<?php

namespace SilverStripe\CMS\Controllers;

use SilverStripe\Admin\AdminRootController;
use SilverStripe\Admin\CMSBatchActionHandler;
use SilverStripe\Admin\CMSPreviewable;
use SilverStripe\Admin\LeftAndMain;
use SilverStripe\CMS\BatchActions\CMSBatchAction_Archive;
use SilverStripe\CMS\BatchActions\CMSBatchAction_Publish;
use SilverStripe\CMS\BatchActions\CMSBatchAction_Restore;
use SilverStripe\CMS\BatchActions\CMSBatchAction_Unpublish;
use SilverStripe\CMS\Model\CurrentPageIdentifier;
use SilverStripe\CMS\Model\RedirectorPage;
use SilverStripe\CMS\Model\SiteTree;
use SilverStripe\Control\Controller;
use SilverStripe\Control\Director;
use SilverStripe\Control\Session;
use SilverStripe\Control\HTTPRequest;
use SilverStripe\Control\HTTPResponse;
use SilverStripe\Control\HTTPResponse_Exception;
use SilverStripe\Core\Convert;
use SilverStripe\Core\Injector\Injector;
use SilverStripe\Core\Cache;
use SilverStripe\Forms\DateField;
use SilverStripe\Forms\DropdownField;
use SilverStripe\Forms\FieldGroup;
use SilverStripe\Forms\FieldList;
use SilverStripe\Forms\Form;
use SilverStripe\Forms\FormAction;
use SilverStripe\Forms\FormField;
use SilverStripe\Forms\GridField\GridField;
use SilverStripe\Forms\GridField\GridFieldConfig;
use SilverStripe\Forms\GridField\GridFieldDataColumns;
use SilverStripe\Forms\GridField\GridFieldLevelup;
use SilverStripe\Forms\GridField\GridFieldPaginator;
use SilverStripe\Forms\GridField\GridFieldSortableHeader;
use SilverStripe\Forms\HiddenField;
use SilverStripe\Forms\LabelField;
use SilverStripe\Forms\LiteralField;
use SilverStripe\Forms\RequiredFields;
use SilverStripe\Forms\ResetFormAction;
use SilverStripe\Forms\TabSet;
use SilverStripe\Forms\TextField;
use SilverStripe\ORM\ArrayList;
use SilverStripe\ORM\DataList;
use SilverStripe\ORM\DataObject;
use SilverStripe\ORM\DB;
use SilverStripe\ORM\HiddenClass;
use SilverStripe\ORM\SS_List;
use SilverStripe\ORM\Versioning\Versioned;
use SilverStripe\Security\Member;
use SilverStripe\Security\Permission;
use SilverStripe\Security\PermissionProvider;
use SilverStripe\Security\Security;
use SilverStripe\Security\SecurityToken;
use SilverStripe\View\ArrayData;
use SilverStripe\View\Requirements;
use Translatable;
use Page;
use Zend_Cache;
use InvalidArgumentException;


/**
 * The main "content" area of the CMS.
 *
 * This class creates a 2-frame layout - left-tree and right-form - to sit beneath the main
 * admin menu.
 *
 * @todo Create some base classes to contain the generic functionality that will be replicated.
 *
 * @mixin LeftAndMainPageIconsExtension
 */
class CMSMain extends LeftAndMain implements CurrentPageIdentifier, PermissionProvider {

	private static $url_segment = 'pages';

	private static $url_rule = '/$Action/$ID/$OtherID';

	// Maintain a lower priority than other administration sections
	// so that Director does not think they are actions of CMSMain
	private static $url_priority = 39;

	private static $menu_title = 'Edit Page';

	private static $menu_priority = 10;

	private static $tree_class = SiteTree::class;

	private static $subitem_class = Member::class;

	private static $session_namespace = 'SilverStripe\\CMS\\Controllers\\CMSMain';

	private static $required_permission_codes = 'CMS_ACCESS_CMSMain';

	/**
	 * Amount of results showing on a single page.
	 *
	 * @config
	 * @var int
	 */
	private static $page_length = 15;

	private static $allowed_actions = array(
		'archive',
		'deleteitems',
		'DeleteItemsForm',
		'dialog',
		'duplicate',
		'duplicatewithchildren',
		'publishall',
		'publishitems',
		'PublishItemsForm',
		'submit',
		'EditForm',
		'SearchForm',
		'SiteTreeAsUL',
		'getshowdeletedsubtree',
		'batchactions',
		'treeview',
		'listview',
		'ListViewForm',
		'childfilter',
	);

	private static $casting = array(
		'TreeIsFiltered' => 'Boolean',
		'AddForm' => 'HTMLFragment',
		'LinkPages' => 'Text',
		'Link' => 'Text',
		'ListViewForm' => 'HTMLFragment',
		'ExtraTreeTools' => 'HTMLFragment',
		'SiteTreeHints' => 'HTMLFragment',
		'SecurityID' => 'Text',
		'SiteTreeAsUL' => 'HTMLFragment',
	);

	public function init() {
		// set reading lang
		if(SiteTree::has_extension('Translatable') && !$this->getRequest()->isAjax()) {
			Translatable::choose_site_locale(array_keys(Translatable::get_existing_content_languages('SilverStripe\\CMS\\Model\\SiteTree')));
		}

		parent::init();

		Requirements::javascript(CMS_DIR . '/client/dist/js/bundle.js');
		Requirements::javascript(CMS_DIR . '/client/dist/js/SilverStripeNavigator.js');
		Requirements::css(CMS_DIR . '/client/dist/styles/bundle.css');
		Requirements::customCSS($this->generatePageIconsCss());
		Requirements::add_i18n_javascript(CMS_DIR . '/client/lang', false, true);

		CMSBatchActionHandler::register('restore', CMSBatchAction_Restore::class);
		CMSBatchActionHandler::register('archive', CMSBatchAction_Archive::class);
		CMSBatchActionHandler::register('unpublish', CMSBatchAction_Unpublish::class);
		CMSBatchActionHandler::register('publish', CMSBatchAction_Publish::class);
	}

	public function index($request) {
		// In case we're not showing a specific record, explicitly remove any session state,
		// to avoid it being highlighted in the tree, and causing an edit form to show.
		if(!$request->param('Action')) {
			$this->setCurrentPageID(null);
		}

		return parent::index($request);
	}

	public function getResponseNegotiator() {
		$negotiator = parent::getResponseNegotiator();
		$controller = $this;
		$negotiator->setCallback('ListViewForm', function() use($controller) {
			return $controller->ListViewForm()->forTemplate();
		});
		return $negotiator;
	}

