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File Content: `plugin-update-checker.php`

<?php
/**
 * Plugin Update Checker Library 3.2
 * http://w-shadow.com/
 * 
 * Copyright 2016 Janis Elsts
 * Released under the MIT license. See license.txt for details.
 */

if ( !class_exists('SiteSEOUpdateChecker_3_2', false) ):

/**
 * A custom plugin update checker. 
 * 
 * @author Janis Elsts
 * @copyright 2016
 * @version 3.2
 * @access public
 */
#[\AllowDynamicProperties]
class SiteSEOUpdateChecker_3_2 {
	public $metadataUrl = ''; //The URL of the plugin's metadata file.
	public $pluginAbsolutePath = ''; //Full path of the main plugin file.
	public $pluginFile = '';  //Plugin filename relative to the plugins directory. Many WP APIs use this to identify plugins.
	public $slug = '';        //Plugin slug.
	public $optionName = '';  //Where to store the update info.
	public $muPluginFile = ''; //For MU plugins, the plugin filename relative to the mu-plugins directory.

	public $debugMode = false; //Set to TRUE to enable error reporting. Errors are raised using trigger_error()
                               //and should be logged to the standard PHP error log.
	public $scheduler;

	protected $upgraderStatus;

	private $debugBarPlugin = null;
	private $cachedInstalledVersion = null;

	private $metadataHost = ''; //The host component of $metadataUrl.

	/**
	 * Class constructor.
	 *
	 * @param string $metadataUrl The URL of the plugin's metadata file.
	 * @param string $pluginFile Fully qualified path to the main plugin file.
	 * @param string $slug The plugin's 'slug'. If not specified, the filename part of $pluginFile sans '.php' will be used as the slug.
	 * @param integer $checkPeriod How often to check for updates (in hours). Defaults to checking every 12 hours. Set to 0 to disable automatic update checks.
	 * @param string $optionName Where to store book-keeping info about update checks. Defaults to 'external_updates-$slug'.
	 * @param string $muPluginFile Optional. The plugin filename relative to the mu-plugins directory.
	 */
	public function __construct($metadataUrl, $pluginFile, $slug = '', $checkPeriod = 12, $optionName = '', $muPluginFile = ''){
		$this->metadataUrl = $metadataUrl;
		$this->pluginAbsolutePath = $pluginFile;
		$this->pluginFile = plugin_basename($this->pluginAbsolutePath);
		$this->muPluginFile = $muPluginFile;
		$this->slug = $slug;
		$this->optionName = $optionName;
		$this->debugMode = (bool)(constant('WP_DEBUG'));

		//If no slug is specified, use the name of the main plugin file as the slug.
		//For example, 'my-cool-plugin/cool-plugin.php' becomes 'cool-plugin'.
		if ( empty($this->slug) ){
			$this->slug = basename($this->pluginFile, '.php');
		}

		//Plugin slugs must be unique.
		$slugCheckFilter = 'puc_is_slug_in_use-' . $this->slug;
		$slugUsedBy = apply_filters($slugCheckFilter, false);
		if ( $slugUsedBy ) {
			$this->triggerError(sprintf(
				'Plugin slug "%s" is already in use by %s. Slugs must be unique.',
				htmlentities($this->slug),
				htmlentities($slugUsedBy)
			), E_USER_ERROR);
		}
		add_filter($slugCheckFilter, array($this, 'getAbsolutePath'));

		
		if ( empty($this->optionName) ){
			$this->optionName = 'external_updates-' . $this->slug;
		}

		//Backwards compatibility: If the plugin is a mu-plugin but no $muPluginFile is specified, assume
		//it's the same as $pluginFile given that it's not in a subdirectory (WP only looks in the base dir).
		if ( (strpbrk($this->pluginFile, '/\\') === false) && $this->isUnknownMuPlugin() ) {
			$this->muPluginFile = $this->pluginFile;
		}

		$this->scheduler = $this->createScheduler($checkPeriod);
		$this->upgraderStatus = new SiteSEO_PucUpgraderStatus_3_2();

		$this->installHooks();
	}

	/**
	 * Create an instance of the scheduler.
	 *
	 * This is implemented as a method to make it possible for plugins to subclass the update checker
	 * and substitute their own scheduler.
	 *
	 * @param int $checkPeriod
	 * @return SiteSEO_PucScheduler_3_2
	 */
	protected function createScheduler($checkPeriod) {
		return new SiteSEO_PucScheduler_3_2($this, $checkPeriod);
	}
	
	/**
	 * Install the hooks required to run periodic update checks and inject update info 
	 * into WP data structures. 
	 * 
	 * @return void
	 */
	protected function installHooks(){
		//Override requests for plugin information
		add_filter('plugins_api', array($this, 'injectInfo'), 20, 3);
		
		//Insert our update info into the update array maintained by WP.
		add_filter('site_transient_update_plugins', array($this,'injectUpdate')); //WP 3.0+
		add_filter('transient_update_plugins', array($this,'injectUpdate')); //WP 2.8+
		add_filter('site_transient_update_plugins', array($this, 'injectTranslationUpdates'));

		add_filter('plugin_row_meta', array($this, 'addCheckForUpdatesLink'), 10, 2);
		add_action('admin_init', array($this, 'handleManualCheck'));
		add_action('all_admin_notices', array($this, 'displayManualCheckResult'));

		//Clear the version number cache when something - anything - is upgraded or WP clears the update cache.
		add_filter('upgrader_post_install', array($this, 'clearCachedVersion'));
		add_action('delete_site_transient_update_plugins', array($this, 'clearCachedVersion'));
		//Clear translation updates when WP clears the update cache.
		//This needs to be done directly because the library doesn't actually remove obsolete plugin updates,
		//it just hides them (see getUpdate()). We can't do that with translations - too much disk I/O.
		add_action('delete_site_transient_update_plugins', array($this, 'clearCachedTranslationUpdates'));

		if ( did_action('plugins_loaded') ) {
			$this->initDebugBarPanel();
		} else {
			add_action('plugins_loaded', array($this, 'initDebugBarPanel'));
		}

		//Rename the update directory to be the same as the existing directory.
		add_filter('upgrader_source_selection', array($this, 'fixDirectoryName'), 10, 3);

		//Enable language support (i18n).
		load_plugin_textdomain('plugin-update-checker', false, plugin_basename(dirname(__FILE__)) . '/languages');

		//Allow HTTP requests to the metadata URL even if it's on a local host.
		$this->metadataHost = @parse_url($this->metadataUrl, PHP_URL_HOST);
		add_filter('http_request_host_is_external', array($this, 'allowMetadataHost'), 10, 2);
	}
	
	/**
	 * Explicitly allow HTTP requests to the metadata URL.
	 *
	 * WordPress has a security feature where the HTTP API will reject all requests that are sent to
	 * another site hosted on the same server as the current site (IP match), a local host, or a local
	 * IP, unless the host exactly matches the current site.
	 *
	 * This feature is opt-in (at least in WP 4.4). Apparently some people enable it.
	 *
	 * That can be a problem when you're developing your plugin and you decide to host the update information
	 * on the same server as your test site. Update requests will mysteriously fail.
	 *
	 * We fix that by adding an exception for the metadata host.
	 *
	 * @param bool $allow
	 * @param string $host
	 * @return bool
	 */
	public function allowMetadataHost($allow, $host) {
		if ( strtolower($host) === strtolower($this->metadataHost) ) {
			return true;
		}
		return $allow;
	}

