<?php
/**
 * Joomla! Content Management System
 *
 * @copyright  (C) 2013 Open Source Matters, Inc. <https://www.joomla.org>
 * @license    GNU General Public License version 2 or later; see LICENSE.txt
 */

namespace Joomla\CMS\Table\Observer;

defined('JPATH_PLATFORM') or die;

/**
 * Abstract class defining methods that can be
 * implemented by an Observer class of a Table class (which is an Observable).
 * Attaches $this Observer to the $table in the constructor.
 * The classes extending this class should not be instantiated directly, as they
 * are automatically instanciated by the \JObserverMapper
 *
 * @since  3.1.2
 */
class Tags extends AbstractObserver
{
	/**
	 * Helper object for managing tags
	 *
	 * @var    \JHelperTags
	 * @since  3.1.2
	 */
	protected $tagsHelper;

	/**
	 * The pattern for this table's TypeAlias
	 *
	 * @var    string
	 * @since  3.1.2
	 */
	protected $typeAliasPattern = null;

	/**
	 * Override for postStoreProcess param newTags, Set by setNewTags, used by onAfterStore and onBeforeStore
	 *
	 * @var    array
	 * @since  3.1.2
	 */
	protected $newTags = false;

	/**
	 * Override for postStoreProcess param replaceTags. Set by setNewTags, used by onAfterStore
	 *
	 * @var    boolean
	 * @since  3.1.2
	 */
	protected $replaceTags = true;

	/**
	 * Not public, so marking private and deprecated, but needed internally in parseTypeAlias for
	 * PHP < 5.4.0 as it's not passing context $this to closure function.
	 *
	 * @var         Tags
	 * @since       3.1.2
	 * @deprecated  Never use this
	 * @private
	 */
	public static $_myTableForPregreplaceOnly;

	/**
	 * Creates the associated observer instance and attaches it to the $observableObject
	 * Creates the associated tags helper class instance
	 * $typeAlias can be of the form "{variableName}.type", automatically replacing {variableName} with table-instance variables variableName
	 *
	 * @param   \JObservableInterface  $observableObject  The subject object to be observed
	 * @param   array                  $params            ( 'typeAlias' => $typeAlias )
	 *
	 * @return  Tags
	 *
	 * @since   3.1.2
	 */
	public static function createObserver(\JObservableInterface $observableObject, $params = array())
	{
		$typeAlias = $params['typeAlias'];

		$observer = new self($observableObject);

		$observer->tagsHelper = new \JHelperTags;
		$observer->typeAliasPattern = $typeAlias;

		return $observer;
	}

	/**
	 * Pre-processor for $table->store($updateNulls)
	 *
	 * @param   boolean  $updateNulls  The result of the load
	 * @param   string   $tableKey     The key of the table
	 *
	 * @return  void
	 *
	 * @since   3.1.2
	 */
	public function onBeforeStore($updateNulls, $tableKey)
	{
		$this->parseTypeAlias();

		if (empty($this->table->tagsHelper->tags))
		{
			$this->tagsHelper->preStoreProcess($this->table);
		}
		else
		{
			$this->tagsHelper->preStoreProcess($this->table, (array) $this->table->tagsHelper->tags);
		}
	}

	/**
	 * Post-processor for $table->store($updateNulls)
	 * You can change optional params newTags and replaceTags of tagsHelper with method setNewTagsToAdd
	 *
	 * @param   boolean  &$result  The result of the load
	 *
	 * @return  void
	 *
	 * @since   3.1.2
	 */
	public function onAfterStore(&$result)
	{
		if ($result)
		{
			if (empty($this->table->tagsHelper->tags))
			{
				$result = $this->tagsHelper->postStoreProcess($this->table);
			}
			else
			{
				$result = $this->tagsHelper->postStoreProcess($this->table, $this->table->tagsHelper->tags);
			}

			// Restore default values for the optional params:
			$this->newTags = array();
			$this->replaceTags = true;
		}
	}

	/**
	 * Pre-processor for $table->delete($pk)
	 *
	 * @param   mixed  $pk  An optional primary key value to delete.  If not set the instance property value is used.
	 *
	 * @return  void
	 *
	 * @since   3.1.2
	 * @throws  \UnexpectedValueException
	 */
	public function onBeforeDelete($pk)
	{
		$this->parseTypeAlias();
		$this->tagsHelper->deleteTagData($this->table, $pk);
	}

	/**
	 * Sets the new tags to be added or to replace existing tags
	 *
	 * @param   array    $newTags      New tags to be added to or replace current tags for an item
	 * @param   boolean  $replaceTags  Replace tags (true) or add them (false)
	 *
	 * @return  boolean
	 *
	 * @since   3.1.2
	 */
	public function setNewTags($newTags, $replaceTags)
	{
		$this->parseTypeAlias();

		return $this->tagsHelper->postStoreProcess($this->table, $newTags, $replaceTags);
	}

	/**
	 * Internal method
	 * Parses a TypeAlias of the form "{variableName}.type", replacing {variableName} with table-instance variables variableName
	 * Storing result into $this->tagsHelper->typeAlias
	 *
	 * @return  void
	 *
	 * @since   3.1.2
	 */
	protected function parseTypeAlias()
	{
		// Needed for PHP < 5.4.0 as it's not passing context $this to closure function
		static::$_myTableForPregreplaceOnly = $this->table;

		$this->tagsHelper->typeAlias = preg_replace_callback('/{([^}]+)}/',
			function($matches)
			{
				return Tags::$_myTableForPregreplaceOnly->{$matches[1]};
			},
			$this->typeAliasPattern
		);
	}
}