	/**
	 * If this is set to true, the "switchView" context in the
	 * template is shown, with links to the staging and publish site.
	 *
	 * @return boolean
	 */
	public function ShowSwitchView() {
		return true;
	}

	/**
	 * Overloads the LeftAndMain::ShowView. Allows to pass a page as a parameter, so we are able
	 * to switch view also for archived versions.
	 *
	 * @param SiteTree $page
	 * @return array
	 */
	public function SwitchView($page = null) {
		if(!$page) {
			$page = $this->currentPage();
		}

		if($page) {
			$nav = SilverStripeNavigator::get_for_record($page);
			return $nav['items'];
		}
	}

	//------------------------------------------------------------------------------------------//
	// Main controllers

	//------------------------------------------------------------------------------------------//
	// Main UI components

	/**
	 * Override {@link LeftAndMain} Link to allow blank URL segment for CMSMain.
	 *
	 * @param string|null $action Action to link to.
	 * @return string
	 */
	public function Link($action = null) {
		$link = Controller::join_links(
			AdminRootController::admin_url(),
			$this->stat('url_segment'), // in case we want to change the segment
			'/', // trailing slash needed if $action is null!
			"$action"
		);
		$this->extend('updateLink', $link);
		return $link;
	}

	public function LinkPages() {
		return CMSPagesController::singleton()->Link();
	}

	public function LinkPagesWithSearch() {
		return $this->LinkWithSearch($this->LinkPages());
	}

	public function LinkTreeView() {
		return $this->LinkWithSearch($this->Link('treeview'));
	}

	public function LinkListView() {
		return $this->LinkWithSearch($this->Link('listview'));
	}

	public function LinkGalleryView() {
		return $this->LinkWithSearch($this->Link('galleryview'));
	}

	public function LinkPageEdit($id = null) {
		if(!$id) {
			$id = $this->currentPageID();
		}
		return $this->LinkWithSearch(
			Controller::join_links(CMSPageEditController::singleton()->Link('show'), $id)
		);
	}

	public function LinkPageSettings() {
		if($id = $this->currentPageID()) {
			return $this->LinkWithSearch(
				Controller::join_links(CMSPageSettingsController::singleton()->Link('show'), $id)
			);
		} else {
			return null;
		}
	}

	public function LinkPageHistory() {
		if($id = $this->currentPageID()) {
			return $this->LinkWithSearch(
				Controller::join_links(CMSPageHistoryController::singleton()->Link('show'), $id)
			);
		} else {
			return null;
		}
	}

	public function LinkWithSearch($link) {
		// Whitelist to avoid side effects
		$params = array(
			'q' => (array)$this->getRequest()->getVar('q'),
			'ParentID' => $this->getRequest()->getVar('ParentID')
		);
		$link = Controller::join_links(
			$link,
			array_filter(array_values($params)) ? '?' . http_build_query($params) : null
		);
		$this->extend('updateLinkWithSearch', $link);
		return $link;
	}

	public function LinkPageAdd($extra = null, $placeholders = null) {
		$link = CMSPageAddController::singleton()->Link();
		$this->extend('updateLinkPageAdd', $link);

		if($extra) {
			$link = Controller::join_links ($link, $extra);
		}

		if($placeholders) {
			$link .= (strpos($link, '?') === false ? "?$placeholders" : "&amp;$placeholders");
		}

		return $link;
	}

	/**
	 * @return string
	 */
	public function LinkPreview() {
		$record = $this->getRecord($this->currentPageID());
		$baseLink = Director::absoluteBaseURL();
		if ($record && $record instanceof Page) {
			// if we are an external redirector don't show a link
			if ($record instanceof RedirectorPage && $record->RedirectionType == 'External') {
				$baseLink = false;
			}
			else {
				$baseLink = $record->Link('?stage=Stage');
			}
		}
		return $baseLink;
	}

	/**
	 * Return the entire site tree as a nested set of ULs
	 */
	public function SiteTreeAsUL() {
		// Pre-cache sitetree version numbers for querying efficiency
		Versioned::prepopulate_versionnumber_cache(SiteTree::class, "Stage");
		Versioned::prepopulate_versionnumber_cache(SiteTree::class, "Live");
		$html = $this->getSiteTreeFor($this->stat('tree_class'));

		$this->extend('updateSiteTreeAsUL', $html);

		return $html;
	}

	/**
	 * @return boolean
	 */
	public function TreeIsFiltered() {
		$query = $this->getRequest()->getVar('q');

		if (!$query || (count($query) === 1 && isset($query['FilterClass']) && $query['FilterClass'] === 'SilverStripe\\CMS\\Controllers\\CMSSiteTreeFilter_Search')) {
			return false;
		}

		return true;
	}

	public function ExtraTreeTools() {
		$html = '';
		$this->extend('updateExtraTreeTools', $html);
		return $html;
	}

	/**
	 * Returns a Form for page searching for use in templates.
	 *
	 * Can be modified from a decorator by a 'updateSearchForm' method
	 *
	 * @return Form
	 */
	public function SearchForm() {
		// Create the fields
		$content = new TextField('q[Term]', _t('CMSSearch.FILTERLABELTEXT', 'Search'));
		$dateFrom = new DateField(
			'q[LastEditedFrom]',
			_t('CMSSearch.FILTERDATEFROM', 'From')
		);
		$dateFrom->setConfig('showcalendar', true);
		$dateTo = new DateField(
			'q[LastEditedTo]',
			_t('CMSSearch.FILTERDATETO', 'To')
		);
		$dateTo->setConfig('showcalendar', true);
		$pageFilter = new DropdownField(
			'q[FilterClass]',
			_t('CMSMain.PAGES', 'Page status'),
			CMSSiteTreeFilter::get_all_filters()
		);
		$pageClasses = new DropdownField(
			'q[ClassName]',
			_t('CMSMain.PAGETYPEOPT', 'Page type', 'Dropdown for limiting search to a page type'),
			$this->getPageTypes()
		);
		$pageClasses->setEmptyString(_t('CMSMain.PAGETYPEANYOPT','Any'));

