<?php
/**
 * This component provides a checkbox which when checked enables drag-and-drop re-ordering of elements displayed in a {@link GridField}
 *
 * @package forms
 */
class GridFieldSortableRows implements GridField_HTMLProvider, GridField_ActionProvider, GridField_DataManipulator {
	protected $sortColumn;
	protected $disable_selection=true;
	protected $append_to_top=false;
	protected $update_versioned_stage=null;
	protected $custom_relation_name=null;

	/**
	 * @param string $sortColumn Column that should be used to update the sort information
	 * @param bool	$disableSelection Disable selection on the GridField when dragging
	 * @param string $updateVersionStage Name of the versioned stage to update this disabled by default unless this is set
	 * @param string $customRelationName Name of the relationship to use, if left null the name is determined from the GridField's name
	 */
	public function __construct($sortColumn, $disableSelection = true, $updateVersionStage = null, $customRelationName = null) {
		$this->sortColumn = $sortColumn;
		$this->disable_selection = $disableSelection;
		$this->update_versioned_stage = $updateVersionStage;
		$this->custom_relation_name = $customRelationName;
	}
	
	/**
	 * Returns a map where the keys are fragment names and the values are pieces of HTML to add to these fragments.
	 * @param GridField $gridField Grid Field Reference
	 * @return Array Map where the keys are fragment names and the values are pieces of HTML to add to these fragments.
	 */
	public function getHTMLFragments($gridField) {
		$dataList = $gridField->getList();

		if(class_exists('UnsavedRelationList') && $dataList instanceof UnsavedRelationList) {
			return array();
		}
		
		$state = $gridField->State->GridFieldSortableRows;
		if(!is_bool($state->sortableToggle)) {
			$state->sortableToggle = false;
		}
		
		//Ensure user can edit
		if(!singleton($gridField->getModelClass())->canEdit()){
			return array();
		}
		
		
		//Sort order toggle
		$sortOrderToggle = GridField_FormAction::create(
			$gridField,
			'sortablerows-toggle',
			'sorttoggle',
			'sortableRowsToggle',
			null
		)->addExtraClass('sortablerows-toggle');
		
		
		$sortOrderSave = GridField_FormAction::create(
			$gridField,
			'sortablerows-savesort',
			'savesort',
			'saveGridRowSort',
			null
		)->addExtraClass('sortablerows-savesort');
		
		
		//Sort to Page Action
		$sortToPage = GridField_FormAction::create(
			$gridField,
			'sortablerows-sorttopage',
			'sorttopage',
			'sortToPage',
			null
		)->addExtraClass('sortablerows-sorttopage');
		
		
		$data = array('SortableToggle' => $sortOrderToggle,
					'SortOrderSave' => $sortOrderSave,
					'SortToPage' => $sortToPage,
					'Checked' => ($state->sortableToggle == true ? ' checked = "checked"':''),
					'List' => $dataList);
		
		$forTemplate = new ArrayData($data);
		
		
		//Inject Requirements
		$custom = Config::inst()->get('GridFieldSortableRows', 'Base');
		$base = $custom ?: SORTABLE_GRIDFIELD_BASE;

		Requirements::css($base . '/css/GridFieldSortableRows.css');
		Requirements::javascript($base . '/javascript/GridFieldSortableRows.js');
		
		
		$args = array('Colspan' => count($gridField->getColumns()), 'ID' => $gridField->ID(), 'DisableSelection' => $this->disable_selection);
		
		
		$fragments=array('header' => $forTemplate->renderWith('GridFieldSortableRows', $args));
		
		if($gridField->getConfig()->getComponentByType('GridFieldPaginator')) {
			$fragments['after']=$forTemplate->renderWith('GridFieldSortableRows_paginator');
		}
		
		return $fragments;
	}
	
	/**
	 * Manipulate the datalist as needed by this grid modifier.
	 * @param GridField $gridField Grid Field Reference
	 * @param SS_List $dataList Data List to adjust
	 * @return DataList Modified Data List
	 */
	public function getManipulatedData(GridField $gridField, SS_List $dataList) {
		//Detect and correct items with a sort column value of 0 (push to bottom)
		$this->fixSortColumn($gridField, $dataList);
		
