<?php

/**
* Paginador de tablas, a partir de un array	
* Basado en MECON_DB_Pager
*/
class MECON_Array_Pager
{
    var $currentpage = 0;
    var $current = 0;
    var $to = 0;

    /**
    * Constructor
    *
    * @param array $res  Contenido de la taba
    * @param int    $from  Nro. de fila 'desde'
    * @param int    $limit  Cantidad de resultados por página
    * @param int    $maxpages  Cantidad máxima de páginas a mostrar
    * @param int    $numrows Nro. de filas de la tabla
    */
    function MECON_Array_Pager (&$res, $from = 0, $limit = 10, $maxpages = 21, $numrows = null)
    {
        $this->dbh = $res->dbh;
        $this->result = $res;
        $this->row_counter = $res->row_counter;
        $this->limit_from = $res->limit_from;
        $this->from = $from;
        $this->limit = $limit;
        $this->numrows = $numrows;
        $this->maxpages = $maxpages;
	$this->build();
    }

    /**
    * Calcula los datos necesarios para que funcione el paginador
    * (es igual a MECON_DB_Pager)
    * @return mixed PEAR_Error if error.
    */
    function build()
    {
        // if there is no numrows given, calculate it
        if ($this->numrows === null) {
            $this->numrows = $this->numRows();
            if (DB::isError($this->numrows)) {
                return $this->numrows;
            }
        }
	// Si no hay resultados no se hace nada.
        if (empty($this->numrows) or ($this->numrows < 0)) {
            return;
        }
        $this->from = empty($this->from) ? 0 : $this->from;

        if ($this->limit <= 0) {
            return PEAR::raiseError (null, 'wrong "limit" param', null,
                                     null, null, 'DB_Error', true);
        }

        // Total number of pages
        $this->numpages = ceil($this->numrows/$this->limit);

        // first & last page
        $this->firstpage = 1;
        $this->lastpage  = $this->numpages;

        // Build pages array
        $this->pages = array();
        for ($i = 1; $i <= $this->numpages; $i++) {
            $offset = $this->limit * ($i - 1);
            $this->pages[$i] = $offset;
            // $from must point to one page
            if ($this->from == $offset) {
                // The current page we are
                $this->currentpage = $i;
            }
        }
        if (!isset($this->currentpage)) {
            return PEAR::raiseError (null, 'wrong "from" param', null,
                                     null, null, 'DB_Error', true);
        }

        // Limit number of pages (goole algoritm)
        if ($this->maxpages) {
            $radio = floor($this->maxpages/2);
            $this->firstpage = $this->currentpage - $radio;
            if (!($this->maxpages % 2)) {
                $this->firstpage++;
            }
            if ($this->firstpage < 1) {
                $this->firstpage = 1;
            }
            $this->lastpage = $this->currentpage + $radio;
            if ($this->lastpage > $this->numpages) {
                $this->lastpage = $this->numpages;
            }
            foreach (range($this->firstpage, $this->lastpage) as $page) {
                $tmp[$page] = $this->pages[$page];
            }
            $this->pages = $tmp;
        }

        // Prev link
        $this->prev = $this->from - $this->limit;
        $this->prev = ($this->prev >= 0) ? $this->prev : null;

        // Next link
        $this->next = $this->from + $this->limit;
        $this->next = ($this->next < $this->numrows) ? $this->next : null;

        // Results remaining in next page & Last row to fetch
        if ($this->currentpage == $this->numpages) {
            $this->remain = 0;
            $this->to = $this->numrows;
        } else {
            if ($this->currentpage == ($this->numpages - 1)) {
                $this->remain = $this->numrows - ($this->limit * ($this->numpages - 1));
            } else {
                $this->remain = $this->limit;
            }
            $this->to = $this->currentpage * $this->limit;
        }

        // Current item (when fetching).
        $this->current = $this->from - 1;
    }

    /**
    * Obtiene la siguiente fila de la tabla
    * @return array
    */
    function fetchRow($mode=null, $rownum=null)
    {
        $this->current++;
        if ($this->current >= $this->to) {
            return null;
        }
        return $this->result[$this->current];
    }

    /**
    * Devuelve la cantidad de filas de la tabla
    * @return int.
    */
    function numRows(){
	return count($this->result);
    }

}
?>