		// Group the Datefields
		$dateGroup = new FieldGroup(
			$dateFrom,
			$dateTo
		);
		$dateGroup->setTitle(_t('CMSSearch.PAGEFILTERDATEHEADING', 'Last edited'));

		// Create the Field list
		$fields = new FieldList(
			$content,
			$pageFilter,
			$pageClasses,
			$dateGroup
		);

		// Create the Search and Reset action
		$actions = new FieldList(
			FormAction::create('doSearch',  _t('CMSMain_left_ss.APPLY_FILTER', 'Search'))
				->addExtraClass('ss-ui-action-constructive'),
			ResetFormAction::create('clear', _t('CMSMain_left_ss.CLEAR_FILTER', 'Clear'))
		);

		// Use <button> to allow full jQuery UI styling on the all of the Actions
		/** @var FormAction $action */
		foreach($actions->dataFields() as $action) {
			/** @var FormAction $action */
			$action->setUseButtonTag(true);
		}

		// Create the form
		/** @skipUpgrade */
		$form = Form::create($this, 'SearchForm', $fields, $actions)
			->addExtraClass('cms-search-form')
			->setFormMethod('GET')
			->setFormAction($this->Link())
			->disableSecurityToken()
			->unsetValidator();

		// Load the form with previously sent search data
		$form->loadDataFrom($this->getRequest()->getVars());

		// Allow decorators to modify the form
		$this->extend('updateSearchForm', $form);

		return $form;
	}

	/**
	 * Returns a sorted array suitable for a dropdown with pagetypes and their translated name
	 *
	 * @return array
	 */
	protected function getPageTypes() {
		$pageTypes = array();
		foreach(SiteTree::page_type_classes() as $pageTypeClass) {
			$pageTypes[$pageTypeClass] = SiteTree::singleton($pageTypeClass)->i18n_singular_name();
		}
		asort($pageTypes);
		return $pageTypes;
	}

	public function doSearch($data, $form) {
		return $this->getsubtree($this->getRequest());
	}

	/**
	 * @param bool $unlinked
	 * @return ArrayList
	 */
	public function Breadcrumbs($unlinked = false) {
		$items = parent::Breadcrumbs($unlinked);

		if($items->count() > 1) {
			// Specific to the SiteTree admin section, we never show the cms section and current
			// page in the same breadcrumbs block.
			$items->shift();
		}

		return $items;
	}

	/**
	 * Create serialized JSON string with site tree hints data to be injected into
	 * 'data-hints' attribute of root node of jsTree.
	 *
	 * @return string Serialized JSON
	 */
	public function SiteTreeHints() {
		$classes = SiteTree::page_type_classes();

	 	$cacheCanCreate = array();
	 	foreach($classes as $class) $cacheCanCreate[$class] = singleton($class)->canCreate();

	 	// Generate basic cache key. Too complex to encompass all variations
	 	$cache = Cache::factory('CMSMain_SiteTreeHints');
	 	$cacheKey = md5(implode('_', array(Member::currentUserID(), implode(',', $cacheCanCreate), implode(',', $classes))));
	 	if($this->getRequest()->getVar('flush')) {
	 		$cache->clean(Zend_Cache::CLEANING_MODE_ALL);
		}
	 	$json = $cache->load($cacheKey);
	 	if(!$json) {
			$def['Root'] = array();
			$def['Root']['disallowedChildren'] = array();

			// Contains all possible classes to support UI controls listing them all,
			// such as the "add page here" context menu.
			$def['All'] = array();

			// Identify disallows and set globals
			foreach($classes as $class) {
				$obj = singleton($class);
				if($obj instanceof HiddenClass) continue;

				// Name item
				$def['All'][$class] = array(
					'title' => $obj->i18n_singular_name()
				);

				// Check if can be created at the root
				$needsPerm = $obj->stat('need_permission');
				if(
					!$obj->stat('can_be_root')
					|| (!array_key_exists($class, $cacheCanCreate) || !$cacheCanCreate[$class])
					|| ($needsPerm && !$this->can($needsPerm))
				) {
					$def['Root']['disallowedChildren'][] = $class;
				}

				// Hint data specific to the class
				$def[$class] = array();

				$defaultChild = $obj->defaultChild();
				if($defaultChild !== 'Page' && $defaultChild !== null) {
					$def[$class]['defaultChild'] = $defaultChild;
				}

				$defaultParent = $obj->defaultParent();
				if ($defaultParent !== 1 && $defaultParent !== null) {
					$def[$class]['defaultParent'] = $defaultParent;
				}
			}

			$this->extend('updateSiteTreeHints', $def);

			$json = Convert::raw2json($def);
			$cache->save($json, $cacheKey);
		}
		return $json;
	}

	/**
	 * Populates an array of classes in the CMS
	 * which allows the user to change the page type.
	 *
	 * @return SS_List
	 */
	public function PageTypes() {
		$classes = SiteTree::page_type_classes();

		$result = new ArrayList();

		foreach($classes as $class) {
			$instance = singleton($class);

			if($instance instanceof HiddenClass) {
				continue;
			}

			// skip this type if it is restricted
			if($instance->stat('need_permission') && !$this->can(singleton($class)->stat('need_permission'))) {
				continue;
			}

			$addAction = $instance->i18n_singular_name();

			// Get description (convert 'Page' to 'SiteTree' for correct localization lookups)
			$i18nClass = ($class == 'Page') ? 'SilverStripe\\CMS\\Model\\SiteTree' : $class;
			$description = _t($i18nClass . '.DESCRIPTION');

			if(!$description) {
				$description = $instance->uninherited('description');
			}

			if($class == 'Page' && !$description) {
				$description = SiteTree::singleton()->uninherited('description');
			}

			$result->push(new ArrayData(array(
				'ClassName' => $class,
				'AddAction' => $addAction,
				'Description' => $description,
				// TODO Sprite support
				'IconURL' => $instance->stat('icon'),
				'Title' => singleton($class)->i18n_singular_name(),
			)));
		}

