Plugin.php

<?php
namespace Phile\Plugin\Phile\DemoPlugin;

use Phile\Core\Registry;
use Phile\Repository\Page;

class Plugin extends \Phile\Plugin\AbstractPlugin implements \Phile\Gateway\EventObserverInterface
{

    public function __construct()
    {
        \Phile\Event::registerEvent('before_render_template', $this);
        \Phile\Event::registerEvent('request_uri', $this);
    }

    public function on($eventKey, $data = null)
    {
        if ($eventKey === 'request_uri') {
            $this->url = $data['uri'];
        }

        if ($eventKey !== 'before_render_template') {
            return;
        }

        $repository = new Page();
        $orgPage = $repository->findByPath($this->url);

        $orgMeta = $orgPage->getMeta();
        if ($orgMeta->template != 'post') {
            return;
        }

        $pages = [$orgPage];

        $needed = 4;
        $next = 2;

        $lastPage = null;

        $page = $orgPage;

        $pages = $this->addNext($page, $pages, $next);
        $needed = $needed - (count($pages) + 1);
        $next = $next - (count($pages) + 1);


        $page = $orgPage;
        while ($needed) {
            $page = $page->getPreviousPage();
            if (!$page) {
                break;
            }

            $meta = $page->getMeta();
            if ($meta->template != 'post') {
                continue;
            }

            array_unshift($pages, $page);
            $needed--;
        }

        if ($next == 0 && $needed > 0) {
            $pages = $this->addNext(end($pages), $pages, $needed);
        }

        $templateVars = Registry::get('templateVars');
        $templateVars['myPages'] = $pages;
        Registry::set('templateVars', $templateVars);
    }

    protected function addNext($page, $pages, $needed = 1) {
        while ($needed) {
            $page = $page->getNextPage();
            if (!$page) {
                break;
            }

            $meta = $page->getMeta();
            if ($meta->template != 'post') {
                continue;
            }

            array_push($pages, $page);

            $needed--;
        }
        return $pages;
    }

}