<?php namespace ProcessWire;

/**
 * ProcessWire Page Path History
 *
 * Keeps track of past URLs where pages have lived and automatically 301 redirects
 * to the new location whenever the past URL is accessed. 
 *
 * ProcessWire 3.x, Copyright 2019 by Ryan Cramer
 * https://processwire.com
 * 
 * @method upgrade($fromVersion, $toVersion)
 * @property int $minimumAge
 * 
 *
 */

class PagePathHistory extends WireData implements Module, ConfigurableModule {

	public static function getModuleInfo() {
		return array(
			'title' => 'Page Path History', 
			'version' => 5, 
			'summary' => "Keeps track of past URLs where pages have lived and automatically redirects (301 permament) to the new location whenever the past URL is accessed.",
			'singular' => true, 
			'autoload' => true, 
			);
	}

	/**
	 * Table created by this module
	 *
	 */
	const dbTableName = 'page_path_history';

	/**
	 * Minimum age in seconds that a page must be before we'll bother remembering its previous path
	 *
	 */
	const minimumAge = 120; 

	/**
	 * Maximum segments to support in a redirect URL
	 *
	 * Used to place a limit on recursion and paths
	 *
	 */
	const maxSegments = 10;

	/**
	 * PagePageHistory module/schema version
	 * 
	 * @var int
	 * 
	 */
	protected $version = 0;

	/**
	 * Construct
	 * 
	 */
	public function __construct() {
		parent::__construct();
		$this->set('minimumAge', self::minimumAge); 
	}

	/**
	 * Initialize the hooks
	 *
	 */
	public function init() {
		$this->pages->addHook('moved', $this, 'hookPageMoved'); 
		$this->pages->addHook('renamed', $this, 'hookPageMoved'); 
		$this->pages->addHook('deleted', $this, 'hookPageDeleted');
		$this->addHook('ProcessPageView::pageNotFound', $this, 'hookPageNotFound'); 
		$this->addHook('Page::addUrl', $this, 'hookPageAddUrl');
		$this->addHook('Page::removeUrl', $this, 'hookPageRemoveUrl');
	}

	/**
	 * Get version of this module/schema
	 * 
	 * @return int
	 * 
	 */
	protected function getVersion() {
		if($this->version) return $this->version;
		$this->version = $this->wire('modules')->getModuleInfoProperty($this, 'version');
		if(!$this->version) $this->version = 1;
		return $this->version;
	}

	/**
	 * Whether or not to consider language_id in page_path_history module table
	 * 
	 * @return Languages|bool Returns Languages object if yes, or boolean false if not
	 * 
	 */
	protected function getLanguages() {
		if($this->getVersion() < 2) return false;
		if(!$this->wire('modules')->isInstalled('LanguageSupportPageNames')) return false;
		return $this->wire('languages');
	}

	/**
	 * Given a language ID, name or Language object, return Language object or NULL if not found
	 * 
	 * @param int|string|Language $language
	 * @return Language|null
	 * 
	 */
	protected function getLanguage($language) {
		$languages = $this->getLanguages();
		if(!$languages) return null;
		if($language instanceof Page) {
			// ok
		} else if($language === 0) {
			$language = $languages->getDefault();
		} else if(is_int($language) || ctype_digit($language)) {
			$language = $languages->get((int) $language);
		} else if(is_string($language) && $language) {
			$language = $languages->get($this->wire('sanitizer')->pageNameUTF8($language));
		}
		if($language && !$language->id) $language = null;
		return $language;
	}

	/**
	 * Set a history path for a page and delete any existing entries for page’s current path
	 * 
	 * @param Page $page
	 * @param string $path
	 * @param Language|int $language
	 * @return bool True on success, or false if path already consumed in history
	 *
	 */
	public function setPathHistory(Page $page, $path, $language = null) {
		
		$database = $this->wire('database');
		$table = self::dbTableName;
		$result = $this->addPathHistory($page, $path, $language);
		
		if($result) {
			// delete any possible entries that overlap with the $page current path since are no longer applicable
			$query = $database->prepare("DELETE FROM $table WHERE path=:path LIMIT 1");
			$query->bindValue(":path", rtrim($this->wire('sanitizer')->pagePathName($page->path, Sanitizer::toAscii), '/'));
			$query->execute();
		}
		
		return $result;
	}

	/**
	 * Add a history path for a page
	 * 
	 * @param Page $page
	 * @param string $path
	 * @param null|Language $language
	 * @return bool True if path was added, or false if it likely overlaps with an existing path
	 * 
	 */
	public function addPathHistory(Page $page, $path, $language = null) {
		