		$result = $result->sort('AddAction');

		return $result;
	}

	/**
	 * Get a database record to be managed by the CMS.
	 *
	 * @param int $id Record ID
	 * @param int $versionID optional Version id of the given record
	 * @return SiteTree
	 */
 	public function getRecord($id, $versionID = null) {
		$treeClass = $this->stat('tree_class');

		if($id instanceof $treeClass) {
			return $id;
		}
		else if($id && is_numeric($id)) {
			$currentStage = Versioned::get_reading_mode();

			if($this->getRequest()->getVar('Version')) {
				$versionID = (int) $this->getRequest()->getVar('Version');
			}

			if($versionID) {
				$record = Versioned::get_version($treeClass, $id, $versionID);
			} else {
				$record = DataObject::get_by_id($treeClass, $id);
			}

			// Then, try getting a record from the live site
			if(!$record) {
				// $record = Versioned::get_one_by_stage($treeClass, "Live", "\"$treeClass\".\"ID\" = $id");
				Versioned::set_stage(Versioned::LIVE);
				singleton($treeClass)->flushCache();

				$record = DataObject::get_by_id($treeClass, $id);
			}

			// Then, try getting a deleted record
			if(!$record) {
				$record = Versioned::get_latest_version($treeClass, $id);
			}

			// Don't open a page from a different locale
			/** The record's Locale is saved in database in 2.4, and not related with Session,
			 *  we should not check their locale matches the Translatable::get_current_locale,
			 * 	here as long as we all the HTTPRequest is init with right locale.
			 *	This bit breaks the all FileIFrameField functions if the field is used in CMS
			 *  and its relevent ajax calles, like loading the tree dropdown for TreeSelectorField.
			 */
			/* if($record && SiteTree::has_extension('Translatable') && $record->Locale && $record->Locale != Translatable::get_current_locale()) {
				$record = null;
			}*/

			// Set the reading mode back to what it was.
			Versioned::set_reading_mode($currentStage);

			return $record;

		} else if(substr($id,0,3) == 'new') {
			return $this->getNewItem($id);
		}
	}

	/**
	 * @param int $id
	 * @param FieldList $fields
	 * @return Form
	 */
	public function getEditForm($id = null, $fields = null) {
		if(!$id) $id = $this->currentPageID();
		$form = parent::getEditForm($id, $fields);

		// TODO Duplicate record fetching (see parent implementation)
		$record = $this->getRecord($id);
		if($record && !$record->canView()) return Security::permissionFailure($this);

		if(!$fields) $fields = $form->Fields();
		$actions = $form->Actions();

		if($record) {
			$deletedFromStage = !$record->isOnDraft();

			$fields->push($idField = new HiddenField("ID", false, $id));
			// Necessary for different subsites
			$fields->push($liveLinkField = new HiddenField("AbsoluteLink", false, $record->AbsoluteLink()));
			$fields->push($liveLinkField = new HiddenField("LiveLink"));
			$fields->push($stageLinkField = new HiddenField("StageLink"));
			$fields->push(new HiddenField("TreeTitle", false, $record->TreeTitle));

			if($record->ID && is_numeric( $record->ID ) ) {
				$liveLink = $record->getAbsoluteLiveLink();
				if($liveLink) $liveLinkField->setValue($liveLink);
				if(!$deletedFromStage) {
					$stageLink = Controller::join_links($record->AbsoluteLink(), '?stage=Stage');
					if($stageLink) $stageLinkField->setValue($stageLink);
				}
			}

			// Added in-line to the form, but plucked into different view by LeftAndMain.Preview.js upon load
			/** @skipUpgrade */
			if($record instanceof CMSPreviewable && !$fields->fieldByName('SilverStripeNavigator')) {
				$navField = new LiteralField('SilverStripeNavigator', $this->getSilverStripeNavigator());
				$navField->setAllowHTML(true);
				$fields->push($navField);
			}

			// getAllCMSActions can be used to completely redefine the action list
			if($record->hasMethod('getAllCMSActions')) {
				$actions = $record->getAllCMSActions();
			} else {
				$actions = $record->getCMSActions();

				// Find and remove action menus that have no actions.
				if ($actions && $actions->count()) {
					/** @var TabSet $tabset */
					$tabset = $actions->fieldByName('ActionMenus');
					if ($tabset) {
						foreach ($tabset->getChildren() as $tab) {
							if (!$tab->getChildren()->count()) {
								$tabset->removeByName($tab->getName());
							}
						}
					}
				}
			}

			// Use <button> to allow full jQuery UI styling
			$actionsFlattened = $actions->dataFields();
			if($actionsFlattened) {
				/** @var FormAction $action */
				foreach($actionsFlattened as $action) {
					$action->setUseButtonTag(true);
				}
			}

			if($record->hasMethod('getCMSValidator')) {
				$validator = $record->getCMSValidator();
			} else {
				$validator = new RequiredFields();
			}

			// TODO Can't merge $FormAttributes in template at the moment
			$form->addExtraClass('center ' . $this->BaseCSSClasses());
			// Set validation exemptions for specific actions
			$form->setValidationExemptActions(array('restore', 'revert', 'deletefromlive', 'delete', 'unpublish', 'rollback', 'doRollback'));

			// Announce the capability so the frontend can decide whether to allow preview or not.
			if ($record instanceof CMSPreviewable) {
				$form->addExtraClass('cms-previewable');
			}
			$form->addExtraClass('fill-height flexbox-area-grow');

			if(!$record->canEdit() || $deletedFromStage) {
				$readonlyFields = $form->Fields()->makeReadonly();
				$form->setFields($readonlyFields);
			}

			$form->Fields()->setForm($form);

			$this->extend('updateEditForm', $form);
			return $form;
		} else if($id) {
			$form = Form::create( $this, "EditForm", new FieldList(
				new LabelField('PageDoesntExistLabel',_t('CMSMain.PAGENOTEXISTS',"This page doesn't exist"))), new FieldList()
			)->setHTMLID('Form_EditForm');
			return $form;
		}
	}

	/**
	 * @param HTTPRequest $request
	 * @return string HTML
	 */
	public function treeview($request) {
		return $this->renderWith($this->getTemplatesWithSuffix('_TreeView'));
	}

	/**
	 * @param HTTPRequest $request
	 * @return string HTML
	 */
	public function listview($request) {
		return $this->renderWith($this->getTemplatesWithSuffix('_ListView'));
	}