		
		$headerState = $gridField->State->GridFieldSortableHeader;
		$state = $gridField->State->GridFieldSortableRows;
		if ((!is_bool($state->sortableToggle) || $state->sortableToggle===false) && $headerState && is_string($headerState->SortColumn) && is_string($headerState->SortDirection)) {
			return $dataList->sort($headerState->SortColumn, $headerState->SortDirection);
		}
		
		if ($state->sortableToggle === true) {
			$gridField->getConfig()->removeComponentsByType('GridFieldFilterHeader');
			$gridField->getConfig()->removeComponentsByType('GridFieldSortableHeader');
		}
		
		return $dataList->sort($this->sortColumn);
	}
	
	/**
	 * Sets if new records should be appended to the top or the bottom of the list
	 * @param bool $value Boolean true to append to the top false to append to the bottom
	 * @return GridFieldSortableRows Returns the current instance
	 */
	public function setAppendToTop($value) {
		$this->append_to_top=$value;
		return $this;
	}
	
	/**
	 * @param bool $value Boolean true to disable selection of table contents false to enable selection
	 * @return GridFieldSortableRows Returns the current instance
	 */
	public function setDisableSelection($value){
		$this->disable_selection = $value;
		return $this;
	}
	
	/**
	 * Sets the suffix of the versioned stage that should be updated along side the default stage
	 * @param string $value Versioned Stage to update this is disabled by default unless this is set
	 * @return GridFieldSortableRows Returns the current instance
	 */
	public function setUpdateVersionedStage($value) {
		$this->update_versioned_stage=$value;
		return $this;
	}
	
	/**
	 * Sets the name of the relationship to use, by default the name is determined from the GridField's name
	 * @param string $value  Name of the relationship to use, by default the name is determined from the GridField's name
	 * @return GridFieldSortableRows Returns the current instance
	 */
	public function setCustomRelationName($value) {
		$this->custom_relation_name=$value;
		return $this;
	}
	
	/**
	 * Detects and corrects items with a sort column value of 0, by appending them to the bottom of the list
	 * @param GridField $gridField Grid Field Reference
	 * @param SS_List $dataList Data List of items to be checked
	 */
	protected function fixSortColumn($gridField, SS_List $dataList) {
		if(class_exists('UnsavedRelationList') && $dataList instanceof UnsavedRelationList) {
			return;
		}
		
		$list=clone $dataList;
		$list=$list->alterDataQuery(function($query, SS_List $tmplist) {
			$query->limit(array());
			return $query;
		});
		
		$many_many = ($list instanceof ManyManyList);
		if (!$many_many) {
			$sng=singleton($gridField->getModelClass());
			$fieldType=$sng->db($this->sortColumn);
			if(!$fieldType || !(strtolower($fieldType) == 'int' || is_subclass_of($fieldType, 'Int') || strtolower($fieldType) == 'dbint' || is_subclass_of($fieldType, 'DBInt'))) {
				if(is_array($fieldType)) {
					user_error('Sort column '.$this->sortColumn.' could not be found in '.$gridField->getModelClass().'\'s ancestry', E_USER_ERROR);
				}else {
					user_error('Sort column '.$this->sortColumn.' must be an instance of DBInt, column is of type '.$fieldType, E_USER_ERROR);
				}
				
				exit;
			}
		}
		
		
		$max = $list->Max($this->sortColumn);
		$list=$list->filter($this->sortColumn, 0)->sort("Created,ID");
		if($list->Count()>0) {
			$owner = $gridField->Form->getRecord();
			$sortColumn = $this->sortColumn;
			$i = 1;
			
			if ($many_many) {
				list($parentClass, $componentClass, $parentField, $componentField, $table) = $owner->many_many((!empty($this->custom_relation_name) ? $this->custom_relation_name:$gridField->getName()));
				$extraFields=$owner->many_many_extraFields((!empty($this->custom_relation_name) ? $this->custom_relation_name:$gridField->getName()));
				
