<?php
/**
 * Simple pager
 *
 * $Id$
 *
 * @author gERD Schaufelberger <gerd@php-tools.net>
 * @license PHP License
 * @package WB
 * @subpackage db
 */

/**
 * Simple pager
 *
 * @version 0.2.1
 * @package WB
 * @subpackage db
 */
class WBDatasource_Pager extends WBStdClass
{
   /**
    * datasource
    * @var WBDatasource
    */
    protected $_source;

   /**
    * id
    * @var string
    */
    protected $_id;

   /**
    * limit
    * @var string
    */
    protected $_limit;

   /**
    * position of options
    * @var int
    */
    protected $_optPos = 1;

   /**
    * current pager
    * @var array
    */
    protected $_pager = array();

   /**
    * args
    * @var array
    */
    protected $_args = array();

   /**
    * session
    * @var patSession_Storage
    */
    protected $_sess;

   /**
    * constructor
    *
    * @param array $parameter
    */
    public function __construct( $parameter = array() )
    {
        if (!isset($parameter['id'])) {
            WBClass::load('WBException_Argument');
            throw new WBException_Argument('Pager id is required.', 1, __CLASS__);
        }
        if (!isset($parameter['source'])) {
            WBClass::load('WBException_Argument');
            throw new WBException_Argument('Source is required.', 2, __CLASS__);
        }
        if (!isset($parameter['limit'])) {
            WBClass::load('WBException_Argument');
            throw new WBException_Argument('Limit is required.', 3, __CLASS__);
        }
        if (!isset($parameter['options'])) {
            WBClass::load('WBException_Argument');
            throw new WBException_Argument('Need to know the position of get options.', 4, __CLASS__);
        }

        $this->_source  =   $parameter['source'];
        $this->_limit   =   $parameter['limit'];
        $this->_optPos  =   $parameter['options'];
        $this->_id      =   $parameter['id'] . '-' . $this->_limit;

        $this->_sess    =   WBClass::create('patSession');
        if ($this->_sess->has( 'WBDatasource.Pager.' . $this->_id)) {
            $this->_pager   =   $this->_sess->get( 'WBDatasource.Pager.' . $this->_id );
        }

        if (empty($this->_pager)) {
            $this->_pager              =   array();
            $this->_pager['limit']     =   $this->_limit;
            $this->_pager['total']     =   '__undefined';
            $this->_pager['pages']     =   '__undefined';
            $this->_pager['next']      =   0;
            $this->_pager['prev']      =   0;
            $this->_pager['offset']    =   0;
            $this->_pager['current']   =   0;
            $this->_pager['page']      =   1;
            $this->_pager['page_prev'] =   0;
            $this->_pager['page_next'] =   0;
        }
    }

   /**
    * destruct
    *
    * save current pager position in session
    */
    public function __destruct()
    {
        $this->_sess->set('WBDatasource.Pager.' . $this->_id, $this->_pager);
    }

   /**
    * init pager
    *
    * @param mixed $args...
    * @return bool true on success
    */
    public function setArgs()
    {
        $this->_args    =   func_get_args();
        return true;
    }

   /**
    * Wrapper for get function to receive a list
    *
    * @return array list
    */
    public function get()
    {
        $this->_args[$this->_optPos]['limit']    =   $this->_pager['limit'];
        $this->_args[$this->_optPos]['offset']   =   $this->_pager['offset'];

        $list   =   call_user_func_array(array($this->_source, 'get'), $this->_args);
        foreach ($list as $i => &$l) {
            $l['pager_row_var'] =   $this->_pager['offset'] + 1 + $i;
        }

        return $list;
    }

   /**
    * go to page number #
    *
    * Calculate offest for next get().
    *
    * @param string|int $goto page number
    * @return array $pager info
    */
    public function browse( $goto = '__first' )
    {
        $total  =   $this->_source->count($this->_args[0]
                                , $this->_args[1]
                                , $this->_args[2]
                                , $this->_args[3]
                                , $this->_args[$this->_optPos]
                                );
        $pages  =   ceil($total / $this->_limit);

        $this->_pager['pages']     =   $pages;
        $this->_pager['total']     =   $total;
        $this->_pager['next']      =   0;
        $this->_pager['prev']      =   0;

        switch (strtolower($goto)) {
            case '__first':
                $goto   =   0;
                break;

            case '__prev':
                $goto   =   $this->_pager['current'];
                --$goto;
                break;

            case '__current':
                $goto   =   $this->_pager['current'];
                break;

            case '__next':
                $goto   =   $this->_pager['current'];
                ++$goto;
                break;

            case '__last':
                $goto   =   $pages - 1;
                break;

             default:
                 // goto starts at zero but human readable pages start at one
                --$goto;
                break;
        }

        // stay within boundaries
        if ($goto < 0) {
            $goto   =   0;
        }
        if ($goto > ($pages - 1)) {
            $goto   =   $pages - 1;
        }

        // is it allow to browse next and previous?
        if ($goto > 0) {
            $this->_pager['prev']   =   1;
        }
        if ($goto < ($pages -1)) {
            $this->_pager['next']   =   1;
        }

        // assample pager information
        $this->_pager['current']    =   $goto;
        $this->_pager['page']       =   $goto + 1;
        $this->_pager['offset']     =   $goto * $this->_limit;
        $this->_pager['page_prev']  =   $this->_pager['page'] - $this->_pager['prev'];
        $this->_pager['page_next']  =   $this->_pager['page'] + $this->_pager['next'];

        return $this->_pager;
    }
}
?>