Location: PHPKode > projects > Habari > system/classes/vocabulary.php
<?php

/**
 * Vocabulary Class
 *
 * Vocabulary is part of the taxonomy system. A vocabulary holds terms and has features.
 *
 * @property-read array $features An array of the features this Vocabulary implements
 *
 */

class Vocabulary extends QueryRecord
{
	/**
	 *
	 * @var Array of strings $features. An array of the features that limit the behaviour of the vocabulary.
	 * Default values can include:
	 *  hierarchical: The vocabulary's terms exist in a parent child hierarchy
	 *  required:
	 *  multiple: More than one term in the vocabulary can be associated with an object
	 *  free: Terms within the vocabulary can have any value
	 *  unique: A term may be associated with exactly 0 or 1 object
	 */
	public static $features = array( 'hierarchical', 'required', 'multiple', 'free', 'unique' );

	/**
	 * Return the defined database columns for a Vocabulary.
	 * @return array Array of columns in the Vocabulary table
	 **/
	public static function default_fields()
	{
		return array(
			'id' => 0,
			'name' => '',
			'description' => '',
			'features' => array(),
		);
	}

	/**
	 * Vocabulary constructor
	 * Creates a Vocabulary instance
	 *
	 * @param array $paramarray an associative array of initial vocabulary values
	 **/
	public function __construct( $paramarray = array() )
	{
		// Defaults
		$this->fields = array_merge(
			self::default_fields(),
			$this->fields
		);

		parent::__construct( $paramarray );

		$this->exclude_fields( 'id' );
		if ( is_string( $this->features ) ) {
			$this->features = unserialize( $this->features );
		}
	}

	/**
	 * Create a vocabulary and save it.
	 *
	 * @param array $paramarray An associative array of vocabulary fields
	 * @return Vocabulary The new vocabulary object
	 */
	static function create( $paramarray )
	{
		$vocabulary = new Vocabulary( $paramarray );
		$vocabulary->insert();
		return $vocabulary;
	}

	/**
	 * function __get
	 * Overrides QueryRecord __get to implement custom object properties
	 * @param string Name of property to return
	 * @return mixed The requested field value
	 **/
	public function __get( $name )
	{
		$out = parent::__get( $name );
		switch ( $name ) {
			case 'features':
				if ( ! is_array( $out ) ) {
					$out = unserialize( $out );
				}
				break;
		}
		if ( is_null( $out ) ) {
			$out = in_array( $name, $this->features );
		}
		return $out;
	}

	/**
	 * Return a Vocabulary by name.
	 * @return Vocabulary The requested vocabulary
	 **/
	public static function get( $name )
	{
		$query = Query::create('{vocabularies}')->select('*');
		$query->where()->add('name = :name', array('name' => $name));
		return $query->row('Vocabulary');
	}

	/**
	 * Return a Vocabulary by id
	 *
	 * @param integer $id The id of the vocabulary
	 * @return Vocabulary The object requested
	 */
	public static function get_by_id( $id )
	{
		$query = Query::create('{vocabularies}')->select('*');
		$query->where()->add('id = :id', array('id' => $id));
		return $query->row('Vocabulary');
	}

	/**
	 * Return all vocabularies as Vocabulary objects
	 *
	 * @return array An array of Vocabulary objects
	 */
	public static function get_all()
	{
		$query = Query::create('{vocabularies}')->select('*');
		return $query->results('Vocabulary');
	}

	/**
	 * Rename a Vocabulary.
	 * @return boolean true if the Vocabulary was renamed, false otherwise
	 **/
	public function rename( $newname )
	{
		$this->name = $newname;
		$result = $this->update();

		return $result;
	}

	/**
	 * Return the names of all vocabularies
	 * @return array Array of Vocabulary names
	 **/
	public static function names()
	{
		$query = Query::create('{vocabularies}')->select('name');
		return $query->column();
	}

	/**
	 * Return the Term objects associated to that type of object with that id in any vocabulary.
	 * For example, return all terms associated with a particular post, from all vocabularies.
	 *
	 * @return array Array of Vocabulary names
	 **/
	public static function get_all_object_terms( $object_type, $id )
	{
		$query = Query::create('{terms}')->select('id', 'term', 'term_display', 'vocabulary_id', 'mptt_left', 'mptt_right');
		$query->join('JOIN {object_terms} ON {terms}.id = {object_terms}.term_id', array(), 'object_terms');
		$query->where()->in('{object_terms}.object_type_id', self::object_type_id( $object_type ));
		$query->where()->in('{object_terms}.object_id', $id);
		return new Terms($query->results('Term'));
	}