		$database = $this->wire('database');
		$table = self::dbTableName;
		$path = $this->wire('sanitizer')->pagePathName('/' . trim($path, '/'), Sanitizer::toAscii);
		
		$selector = "path=$path";
		if($this->wire('modules')->isInstalled('PagePaths')) $selector .= ", id!=$page->id";
		if($this->wire('pages')->count($selector)) return false; 
		
		$language = $this->getLanguage($language);

		$sql = "INSERT INTO $table SET path=:path, pages_id=:pages_id, created=NOW()";
		if($language) $sql .= ', language_id=:language_id';

		$query = $database->prepare($sql);
		$query->bindValue(":path", $path);
		$query->bindValue(":pages_id", $page->id, \PDO::PARAM_INT);
		if($language) $query->bindValue(':language_id', $language->id, \PDO::PARAM_INT);

		try {
			$result = $query->execute();
		} catch(\Exception $e) {
			// ignore the exception because it means there is already a past URL (duplicate)
			$result = false;
		}
		
		return $result;
	}
	
	/**
	 * Delete path entry for given page and path
	 * 
	 * @param Page $page
	 * @param string $path
	 * @return int
	 * 
	 */
	public function deletePathHistory(Page $page, $path) {
		
		$database = $this->wire('database');
		$table = self::dbTableName;
		$path = $this->wire('sanitizer')->pagePathName('/' . trim($path, '/'), Sanitizer::toAscii);
		
		$sql = "DELETE FROM $table WHERE path=:path AND pages_id=:pages_id LIMIT 1";
		$query = $database->prepare($sql);
		$query->bindValue(':path', $path);
		$query->bindValue(':pages_id', $page->id, \PDO::PARAM_INT);
		$query->execute();
		
		$cnt = $query->rowCount();
		$query->closeCursor();
		
		return $cnt;
	}
	
	/**
	 * Get an array of all paths the given page has previously had, oldest to newest
	 *
	 * For the options argument: 
	 * - Optionally specify a Language instance (or name or ID) to isolate results to a specific language.
	 * - Optionally specify boolean true to return verbose info. 
	 * 
	 * @param Page $page Page to retrieve paths for. 
	 * @param Language|null|array|bool Specify an option below: 
	 *  - `language` (Language|int|string): Limit returned paths to this language. If none specified, then all languages are included.
	 *  - `verbose` (bool): Return associative array for each path with additional info (date and language, if present).
	 *  - `virtual` (bool): Return history that includes auto-determined virtual entries from parent history? (default=true)
	 *     What this does is also include changes to parent pages that would affect overall URL to requested page. 
	 *  - Or you may specify the `language` option for the options argument. 
	 *  - Or you may specify boolean `true` for options argument as a shortcut for the `verbose` option. 
	 * @return array of paths
	 * 
	 */
	public function getPathHistory(Page $page, $options = array()) {
		
		static $level = 0;
		$level++;
		
		$defaults = array(
			'language' => !is_array($options) && !is_bool($options) ? $options : null, 
			'verbose' => is_bool($options) ? $options : false, 
			'virtual' => true, 
		);
		
		/** @var WireDatabasePDO $database */
		$database = $this->wire('database');
		
		/** @var Sanitizer $sanitizer */
		$sanitizer = $this->wire('sanitizer');
		
		$paths = array();
		$options = is_array($options) ? array_merge($defaults, $options) : $defaults;
		
		if($this->getVersion() < 2) {
			$options['language'] = null;
			$allowLanguage = false;
		} else {
			$allowLanguage = $this->wire('languages') && $this->wire('modules')->isInstalled('LanguageSupportPageNames');
		}
		
		$language = $options['language'] && $allowLanguage ? $this->getLanguage($options['language']) : null;
		$finds = array('pages_id' => $page->id);
		$selects = array('path');
		$wheres = array();
		
		if($options['verbose']) $selects[] = 'created';
		if($options['verbose'] && $allowLanguage) $selects[] = 'language_id';
		if($language) $finds['language_id'] = $language->isDefault() ? 0 : $language->id;
		
		foreach($finds as $col => $value) {
			$wheres[] = "$col=:$col";
		}
	
		$query = $database->prepare(
			'SELECT ' . implode(', ', $selects) . ' FROM ' . self::dbTableName . ' ' . 
			'WHERE ' . implode(' AND ', $wheres) . ' ' . 
			"ORDER BY created"
		);
		
		foreach($finds as $col => $value) {
			$query->bindValue(":$col", $value, \PDO::PARAM_INT); 
		}
		
		try {
			$query->execute();
			