	/**
	 * Retrieve plugin info from the configured API endpoint.
	 * 
	 * @uses wp_remote_get()
	 * 
	 * @param array $queryArgs Additional query arguments to append to the request. Optional.
	 * @return SiteSEOInfo_3_2
	 */
	public function requestInfo($queryArgs = array()){
		//Query args to append to the URL. Plugins can add their own by using a filter callback (see addQueryArgFilter()).
		$installedVersion = $this->getInstalledVersion();
		$queryArgs['installed_version'] = ($installedVersion !== null) ? $installedVersion : '';
		$queryArgs = apply_filters('puc_request_info_query_args-'.$this->slug, $queryArgs);
		
		//Various options for the wp_remote_get() call. Plugins can filter these, too.
		$options = array(
			'timeout' => 10, //seconds
			'headers' => array(
				'Accept' => 'application/json'
			),
		);
		$options = apply_filters('puc_request_info_options-'.$this->slug, $options);
		
		//The plugin info should be at 'http://your-api.com/url/here/$slug/info.json'
		$url = $this->metadataUrl; 
		if ( !empty($queryArgs) ){
			$url = add_query_arg($queryArgs, $url);
		}
		
		$result = wp_remote_get(
			$url,
			$options
		);

		//Try to parse the response
		$status = $this->validateApiResponse($result);
		$pluginInfo = null;
		if ( !is_wp_error($status) ){
			$pluginInfo = SiteSEOInfo_3_2::fromJson($result['body']);
			if ( $pluginInfo !== null ) {
				$pluginInfo->filename = $this->pluginFile;
				$pluginInfo->slug = $this->slug;
			}
		} else {
			$this->triggerError(
				sprintf('The URL %s does not point to a valid plugin metadata file. ', $url)
					. $status->get_error_message(),
				E_USER_WARNING
			);
		}

		$pluginInfo = apply_filters('puc_request_info_result-'.$this->slug, $pluginInfo, $result);
		return $pluginInfo;
	}

	/**
	 * Check if $result is a successful update API response.
	 *
	 * @param array|WP_Error $result
	 * @return true|WP_Error
	 */
	private function validateApiResponse($result) {
		if ( is_wp_error($result) ) { /** @var WP_Error $result */
			return new WP_Error($result->get_error_code(), 'WP HTTP Error: ' . $result->get_error_message());
		}

		if ( !isset($result['response']['code']) ) {
			return new WP_Error('puc_no_response_code', 'wp_remote_get() returned an unexpected result.');
		}

		if ( $result['response']['code'] !== 200 ) {
			return new WP_Error(
				'puc_unexpected_response_code',
				'HTTP response code is ' . $result['response']['code'] . ' (expected: 200)'
			);
		}

		if ( empty($result['body']) ) {
			return new WP_Error('puc_empty_response', 'The metadata file appears to be empty.');
		}

		return true;
	}

	/**
	 * Retrieve the latest update (if any) from the configured API endpoint.
	 *
	 * @uses SiteSEOUpdateChecker::requestInfo()
	 *
	 * @return SiteSEOUpdate_3_2 An instance of SiteSEOUpdate, or NULL when no updates are available.
	 */
	public function requestUpdate(){
		//For the sake of simplicity, this function just calls requestInfo() 
		//and transforms the result accordingly.
		$pluginInfo = $this->requestInfo(array('checking_for_updates' => '1'));
		if ( $pluginInfo == null ){
			return null;
		}
		$update = SiteSEOUpdate_3_2::fromSiteSEOInfo($pluginInfo);

		//Keep only those translation updates that apply to this site.
		$update->translations = $this->filterApplicableTranslations($update->translations);

		return $update;
	}

	/**
	 * Filter a list of translation updates and return a new list that contains only updates
	 * that apply to the current site.
	 *
	 * @param array $translations
	 * @return array
	 */
	private function filterApplicableTranslations($translations) {
		$languages = array_flip(array_values(get_available_languages()));
		$installedTranslations = wp_get_installed_translations('plugins');
		if ( isset($installedTranslations[$this->slug]) ) {
			$installedTranslations = $installedTranslations[$this->slug];
		} else {
			$installedTranslations = array();
		}

		$applicableTranslations = array();
		foreach($translations as $translation) {
			//Does it match one of the available core languages?
			$isApplicable = array_key_exists($translation->language, $languages);
			//Is it more recent than an already-installed translation?
			if ( isset($installedTranslations[$translation->language]) ) {
				$updateTimestamp = strtotime($translation->updated);
				$installedTimestamp = strtotime($installedTranslations[$translation->language]['PO-Revision-Date']);
				$isApplicable = $updateTimestamp > $installedTimestamp;
			}

			if ( $isApplicable ) {
				$applicableTranslations[] = $translation;
			}
		}

		return $applicableTranslations;
	}
	
	/**
	 * Get the currently installed version of the plugin.
	 * 
	 * @return string Version number.
	 */
	public function getInstalledVersion(){
		if ( isset($this->cachedInstalledVersion) ) {
			return $this->cachedInstalledVersion;
		}

		$pluginHeader = $this->getPluginHeader();
		if ( isset($pluginHeader['Version']) ) {
			$this->cachedInstalledVersion = $pluginHeader['Version'];
			return $pluginHeader['Version'];
		} else {
			//This can happen if the filename points to something that is not a plugin.
			$this->triggerError(
				sprintf(
					"Can't to read the Version header for '%s'. The filename is incorrect or is not a plugin.",
					$this->pluginFile
				),
				E_USER_WARNING
			);
			return null;
		}
	}

	/**
	 * Get plugin's metadata from its file header.
	 *
	 * @return array
	 */
	protected function getPluginHeader() {
		if ( !is_file($this->pluginAbsolutePath) ) {
			//This can happen if the plugin filename is wrong.
			$this->triggerError(
				sprintf(
					"Can't to read the plugin header for '%s'. The file does not exist.",
					$this->pluginFile
				),
				E_USER_WARNING
			);
			return array();
		}

		if ( !function_exists('get_plugin_data') ){
			/** @noinspection PhpIncludeInspection */
			require_once( ABSPATH . '/wp-admin/includes/plugin.php' );
		}
		return get_plugin_data($this->pluginAbsolutePath, false, false);
	}

	/**
	 * Check for plugin updates.
	 * The results are stored in the DB option specified in $optionName.
	 *
	 * @return SiteSEOUpdate_3_2|null
	 */
	public function checkForUpdates(){
		$installedVersion = $this->getInstalledVersion();
		//Fail silently if we can't find the plugin or read its header.
		if ( $installedVersion === null ) {
			$this->triggerError(
				sprintf('Skipping update check for %s - installed version unknown.', $this->pluginFile),
				E_USER_WARNING
			);
			return null;
		}

		$state = $this->getUpdateState();
		if ( empty($state) ){
			$state = new stdClass;
			$state->lastCheck = 0;
			$state->checkedVersion = '';
			$state->update = null;
		}
		