	/**
	 * Determine whether a vocabulary exists
	 * @param string $name a vocabulary name
	 * @return bool whether the vocabulary exists or not
	**/
	public static function exists( $name )
	{
		$query = Query::create('{vocabularies}')->select('count(id)');
		$query->where()->add('name = :name', array('name' => $name));
		return ((int) $query->value()) > 0;
	}

	/**
	 * function insert
	 * Saves a new vocabulary to the vocabularies table
	 */
	public function insert()
	{
		// Don't allow duplicate vocabularies
		if ( Vocabulary::exists( $this->fields['name'] ) ) {
			return false;
		}

		// Let plugins disallow and act before we write to the database
		$allow = true;
		$allow = Plugins::filter( 'vocabulary_insert_allow', $allow, $this );
		if ( !$allow ) {
			return false;
		}
		Plugins::act( 'vocabulary_insert_before', $this );

		// Serialize features before they are stored
		if ( isset( $this->newfields['features'] ) ) {
			$this->newfields['features'] = serialize( $this->newfields['features'] );
		}
		if ( isset( $this->fields['features'] ) ) {
			$this->fields['features'] = serialize( $this->fields['features'] );
		}
		$result = parent::insertRecord( DB::table( 'vocabularies' ) );

		// Make sure the id is set in the vocabulary object to match the row id
		$this->newfields['id'] = DB::last_insert_id();

		// Update the vocabulary's fields with anything that changed
		$this->fields = array_merge( $this->fields, $this->newfields );
		// And unserialize the features
		if ( isset( $this->fields['features'] ) ) {
			$this->fields['features'] = unserialize( $this->fields['features'] );
		}

		// We've inserted the vocabulary, reset newfields
		$this->newfields = array();

		EventLog::log( _t( 'New vocabulary %1$s (%2$s)', array( $this->id, $this->name ) ), 'info', 'content', 'habari' );

		// Let plugins act after we write to the database
		Plugins::act( 'vocabulary_insert_after', $this );

		return $result;
	}

	/**
	 * function update
	 * Updates an existing vocabulary in the vocabularies table
	 */
	public function update()
	{
		// Don't allow duplicate vocabularies
		if ( isset( $this->newfields['name'] ) && Vocabulary::exists( $this->newfields['name'] ) ) {
			return false;
		}

		// Let plugins disallow and act before we write to the database
		$allow = true;
		$allow = Plugins::filter( 'vocabulary_update_allow', $allow, $this );
		if ( !$allow ) {
			return;
		}
		Plugins::act( 'vocabulary_update_before', $this );

		if ( isset( $this->newfields['features'] ) ) {
			$this->newfields['features'] = serialize( $this->newfields['features'] );
		}
		if ( isset( $this->fields['features'] ) ) {
			$this->fields['features'] = serialize( $this->fields['features'] );
		}
		$result = parent::updateRecord( '{vocabularies}', array( 'id' => $this->id ) );

		$this->fields = array_merge( $this->fields, $this->newfields );
		$this->newfields = array();

		if ( isset( $this->fields['features'] ) ) {
			$this->fields['features'] = unserialize( $this->fields['features'] );
		}

		// Let plugins act after we write to the database
		Plugins::act( 'vocabulary_update_after', $this );

		return $result;
	}

	/**
	 * Delete an existing vocabulary
	 */
	public function delete()
	{
		// Let plugins disallow and act before we write to the database
		$allow = true;
		$allow = Plugins::filter( 'vocabulary_delete_allow', $allow, $this );
		if ( !$allow ) {
			return;
		}
		Plugins::act( 'vocabulary_delete_before', $this );

		// Get the ids for all this vocabulary's terms
		$ids = DB::get_column( 'SELECT id FROM {terms} WHERE vocabulary_id = ?', array( $this->id ) );

		// Delete the records from object_terms for those ids (if there were any)
		if ( count( $ids ) ) {
			$placeholder = Utils::placeholder_string( count( $ids ) );
			DB::query( "DELETE FROM {object_terms} WHERE term_id IN ($placeholder)", $ids );
		}