				if(!$extraFields || !array_key_exists($this->sortColumn, $extraFields) || !(strtolower($extraFields[$this->sortColumn])=='int' || is_subclass_of('Int', $extraFields[$this->sortColumn]) || strtolower($extraFields[$this->sortColumn])=='dbint' || is_subclass_of('DBInt', $extraFields[$this->sortColumn]))) {
					user_error('Sort column '.$this->sortColumn.' must be an instance of DBInt, column is of type '.$extraFields[$this->sortColumn], E_USER_ERROR);
					exit;
				}
			}else {
				//Find table containing the sort column
				$table=false;
				$class=$gridField->getModelClass();
				
				$db = Config::inst()->get($class, "db", CONFIG::UNINHERITED);
				if(!empty($db) && array_key_exists($sortColumn, $db)) {
					$table=$class;
				}else {
					$classes=ClassInfo::ancestry($class, true);
					foreach($classes as $class) {
						$db = Config::inst()->get($class, "db", CONFIG::UNINHERITED);
						if(!empty($db) && array_key_exists($sortColumn, $db)) {
							$table=$class;
							break;
						}
					}
				}
				
				if($table===false) {
					user_error('Sort column '.$this->sortColumn.' could not be found in '.$gridField->getModelClass().'\'s ancestry', E_USER_ERROR);
					exit;
				}
				
				$baseDataClass=ClassInfo::baseDataClass($gridField->getModelClass());
			}
			
			
			//Start transaction if supported
			if(DB::getConn()->supportsTransactions()) {
				DB::getConn()->transactionStart();
			}
			
			$idCondition=null;
			if($this->append_to_top && !($list instanceof RelationList)) {
				$idCondition='"ID" IN(\''.implode("','", $dataList->getIDList()).'\')';
			}
			
			if($this->append_to_top) {
				$topIncremented=array();
			}
			
			foreach($list as $obj) {
				if($many_many) {
					if($this->append_to_top) {
						//Upgrade all the records (including the last inserted from 0 to 1)
						DB::query('UPDATE "' . $table
								. '" SET "' . $sortColumn . '" = "' . $sortColumn .'"+1'
								. ' WHERE "' . $parentField . '" = ' . $owner->ID . (!empty($topIncremented) ? ' AND "' . $componentField . '" NOT IN(\''.implode('\',\'', $topIncremented).'\')':''));
						
						$topIncremented[]=$obj->ID;
					}else {
						//Append the last record to the bottom
						DB::query('UPDATE "' . $table
								. '" SET "' . $sortColumn .'" = ' . ($max + $i)
								. ' WHERE "' . $componentField . '" = ' . $obj->ID . ' AND "' . $parentField . '" = ' . $owner->ID);
					}
				}else if($this->append_to_top) {
					//Upgrade all the records (including the last inserted from 0 to 1)
					DB::query('UPDATE "' . $table
							. '" SET "' . $sortColumn . '" = "' . $sortColumn .'"+1'
							. ' WHERE '.($list instanceof RelationList ? '"' . $list->foreignKey . '" = '. $owner->ID:$idCondition) . (!empty($topIncremented) ? ' AND "ID" NOT IN(\''.implode('\',\'', $topIncremented).'\')':''));
					
					if($this->update_versioned_stage && class_exists($table) && SS_Object::has_extension($table, 'Versioned')) {
						DB::query('UPDATE "' . $table . '_' . $this->update_versioned_stage
								. '" SET "' . $sortColumn . '" = "' . $sortColumn .'"+1'
								. ' WHERE '. ($list instanceof RelationList ? '"' . $list->foreignKey . '" = '. $owner->ID:$idCondition) . (!empty($topIncremented) ? ' AND "ID" NOT IN(\''.implode('\',\'', $topIncremented).'\')':''));
					}
					