			/** @noinspection PhpAssignmentInConditionInspection */
			while($row = $query->fetch(\PDO::FETCH_ASSOC)) {
				
				$path = $sanitizer->pagePathName($row['path'], Sanitizer::toUTF8);
				
				if($options['verbose']) {
					$value = array('path' => $path);
					$pathDate = $row['created'];
					$value['date'] = $pathDate;
					if($allowLanguage && isset($row['language_id'])) {
						$pathLanguage = $this->getLanguage((int) $row['language_id']);
						$value['language'] = $pathLanguage && $pathLanguage->id ? $pathLanguage : null;
					}
				} else {
					$value = $path;
				}
				
				$paths[$path] = $value;
			}
		} catch(\Exception $e) {
			// intentionally blank
		}
		
		if($options['virtual']) {
			// get changes to current and previous parents as well
			foreach($paths as $value) {
				$virtualPaths = $this->getVirtualHistory($page, $value, $options);
				foreach($virtualPaths as $virtualPath => $virtualInfo) {
					if(isset($paths[$virtualPath])) continue;
					$paths[$virtualPath] = $virtualInfo;
				}
			}
			if($level === 1 && $options['verbose']) {
				$paths = $this->sortVerbosePathInfo($paths); 
			}
		}	
	
		$level--;
		
		return array_values($paths);
	}

	/**
	 * Sort verbose paths by date
	 * 
	 * @param array $paths Verbose paths
	 * @param bool $newest Sort newest to oldest? Specify false so sort oldest to newest. (default=true)
	 * @return array
	 * 
	 */
	protected function sortVerbosePathInfo(array $paths, $newest = true) {
		
		$sortPaths = array();
		
		foreach($paths as $value) {
			$date = strtotime($value['date']);
			while(isset($sortPaths[$date])) $date++;
			$sortPaths[$date] = $value;
		}
		
		if($newest) {
			krsort($sortPaths);
		} else {
			ksort($sortPaths);
		}
		
		return $sortPaths;
	}

	/**
	 * Get history which includes entries not actually in pages_paths table reflecting changes to parents
	 * 
	 * @param Page $page
	 * @param string|array $path
	 * @param array $options
	 *
	 * @return array
	 * 
	 */
	protected function getVirtualHistory(Page $page, $path, array $options) {
		
		$paths = array();
		$checkParents = array();
		
		if(is_array($path)) {
			// path is verbose info
			$pathInfo = $path;
			$path = $pathInfo['path'];
		} else {
			// path is string
			$pathInfo = array('path');
		}
	
		// separate page name and parent path
		$parts = explode('/', trim($path, '/'));
		$pageName = array_pop($parts);
		$parentPath = implode('/', $parts);
	
		// if page’s current parent is not homepage, include it 
		if($page->parent_id > 1) {
			$checkParents[] = $page->parent;
		}

		// if historical parent path differs from page’s current parent path, include it
		if($parentPath === '' || $parentPath === '/') {
			// historial parent is root/home
		} else if($parentPath === trim($page->parent()->path(), '/')) {
			// historial parent is the same as current parent
		} else if($parentPath === trim($page->path(), '/')) {
			// historial parent is the page itself
		} else {
			// historial parent may be one we want to check
			$parent = $this->wire()->pages->get("/$parentPath");
			if(!$parent->id) $parent = $this->getPage($parentPath);
			// if parent from path is different from current page parent, include in our list of parents to check
			if($parent->id > 1 && $parent->id != $page->parent_id && $parent->id != $page->id) {
				$checkParents[] = $parent;
			}
		}

		// get paths for each parent 
		foreach($checkParents as $parent) {
			$parentPaths = $this->getVirtualHistoryParent($page, $pageName, $pathInfo, $parent, $options);
			foreach($parentPaths as $parentPath => $parentInfo) {
				if(!isset($paths[$parentPath])) {
					$paths[$parentPath] = $parentInfo;
				}
			}
		}
		
		return $paths;
	}

	/**
	 * Get virtual history for page in context of a specific parent (companion to getVirtualHistory method)
	 * 
	 * @param Page $page
	 * @param string $pageName Historical name (or same as page->name)
	 * @param array|string $pagePathInfo Path or pathInfo array
	 * @param Page $parent
	 * @param array $options
	 * @return array
	 * 
	 */
	protected function getVirtualHistoryParent(Page $page, $pageName, array $pagePathInfo, Page $parent, array $options) {
		