		$state->lastCheck = time();
		$state->checkedVersion = $installedVersion;
		$this->setUpdateState($state); //Save before checking in case something goes wrong 
		
		$state->update = $this->requestUpdate();
		$this->setUpdateState($state);

		return $this->getUpdate();
	}
	
	/**
	 * Load the update checker state from the DB.
	 *  
	 * @return stdClass|null
	 */
	public function getUpdateState() {
		$state = get_site_option($this->optionName, null);
		if ( empty($state) || !is_object($state)) {
			$state = null;
		}

		if ( isset($state, $state->update) && is_object($state->update) ) {
			$state->update = SiteSEOUpdate_3_2::fromObject($state->update);
		}
		return $state;
	}
	
	
	/**
	 * Persist the update checker state to the DB.
	 * 
	 * @param StdClass $state
	 * @return void
	 */
	private function setUpdateState($state) {
		if ( isset($state->update) && is_object($state->update) && method_exists($state->update, 'toStdClass') ) {
			$update = $state->update; /** @var SiteSEOUpdate_3_2 $update */
			$state->update = $update->toStdClass();
		}
		update_site_option($this->optionName, $state);
	}

	/**
	 * Reset update checker state - i.e. last check time, cached update data and so on.
	 *
	 * Call this when your plugin is being uninstalled, or if you want to
	 * clear the update cache.
	 */
	public function resetUpdateState() {
		delete_site_option($this->optionName);
	}
	
	/**
	 * Intercept plugins_api() calls that request information about our plugin and 
	 * use the configured API endpoint to satisfy them. 
	 * 
	 * @see plugins_api()
	 * 
	 * @param mixed $result
	 * @param string $action
	 * @param array|object $args
	 * @return mixed
	 */
	public function injectInfo($result, $action = null, $args = null){
    	$relevant = ($action == 'plugin_information') && isset($args->slug) && (
			($args->slug == $this->slug) || ($args->slug == dirname($this->pluginFile))
		);
		if ( !$relevant ) {
			return $result;
		}
		
		$pluginInfo = $this->requestInfo();
		$pluginInfo = apply_filters('puc_pre_inject_info-' . $this->slug, $pluginInfo);
		if ( $pluginInfo ) {
			return $pluginInfo->toWpFormat();
		}
				
		return $result;
	}
	
	/**
	 * Insert the latest update (if any) into the update list maintained by WP.
	 * 
	 * @param StdClass $updates Update list.
	 * @return StdClass Modified update list.
	 */
	public function injectUpdate($updates){
		//Is there an update to insert?
		$update = $this->getUpdate();

		//No update notifications for mu-plugins unless explicitly enabled. The MU plugin file
		//is usually different from the main plugin file so the update wouldn't show up properly anyway.
		if ( $this->isUnknownMuPlugin() ) {
			$update = null;
		}

		if ( !empty($update) ) {
			//Let plugins filter the update info before it's passed on to WordPress.
			$update = apply_filters('puc_pre_inject_update-' . $this->slug, $update);
			$updates = $this->addUpdateToList($updates, $update);
		} else {
			//Clean up any stale update info.
			$updates = $this->removeUpdateFromList($updates);
		}

		return $updates;
	}

	/**
	 * @param StdClass|null $updates
	 * @param SiteSEOUpdate_3_2 $updateToAdd
	 * @return StdClass
	 */
	private function addUpdateToList($updates, $updateToAdd) {
		if ( !is_object($updates) ) {
			$updates = new stdClass();
			$updates->response = array();
		}

		$wpUpdate = $updateToAdd->toWpFormat();
		$pluginFile = $this->pluginFile;

		if ( $this->isMuPlugin() ) {
			//WP does not support automatic update installation for mu-plugins, but we can still display a notice.
			$wpUpdate->package = null;
			$pluginFile = $this->muPluginFile;
		}
		$updates->response[$pluginFile] = $wpUpdate;
		return $updates;
	}

	/**
	 * @param stdClass|null $updates
	 * @return stdClass|null
	 */
	private function removeUpdateFromList($updates) {
		if ( isset($updates, $updates->response) ) {
			unset($updates->response[$this->pluginFile]);
			if ( !empty($this->muPluginFile) ) {
				unset($updates->response[$this->muPluginFile]);
			}
		}
		return $updates;
	}

	/**
	 * Insert translation updates into the list maintained by WordPress.
	 *
	 * @param stdClass $updates
	 * @return stdClass
	 */
	public function injectTranslationUpdates($updates) {
		$translationUpdates = $this->getTranslationUpdates();
		if ( empty($translationUpdates) ) {
			return $updates;
		}

		//Being defensive.
		if ( !is_object($updates) ) {
			$updates = new stdClass();
		}
		if ( !isset($updates->translations) ) {
			$updates->translations = array();
		}

		//In case there's a name collision with a plugin hosted on wordpress.org,
		//remove any preexisting updates that match our plugin.
		$translationType = 'plugin';
		$filteredTranslations = array();
		foreach($updates->translations as $translation) {
			if ( ($translation['type'] === $translationType) && ($translation['slug'] === $this->slug) ) {
				continue;
			}
			$filteredTranslations[] = $translation;
		}
		$updates->translations = $filteredTranslations;

		//Add our updates to the list.
		foreach($translationUpdates as $update) {
			$convertedUpdate = array_merge(
				array(
					'type' => $translationType,
					'slug' => $this->slug,
					'autoupdate' => 0,
					//AFAICT, WordPress doesn't actually use the "version" field for anything.
					//But lets make sure it's there, just in case.
					'version' => isset($update->version) ? $update->version : ('1.' . strtotime($update->updated)),
				),
				(array)$update
			);

			$updates->translations[] = $convertedUpdate;
		}

		return $updates;
	}

	/**
	 * Rename the update directory to match the existing plugin directory.
	 *
	 * When WordPress installs a plugin or theme update, it assumes that the ZIP file will contain
	 * exactly one directory, and that the directory name will be the same as the directory where
	 * the plugin/theme is currently installed.
	 *
	 * GitHub and other repositories provide ZIP downloads, but they often use directory names like
	 * "project-branch" or "project-tag-hash". We need to change the name to the actual plugin folder.
	 *
	 * This is a hook callback. Don't call it from a plugin.
	 *
	 * @param string $source The directory to copy to /wp-content/plugins. Usually a subdirectory of $remoteSource.
	 * @param string $remoteSource WordPress has extracted the update to this directory.
	 * @param WP_Upgrader $upgrader
	 * @return string|WP_Error
	 */
	public function fixDirectoryName($source, $remoteSource, $upgrader) {
		global $wp_filesystem; /** @var WP_Filesystem_Base $wp_filesystem */

		//Basic sanity checks.
		if ( !isset($source, $remoteSource, $upgrader, $upgrader->skin, $wp_filesystem) ) {
			return $source;
		}

		//If WordPress is upgrading anything other than our plugin, leave the directory name unchanged.
		if ( !$this->isPluginBeingUpgraded($upgrader) ) {
			return $source;
		}