					$topIncremented[]=$obj->ID;
				}else {
					//Append the last record to the bottom
					DB::query('UPDATE "' . $table
							 . '" SET "' . $sortColumn . '" = ' . ($max + $i)
							 . ' WHERE "ID" = '. $obj->ID);
					//LastEdited
					DB::query('UPDATE "' . $baseDataClass
							 . '" SET "LastEdited" = \'' . date('Y-m-d H:i:s') . '\''
							 . ' WHERE "ID" = '. $obj->ID);
	 				
	 				if($this->update_versioned_stage && class_exists($table) && SS_Object::has_extension($table, 'Versioned')) {
	 					DB::query('UPDATE "' . $table . '_' . $this->update_versioned_stage
	 							. '" SET "' . $sortColumn . '" = ' . ($max + $i)
	 							. ' WHERE "ID" = '. $obj->ID);
	 					
	 					if(SS_Object::has_extension($baseDataClass, 'Versioned')) {
	 						DB::query('UPDATE "' . $baseDataClass . '_' . $this->update_versioned_stage
	 								. '" SET "LastEdited" = \'' . date('Y-m-d H:i:s') . '\''
	 								. ' WHERE "ID" = '. $obj->ID);
	 					}
	 				}
				}
				
				$i++;
			}
			
			//Update LastEdited for affected records when using append to top on a many_many relationship
			if(!$many_many && $this->append_to_top && count($topIncremented)>0) {
				DB::query('UPDATE "' . $baseDataClass
						. '" SET "LastEdited" = \'' . date('Y-m-d H:i:s') . '\''
						. ' WHERE "ID" IN(\''.implode('\',\'', $topIncremented).'\')');
				
				if($this->update_versioned_stage && class_exists($table) && SS_Object::has_extension($table, 'Versioned') && SS_Object::has_extension($baseDataClass, 'Versioned')) {
					DB::query('UPDATE "' . $baseDataClass . '_' . $this->update_versioned_stage
							. '" SET "LastEdited" = \'' . date('Y-m-d H:i:s') . '\''
							. ' WHERE "ID" IN(\''.implode('\',\'', $topIncremented).'\')');
				}
			}
			
			
			//End transaction if supported
			if(DB::getConn()->supportsTransactions()) {
				DB::getConn()->transactionEnd();
			}
		}
	}
	
	/**
	 * Return a list of the actions handled by this action provider.
	 * @param GridField $gridField Grid Field Reference
	 * @return Array Array with action identifier strings.
	 */
	public function getActions($gridField) {
		return array('saveGridRowSort', 'sortableRowsToggle', 'sortToPage');
	}
	
	/**
	 * Handle an action on the given grid field.
	 * @param GridField $gridField Grid Field Reference
	 * @param String $actionName Action identifier, see {@link getActions()}.
	 * @param Array $arguments Arguments relevant for this
	 * @param Array $data All form data
	 */
	public function handleAction(GridField $gridField, $actionName, $arguments, $data) {
		$state = $gridField->State->GridFieldSortableRows;
		if (!is_bool($state->sortableToggle)) {
			$state->sortableToggle = false;
		} else if ($state->sortableToggle == true) {
			$gridField->getConfig()->removeComponentsByType('GridFieldFilterHeader');
			$gridField->getConfig()->removeComponentsByType('GridFieldSortableHeader');
		}
		
		
		if ($actionName == 'savegridrowsort') {
			return $this->saveGridRowSort($gridField, $data);
		} else if ($actionName == 'sorttopage') {
			return $this->sortToPage($gridField, $data);
		}
	}
	
	/**
	 * Handles saving of the row sort order
	 * @param GridField $gridField Grid Field Reference
	 * @param Array $data Data submitted in the request
	 */
	protected function saveGridRowSort(GridField $gridField, $data) {
		$dataList = $gridField->getList();

		if(class_exists('UnsavedRelationList') && $dataList instanceof UnsavedRelationList) {
			user_error('Cannot sort an UnsavedRelationList', E_USER_ERROR);
			return;
		}
		
		if(!singleton($gridField->getModelClass())->canEdit()){
			throw new ValidationException(_t('GridFieldSortableRows.EditPermissionsFailure', "No edit permissions"),0);
		}
		
		if (empty($data['ItemIDs'])) {
			user_error('No items to sort', E_USER_ERROR);
		}
		