	/**
	 * Callback to request the list of page types allowed under a given page instance.
	 * Provides a slower but more precise response over SiteTreeHints
	 *
	 * @param HTTPRequest $request
	 * @return HTTPResponse
	 */
	public function childfilter($request) {
		// Check valid parent specified
		$parentID = $request->requestVar('ParentID');
		$parent = SiteTree::get()->byID($parentID);
		if(!$parent || !$parent->exists()) return $this->httpError(404);

		// Build hints specific to this class
		// Identify disallows and set globals
		$classes = SiteTree::page_type_classes();
		$disallowedChildren = array();
		foreach($classes as $class) {
			$obj = singleton($class);
			if($obj instanceof HiddenClass) continue;

			if(!$obj->canCreate(null, array('Parent' => $parent))) {
				$disallowedChildren[] = $class;
			}
		}

		$this->extend('updateChildFilter', $disallowedChildren, $parentID);
		return $this
			->getResponse()
			->addHeader('Content-Type', 'application/json; charset=utf-8')
			->setBody(Convert::raw2json($disallowedChildren));
	}

	/**
	 * Safely reconstruct a selected filter from a given set of query parameters
	 *
	 * @param array $params Query parameters to use
	 * @return CMSSiteTreeFilter The filter class, or null if none present
	 * @throws InvalidArgumentException if invalid filter class is passed.
	 */
	protected function getQueryFilter($params) {
		if(empty($params['FilterClass'])) return null;
		$filterClass = $params['FilterClass'];
		if(!is_subclass_of($filterClass, 'SilverStripe\\CMS\\Controllers\\CMSSiteTreeFilter')) {
			throw new InvalidArgumentException("Invalid filter class passed: {$filterClass}");
		}
		return $filterClass::create($params);
	}

	/**
	 * Returns the pages meet a certain criteria as {@see CMSSiteTreeFilter} or the subpages of a parent page
	 * defaulting to no filter and show all pages in first level.
	 * Doubles as search results, if any search parameters are set through {@link SearchForm()}.
	 *
	 * @param array $params Search filter criteria
	 * @param int $parentID Optional parent node to filter on (can't be combined with other search criteria)
	 * @return SS_List
	 * @throws InvalidArgumentException if invalid filter class is passed.
	 */
	public function getList($params = array(), $parentID = 0) {
		if($filter = $this->getQueryFilter($params)) {
			return $filter->getFilteredPages();
		} else {
			$list = DataList::create($this->stat('tree_class'));
			$parentID = is_numeric($parentID) ? $parentID : 0;
			return $list->filter("ParentID", $parentID);
		}
	}

	/**
	 * @return Form
	 */
	public function ListViewForm() {
		$params = $this->getRequest()->requestVar('q');
		$list = $this->getList($params, $parentID = $this->getRequest()->requestVar('ParentID'));
		$gridFieldConfig = GridFieldConfig::create()->addComponents(
			new GridFieldSortableHeader(),
			new GridFieldDataColumns(),
			new GridFieldPaginator(self::config()->page_length)
		);
		if($parentID){
			$linkSpec = $this->Link();
			$linkSpec = $linkSpec . (strstr($linkSpec, '?') ? '&' : '?') . 'ParentID=%d&view=list';
			$gridFieldConfig->addComponent(
				GridFieldLevelup::create($parentID)
					->setLinkSpec($linkSpec)
					->setAttributes(array('data-pjax' => 'ListViewForm,Breadcrumbs'))
			);
		}
		$gridField = new GridField('Page','Pages', $list, $gridFieldConfig);
		/** @var GridFieldDataColumns $columns */
		$columns = $gridField->getConfig()->getComponentByType('SilverStripe\\Forms\\GridField\\GridFieldDataColumns');

		// Don't allow navigating into children nodes on filtered lists
		$fields = array(
			'getTreeTitle' => _t('SiteTree.PAGETITLE', 'Page Title'),
			'singular_name' => _t('SiteTree.PAGETYPE'),
			'LastEdited' => _t('SiteTree.LASTUPDATED', 'Last Updated'),
		);
		/** @var GridFieldSortableHeader $sortableHeader */
		$sortableHeader = $gridField->getConfig()->getComponentByType('SilverStripe\\Forms\\GridField\\GridFieldSortableHeader');
		$sortableHeader->setFieldSorting(array('getTreeTitle' => 'Title'));
		$gridField->getState()->ParentID = $parentID;

		if(!$params) {
			$fields = array_merge(array('listChildrenLink' => ''), $fields);
		}

		$columns->setDisplayFields($fields);
		$columns->setFieldCasting(array(
			'Created' => 'DBDatetime->Ago',
			'LastEdited' => 'DBDatetime->FormatFromSettings',
			'getTreeTitle' => 'HTMLFragment'
		));

		$controller = $this;
		$columns->setFieldFormatting(array(
			'listChildrenLink' => function($value, &$item) use($controller) {
				/** @var SiteTree $item */
				$num = $item ? $item->numChildren() : null;
				if($num) {
					return sprintf(
						'<a class="btn btn-secondary btn--no-text btn--icon-large font-icon-right-dir cms-panel-link list-children-link" data-pjax-target="ListViewForm,Breadcrumbs" href="%s"><span class="sr-only">%s child pages</span></a>',
						Controller::join_links(
							$controller->Link(),
							sprintf("?ParentID=%d&view=list", (int)$item->ID)
						),
						$num
					);
				}
			},
			'getTreeTitle' => function($value, &$item) use($controller) {
				return sprintf(
					'<a class="action-detail" href="%s">%s</a>',
					Controller::join_links(
						CMSPageEditController::singleton()->Link('show'),
						(int)$item->ID
					),
					$item->TreeTitle // returns HTML, does its own escaping
				);
			}
		));

		$negotiator = $this->getResponseNegotiator();
		$listview = Form::create(
			$this,
			'ListViewForm',
			new FieldList($gridField),
			new FieldList()
		)->setHTMLID('Form_ListViewForm');
		$listview->setAttribute('data-pjax-fragment', 'ListViewForm');
		$listview->setValidationResponseCallback(function() use ($negotiator, $listview) {
			$request = $this->getRequest();
			if($request->isAjax() && $negotiator) {
				$listview->setupFormErrors();
				$result = $listview->forTemplate();

				return $negotiator->respond($request, array(
					'CurrentForm' => function() use($result) {
						return $result;
					}
				));
			}
		});