		//Rename the source to match the existing plugin directory.
		$pluginDirectoryName = dirname($this->pluginFile);
		if ( $pluginDirectoryName === '.' ) {
			return $source;
		}
		$correctedSource = trailingslashit($remoteSource) . $pluginDirectoryName . '/';
		if ( $source !== $correctedSource ) {
			//The update archive should contain a single directory that contains the rest of plugin files. Otherwise,
			//WordPress will try to copy the entire working directory ($source == $remoteSource). We can't rename
			//$remoteSource because that would break WordPress code that cleans up temporary files after update.
			if ( $this->isBadDirectoryStructure($remoteSource) ) {
				return new WP_Error(
					'puc-incorrect-directory-structure',
					sprintf(
						'The directory structure of the update is incorrect. All plugin files should be inside ' .
						'a directory named <span class="code">%s</span>, not at the root of the ZIP file.',
						htmlentities($this->slug)
					)
				);
			}

			/** @var WP_Upgrader_Skin $upgrader->skin */
			$upgrader->skin->feedback(sprintf(
				'Renaming %s to %s&#8230;',
				'<span class="code">' . basename($source) . '</span>',
				'<span class="code">' . $pluginDirectoryName . '</span>'
			));

			if ( $wp_filesystem->move($source, $correctedSource, true) ) {
				$upgrader->skin->feedback('Plugin directory successfully renamed.');
				return $correctedSource;
			} else {
				return new WP_Error(
					'puc-rename-failed',
					'Unable to rename the update to match the existing plugin directory.'
				);
			}
		}

		return $source;
	}

	/**
	 * Check for incorrect update directory structure. An update must contain a single directory,
	 * all other files should be inside that directory.
	 *
	 * @param string $remoteSource Directory path.
	 * @return bool
	 */
	private function isBadDirectoryStructure($remoteSource) {
		global $wp_filesystem; /** @var WP_Filesystem_Base $wp_filesystem */

		$sourceFiles = $wp_filesystem->dirlist($remoteSource);
		if ( is_array($sourceFiles) ) {
			$sourceFiles = array_keys($sourceFiles);
			$firstFilePath = trailingslashit($remoteSource) . $sourceFiles[0];
			return (count($sourceFiles) > 1) || (!$wp_filesystem->is_dir($firstFilePath));
		}

		//Assume it's fine.
		return false;
	}

	/**
	 * Is there and update being installed RIGHT NOW, for this specific plugin?
	 *
	 * @param WP_Upgrader|null $upgrader The upgrader that's performing the current update.
	 * @return bool
	 */
	public function isPluginBeingUpgraded($upgrader = null) {
		return $this->upgraderStatus->isPluginBeingUpgraded($this->pluginFile, $upgrader);
	}

	/**
	 * Get the details of the currently available update, if any.
	 *
	 * If no updates are available, or if the last known update version is below or equal
	 * to the currently installed version, this method will return NULL.
	 *
	 * Uses cached update data. To retrieve update information straight from
	 * the metadata URL, call requestUpdate() instead.
	 *
	 * @return SiteSEOUpdate_3_2|null
	 */
	public function getUpdate() {
		$state = $this->getUpdateState(); /** @var StdClass $state */

		//Is there an update available?
		if ( isset($state, $state->update) ) {
			$update = $state->update;
			//Check if the update is actually newer than the currently installed version.
			$installedVersion = $this->getInstalledVersion();
			if ( ($installedVersion !== null) && version_compare($update->version, $installedVersion, '>') ){
				$update->filename = $this->pluginFile;
				return $update;
			}
		}
		return null;
	}

	/**
	 * Get a list of available translation updates.
	 *
	 * This method will return an empty array if there are no updates.
	 * Uses cached update data.
	 *
	 * @return array
	 */
	public function getTranslationUpdates() {
		$state = $this->getUpdateState();
		if ( isset($state, $state->update, $state->update->translations) ) {
			return $state->update->translations;
		}
		return array();
	}

	/**
	 * Remove all cached translation updates.
	 *
	 * @see wp_clean_update_cache
	 */
	public function clearCachedTranslationUpdates() {
		$state = $this->getUpdateState();
		if ( isset($state, $state->update, $state->update->translations) ) {
			$state->update->translations = array();
			$this->setUpdateState($state);
		}
	}

	/**
	 * Add a "Check for updates" link to the plugin row in the "Plugins" page. By default,
	 * the new link will appear after the "Visit plugin site" link.
	 *
	 * You can change the link text by using the "puc_manual_check_link-$slug" filter.
	 * Returning an empty string from the filter will disable the link.
	 *
	 * @param array $pluginMeta Array of meta links.
	 * @param string $pluginFile
	 * @return array
	 */
	public function addCheckForUpdatesLink($pluginMeta, $pluginFile) {
		$isRelevant = ($pluginFile == $this->pluginFile)
		              || (!empty($this->muPluginFile) && $pluginFile == $this->muPluginFile);

		if ( $isRelevant && current_user_can('update_plugins') ) {
			$linkUrl = wp_nonce_url(
				add_query_arg(
					array(
						'puc_check_for_updates' => 1,
						'puc_slug' => $this->slug,
					),
					self_admin_url('plugins.php')
				),
				'puc_check_for_updates'
			);

			$linkText = apply_filters('puc_manual_check_link-' . $this->slug, __('Check for updates', 'siteseo-pro'));
			if ( !empty($linkText) ) {
				$final_link = sprintf('<a href="%s">%s</a>', esc_attr($linkUrl), $linkText);
				$pluginMeta[] = apply_filters('puc_manual_final_check_link-' . $this->slug, $final_link);
			}
		}
		return $pluginMeta;
	}

	/**
	 * Check for updates when the user clicks the "Check for updates" link.
	 * @see self::addCheckForUpdatesLink()
	 *
	 * @return void
	 */
	public function handleManualCheck() {
		$shouldCheck =
			   isset($_GET['puc_check_for_updates'], $_GET['puc_slug'])
			&& $_GET['puc_slug'] == $this->slug
			&& current_user_can('update_plugins')
			&& check_admin_referer('puc_check_for_updates');

		if ( $shouldCheck ) {
			$update = $this->checkForUpdates();
			$status = ($update === null) ? 'no_update' : 'update_available';
			wp_redirect(add_query_arg(
				array(
					'puc_update_check_result' => $status,
					'puc_slug' => $this->slug,
				),
				self_admin_url('plugins.php')
			));
		}
	}

	/**
	 * Display the results of a manual update check.
	 * @see self::handleManualCheck()
	 *
	 * You can change the result message by using the "puc_manual_check_message-$slug" filter.
	 */
	public function displayManualCheckResult() {
		if ( isset($_GET['puc_update_check_result'], $_GET['puc_slug']) && ($_GET['puc_slug'] == $this->slug) ) {
			$status = strval($_GET['puc_update_check_result']);
			if ( $status == 'no_update' ) {
				$message = __('This plugin is up to date.', 'siteseo-pro');
			} else if ( $status == 'update_available' ) {
				$message = __('A new version of this plugin is available.', 'siteseo-pro');
			} else {
				// Translators: %s is the status of the update checker.
				$message = sprintf(__('Unknown update checker status "%s"', 'siteseo-pro'), htmlentities($status));
			}
			printf(
				'<div class="updated notice is-dismissible"><p>%s</p></div>',
				apply_filters('puc_manual_check_message-' . $this->slug, $message, $status)
			);
		}
	}

