<?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 PostgreSQL database.
 *
 * Connection options:
 *   - 'host','hostaddr','port','dbname','user','password','connect_timeout','options','sslmode','service' - see PostgreSQL API
 *   - 'string' - or use connection string
 *   - 'persistent' - try to find a persistent link?
 *   - 'charset' - character encoding to set
 *   - 'schema' - the schema search path
 *   - '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 DibiPostgreDriver extends /*Nette::*/Object implements IDibiDriver
{

    /**
     * Connection resource.
     * @var resource
     */
    private $connection;


    /**
     * Resultset resource.
     * @var resource
     */
    private $resultset;


    /**
     * Escape method.
     * @var bool
     */
    private $escMethod = FALSE;



    /**
     * @throws DibiException
     */
    public function __construct()
    {
        if (!extension_loaded('pgsql')) {
            throw new DibiDriverException("PHP extension 'pgsql' is not loaded.");
        }
    }



    /**
     * Connects to a database.
     *
     * @return void
     * @throws DibiException
     */
    public function connect(array &$config)
    {
        if (isset($config['string'])) {
            $string = $config['string'];
        } else {
            $string = '';
            foreach (array('host','hostaddr','port','dbname','user','password','connect_timeout','options','sslmode','service') as $key) {
                if (isset($config[$key])) $string .= $key . '=' . $config[$key] . ' ';
            }
        }

        DibiDriverException::tryError();
        if (isset($config['persistent'])) {
            $this->connection = pg_connect($string, PGSQL_CONNECT_FORCE_NEW);
        } else {
            $this->connection = pg_pconnect($string, PGSQL_CONNECT_FORCE_NEW);
        }
        if (DibiDriverException::catchError($msg)) {
            throw new DibiDriverException($msg, 0);
        }

        if (!is_resource($this->connection)) {
            throw new DibiDriverException('Connecting error.');
        }

        if (isset($config['charset'])) {
            DibiDriverException::tryError();
            pg_set_client_encoding($this->connection, $config['charset']);
            if (DibiDriverException::catchError($msg)) {
                throw new DibiDriverException($msg, 0);
            }
        }

        if (isset($config['schema'])) {
            $this->query('SET search_path TO ' . $config['schema']);
        }

        $this->escMethod = version_compare(PHP_VERSION , '5.2.0', '>=');
    }



    /**
     * Disconnects from a database.
     *
     * @return void
     */
    public function disconnect()
    {
        pg_close($this->connection);
    }



    /**
     * Executes the SQL query.
     *
     * @param  string      SQL statement.
     * @param  bool        update affected rows?
     * @return bool        have resultset?
     * @throws DibiDriverException
     */
    public function query($sql)
    {
        $this->resultset = @pg_query($this->connection, $sql);

        if ($this->resultset === FALSE) {
            throw new DibiDriverException(pg_last_error($this->connection), 0, $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 pg_affected_rows($this->resultset);
    }



    /**
     * 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($sequence)
    {
        if ($sequence === NULL) {
            // PostgreSQL 8.1 is needed
            $has = $this->query("SELECT LASTVAL()");
        } else {
            $has = $this->query("SELECT CURRVAL('$sequence')");
        }

        if (!$has) return FALSE;

        $row = $this->fetch(FALSE);
        $this->free();
        return is_array($row) ? $row[0] : FALSE;
    }



    /**
     * 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) {
            if ($this->escMethod) return "'" . pg_escape_string($this->connection, $value) . "'";
            return "'" . pg_escape_string($value) . "'";
        }

        if ($type === dibi::IDENTIFIER) {
            $a = strrpos($value, '.');
            if ($a === FALSE) return '"' . str_replace('"', '""', $value) . '"';
            // table.col delimite as table."col"
            return substr($value, 0, $a) . '."' . str_replace('"', '""', substr($value, $a + 1)) . '"';
        }

        if ($type === dibi::FIELD_BOOL) return $value ? 'TRUE' : 'FALSE';
        if ($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)
            $sql .= ' LIMIT ' . (int) $limit;

        if ($offset > 0)
            $sql .= ' OFFSET ' . (int) $offset;
    }



    /**
     * Returns the number of rows in a result set.
     *
     * @return int
     */
    public function rowCount()
    {
        return pg_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($type)
    {
        return pg_fetch_array($this->resultset, NULL, $type ? PGSQL_ASSOC : PGSQL_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($row)
    {
        return pg_result_seek($this->resultset, $row);
    }



    /**
     * Frees the resources allocated for this result set.
     *
     * @return void
     */
    public function free()
    {
        pg_free_result($this->resultset);
        $this->resultset = NULL;
    }



    /**
     * Returns metadata for all columns in a result set.
     *
     * @return array
     */
    public function getColumnsMeta()
    {
        $hasTable = version_compare(PHP_VERSION , '5.2.0', '>=');
        $count = pg_num_fields($this->resultset);
        $meta = array();
        for ($i = 0; $i < $count; $i++) {
            // items 'name' and 'table' are required
            $meta[] = array(
                'name'      => pg_field_name($this->resultset, $i),
                'table'     => $hasTable ? pg_field_table($this->resultset, $i) : NULL,
                'type'      => pg_field_type($this->resultset, $i),
                'size'      => pg_field_size($this->resultset, $i),
                'prtlen'    => pg_field_prtlen($this->resultset, $i),
            );
        }
        return $meta;
    }



    /**
     * 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()
    {}

}