		$this->extend('updateListView', $listview);

		$listview->disableSecurityToken();
		return $listview;
	}

	public function currentPageID() {
		$id = parent::currentPageID();

		$this->extend('updateCurrentPageID', $id);

		return $id;
	}

	//------------------------------------------------------------------------------------------//
	// Data saving handlers

	/**
	 * Save and Publish page handler
	 *
	 * @param array $data
	 * @param Form $form
	 * @return HTTPResponse
	 * @throws HTTPResponse_Exception
	 */
	public function save($data, $form) {
		$className = $this->stat('tree_class');

		// Existing or new record?
		$id = $data['ID'];
		if(substr($id,0,3) != 'new') {
			/** @var SiteTree $record */
			$record = DataObject::get_by_id($className, $id);
			// Check edit permissions
			if($record && !$record->canEdit()) {
				return Security::permissionFailure($this);
			}
			if(!$record || !$record->ID) {
				throw new HTTPResponse_Exception("Bad record ID #$id", 404);
			}
		} else {
			if(!$className::singleton()->canCreate()) {
				return Security::permissionFailure($this);
			}
			$record = $this->getNewItem($id, false);
		}

		// Check publishing permissions
		$doPublish = !empty($data['publish']);
		if($record && $doPublish && !$record->canPublish()) {
			return Security::permissionFailure($this);
		}

		// TODO Coupling to SiteTree
		$record->HasBrokenLink = 0;
		$record->HasBrokenFile = 0;

		if (!$record->ObsoleteClassName) {
			$record->writeWithoutVersion();
		}

		// Update the class instance if necessary
		if(isset($data['ClassName']) && $data['ClassName'] != $record->ClassName) {
			// Replace $record with a new instance of the new class
			$newClassName = $data['ClassName'];
			$record = $record->newClassInstance($newClassName);
		}

		// save form data into record
		$form->saveInto($record);
		$record->write();

		// If the 'Save & Publish' button was clicked, also publish the page
		if ($doPublish) {
			$record->publishRecursive();
			$message = _t(
				'CMSMain.PUBLISHED',
				"Published '{title}' successfully.",
				['title' => $record->Title]
			);
		} else {
			$message = _t(
				'CMSMain.SAVED',
				"Saved '{title}' successfully.",
				['title' => $record->Title]
			);
		}

		$this->getResponse()->addHeader('X-Status', rawurlencode($message));
		return $this->getResponseNegotiator()->respond($this->getRequest());
	}

	/**
	 * @uses LeftAndMainExtension->augmentNewSiteTreeItem()
	 *
	 * @param int|string $id
	 * @param bool $setID
	 * @return mixed|DataObject
	 * @throws HTTPResponse_Exception
	 */
	public function getNewItem($id, $setID = true) {
		$parentClass = $this->stat('tree_class');
		list($dummy, $className, $parentID, $suffix) = array_pad(explode('-',$id),4,null);

		if (!is_a($className, $parentClass, true)) {
			$response = Security::permissionFailure($this);
			if (!$response) {
				$response = $this->getResponse();
			}
			throw new HTTPResponse_Exception($response);
		}

		/** @var SiteTree $newItem */
		$newItem = Injector::inst()->create($className);
		if( !$suffix ) {
			$sessionTag = "NewItems." . $parentID . "." . $className;
			if(Session::get($sessionTag)) {
				$suffix = '-' . Session::get($sessionTag);
				Session::set($sessionTag, Session::get($sessionTag) + 1);
			}
			else
				Session::set($sessionTag, 1);

				$id = $id . $suffix;
		}

		$newItem->Title = _t(
			'CMSMain.NEWPAGE',
			"New {pagetype}",'followed by a page type title',
			array('pagetype' => singleton($className)->i18n_singular_name())
		);
		$newItem->ClassName = $className;
		$newItem->ParentID = $parentID;

		// DataObject::fieldExists only checks the current class, not the hierarchy
		// This allows the CMS to set the correct sort value
		if($newItem->castingHelper('Sort')) {
			$newItem->Sort = DB::prepared_query('SELECT MAX("Sort") FROM "SiteTree" WHERE "ParentID" = ?', array($parentID))->value() + 1;
		}

		if($setID) $newItem->ID = $id;

		# Some modules like subsites add extra fields that need to be set when the new item is created
		$this->extend('augmentNewSiteTreeItem', $newItem);

		return $newItem;
	}

	/**
	 * Actually perform the publication step
	 *
	 * @param Versioned|DataObject $record
	 * @return mixed
	 */
	public function performPublish($record) {
		if($record && !$record->canPublish()) {
			return Security::permissionFailure($this);
		}

		$record->publishRecursive();
	}

	/**
	 * Reverts a page by publishing it to live.
	 * Use {@link restorepage()} if you want to restore a page
	 * which was deleted from draft without publishing.
	 *
	 * @uses SiteTree->doRevertToLive()
	 *
	 * @param array $data
	 * @param Form $form
	 * @return HTTPResponse
	 * @throws HTTPResponse_Exception
	 */
	public function revert($data, $form) {
		if(!isset($data['ID'])) {
			throw new HTTPResponse_Exception("Please pass an ID in the form content", 400);
		}

		$id = (int) $data['ID'];
		$restoredPage = Versioned::get_latest_version(SiteTree::class, $id);
		if(!$restoredPage) {
			throw new HTTPResponse_Exception("SiteTree #$id not found", 400);
		}

		/** @var SiteTree $record */
		$record = Versioned::get_one_by_stage('SilverStripe\\CMS\\Model\\SiteTree', 'Live', array(
			'"SiteTree_Live"."ID"' => $id
		));

		// a user can restore a page without publication rights, as it just adds a new draft state
		// (this action should just be available when page has been "deleted from draft")
		if($record && !$record->canEdit()) {
			return Security::permissionFailure($this);
		}
		if(!$record || !$record->ID) {
			throw new HTTPResponse_Exception("Bad record ID #$id", 404);
		}

		$record->doRevertToLive();