	/**
	 * Check if the plugin file is inside the mu-plugins directory.
	 *
	 * @return bool
	 */
	protected function isMuPlugin() {
		static $cachedResult = null;

		if ( $cachedResult === null ) {
			//Convert both paths to the canonical form before comparison.
			$muPluginDir = realpath(WPMU_PLUGIN_DIR);
			$pluginPath  = realpath($this->pluginAbsolutePath);
			
			if(!empty($muPluginDir)){
				$cachedResult = (strpos($pluginPath, $muPluginDir) === 0);
			}else{
				$cachedResult = false;
			}
		}

		return $cachedResult;
	}

	/**
	 * MU plugins are partially supported, but only when we know which file in mu-plugins
	 * corresponds to this plugin.
	 *
	 * @return bool
	 */
	protected function isUnknownMuPlugin() {
		return empty($this->muPluginFile) && $this->isMuPlugin();
	}

	/**
	 * Clear the cached plugin version. This method can be set up as a filter (hook) and will
	 * return the filter argument unmodified.
	 *
	 * @param mixed $filterArgument
	 * @return mixed
	 */
	public function clearCachedVersion($filterArgument = null) {
		$this->cachedInstalledVersion = null;
		return $filterArgument;
	}

	/**
	 * Get absolute path to the main plugin file.
	 *
	 * @return string
	 */
	public function getAbsolutePath() {
		return $this->pluginAbsolutePath;
	}

	/**
	 * Register a callback for filtering query arguments. 
	 * 
	 * The callback function should take one argument - an associative array of query arguments.
	 * It should return a modified array of query arguments.
	 * 
	 * @uses add_filter() This method is a convenience wrapper for add_filter().
	 * 
	 * @param callable $callback
	 * @return void
	 */
	public function addQueryArgFilter($callback){
		add_filter('puc_request_info_query_args-'.$this->slug, $callback);
	}
	
	/**
	 * Register a callback for filtering arguments passed to wp_remote_get().
	 * 
	 * The callback function should take one argument - an associative array of arguments -
	 * and return a modified array or arguments. See the WP documentation on wp_remote_get()
	 * for details on what arguments are available and how they work. 
	 * 
	 * @uses add_filter() This method is a convenience wrapper for add_filter().
	 * 
	 * @param callable $callback
	 * @return void
	 */
	public function addHttpRequestArgFilter($callback){
		add_filter('puc_request_info_options-'.$this->slug, $callback);
	}
	
	/**
	 * Register a callback for filtering the plugin info retrieved from the external API.
	 * 
	 * The callback function should take two arguments. If the plugin info was retrieved 
	 * successfully, the first argument passed will be an instance of  SiteSEOInfo. Otherwise, 
	 * it will be NULL. The second argument will be the corresponding return value of 
	 * wp_remote_get (see WP docs for details).
	 *  
	 * The callback function should return a new or modified instance of SiteSEOInfo or NULL.
	 * 
	 * @uses add_filter() This method is a convenience wrapper for add_filter().
	 * 
	 * @param callable $callback
	 * @return void
	 */
	public function addResultFilter($callback){
		add_filter('puc_request_info_result-'.$this->slug, $callback, 10, 2);
	}

	/**
	 * Register a callback for one of the update checker filters.
	 *
	 * Identical to add_filter(), except it automatically adds the "puc_" prefix
	 * and the "-$plugin_slug" suffix to the filter name. For example, "request_info_result"
	 * becomes "puc_request_info_result-your_plugin_slug".
	 *
	 * @param string $tag
	 * @param callable $callback
	 * @param int $priority
	 * @param int $acceptedArgs
	 */
	public function addFilter($tag, $callback, $priority = 10, $acceptedArgs = 1) {
		add_filter('puc_' . $tag . '-' . $this->slug, $callback, $priority, $acceptedArgs);
	}

	/**
	 * Initialize the update checker Debug Bar plugin/add-on thingy.
	 */
	public function initDebugBarPanel() {
		$debugBarPlugin = dirname(__FILE__) . '/debug-bar-plugin.php';
		if ( class_exists('Debug_Bar', false) && file_exists($debugBarPlugin) ) {
			/** @noinspection PhpIncludeInspection */
			require_once $debugBarPlugin;
			$this->debugBarPlugin = new SiteSEO_PucDebugBarPlugin_3_2($this);
		}
	}

	/**
	 * Trigger a PHP error, but only when $debugMode is enabled.
	 *
	 * @param string $message
	 * @param int $errorType
	 */
	protected function triggerError($message, $errorType) {
		if ( $this->debugMode ) {
			trigger_error($message, $errorType);
		}
	}
}

endif;

if ( !class_exists('SiteSEOInfo_3_2', false) ):

/**
 * A container class for holding and transforming various plugin metadata.
 * 
 * @author Janis Elsts
 * @copyright 2016
 * @version 3.2
 * @access public
 */
#[\AllowDynamicProperties]
class SiteSEOInfo_3_2 {
	//Most fields map directly to the contents of the plugin's info.json file.
	//See the relevant docs for a description of their meaning.  
	public $name;
	public $slug;
	public $version;
	public $homepage;
	public $sections = array();
	public $banners;
	public $translations = array();
	public $download_url;

	public $author;
	public $author_homepage;
	
	public $requires;
	public $tested;
	public $upgrade_notice;
	
	public $rating;
	public $num_ratings;
	public $downloaded;
	public $active_installs;
	public $last_updated;
	
	public $id = 0; //The native WP.org API returns numeric plugin IDs, but they're not used for anything.

	public $filename; //Plugin filename relative to the plugins directory.
		
	/**
	 * Create a new instance of SiteSEOInfo from JSON-encoded plugin info 
	 * returned by an external update API.
	 * 
	 * @param string $json Valid JSON string representing plugin info.
	 * @return SiteSEOInfo_3_2|null New instance of SiteSEOInfo, or NULL on error.
	 */
	public static function fromJson($json){
		/** @var StdClass $apiResponse */
		$apiResponse = json_decode($json);
		if ( empty($apiResponse) || !is_object($apiResponse) ){
			trigger_error(
				"Failed to parse plugin metadata. Try validating your .json file with http://jsonlint.com/",
				E_USER_NOTICE
			);
			return null;
		}
		
		$valid = self::validateMetadata($apiResponse);
		if ( is_wp_error($valid) ){
			trigger_error($valid->get_error_message(), E_USER_NOTICE);
			return null;
		}
		
		$info = new self();
		foreach(get_object_vars($apiResponse) as $key => $value){
			$info->$key = $value;
		}

		//json_decode decodes assoc. arrays as objects. We want it as an array.
		$info->sections = (array)$info->sections;
		
		return $info;		
	}

	/**
	 * Very, very basic validation.
	 *
	 * @param StdClass $apiResponse
	 * @return bool|WP_Error
	 */
	protected static function validateMetadata($apiResponse) {
		if (
			!isset($apiResponse->name, $apiResponse->version)
			|| empty($apiResponse->name)
			|| empty($apiResponse->version)
		) {
			return new WP_Error(
				'puc-invalid-metadata',
				"The plugin metadata file does not contain the required 'name' and/or 'version' keys."
			);
		}
		return true;
	}

