InfinitePager.php

<?php

/*
 * This file is part of the PagerBundle package.
 *
 * (c) Marcin Butlak <contact@maker-labs.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace MakerLabs\PagerBundle;

use MakerLabs\PagerBundle\Adapter\PagerAdapterInterface;

/**
 * Pager 
 * 
 * @author Ross Crawford-d'Heureuse <sendrossemail@gmail.com>
 */
class InfinitePager
{
    /**
     *
     * @var integer
     */
    protected $page = 1;

    /**
     *
     * @var integer
     */
    protected $limit = 20;
    
     /**
      * 
      * @var integer
      */
     protected $maxPages = 10;

     /**
      * To store database intensive values is null at first
      * @var boolean
      */
     protected $hasResults = null;

     /**
      * To store database intensive values is null at first
      * @var boolean
      */
     protected $hasNextPage = null;

     /**
      * To store database intensive values is null at first
      * @var boolean
      */
     protected $results = null;

    /**
     * Constructor
     * 
     * @param PagerAdapterInterface $adapter The pager adapter
     * @param array $options Additional options
     */
    public function __construct(PagerAdapterInterface $adapter, array $options = array())
    {
        $this->adapter = $adapter;

        if (isset($options['limit'])) {
            $this->setLimit($options['limit']);
        }

        if (isset($options['page'])) {
            $this->setPage($options['page']);
        }
        
        if (isset($options['max_pages'])) {
            $this->setMaxPages($options['max_pages']);
        }
    }

    /**
     * Sets the current page number
     * 
     * @param integer $page The current page number
     * @return Pager instance
     */
    public function setPage($page)
    {
        $this->page = min($page > 0 ? $page : $this->getFirstPage(), $page+1);

        return $this;
    }

    /**
     * Returns the current page number
     * 
     * @return integer 
     */
    public function getPage()
    {
        return $this->page;
    }

    /**
     * Sets the results limit for one page
     * 
     * @param integer $limit
     * @return Pager instance
     */
    public function setLimit($limit)
    {
        $this->limit = $limit > 0 ? $limit : 1;

        $this->setPage($this->page);

        return $this;
    }

    /**
     * Returns the current results limit for one page
     *  
     * @return integer 
     */
    public function getLimit()
    {
        return $this->limit;
    }

    /**
     * Returns the next page number
     * 
     * @return integer 
     */
    public function getNextPage()
    {
        return (isset($this->page) && $this->page >= 1) ? $this->page + 1: 2 ;
    }

    /**
     * Returns the previous page number
     * 
     * @return integer 
     */
    public function getPreviousPage()
    {
        return ($this->page > 0) ? $this->page - 1 : 1 ;
    }

    /**
     * Returns true if the current page is first
     * 
     * @return boolean 
     */
    public function isFirstPage()
    {
        return $this->page == 1;
    }

    /**
     * Returns the first page number
     * 
     * @return integer 
     */
    public function getFirstPage()
    {
        return 1;
    }

    /**
     * Returns true if the current page is last
     * 
     * @return boolean
     */
    public function isLastPage()
    {
        return $this->hasNextPage() == false;
    }

    /**
     * Returns null as with infinite paging you never know when the last page is
 	 * as its defined by current page limt + 1 record more (which is on the next page)
     * 
     * @return integer 
     */
    public function getLastPage()
    {
        return null;
    }

    /**
     * Returns true if the current result set requires pagination
     * 
     * @return boolean 
     */
    public function isPaginable()
    {
//        return $this->adapter->getTotalResults() > $this->limit;
		return true;
    }

    /**
     * Generates a page list 
     * 
     * @param integer $pages Number of pages to generate
     * @return array The page list 
     */
    public function getPages()
    {
        throw NotImplementedException('getPages does not apply for InfinitePage');
    }

	/**
	 * Tests if there is a next page available
	 *
	 * @return void
	 * @author Ross Crawford-d'Heureuse
	 */
	public function hasNextPage()
	{
		if ($this->hasNextPage === null)
		{
			return $this->hasNextPage = $this->adapter->getResults(($this->page) * $this->limit+1, 1) ? true : false;
		}else{
			return $this->hasNextPage;
		}
	}

	/**
	 * Tests if a previous page is available
	 *
	 * @return void
	 * @author Ross Crawford-d'Heureuse
	 */
	public function hasPreviousPage()
	{
		return (isset($this->page) && $this->page > 1) ? true : false ;
	}

    /**
     * Returns true if the current result set is not empty
     * 
     * @return boolean 
     */
    public function hasResults()
    {
		if ($this->hasResults === null)
		{
        	return $this->hasResults = $this->adapter->getResults(($this->page - 1) * $this->limit+1, 1) > 0;
		}else{
			return $this->hasResults;
		}
    }

    /**
     *
     * Returns results list for the current page and limit
     * 
     * @return array 
     */
    public function getResults()
    {
		if ($this->results === null)
		{
        	return $this->results = $this->hasResults() ? $this->adapter->getResults(($this->page - 1) * $this->limit, $this->limit) : array();
		}else{
			return $this->results;
		}
    }

    /**
     * Returns the current adapter instance
     * 
     * @return PagerAdapterInterface 
     */
    public function getAdapter()
    {
        return $this->adapter;
    }
}