		$this->getResponse()->addHeader(
			'X-Status',
			rawurlencode(_t(
				'CMSMain.RESTORED',
				"Restored '{title}' successfully",
				'Param %s is a title',
				array('title' => $record->Title)
			))
		);

		return $this->getResponseNegotiator()->respond($this->getRequest());
	}

	/**
	 * Delete the current page from draft stage.
	 *
	 * @see deletefromlive()
	 *
	 * @param array $data
	 * @param Form $form
	 * @return HTTPResponse
	 * @throws HTTPResponse_Exception
	 */
	public function delete($data, $form) {
		$id = $data['ID'];
		$record = SiteTree::get()->byID($id);
		if($record && !$record->canDelete()) {
			return Security::permissionFailure();
		}
		if(!$record || !$record->ID) {
			throw new HTTPResponse_Exception("Bad record ID #$id", 404);
		}

		// Delete record
		$record->delete();

		$this->getResponse()->addHeader(
			'X-Status',
			rawurlencode(sprintf(_t('CMSMain.REMOVEDPAGEFROMDRAFT',"Removed '%s' from the draft site"), $record->Title))
		);

		// Even if the record has been deleted from stage and live, it can be viewed in "archive mode"
		return $this->getResponseNegotiator()->respond($this->getRequest());
	}

	/**
	 * Delete this page from both live and stage
	 *
	 * @param array $data
	 * @param Form $form
	 * @return HTTPResponse
	 * @throws HTTPResponse_Exception
	 */
	public function archive($data, $form) {
		$id = $data['ID'];
		/** @var SiteTree $record */
		$record = SiteTree::get()->byID($id);
		if(!$record || !$record->exists()) {
			throw new HTTPResponse_Exception("Bad record ID #$id", 404);
		}
		if(!$record->canArchive()) {
			return Security::permissionFailure();
		}

		// Archive record
		$record->doArchive();

		$this->getResponse()->addHeader(
			'X-Status',
			rawurlencode(sprintf(_t('CMSMain.ARCHIVEDPAGE',"Archived page '%s'"), $record->Title))
		);

		// Even if the record has been deleted from stage and live, it can be viewed in "archive mode"
		return $this->getResponseNegotiator()->respond($this->getRequest());
	}

	public function publish($data, $form) {
		$data['publish'] = '1';

		return $this->save($data, $form);
	}

	public function unpublish($data, $form) {
		$className = $this->stat('tree_class');
		/** @var SiteTree $record */
		$record = DataObject::get_by_id($className, $data['ID']);

		if($record && !$record->canUnpublish()) {
			return Security::permissionFailure($this);
		}
		if(!$record || !$record->ID) {
			throw new HTTPResponse_Exception("Bad record ID #" . (int)$data['ID'], 404);
		}

		$record->doUnpublish();

		$this->getResponse()->addHeader(
			'X-Status',
			rawurlencode(_t('CMSMain.REMOVEDPAGE',"Removed '{title}' from the published site", array('title' => $record->Title)))
		);

		return $this->getResponseNegotiator()->respond($this->getRequest());
	}

	/**
	 * @return HTTPResponse
	 */
	public function rollback() {
		return $this->doRollback(array(
			'ID' => $this->currentPageID(),
			'Version' => $this->getRequest()->param('VersionID')
		), null);
	}

	/**
	 * Rolls a site back to a given version ID
	 *
	 * @param array $data
	 * @param Form $form
	 * @return HTTPResponse
	 */
	public function doRollback($data, $form) {
		$this->extend('onBeforeRollback', $data['ID']);

		$id = (isset($data['ID'])) ? (int) $data['ID'] : null;
		$version = (isset($data['Version'])) ? (int) $data['Version'] : null;

		/** @var DataObject|Versioned $record */
		$record = DataObject::get_by_id($this->stat('tree_class'), $id);
		if($record && !$record->canEdit()) {
			return Security::permissionFailure($this);
		}

		if($version) {
			$record->doRollbackTo($version);
			$message = _t(
				'CMSMain.ROLLEDBACKVERSIONv2',
				"Rolled back to version #%d.",
				array('version' => $data['Version'])
			);
		} else {
			$record->doRevertToLive();
			$message = _t(
				'CMSMain.ROLLEDBACKPUBv2',"Rolled back to published version."
			);
		}

		$this->getResponse()->addHeader('X-Status', rawurlencode($message));

		// Can be used in different contexts: In normal page edit view, in which case the redirect won't have any effect.
		// Or in history view, in which case a revert causes the CMS to re-load the edit view.
		// The X-Pjax header forces a "full" content refresh on redirect.
		$url = Controller::join_links(CMSPageEditController::singleton()->Link('show'), $record->ID);
		$this->getResponse()->addHeader('X-ControllerURL', $url);
		$this->getRequest()->addHeader('X-Pjax', 'Content');
		$this->getResponse()->addHeader('X-Pjax', 'Content');

		return $this->getResponseNegotiator()->respond($this->getRequest());
	}

	/**
	 * Batch Actions Handler
	 */
	public function batchactions() {
		return new CMSBatchActionHandler($this, 'batchactions');
	}

	public function BatchActionParameters() {
		$batchActions = CMSBatchActionHandler::config()->batch_actions;

		$forms = array();
		foreach($batchActions as $urlSegment => $batchAction) {
			$SNG_action = singleton($batchAction);
			if ($SNG_action->canView() && $fieldset = $SNG_action->getParameterFields()) {
				$formHtml = '';
				/** @var FormField $field */
				foreach($fieldset as $field) {
					$formHtml .= $field->Field();
				}
				$forms[$urlSegment] = $formHtml;
			}
		}
		$pageHtml = '';
		foreach($forms as $urlSegment => $html) {
			$pageHtml .= "<div class=\"params\" id=\"BatchActionParameters_$urlSegment\">$html</div>\n\n";
		}
		return new LiteralField("BatchActionParameters", '<div id="BatchActionParameters" style="display:none">'.$pageHtml.'</div>');
	}
	/**
	 * Returns a list of batch actions
	 */
	public function BatchActionList() {
		return $this->batchactions()->batchActionList();
	}

	public function publishall($request) {
		if(!Permission::check('ADMIN')) return Security::permissionFailure($this);

		increase_time_limit_to();
		increase_memory_limit_to();

		$response = "";

		if(isset($this->requestParams['confirm'])) {
			// Protect against CSRF on destructive action
			if(!SecurityToken::inst()->checkRequest($request)) return $this->httpError(400);