	
	/**
	 * Transform plugin info into the format used by the native WordPress.org API
	 * 
	 * @return object
	 */
	public function toWpFormat(){
		$info = new stdClass;
		
		//The custom update API is built so that many fields have the same name and format
		//as those returned by the native WordPress.org API. These can be assigned directly. 
		$sameFormat = array(
			'name', 'slug', 'version', 'requires', 'tested', 'rating', 'upgrade_notice',
			'num_ratings', 'downloaded', 'active_installs', 'homepage', 'last_updated',
		);
		foreach($sameFormat as $field){
			if ( isset($this->$field) ) {
				$info->$field = $this->$field;
			} else {
				$info->$field = null;
			}
		}

		//Other fields need to be renamed and/or transformed.
		$info->download_link = $this->download_url;
		$info->author = $this->getFormattedAuthor();
		$info->sections = array_merge(array('description' => ''), $this->sections);

		if ( !empty($this->banners) ) {
			//WP expects an array with two keys: "high" and "low". Both are optional.
			//Docs: https://wordpress.org/plugins/about/faq/#banners
			$info->banners = is_object($this->banners) ? get_object_vars($this->banners) : $this->banners;
			$info->banners = array_intersect_key($info->banners, array('high' => true, 'low' => true));
		}

		return $info;
	}

	protected function getFormattedAuthor() {
		if ( !empty($this->author_homepage) ){
			return sprintf('<a href="%s">%s</a>', $this->author_homepage, $this->author);
		}
		return $this->author;
	}
}
	
endif;

if ( !class_exists('SiteSEOUpdate_3_2', false) ):

/**
 * A simple container class for holding information about an available update.
 * 
 * @author Janis Elsts
 * @copyright 2016
 * @version 3.2
 * @access public
 */
#[\AllowDynamicProperties]
class SiteSEOUpdate_3_2 {
	public $id = 0;
	public $slug;
	public $version;
	public $homepage;
	public $download_url;
	public $upgrade_notice;
	public $tested;
	public $translations = array();
	public $filename; //Plugin filename relative to the plugins directory.

	private static $fields = array(
		'id', 'slug', 'version', 'homepage', 'tested',
		'download_url', 'upgrade_notice', 'filename',
		'translations'
	);
	
	/**
	 * Create a new instance of SiteSEOUpdate from its JSON-encoded representation.
	 * 
	 * @param string $json
	 * @return SiteSEOUpdate_3_2|null
	 */
	public static function fromJson($json){
		//Since update-related information is simply a subset of the full plugin info,
		//we can parse the update JSON as if it was a plugin info string, then copy over
		//the parts that we care about.
		$pluginInfo = SiteSEOInfo_3_2::fromJson($json);
		if ( $pluginInfo != null ) {
			return self::fromSiteSEOInfo($pluginInfo);
		} else {
			return null;
		}
	}

	/**
	 * Create a new instance of SiteSEOUpdate based on an instance of SiteSEOInfo.
	 * Basically, this just copies a subset of fields from one object to another.
	 * 
	 * @param SiteSEOInfo_3_2 $info
	 * @return SiteSEOUpdate_3_2
	 */
	public static function fromSiteSEOInfo($info){
		return self::fromObject($info);
	}
	
	/**
	 * Create a new instance of SiteSEOUpdate by copying the necessary fields from 
	 * another object.
	 *  
	 * @param StdClass|SiteSEOInfo_3_2|SiteSEOUpdate_3_2 $object The source object.
	 * @return SiteSEOUpdate_3_2 The new copy.
	 */
	public static function fromObject($object) {
		$update = new self();
		$fields = self::$fields;
		if ( !empty($object->slug) ) {
			$fields = apply_filters('puc_retain_fields-' . $object->slug, $fields);
		}
		foreach($fields as $field){
			if (property_exists($object, $field)) {
				$update->$field = $object->$field;
			}
		}
		return $update;
	}
	
	/**
	 * Create an instance of StdClass that can later be converted back to 
	 * a SiteSEOUpdate. Useful for serialization and caching, as it avoids
	 * the "incomplete object" problem if the cached value is loaded before
	 * this class.
	 * 
	 * @return StdClass
	 */
	public function toStdClass() {
		$object = new stdClass();
		$fields = self::$fields;
		if ( !empty($this->slug) ) {
			$fields = apply_filters('puc_retain_fields-' . $this->slug, $fields);
		}
		foreach($fields as $field){
			if (property_exists($this, $field)) {
				$object->$field = $this->$field;
			}
		}
		return $object;
	}
	
	
	/**
	 * Transform the update into the format used by WordPress native plugin API.
	 * 
	 * @return object
	 */
	public function toWpFormat(){
		$update = new stdClass;

		$update->id = $this->id;
		$update->slug = $this->slug;
		$update->new_version = $this->version;
		$update->url = $this->homepage;
		$update->package = $this->download_url;
		$update->tested = $this->tested;
		$update->plugin = $this->filename;

		if ( !empty($this->upgrade_notice) ){
			$update->upgrade_notice = $this->upgrade_notice;
		}
		
		return $update;
	}
}
	
endif;

if ( !class_exists('SiteSEO_PucScheduler_3_2', false) ):

/**
 * The scheduler decides when and how often to check for updates.
 * It calls @see SiteSEOUpdateChecker::checkForUpdates() to perform the actual checks.
 *
 * @version 3.2
 */
class SiteSEO_PucScheduler_3_2 {
	public $checkPeriod = 12; //How often to check for updates (in hours).
	public $throttleRedundantChecks = false; //Check less often if we already know that an update is available.
	public $throttledCheckPeriod = 72;

	/**
	 * @var SiteSEOUpdateChecker_3_2
	 */
	protected $updateChecker;

	private $cronHook = null;

	/**
	 * Scheduler constructor.
	 *
	 * @param SiteSEOUpdateChecker_3_2 $updateChecker
	 * @param int $checkPeriod How often to check for updates (in hours).
	 */
	public function __construct($updateChecker, $checkPeriod) {
		$this->updateChecker = $updateChecker;
		$this->checkPeriod = $checkPeriod;

		//Set up the periodic update checks
		$this->cronHook = 'check_plugin_updates-' . $this->updateChecker->slug;
		if ( $this->checkPeriod > 0 ){

			//Trigger the check via Cron.
			//Try to use one of the default schedules if possible as it's less likely to conflict
			//with other plugins and their custom schedules.
			$defaultSchedules = array(
				1  => 'hourly',
				12 => 'twicedaily',
				24 => 'daily',
			);
			if ( array_key_exists($this->checkPeriod, $defaultSchedules) ) {
				$scheduleName = $defaultSchedules[$this->checkPeriod];
			} else {
				//Use a custom cron schedule.
				$scheduleName = 'every' . $this->checkPeriod . 'hours';
				add_filter('cron_schedules', array($this, '_addCustomSchedule'));
			}

			if ( !wp_next_scheduled($this->cronHook) && !defined('WP_INSTALLING') ) {
				wp_schedule_event(time(), $scheduleName, $this->cronHook);
			}
			add_action($this->cronHook, array($this, 'maybeCheckForUpdates'));

			register_deactivation_hook($this->updateChecker->pluginFile, array($this, '_removeUpdaterCron'));

