user')
 *   - 'password' (or 'pass')
 *   - 'persistent' - try to find a persistent link?
 *   - 'database' - the database name to select
 *   - 'charset' - character encoding to set
 *   - 'unbuffered' - sends query without fetching and buffering the result rows automatically?
 *   - 'options' - driver specific constants (MYSQL_*)
 *   - 'sqlmode' - see http://dev.mysql.com/doc/refman/5.0/en/server-sql-mode.html
 *   - 'lazy' - if TRUE, connection will be established only when required
 *
 * @author     David Grudl
 * @copyright  Copyright (c) 2005, 2008 David Grudl
 * @package    dibi
 * @version    $Revision$ $Date$
 */
class DibiMySqlDriver extends /*Nette::*/Object implements IDibiDriver
{

    /**
     * Connection resource.
     * @var resource
     */
    private $connection;


    /**
     * Resultset resource.
     * @var resource
     */
    private $resultset;


    /**
     * Is buffered (seekable and countable)?
     * @var bool
     */
    private $buffered;



    /**
     * @throws DibiException
     */
    public function __construct()
    {
        if (!extension_loaded('mysql')) {
            throw new DibiDriverException("PHP extension 'mysql' is not loaded.");
        }
    }



    /**
     * Connects to a database.
     *
     * @return void
     * @throws DibiException
     */
    public function connect(array &$config)
    {
        DibiConnection::alias($config, 'username', 'user');
        DibiConnection::alias($config, 'password', 'pass');
        DibiConnection::alias($config, 'options');

        // default values
        if (!isset($config['username'])) $config['username'] = ini_get('mysql.default_user');
        if (!isset($config['password'])) $config['password'] = ini_get('mysql.default_password');
        if (!isset($config['host'])) {
            $host = ini_get('mysql.default_host');
            if ($host) {
                $config['host'] = $host;
                $config['port'] = ini_get('mysql.default_port');
            } else {
                if (!isset($config['socket'])) $config['socket'] = ini_get('mysql.default_socket');
                $config['host'] = NULL;
            }
        }

        if (empty($config['socket'])) {
            $host = $config['host'] . (empty($config['port']) ? '' : ':' . $config['port']);
        } else {
            $host = ':' . $config['socket'];
        }

        if (empty($config['persistent'])) {
            $this->connection = @mysql_connect($host, $config['username'], $config['password'], TRUE, $config['options']);
        } else {
            $this->connection = @mysql_pconnect($host, $config['username'], $config['password'], $config['options']);
        }

        if (!is_resource($this->connection)) {
            throw new DibiDriverException(mysql_error(), mysql_errno());
        }

        if (isset($config['charset'])) {
            $ok = FALSE;
            if (function_exists('mysql_set_charset')) {
                // affects the character set used by mysql_real_escape_string() (was added in MySQL 5.0.7 and PHP 5.2.3)
                $ok = @mysql_set_charset($config['charset'], $this->connection);
            }
            if (!$ok) $ok = @mysql_query("SET NAMES '$config[charset]'", $this->connection);
            if (!$ok) $this->throwException();
        }

        if (isset($config['database'])) {
            @mysql_select_db($config['database'], $this->connection) or $this->throwException();
        }

        if (isset($config['sqlmode'])) {
            if (!@mysql_query("SET sql_mode='$config[sqlmode]'", $this->connection)) $this->throwException();
        }

        $this->buffered = empty($config['unbuffered']);
    }



    /**
     * Disconnects from a database.
     *
     * @return void
     */
    public function disconnect()
    {
        mysql_close($this->connection);
    }



    /**
     * Executes the SQL query.
     *
     * @param  string      SQL statement.
     * @return bool        have resultset?
     * @throws DibiDriverException
     */
    public function query($sql)
    {
        if ($this->buffered) {
            $this->resultset = @mysql_query($sql, $this->connection);
        } else {
            $this->resultset = @mysql_unbuffered_query($sql, $this->connection);
        }

        if (mysql_errno($this->connection)) {
            $this->throwException($sql);
        }

        return is_resource($this->resultset);
    }



    /**
     * Gets the number of affected rows by the last INSERT, UPDATE or DELETE query.
     *
     * @return int|FALSE  number of rows or FALSE on error
     */
    public function affectedRows()
    {
        return mysql_affected_rows($this->connection);
    }



    /**
     * Retrieves the ID generated for an AUTO_INCREMENT column by the previous INSERT query.
     *
     * @return int|FALSE  int on success or FALSE on failure
     */
    public function insertId($sequence)
    {
        return mysql_insert_id($this->connection);
    }