		$className = $gridField->getModelClass();
		$owner = $gridField->Form->getRecord();
		$items = clone $gridField->getList();
		$many_many = ($items instanceof ManyManyList);
		$sortColumn = $this->sortColumn;
		$pageOffset = 0;
		
		if ($paginator = $gridField->getConfig()->getComponentsByType('GridFieldPaginator')->First()) {
			$pageState = $gridField->State->GridFieldPaginator;
			
			if($pageState->currentPage && is_int($pageState->currentPage) && $pageState->currentPage>1) {
				$pageOffset = $paginator->getItemsPerPage() * ($pageState->currentPage - 1);
			}
		}
		
		
		if ($many_many) {
			list($parentClass, $componentClass, $parentField, $componentField, $table) = $owner->many_many((!empty($this->custom_relation_name) ? $this->custom_relation_name:$gridField->getName()));
		}else {
			//Find table containing the sort column
			$table=false;
			$class=$gridField->getModelClass();
			$db = Config::inst()->get($class, "db", CONFIG::UNINHERITED);
			if(!empty($db) && array_key_exists($sortColumn, $db)) {
				$table=$class;
			}else {
				$classes=ClassInfo::ancestry($class, true);
				foreach($classes as $class) {
					$db = Config::inst()->get($class, "db", CONFIG::UNINHERITED);
					if(!empty($db) && array_key_exists($sortColumn, $db)) {
						$table=$class;
						break;
					}
				}
			}
			
			if($table===false) {
				user_error('Sort column '.$this->sortColumn.' could not be found in '.$gridField->getModelClass().'\'s ancestry', E_USER_ERROR);
				exit;
			}
			
			$baseDataClass=ClassInfo::baseDataClass($gridField->getModelClass());
		}
		
		
		//Event to notify the Controller or owner DataObject before list sort
		if($owner && $owner instanceof DataObject && method_exists($owner, 'onBeforeGridFieldRowSort')) {
			$owner->onBeforeGridFieldRowSort(clone $items);
		}else if(Controller::has_curr() && Controller::curr() instanceof ModelAdmin && method_exists(Controller::curr(), 'onBeforeGridFieldRowSort')) {
			Controller::curr()->onBeforeGridFieldRowSort(clone $items);
		}
		
		
		//Start transaction if supported
		if(DB::getConn()->supportsTransactions()) {
			DB::getConn()->transactionStart();
		}
		
		
		//Perform sorting
		$ids = explode(',', $data['ItemIDs']);
		for($sort = 0;$sort<count($ids);$sort++) {
			$id = intval($ids[$sort]);
			if ($many_many) {
				DB::query('UPDATE "' . $table
						. '" SET "' . $sortColumn.'" = ' . (($sort + 1) + $pageOffset)
						. ' WHERE "' . $componentField . '" = ' . $id . ' AND "' . $parentField . '" = ' . $owner->ID);
			} else {
				DB::query('UPDATE "' . $table
						. '" SET "' . $sortColumn . '" = ' . (($sort + 1) + $pageOffset)
						. ' WHERE "ID" = '. $id);
				
				DB::query('UPDATE "' . $baseDataClass
						. '" SET "LastEdited" = \'' . date('Y-m-d H:i:s') . '\''
						. ' WHERE "ID" = '. $id);
				
				if($this->update_versioned_stage && class_exists($table) && SS_Object::has_extension($table, 'Versioned')) {
					DB::query('UPDATE "' . $table . '_' . $this->update_versioned_stage
							. '" SET "' . $sortColumn . '" = ' . (($sort + 1) + $pageOffset)
							. ' WHERE "ID" = '. $id);
					
					if(SS_Object::has_extension($baseDataClass, 'Versioned')) {
						DB::query('UPDATE "' . $baseDataClass . '_' . $this->update_versioned_stage
								. '" SET "LastEdited" = \'' . date('Y-m-d H:i:s') . '\''
								. ' WHERE "ID" = '. $id);
					}
				}
			}
		}
		