			$start = 0;
			$pages = SiteTree::get()->limit("$start,30");
			$count = 0;
			while($pages) {
				/** @var SiteTree $page */
				foreach($pages as $page) {
					if($page && !$page->canPublish()) {
						return Security::permissionFailure($this);
					}

					$page->publishRecursive();
					$page->destroy();
					unset($page);
					$count++;
					$response .= "<li>$count</li>";
				}
				if($pages->count() > 29) {
					$start += 30;
					$pages = SiteTree::get()->limit("$start,30");
				} else {
					break;
				}
			}
			$response .= _t('CMSMain.PUBPAGES',"Done: Published {count} pages", array('count' => $count));

		} else {
			$token = SecurityToken::inst();
			$fields = new FieldList();
			$token->updateFieldSet($fields);
			$tokenField = $fields->first();
			$tokenHtml = ($tokenField) ? $tokenField->FieldHolder() : '';
			$response .= '<h1>' . _t('CMSMain.PUBALLFUN','"Publish All" functionality') . '</h1>
				<p>' . _t('CMSMain.PUBALLFUN2', 'Pressing this button will do the equivalent of going to every page and pressing "publish".  It\'s
				intended to be used after there have been massive edits of the content, such as when the site was
				first built.') . '</p>
				<form method="post" action="publishall">
					<input type="submit" name="confirm" value="'
					. _t('CMSMain.PUBALLCONFIRM',"Please publish every page in the site, copying content stage to live",'Confirmation button') .'" />'
					. $tokenHtml .
				'</form>';
		}

		return $response;
	}

	/**
	 * Restore a completely deleted page from the SiteTree_versions table.
	 *
	 * @param array $data
	 * @param Form $form
	 * @return HTTPResponse
	 */
	public function restore($data, $form) {
		if(!isset($data['ID']) || !is_numeric($data['ID'])) {
			return new HTTPResponse("Please pass an ID in the form content", 400);
		}

		$id = (int)$data['ID'];
		/** @var SiteTree $restoredPage */
		$restoredPage = Versioned::get_latest_version(SiteTree::class, $id);
		if(!$restoredPage) {
			return new HTTPResponse("SiteTree #$id not found", 400);
		}

		$restoredPage = $restoredPage->doRestoreToStage();

		$this->getResponse()->addHeader(
			'X-Status',
			rawurlencode(_t(
				'CMSMain.RESTORED',
				"Restored '{title}' successfully",
				array('title' => $restoredPage->Title)
			))
		);

		return $this->getResponseNegotiator()->respond($this->getRequest());
	}

	public function duplicate($request) {
		// Protect against CSRF on destructive action
		if(!SecurityToken::inst()->checkRequest($request)) return $this->httpError(400);

		if(($id = $this->urlParams['ID']) && is_numeric($id)) {
			/** @var SiteTree $page */
			$page = SiteTree::get()->byID($id);
			if($page && (!$page->canEdit() || !$page->canCreate(null, array('Parent' => $page->Parent())))) {
				return Security::permissionFailure($this);
			}
			if(!$page || !$page->ID) throw new HTTPResponse_Exception("Bad record ID #$id", 404);

			$newPage = $page->duplicate();

			// ParentID can be hard-set in the URL.  This is useful for pages with multiple parents
			if(isset($_GET['parentID']) && is_numeric($_GET['parentID'])) {
				$newPage->ParentID = $_GET['parentID'];
				$newPage->write();
			}

			$this->getResponse()->addHeader(
				'X-Status',
				rawurlencode(_t(
					'CMSMain.DUPLICATED',
					"Duplicated '{title}' successfully",
					array('title' => $newPage->Title)
				))
			);
			$url = Controller::join_links(CMSPageEditController::singleton()->Link('show'), $newPage->ID);
			$this->getResponse()->addHeader('X-ControllerURL', $url);
			$this->getRequest()->addHeader('X-Pjax', 'Content');
			$this->getResponse()->addHeader('X-Pjax', 'Content');

			return $this->getResponseNegotiator()->respond($this->getRequest());
		} else {
			return new HTTPResponse("CMSMain::duplicate() Bad ID: '$id'", 400);
		}
	}

	public function duplicatewithchildren($request) {
		// Protect against CSRF on destructive action
		if(!SecurityToken::inst()->checkRequest($request)) return $this->httpError(400);
		increase_time_limit_to();
		if(($id = $this->urlParams['ID']) && is_numeric($id)) {
			/** @var SiteTree $page */
			$page = SiteTree::get()->byID($id);
			if($page && (!$page->canEdit() || !$page->canCreate(null, array('Parent' => $page->Parent())))) {
				return Security::permissionFailure($this);
			}
			if(!$page || !$page->ID) throw new HTTPResponse_Exception("Bad record ID #$id", 404);

			$newPage = $page->duplicateWithChildren();

			$this->getResponse()->addHeader(
				'X-Status',
				rawurlencode(_t(
					'CMSMain.DUPLICATEDWITHCHILDREN',
					"Duplicated '{title}' and children successfully",
					array('title' => $newPage->Title)
				))
			);
			$url = Controller::join_links(CMSPageEditController::singleton()->Link('show'), $newPage->ID);
			$this->getResponse()->addHeader('X-ControllerURL', $url);
			$this->getRequest()->addHeader('X-Pjax', 'Content');
			$this->getResponse()->addHeader('X-Pjax', 'Content');

			return $this->getResponseNegotiator()->respond($this->getRequest());
		} else {
			return new HTTPResponse("CMSMain::duplicatewithchildren() Bad ID: '$id'", 400);
		}
	}

	public function providePermissions() {
		$title = CMSPagesController::menu_title();
		return array(
			"CMS_ACCESS_CMSMain" => array(
				'name' => _t('CMSMain.ACCESS', "Access to '{title}' section", array('title' => $title)),
				'category' => _t('Permission.CMS_ACCESS_CATEGORY', 'CMS Access'),
				'help' => _t(
					'CMSMain.ACCESS_HELP',
					'Allow viewing of the section containing page tree and content. View and edit permissions can be handled through page specific dropdowns, as well as the separate "Content permissions".'
				),
				'sort' => -99 // below "CMS_ACCESS_LeftAndMain", but above everything else
			)
		);
	}

}