		$paths = array();
		
		// get path history for this parent
		$parentPaths = $this->getPathHistory($parent, $options);

		// pageNamesDates is array of name => timestamp
		$pageNamesDates = array(
			$pageName => isset($pagePathInfo['date']) ? strtotime($pagePathInfo['date']) : 0
		);

		// if historical name differs from current name, include current name in pageNamesDates
		if($page->name != $pageName) {
			$pageNamesDates[$page->name] = $page->modified;
		}

		// iterate through each of the names this page has had, along with the date that it was changed to it
		foreach($pageNamesDates as $name => $date) {

			// iterate through all possible parent paths
			foreach($parentPaths as $parentPathInfo) {

				$parentPath = $options['verbose'] ? $parentPathInfo['path'] : $parentPathInfo;

				// create path that is historical parent path plus current iteration of page name
				$path = $parentPath . '/' . $name;

				// if we've already got this path, skip it
				if(isset($paths[$path])) continue;

				// non-verbose mode only includes paths
				if(empty($options['verbose'])) {
					$paths[$path] = $path;
					continue;
				}
				
				// if parent change date is older than page change date, then we can skip it
				if(strtotime($parentPathInfo['date']) < $date) continue;
			
				// if path is related to trash do not include it
				if(strpos($path, '/trash/') === 0 || preg_match('!/\d+\.\d+\.\d+_[-_a-z0-9]+!', $path)) {
					continue;
				}
				
				// create verbose info for this entry
				$pathInfo = array(
					'path' => $path,
					'date' => $parentPathInfo['date'],
					'virtual' => $parent->id
				);
				
				// if parent is specific to a language, include that info in the verbose value
				if(isset($parentPathInfo['language'])) {
					$pathInfo['language'] = $parentPathInfo['language'];
				}
				
				$paths[$path] = $pathInfo;
			}
		}
		
		return $paths;
	}

	/**
	 * Hook called when a page is moved or renamed
	 * 
	 * @param HookEvent $event
	 *
	 */
	public function hookPageMoved(HookEvent $event) {

		/** @var Page $page */
		$page = $event->arguments[0];
		/** @var Languages $languages */
		$languages = $this->getLanguages();

		$age = time() - $page->created;
		if($page->template == 'admin' || $this->wire('pages')->cloning || $age < $this->minimumAge) return;

		// note that the paths we store have no trailing slash
		
		if($languages) {
			$parent = $page->parent();
			$parentPrevious = $page->parentPrevious;
			if($parentPrevious && $parentPrevious->id == $parent->id) $parentPrevious = null;
			foreach($languages as $language) {
				/** @var Language $language */
				if($language->isDefault()) continue;
				$namePrevious = $page->get("-name$language");
				if(!$namePrevious && !$parentPrevious) continue;
				if(!$namePrevious) $namePrevious = $page->name;
				$languages->setLanguage($language);
				$pathPrevious = $parentPrevious ? $parentPrevious->path() : $page->parent()->path();
				$pathPrevious = rtrim($pathPrevious, '/') . "/$namePrevious";
				$this->setPathHistory($page, $pathPrevious, $language->id);
				$languages->unsetLanguage();
			}
		}

		if(!$page->namePrevious) {
			// abort saving a former URL if it looks like there isn't going to be one
			if(!$page->parentPrevious || $page->parentPrevious->id == $page->parent->id) return;
		}

		if($page->parentPrevious) {

			// if former or current parent is in trash, then don't bother saving redirects
			if($page->parentPrevious->isTrash() || $page->parent->isTrash()) return; 

			// the start of our redirect URL will be the previous parent's URL
			$path = $page->parentPrevious->path;

		} else {
			// the start of our redirect URL will be the current parent's URL (i.e. name changed)
			$path = $page->parent->path;
		}

		if($page->namePrevious) {
			$path = rtrim($path, '/') . '/' . $page->namePrevious;
		} else {
			$path = rtrim($path, '/') . '/' . $page->name;
		}
		
		if($languages) $languages->setDefault();
		$this->setPathHistory($page, $path);
		if($languages) $languages->unsetDefault();
	}

	/**
	 * Hook called upon 404 from ProcessPageView::pageNotFound
	 * 
	 * @param HookEvent $event
	 *
	 */
	public function hookPageNotFound(HookEvent $event) {
	