			//In case Cron is disabled or unreliable, we also manually trigger
			//the periodic checks while the user is browsing the Dashboard.
			add_action( 'admin_init', array($this, 'maybeCheckForUpdates') );

			//Like WordPress itself, we check more often on certain pages.
			/** @see wp_update_plugins */
			add_action('load-update-core.php', array($this, 'maybeCheckForUpdates'));
			add_action('load-plugins.php', array($this, 'maybeCheckForUpdates'));
			add_action('load-update.php', array($this, 'maybeCheckForUpdates'));
			//This hook fires after a bulk update is complete.
			add_action('upgrader_process_complete', array($this, 'maybeCheckForUpdates'), 11, 0);

		} else {
			//Periodic checks are disabled.
			wp_clear_scheduled_hook($this->cronHook);
		}
	}

	/**
	 * Check for updates if the configured check interval has already elapsed.
	 * Will use a shorter check interval on certain admin pages like "Dashboard -> Updates" or when doing cron.
	 *
	 * You can override the default behaviour by using the "puc_check_now-$slug" filter.
	 * The filter callback will be passed three parameters:
	 *     - Current decision. TRUE = check updates now, FALSE = don't check now.
	 *     - Last check time as a Unix timestamp.
	 *     - Configured check period in hours.
	 * Return TRUE to check for updates immediately, or FALSE to cancel.
	 *
	 * This method is declared public because it's a hook callback. Calling it directly is not recommended.
	 */
	public function maybeCheckForUpdates(){
		if ( empty($this->checkPeriod) ){
			return;
		}

		$state = $this->updateChecker->getUpdateState();
		$shouldCheck =
			empty($state) ||
			!isset($state->lastCheck) ||
			( (time() - $state->lastCheck) >= $this->getEffectiveCheckPeriod() );

		//Let plugin authors substitute their own algorithm.
		$shouldCheck = apply_filters(
			'puc_check_now-' . $this->updateChecker->slug,
			$shouldCheck,
			(!empty($state) && isset($state->lastCheck)) ? $state->lastCheck : 0,
			$this->checkPeriod
		);

		if ( $shouldCheck ) {
			$this->updateChecker->checkForUpdates();
		}
	}

	/**
	 * Calculate the actual check period based on the current status and environment.
	 *
	 * @return int Check period in seconds.
	 */
	protected function getEffectiveCheckPeriod() {
		$currentFilter = current_filter();
		if ( in_array($currentFilter, array('load-update-core.php', 'upgrader_process_complete')) ) {
			//Check more often when the user visits "Dashboard -> Updates" or does a bulk update.
			$period = 60;
		} else if ( in_array($currentFilter, array('load-plugins.php', 'load-update.php')) ) {
			//Also check more often on the "Plugins" page and /wp-admin/update.php.
			$period = 3600;
		} else if ( $this->throttleRedundantChecks && ($this->updateChecker->getUpdate() !== null) ) {
			//Check less frequently if it's already known that an update is available.
			$period = $this->throttledCheckPeriod * 3600;
		} else if ( defined('DOING_CRON') && constant('DOING_CRON') ) {
			//WordPress cron schedules are not exact, so lets do an update check even
			//if slightly less than $checkPeriod hours have elapsed since the last check.
			$cronFuzziness = 20 * 60;
			$period = $this->checkPeriod * 3600 - $cronFuzziness;
		} else {
			$period = $this->checkPeriod * 3600;
		}

		return $period;
	}

	/**
	 * Add our custom schedule to the array of Cron schedules used by WP.
	 *
	 * @param array $schedules
	 * @return array
	 */
	public function _addCustomSchedule($schedules){
		if ( $this->checkPeriod && ($this->checkPeriod > 0) ){
			$scheduleName = 'every' . $this->checkPeriod . 'hours';
			$schedules[$scheduleName] = array(
				'interval' => $this->checkPeriod * 3600,
				'display' => sprintf('Every %d hours', $this->checkPeriod),
			);
		}
		return $schedules;
	}

	/**
	 * Remove the scheduled cron event that the library uses to check for updates.
	 *
	 * @return void
	 */
	public function _removeUpdaterCron(){
		wp_clear_scheduled_hook($this->cronHook);
	}

	/**
	 * Get the name of the update checker's WP-cron hook. Mostly useful for debugging.
	 *
	 * @return string
	 */
	public function getCronHookName() {
		return $this->cronHook;
	}
}

endif;


if ( !class_exists('SiteSEO_PucUpgraderStatus_3_2', false) ):

/**
 * A utility class that helps figure out which plugin WordPress is upgrading.
 *
 * It may seem strange to have an separate class just for that, but the task is surprisingly complicated.
 * Core classes like Plugin_Upgrader don't expose the plugin file name during an in-progress update (AFAICT).
 * This class uses a few workarounds and heuristics to get the file name.
 */
#[\AllowDynamicProperties]
class SiteSEO_PucUpgraderStatus_3_2 {
	private $upgradedPluginFile = null; //The plugin that is currently being upgraded by WordPress.

	public function __construct() {
		//Keep track of which plugin WordPress is currently upgrading.
		add_filter('upgrader_pre_install', array($this, 'setUpgradedPlugin'), 10, 2);
		add_filter('upgrader_package_options', array($this, 'setUpgradedPluginFromOptions'), 10, 1);
		add_filter('upgrader_post_install', array($this, 'clearUpgradedPlugin'), 10, 1);
		add_action('upgrader_process_complete', array($this, 'clearUpgradedPlugin'), 10, 1);
	}

	/**
	 * Is there and update being installed RIGHT NOW, for a specific plugin?
	 *
	 * Caution: This method is unreliable. WordPress doesn't make it easy to figure out what it is upgrading,
	 * and upgrader implementations are liable to change without notice.
	 *
	 * @param string $pluginFile The plugin to check.
	 * @param WP_Upgrader|null $upgrader The upgrader that's performing the current update.
	 * @return bool True if the plugin identified by $pluginFile is being upgraded.
	 */
	public function isPluginBeingUpgraded($pluginFile, $upgrader = null) {
		if ( isset($upgrader) ) {
			$upgradedPluginFile = $this->getPluginBeingUpgradedBy($upgrader);
			if ( !empty($upgradedPluginFile) ) {
				$this->upgradedPluginFile = $upgradedPluginFile;
			}
		}
		return ( !empty($this->upgradedPluginFile) && ($this->upgradedPluginFile === $pluginFile) );
	}

	/**
	 * Get the file name of the plugin that's currently being upgraded.
	 *
	 * @param Plugin_Upgrader|WP_Upgrader $upgrader
	 * @return string|null
	 */
	private function getPluginBeingUpgradedBy($upgrader) {
		if ( !isset($upgrader, $upgrader->skin) ) {
			return null;
		}