		
		//End transaction if supported
		if(DB::getConn()->supportsTransactions()) {
			DB::getConn()->transactionEnd();
		}
		
		
		//Event to notify the Controller or owner DataObject after list sort
		if($owner && $owner instanceof DataObject && method_exists($owner, 'onAfterGridFieldRowSort')) {
			$owner->onAfterGridFieldRowSort(clone $items);
		}else if(Controller::has_curr() && Controller::curr() instanceof ModelAdmin && method_exists(Controller::curr(), 'onAfterGridFieldRowSort')) {
			Controller::curr()->onAfterGridFieldRowSort(clone $items);
		}
	}
	
	/**
	 * Handles sorting across pages
	 * @param GridField $gridField Grid Field Reference
	 * @param Array $data Data submitted in the request
	 */
	protected function sortToPage(GridField $gridField, $data) {
		if (!$paginator = $gridField->getConfig()->getComponentsByType('GridFieldPaginator')->First()) {
			user_error('Paginator not detected', E_USER_ERROR);
		}
		
		if (empty($data['ItemID'])) {
			user_error('No item to sort', E_USER_ERROR);
		}
		
		if (empty($data['Target'])) {
			user_error('No target page', E_USER_ERROR);
		}
		
		
		$className = $gridField->getModelClass();
		$owner = $gridField->Form->getRecord();
		$items = clone $gridField->getList();
		$many_many = ($items instanceof ManyManyList);
		$sortColumn = $this->sortColumn;
		$targetItem = $items->byID(intval($data['ItemID']));
		
		if (!$targetItem) {
			user_error('Target item not found', E_USER_ERROR);
		}
		
		$currentPage = 1;
		
		
		$pageState = $gridField->State->GridFieldPaginator;
		if($pageState->currentPage && $pageState->currentPage>1) {
			$currentPage = $pageState->currentPage;
		}
		
		
		if ($many_many) {
			list($parentClass, $componentClass, $parentField, $componentField, $table) = $owner->many_many((!empty($this->custom_relation_name) ? $this->custom_relation_name:$gridField->getName()));
		}
		
		
		if ($data['Target'] == 'previouspage') {
			$items = $items->limit($paginator->getItemsPerPage() + 1, ($paginator->getItemsPerPage() * ($currentPage - 1)) - 1);
		} else if ($data['Target'] == 'nextpage') {
			$items = $items->limit($paginator->getItemsPerPage() + 1, $paginator->getItemsPerPage() * ($currentPage - 1));
		} else {
			user_error('Not implemented: '.$data['Target'], E_USER_ERROR);
		}
		
		$sortPositions = $items->column($sortColumn);
		
		
		//Event to notify the Controller or owner DataObject before list sort
		if($owner && $owner instanceof DataObject && method_exists($owner, 'onBeforeGridFieldPageSort')) {
			$owner->onBeforeGridFieldPageSort(clone $items);
		}else if(Controller::has_curr() && Controller::curr() instanceof ModelAdmin && method_exists(Controller::curr(), 'onBeforeGridFieldPageSort')) {
			Controller::curr()->onBeforeGridFieldPageSort(clone $items);
		}
		
		
		//Find the sort column
		if($this->update_versioned_stage && SS_Object::has_extension($className, 'Versioned')) {
			$table=false;
			$classes=ClassInfo::ancestry($className, true);
			foreach($classes as $class) {
				$db = Config::inst()->get($class, "db", CONFIG::UNINHERITED);
				if(!empty($db) && array_key_exists($sortColumn, $db)) {
					$table=$class;
					break;
				}
			}
			
			if($table===false) {
				user_error('Sort column '.$this->sortColumn.' could not be found in '.$gridField->getModelClass().'\'s ancestry', E_USER_ERROR);
				exit;
			}
		}
		