		/** @var Page $page */
		$page = $event->arguments(0);
		/** @var Wire404Exception $exception */
		$exception = $event->arguments(4); 

		// If there is a page object set, then it means the 404 was triggered
		// by the user not having access to it, or by the $page's template 
		// throwing a 404 exception. In either case, we don't want to do a 
		// redirect if there is a $page since any 404 is intentional there.
		if($page && $page->id) {
			// it did resolve to a Page: maybe a front-end 404
			if(!$exception) {
				// pageNotFound was called without an Exception
				return;
			} else if($exception->getCode() == Wire404Exception::codeFunction) {
				// the wire404() function was called: allow PagePathHistory
			} else if($exception->getMessage() === "1") {
				// also allow PagePathHistory to operate when: throw new WireException(true);
			} else {
				// likely user didn't have access or intentional 404 that should not redirect
				return;
			} 
		}
		
		$languages = $this->getLanguages();
		if($languages) {
			// the LanguageSupportPageNames may change the original requested path, so we ask it for the original
			$path = $this->wire('modules')->get('LanguageSupportPageNames')->getRequestPath();
			$path = $path ? $this->wire('sanitizer')->pagePathName($path) : $event->arguments(1);
		} else {
			$path = $event->arguments(1);
		}
		
		$page = $this->getPage($path);
		
		if($page->id && $page->viewable()) {
			// if a page was found, redirect to it...
			$language = $page->get('_language');
			if($language && $languages) {
				// ...optionally for a specific language
				if($page->get("status$language")) {
					$languages->setLanguage($language);
				}
			}
			$this->session->redirect($page->url);
		}
	}

	/**
	 * Given a previously existing path, return the matching Page object or NullPage if not found.
	 * 
	 * If the path is for a specific language, this method also sets a $page->_language property
	 * containing the Language object the path is for. 
	 *
	 * @param string $path Historical path of page you want to retrieve
	 * @param int $level Recursion level for internal recursive use only
	 * @return Page|NullPage
	 *
	 */
	public function getPage($path, $level = 0) {
		
		$page = $this->wire('pages')->newNullPage();
		$pathRemoved = '';
		$cnt = 0;
		$database = $this->wire('database');
		$table = self::dbTableName;
		$languages = $this->getLanguages();
		
		if(!$level) $path = $this->wire('sanitizer')->pagePathName($path, Sanitizer::toAscii);
		$path = '/' . trim($path, '/');

		while(strlen($path) && !$page->id && $cnt < self::maxSegments) {

			$sql = "SELECT pages_id ";
			if($languages) $sql .= ", language_id ";
			$sql .= "FROM $table WHERE path=:path";
			$query = $database->prepare($sql);
			$query->bindValue(":path", $path); 
			$error = false;
			
			try {
				$query->execute();
			} catch(\Exception $e) {
				if(strpos($e->getMessage(), '1054') !== false) $this->upgrade(1, 2);
				$this->wire('log')->error('PagePathHistory::getPage() - ' . $e->getMessage());
				$error = true;
			}
			
			if($error) break;
			
			if($query->rowCount() > 0) {
				// found a match
				$row = $query->fetch(\PDO::FETCH_NUM);
				$pages_id = (int) $row[0];
				$language_id = $languages && isset($row[1]) ? $row[1] : 0;
				$page = $this->pages->get((int) $pages_id);
				if($language_id) $page->setQuietly("_language", $this->getLanguage($language_id));
			} else {
				// didn't find a match, we'll pop the last segment off and try again for the parent
				$pos = strrpos($path, '/');
				$pathRemoved = substr($path, $pos) . $pathRemoved;
				$path = substr($path, 0, $pos);
			}
			
			$query->closeCursor();
			$cnt++;
		} 

		// if no page was found, then we can stop trying now
		if(!$page->id) return $page; 

		if($cnt > 1) {
			// a parent match was found if our counter is > 1
			$parent = $page; 
			// use the new parent path and add the removed components back on to it
			$path = rtrim($parent->path, '/') . $pathRemoved; 
			// see if it might exist at the new parent's URL
			$page = $this->wire('pages')->getByPath($path, array(
				'useHistory' => false,
				'useLanguages' => $languages ? true : false
			)); 
			if($page->id) {
				// found a page
				if($languages) {
					$language = $this->wire('modules')->get('LanguageSupportPageNames')->getPagePathLanguage($path, $page);
					if($language) $page->setQuietly('_language', $language);
				}
			} else if($level < self::maxSegments) {
				// if not, then go recursive, trying again
				$page = $this->getPage($path, $level + 1);
			}
		}
		
