silverstripe-googlesitemaps/code/GoogleSitemapDecorator.php

<?php

/**
 * Decorate the page object to provide google sitemaps with 
 * additionally options and configuration.
 * 
 * @package googlesitemaps
 */
class GoogleSitemapDecorator extends DataExtension {
    
}

/**
 * @package googlesitemaps
 */
class GoogleSitemapSiteTreeDecorator extends DataExtension {

	/**
	 * @var array
	 */
	public static $db = array(
		"Priority" => "Varchar(5)"
	);

	/**
	 * @param FieldList
	 */
	public function updateSettingsFields(&$fields) {
		$prorities = array(
			'' => _t('SiteTree.PRIORITYAUTOSET', 'Auto-set based on page depth'),
			'-1' => _t('SiteTree.PRIORITYNOTINDEXED', "Not indexed"), // We set this to -ve one because a blank value implies auto-generation of Priority
			'1.0' => '1 - ' . _t('SiteTree.PRIORITYMOSTIMPORTANT', "Most important"),
			'0.9' => '2',
			'0.8' => '3',
			'0.7' => '4',
			'0.6' => '5',
			'0.5' => '6',
			'0.4' => '7',
			'0.3' => '8',
			'0.2' => '9',
			'0.1' => '10 - ' . _t('SiteTree.PRIORITYLEASTIMPORTANT', "Least important")
		);

		$tabset = $fields->findOrMakeTab('Root.Settings');
		
		$message = "<p>";
		$message .= sprintf(_t('SiteTree.METANOTEPRIORITY', "Manually specify a Google Sitemaps priority for this page (%s)"), 
			'<a href="http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=71936#prioritize" target="_blank">?</a>'
		);
		$message .=  "</p>";
		
		$tabset->push(new Tab('GoogleSitemap', _t('SiteTree.TABGOOGLESITEMAP', 'Google Sitemap'),
			new LiteralField("GoogleSitemapIntro", $message),
			new DropdownField("Priority", $this->owner->fieldLabel('Priority'), $prorities)
		));
	}

	public function updateFieldLabels(&$labels) {
		parent::updateFieldLabels($labels);

		$labels['Priority'] = _t('SiteTree.METAPAGEPRIO', "Page Priority");
	}

	/**
	 * @return void
	 */
	public function onAfterPublish() {
		GoogleSitemap::ping();
	}

	/**
	 * @return void
	 */
	public function onAfterUnpublish() {
		GoogleSitemap::ping();
	}

	/**
	 * The default value of the priority field depends on the depth of the page in
	 * the site tree, so it must be calculated dynamically.
	 *
	 * @return float
	 */
	public function getPriority() {
		if(!$this->owner->getField('Priority')) {
			$parentStack = $this->owner->parentStack();
			$numParents = is_array($parentStack) ? count($parentStack) - 1 : 0;
			
			return max(0.1, 1.0 - ($numParents / 10));
		} 
		elseif ($this->owner->getField('Priority') == -1) {
			return -1;
		} 
		else {
			$priority = abs($this->owner->getField('Priority'));
			
			return (is_float($priority) && $priority <= 1.0) ? $priority : 0.5;
		}
	}

	/**
	 * Returns a pages change frequency calculated by pages age and number of 
	 * versions. Google expects always, hourly, daily, weekly, monthly, yearly 
	 * or never as values.
	 * 
	 * @see http://support.google.com/webmasters/bin/answer.py?hl=en&answer=183668&topic=8476&ctx=topic
	 *
	 * @return SS_Datetime
	 */
	public function getChangeFrequency() {
		$date = date('Y-m-d H:i:s');
		$prop = $this->owner->toMap();

		$created = new SS_Datetime();
		$created->value = (isset($prop['Created'])) ? $prop['Created'] : $date;

		$now = new SS_Datetime();
		$now->value = $date;
		
		$versions = (isset($prop['Version'])) ? $prop['Version'] : 1;
		$timediff = $now->format('U') - $created->format('U');

		// Check how many revisions have been made over the lifetime of the
		// Page for a rough estimate of it's changing frequency.
		$period = $timediff / ($versions + 1);

		if ($period > 60 * 60 * 24 * 365) {
			$freq = 'yearly';
		} elseif ($period > 60 * 60 * 24 * 30) {
			$freq = 'monthly';
		} elseif ($period > 60 * 60 * 24 * 7) {
			$freq = 'weekly';
		} elseif ($period > 60 * 60 * 24) {
			$freq = 'daily';
		} elseif ($period > 60 * 60) {
			$freq = 'hourly';
		} else {
			$freq = 'always';
		}

		return $freq;
	}
}