		
		//Start transaction if supported
		if(DB::getConn()->supportsTransactions()) {
			DB::getConn()->transactionStart();
		}
		
		if($data['Target']=='previouspage') {
			if ($many_many) {
				DB::query('UPDATE "' . $table
						. '" SET "' . $sortColumn.'" = ' . $sortPositions[0]
						. ' WHERE "' . $componentField . '" = ' . $targetItem->ID . ' AND "' . $parentField . '" = ' . $owner->ID);
			} else {
				$targetItem->$sortColumn = $sortPositions[0];
				$targetItem->write();
				
				if($this->update_versioned_stage && SS_Object::has_extension($className, 'Versioned')) {
					DB::query('UPDATE "' . $table . '_' . $this->update_versioned_stage
							. '" SET "' . $sortColumn.'" = ' . $sortPositions[0]
							. ' WHERE "ID" = ' . $targetItem->ID);
				}
			}
			
			
			$i = 1;
			foreach ($items as $obj) {
				if ($obj->ID == $targetItem->ID || $i >= count($sortPositions)) {
					continue;
				}
				
				
				if ($many_many) {
					DB::query('UPDATE "' . $table
							. '" SET "' . $sortColumn.'" = ' . $sortPositions[$i]
							. ' WHERE "' . $componentField . '" = ' . $obj->ID . ' AND "' . $parentField . '" = ' . $owner->ID);
				} else {
					$obj->$sortColumn = $sortPositions[$i];
					$obj->write();
					
					if($this->update_versioned_stage && SS_Object::has_extension($className, 'Versioned')) {
						DB::query('UPDATE "' . $table . '_' . $this->update_versioned_stage
								. '" SET "' . $sortColumn.'" = ' . $sortPositions[$i]
								. ' WHERE "ID" = ' . $obj->ID);
					}
				}
				
				$i++;
			}
		} else {
			if ($many_many) {
				DB::query('UPDATE "' . $table
						. '" SET "' . $sortColumn.'" = ' . $sortPositions[count($sortPositions) - 1]
						. ' WHERE "' . $componentField . '" = ' . $targetItem->ID . ' AND "' . $parentField . '" = ' . $owner->ID);
			} else {
				$targetItem->$sortColumn = $sortPositions[count($sortPositions) - 1];
				$targetItem->write();
				
				if($this->update_versioned_stage && SS_Object::has_extension($className, 'Versioned')) {
					DB::query('UPDATE "' . $table . '_' . $this->update_versioned_stage
							. '" SET "' . $sortColumn.'" = ' . $sortPositions[count($sortPositions) - 1]
							. ' WHERE "ID" = ' . $targetItem->ID);
				}
			}
			
			
			$i = 0;
			foreach ($items as $obj) {
				if ($obj->ID == $targetItem->ID) {
					continue;
				}
				
				
				if ($many_many) {
					DB::query('UPDATE "' . $table
							. '" SET "' . $sortColumn.'" = ' . $sortPositions[$i]
							. ' WHERE "' . $componentField . '" = ' . $obj->ID . ' AND "' . $parentField . '" = ' . $owner->ID);
				} else {
					$obj->$sortColumn = $sortPositions[$i];
					$obj->write();
					
					if($this->update_versioned_stage && SS_Object::has_extension($className, 'Versioned')) {
						DB::query('UPDATE "' . $table . '_' . $this->update_versioned_stage
								. '" SET "' . $sortColumn.'" = ' . $sortPositions[$i]
								. ' WHERE "ID" = ' . $obj->ID);
					}
				}
				
				$i++;
			}
		}
		
		
		//End transaction if supported
		if(DB::getConn()->supportsTransactions()) {
			DB::getConn()->transactionEnd();
		}
		
		
		//Event to notify the Controller or owner DataObject after list sort
		if($owner && $owner instanceof DataObject && method_exists($owner, 'onAfterGridFieldPageSort')) {
			$owner->onAfterGridFieldPageSort(clone $items);
		}else if(Controller::has_curr() && Controller::curr() instanceof ModelAdmin && method_exists(Controller::curr(), 'onAfterGridFieldPageSort')) {
			Controller::curr()->onAfterGridFieldPageSort(clone $items);
		}
	}
}