    /**
     * Begins a transaction (if supported).
     * @return void
     * @throws DibiDriverException
     */
    public function begin()
    {
        $this->query('START TRANSACTION');
    }



    /**
     * Commits statements in a transaction.
     * @return void
     * @throws DibiDriverException
     */
    public function commit()
    {
        $this->query('COMMIT');
    }



    /**
     * Rollback changes in a transaction.
     * @return void
     * @throws DibiDriverException
     */
    public function rollback()
    {
        $this->query('ROLLBACK');
    }



    /**
     * Format to SQL command.
     *
     * @param  string    value
     * @param  string    type (dibi::FIELD_TEXT, dibi::FIELD_BOOL, dibi::FIELD_DATE, dibi::FIELD_DATETIME, dibi::IDENTIFIER)
     * @return string    formatted value
     * @throws InvalidArgumentException
     */
    public function format($value, $type)
    {
        if ($type === dibi::FIELD_TEXT) return "'" . mysql_real_escape_string($value, $this->connection) . "'";
        if ($type === dibi::IDENTIFIER) return '`' . str_replace('.', '`.`', $value) . '`';
        if ($type === dibi::FIELD_BOOL) return $value ? 1 : 0;
        if ($type === dibi::FIELD_DATE) return date("'Y-m-d'", $value);
        if ($type === dibi::FIELD_DATETIME) return date("'Y-m-d H:i:s'", $value);
        throw new InvalidArgumentException('Unsupported formatting type.');
    }



    /**
     * Injects LIMIT/OFFSET to the SQL query.
     *
     * @param  string &$sql  The SQL query that will be modified.
     * @param  int $limit
     * @param  int $offset
     * @return void
     */
    public function applyLimit(&$sql, $limit, $offset)
    {
        if ($limit < 0 && $offset < 1) return;

        // see http://dev.mysql.com/doc/refman/5.0/en/select.html
        $sql .= ' LIMIT ' . ($limit < 0 ? '18446744073709551615' : (int) $limit)
             . ($offset > 0 ? ' OFFSET ' . (int) $offset : '');
    }



    /**
     * Returns the number of rows in a result set.
     *
     * @return int
     */
    public function rowCount()
    {
        if (!$this->buffered) {
            throw new DibiDriverException('Row count is not available for unbuffered queries.');
        }
        return mysql_num_rows($this->resultset);
    }



    /**
     * Fetches the row at current position and moves the internal cursor to the next position.
     * internal usage only
     *
     * @param  bool     TRUE for associative array, FALSE for numeric
     * @return array    array on success, nonarray if no next record
     */
    public function fetch($type)
    {
        return mysql_fetch_array($this->resultset, $type ? MYSQL_ASSOC : MYSQL_NUM);
    }



    /**
     * Moves cursor position without fetching row.
     *
     * @param  int      the 0-based cursor pos to seek to
     * @return boolean  TRUE on success, FALSE if unable to seek to specified record
     * @throws DibiException
     */
    public function seek($row)
    {
        if (!$this->buffered) {
            throw new DibiDriverException('Cannot seek an unbuffered result set.');
        }

        return mysql_data_seek($this->resultset, $row);
    }



    /**
     * Frees the resources allocated for this result set.
     *
     * @return void
     */
    public function free()
    {
        mysql_free_result($this->resultset);
        $this->resultset = NULL;
    }



    /**
     * Returns metadata for all columns in a result set.
     *
     * @return array
     */
    public function getColumnsMeta()
    {
        $count = mysql_num_fields($this->resultset);
        $meta = array();
        for ($i = 0; $i < $count; $i++) {
            // items 'name' and 'table' are required
            $meta[] = (array) mysql_fetch_field($this->resultset, $i);
        }
        return $meta;
    }



    /**
     * Converts database error to DibiDriverException.
     *
     * @throws DibiDriverException
     */
    protected function throwException($sql = NULL)
    {
        throw new DibiDriverException(mysql_error($this->connection), mysql_errno($this->connection), $sql);
    }



    /**
     * Returns the connection resource.
     *
     * @return mixed
     */
    public function getResource()
    {
        return $this->connection;
    }



    /**
     * Returns the resultset resource.
     *
     * @return mixed
     */
    public function getResultResource()
    {
        return $this->resultset;
    }



    /**
     * Gets a information of the current database.
     *
     * @return DibiReflection
     */
    function getDibiReflection()
    {}

}