silverstripe-cms/code/Controllers/SilverStripeNavigator.php

<?php

namespace SilverStripe\CMS\Controllers;

use SilverStripe\Admin\CMSPreviewable;
use SilverStripe\Core\ClassInfo;
use SilverStripe\ORM\ArrayList;
use SilverStripe\ORM\DataObject;
use SilverStripe\ORM\SS_List;
use SilverStripe\View\ViewableData;

/**
 * Utility class representing links to different views of a record
 * for CMS authors, usually for {@link SiteTree} objects with "stage" and "live" links.
 * Useful both in the CMS and alongside the page template (for logged in authors).
 * The class can be used for any {@link DataObject} subclass implementing the {@link CMSPreviewable} interface.
 *
 * New item types can be defined by extending the {@link SilverStripeNavigatorItem} class,
 * for example the "cmsworkflow" module defines a new "future state" item with a date selector
 * to view embargoed data at a future point in time. So the item doesn't always have to be a simple link.
 */
class SilverStripeNavigator extends ViewableData {

	/**
	 * @var DataObject|CMSPreviewable
	 */
	protected $record;

	/**
	 * @param DataObject|CMSPreviewable $record
	 */
	public function __construct(CMSPreviewable $record) {
		parent::__construct();
		$this->record = $record;
	}

	/**
	 * @return SS_List of SilverStripeNavigatorItem
	 */
	public function getItems() {
		$items = array();

		$classes = ClassInfo::subclassesFor('SilverStripe\\CMS\\Controllers\\SilverStripeNavigatorItem');
		unset($classes['SilverStripe\\CMS\\Controllers\\SilverStripeNavigatorItem']);

		// Sort menu items according to priority
		foreach($classes as $class) {
			/** @var SilverStripeNavigatorItem $item */
			$item = new $class($this->record);
			if(!$item->canView()) {
				continue;
			}

			// This funny litle formula ensures that the first item added with the same priority will be left-most.
			$priority = $item->getPriority() * 100 - 1;

			// Ensure that we can have duplicates with the same (default) priority
			while(isset($items[$priority])) {
				$priority++;
			}

			$items[$priority] = $item;
		}
		ksort($items);

		// Drop the keys and let the ArrayList handle the numbering, so $First, $Last and others work properly.
		return new ArrayList(array_values($items));
	}

	/**
	 * @return DataObject|CMSPreviewable
	 */
	public function getRecord() {
		return $this->record;
	}

	/**
	 * @param DataObject|CMSPreviewable $record
	 * @return array template data
	 */
	static public function get_for_record($record) {
		$html = '';
		$message = '';
		$navigator = new SilverStripeNavigator($record);
		$items = $navigator->getItems();
		foreach($items as $item) {
			$text = $item->getHTML();
			if($text) $html .= $text;
			$newMessage = $item->getMessage();
			if($newMessage && $item->isActive()) $message = $newMessage;
		}

		return array(
			'items' => $html,
			'message' => $message
		);
	}
}