		return $page; 	
	}

	/**
	 * When a page is deleted, remove it from our redirects list as well
	 * 
	 * @param HookEvent $event
	 *
	 */
	public function hookPageDeleted(HookEvent $event) {
		$page = $event->arguments[0];
		$database = $this->wire('database');
		$query = $database->prepare("DELETE FROM " . self::dbTableName . " WHERE pages_id=:pages_id"); 
		$query->bindValue(":pages_id", $page->id, \PDO::PARAM_INT);
		$query->execute();
	}

	/**
	 * Implementation for $page->addUrl($url, [$language]) method
	 * 
	 * @param HookEvent $event
	 * 
	 */
	public function hookPageAddUrl(HookEvent $event) {
		/** @var Page $page */
		$page = $event->object; 
		/** @var string $url */
		$url = $event->arguments(0);
		/** @var Language|null $language */
		$language = $event->arguments(1);
		$event->return = $this->addPathHistory($page, $this->urlToPath($url), $language); 
	}
	
	/**
	 * Implementation for $page->removeUrl($url, [$language]) method
	 *
	 * @param HookEvent $event
	 *
	 */
	public function hookPageRemoveUrl(HookEvent $event) {
		/** @var page $page */
		$page = $event->object;
		/** @var string $url */
		$url = $event->arguments(0);
		$event->return = (bool) $this->deletePathHistory($page, $this->urlToPath($url));
	}

	/**
	 * Given URL that may include a root subdirectory, convert it to path relative to root subdirectory
	 * 
	 * @param string $url
	 * @return string
	 * 
	 */
	protected function urlToPath($url) {
		$rootUrl = $this->wire('config')->urls->root;
		if(strlen($rootUrl) > 1 && strpos($url, $rootUrl) === 0) {
			$path = substr($url, strlen($rootUrl) - 1);
		} else {
			$path = $url;
		}
		return $path;
	}

	/**
	 * Install
	 * 
	 */
	public function ___install() {
		
		$len = $this->wire('database')->getMaxIndexLength();

		$sql = 	"CREATE TABLE " . self::dbTableName . " (" . 
				"path VARCHAR($len) NOT NULL, " . 
				"pages_id INT UNSIGNED NOT NULL, " .
				"language_id INT UNSIGNED DEFAULT 0, " . // v2
				"created TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP, " . 
				"PRIMARY KEY path (path), " . 
				"INDEX pages_id (pages_id), " . 
				"INDEX created (created) " . 
				") ENGINE={$this->config->dbEngine} DEFAULT CHARSET={$this->config->dbCharset}";

		$this->wire('database')->exec($sql); 

	}

	/**
	 * Uninstall
	 * 
	 */
	public function ___uninstall() {
		$this->wire('database')->query("DROP TABLE " . self::dbTableName); 
	}

	/**
	 * Upgrade PagePathHistory module schema
	 * 
	 * @param int $fromVersion
	 * @param int $toVersion
	 * 
	 */
	public function ___upgrade($fromVersion, $toVersion) {
		
		if($fromVersion == 1) {
		
			$messagePrefix = "PagePathHistory v$fromVersion => v$toVersion: ";
			$database = $this->wire('database');
			$table = self::dbTableName;
			
			try {
				$database->exec("ALTER TABLE $table ADD language_id INT UNSIGNED DEFAULT 0");
				$message = "Added 'language_id' column";
				$error = false;
			} catch(\Exception $e) {
				$error = true;
				$message = $e->getMessage();
			}
			
			$message = $messagePrefix . $message;
			$error ? $this->error($message) : $this->message($message);
		}
	}

	/**
	 * Module config
	 * 
	 * @param InputfieldWrapper $inputfields
	 * 
	 */
	public function getModuleConfigInputfields(InputfieldWrapper $inputfields) {
		/** @var InputfieldInteger $f */
		$f = $this->wire('modules')->get('InputfieldInteger');
		$f->attr('name', 'minimumAge');
		$f->label = $this->_('Minimum age (seconds)');
		$f->description = $this->_('Start recording history for a page this many seconds after it has been created. At least 2 or more seconds recommended.');
		$f->notes = sprintf($this->_('Default: %s'), self::minimumAge);
		$f->val((int) $this->minimumAge);
		$f->required = true;
		$inputfields->add($f);
	}

}