		//Figure out which plugin is being upgraded.
		$pluginFile = null;
		$skin = $upgrader->skin;
		if ( $skin instanceof Plugin_Upgrader_Skin ) {
			if ( isset($skin->plugin) && is_string($skin->plugin) && ($skin->plugin !== '') ) {
				$pluginFile = $skin->plugin;
			}
		} elseif ( isset($skin->plugin_info) && is_array($skin->plugin_info) ) {
			//This case is tricky because Bulk_Plugin_Upgrader_Skin (etc) doesn't actually store the plugin
			//filename anywhere. Instead, it has the plugin headers in $plugin_info. So the best we can
			//do is compare those headers to the headers of installed plugins.
			$pluginFile = $this->identifyPluginByHeaders($skin->plugin_info);
		}

		return $pluginFile;
	}

	/**
	 * Identify an installed plugin based on its headers.
	 *
	 * @param array $searchHeaders The plugin file header to look for.
	 * @return string|null Plugin basename ("foo/bar.php"), or NULL if we can't identify the plugin.
	 */
	private function identifyPluginByHeaders($searchHeaders) {
		if ( !function_exists('get_plugins') ){
			/** @noinspection PhpIncludeInspection */
			require_once( ABSPATH . '/wp-admin/includes/plugin.php' );
		}

		$installedPlugins = get_plugins();
		$matches = array();
		foreach($installedPlugins as $pluginBasename => $headers) {
			$diff1 = array_diff_assoc($headers, $searchHeaders);
			$diff2 = array_diff_assoc($searchHeaders, $headers);
			if ( empty($diff1) && empty($diff2) ) {
				$matches[] = $pluginBasename;
			}
		}

		//It's possible (though very unlikely) that there could be two plugins with identical
		//headers. In that case, we can't unambiguously identify the plugin that's being upgraded.
		if ( count($matches) !== 1 ) {
			return null;
		}

		return reset($matches);
	}

	/**
	 * @access private
	 *
	 * @param mixed $input
	 * @param array $hookExtra
	 * @return mixed Returns $input unaltered.
	 */
	public function setUpgradedPlugin($input, $hookExtra) {
		if (!empty($hookExtra['plugin']) && is_string($hookExtra['plugin'])) {
			$this->upgradedPluginFile = $hookExtra['plugin'];
		} else {
			$this->upgradedPluginFile = null;
		}
		return $input;
	}

	/**
	 * @access private
	 *
	 * @param array $options
	 * @return array
	 */
	public function setUpgradedPluginFromOptions($options) {
		if (isset($options['hook_extra']['plugin']) && is_string($options['hook_extra']['plugin'])) {
			$this->upgradedPluginFile = $options['hook_extra']['plugin'];
		} else {
			$this->upgradedPluginFile = null;
		}
		return $options;
	}

	/**
	 * @access private
	 *
	 * @param mixed $input
	 * @return mixed Returns $input unaltered.
	 */
	public function clearUpgradedPlugin($input = null) {
		$this->upgradedPluginFile = null;
		return $input;
	}
}

endif;


if ( !class_exists('SiteSEO_PucFactory', false) ):

/**
 * A factory that builds instances of other classes from this library.
 *
 * When multiple versions of the same class have been loaded (e.g. SiteSEOUpdateChecker 1.2
 * and 1.3), this factory will always use the latest available version. Register class
 * versions by calling {@link SiteSEO_PucFactory::addVersion()}.
 *
 * At the moment it can only build instances of the SiteSEOUpdateChecker class. Other classes
 * are intended mainly for internal use and refer directly to specific implementations. If you
 * want to instantiate one of them anyway, you can use {@link SiteSEO_PucFactory::getLatestClassVersion()}
 * to get the class name and then create it with <code>new $class(...)</code>.
 */
#[\AllowDynamicProperties]
class SiteSEO_PucFactory {
	protected static $classVersions = array();
	protected static $sorted = false;

	/**
	 * Create a new instance of SiteSEOUpdateChecker.
	 *
	 * @see SiteSEOUpdateChecker::__construct()
	 *
	 * @param $metadataUrl
	 * @param $pluginFile
	 * @param string $slug
	 * @param int $checkPeriod
	 * @param string $optionName
	 * @param string $muPluginFile
	 * @return SiteSEOUpdateChecker_3_2
	 */
	public static function buildUpdateChecker($metadataUrl, $pluginFile, $slug = '', $checkPeriod = 12, $optionName = '', $muPluginFile = '') {
		$class = self::getLatestClassVersion('SiteSEOUpdateChecker');
		return new $class($metadataUrl, $pluginFile, $slug, $checkPeriod, $optionName, $muPluginFile);
	}

	/**
	 * Get the specific class name for the latest available version of a class.
	 *
	 * @param string $class
	 * @return string|null
	 */
	public static function getLatestClassVersion($class) {
		if ( !self::$sorted ) {
			self::sortVersions();
		}

		if ( isset(self::$classVersions[$class]) ) {
			return reset(self::$classVersions[$class]);
		} else {
			return null;
		}
	}

	/**
	 * Sort available class versions in descending order (i.e. newest first).
	 */
	protected static function sortVersions() {
		foreach ( self::$classVersions as $class => $versions ) {
			uksort($versions, array(__CLASS__, 'compareVersions'));
			self::$classVersions[$class] = $versions;
		}
		self::$sorted = true;
	}

	protected static function compareVersions($a, $b) {
		return -version_compare($a, $b);
	}

	/**
	 * Register a version of a class.
	 *
	 * @access private This method is only for internal use by the library.
	 *
	 * @param string $generalClass Class name without version numbers, e.g. 'SiteSEOUpdateChecker'.
	 * @param string $versionedClass Actual class name, e.g. 'SiteSEOUpdateChecker_1_2'.
	 * @param string $version Version number, e.g. '1.2'.
	 */
	public static function addVersion($generalClass, $versionedClass, $version) {
		if ( !isset(self::$classVersions[$generalClass]) ) {
			self::$classVersions[$generalClass] = array();
		}
		self::$classVersions[$generalClass][$version] = $versionedClass;
		self::$sorted = false;
	}
}

endif;

//Register classes defined in this file with the factory.
SiteSEO_PucFactory::addVersion('SiteSEOUpdateChecker', 'SiteSEOUpdateChecker_3_2', '3.2');
SiteSEO_PucFactory::addVersion('SiteSEOUpdate', 'SiteSEOUpdate_3_2', '3.2');
SiteSEO_PucFactory::addVersion('SiteSEOInfo', 'SiteSEOInfo_3_2', '3.2');
SiteSEO_PucFactory::addVersion('SiteSEO_PucGitHubChecker', 'SiteSEO_PucGitHubChecker_3_2', '3.2');
Name	Size	Permission
settings	---	0755
admin.php	15871 bytes	0644
ai.php	9376 bytes	0644
ajax.php	31513 bytes	0644
breadcrumbs.php	7862 bytes	0644
googleconsole.php	38176 bytes	0644
googlenews.php	3881 bytes	0644
gscsetup.php	14134 bytes	0644
importschema.php	4366 bytes	0644
install.php	2606 bytes	0644
llmtxtfile.php	2823 bytes	0644
plugin-update-checker.php	53836 bytes	0644
redirectmanager.php	7063 bytes	0644
registerblocks.php	1612 bytes	0644
rsssitemap.php	7120 bytes	0644
structureddata.php	50708 bytes	0644
tags.php	14468 bytes	0644
videositemap.php	14032 bytes	0644
File Content: plugin-update-checker.php

File Content: `plugin-update-checker.php`