		// Delete this vocabulary's terms
		DB::delete( '{terms}', array( 'vocabulary_id' => $this->id ) );

		// Finally, delete the vocabulary
		$result = parent::deleteRecord( '{vocabularies}', array( 'id'=>$this->id ) );
		EventLog::log( _t( 'Vocabulary %1$s (%2$s) deleted.', array( $this->id, $this->name ) ), 'info', 'content', 'habari' );

		// Let plugins act after we write to the database
		Plugins::act( 'vocabulary_delete_after', $this );
		return $result;
	}

	/**
	 * Adds a term to the vocabulary. Returns a Term object. null parameters append the term to the end of any hierarchies.
	 * @return Term The Term object added
	 **/
	public function add_term( $term, $target_term = null, $before = false )
	{
		$new_term = $term;
		if ( is_string( $term ) ) {
			$new_term = new Term( array( 'term_display' => $term ) );
		}

		$new_term->vocabulary_id = $this->id;

		$ref = 0;
		DB::begin_transaction();

		// If there are terms in the vocabulary, work out the reference point
		if ( !$this->is_empty() ) {

			if ( $this->hierarchical ) {
				// If no parent is specified, put the new term after the last term
				if ( null == $target_term ) {
					$ref = DB::get_value( 'SELECT mptt_right FROM {terms} WHERE vocabulary_id=? ORDER BY mptt_right DESC LIMIT 1', array( $this->id ) );
				}
				else {
					if ( ! $before ) {
						$ref = $target_term->mptt_right - 1;
					}
					else {
						$ref = $target_term->mptt_left - 1;
					}
				}
			}
			else {
				// If no before_term is specified, put the new term after the last term
				if ( ! $before ) {
					$ref = DB::get_value( 'SELECT mptt_right FROM {terms} WHERE vocabulary_id=? ORDER BY mptt_right DESC LIMIT 1', array( $this->id ) );
				}
				else {
					$ref = $target_term->mptt_left - 1;
				}
			}

			// Make space for the new node
			$params = array( 'vocab_id' => $this->id, 'ref' => $ref );
			$res = DB::query( 'UPDATE {terms} SET mptt_right=mptt_right+2 WHERE vocabulary_id=:vocab_id AND mptt_right>:ref', $params );
			if ( ! $res ) {
				DB::rollback();
				return false;
			}
			$res = DB::query( 'UPDATE {terms} SET mptt_left=mptt_left+2 WHERE vocabulary_id=:vocab_id AND mptt_left>:ref', $params );
			if ( ! $res ) {
				DB::rollback();
				return false;
			}

		}

		// Set the right and left appropriately
		$new_term->mptt_left = $ref + 1;
		$new_term->mptt_right = $ref + 2;

		// Insert the new node
		$result = $new_term->insert();
		if( $result ) {
			DB::commit();
			return $new_term;
		}
		else {
			DB::rollback();
			return false;
		}

	}

	/**
	 * Gets the term object by id. No parameter returns the root Term object.
	 * @param mixed $term A Term object, null (for the first node in the tree), a string (for a term slug or display), or an integer (for a Term ID).
	 * @param string $term_class The class of the returned term object.
	 * @return Term The Term object requested
	 * @todo improve selective fetching by term slug vs term_display
	 **/
	public function get_term( $term = null, $term_class = 'Term' )
	{
		$params = array( 'vocab_id' => $this->id );
		$query = '';
		if ( $term instanceof Term ) {
			$params[ 'term_id' ] = $term->id;
			$query = 'SELECT * FROM {terms} WHERE vocabulary_id = :vocab_id AND id = ABS(:term_id)';
		}
		elseif ( is_null( $term )  ) {
			// The root node has an mptt_left value of 1
			$params[ 'left' ] = 1;
			$query = 'SELECT * FROM {terms} WHERE vocabulary_id = :vocab_id AND mptt_left = :left';
		}
		elseif ( is_string( $term ) ) {
			$params[ 'term' ] = $term;
			$query = 'SELECT * FROM {terms} WHERE vocabulary_id = :vocab_id AND (term = :term OR term_display = :term)';
		}
		elseif ( is_int( $term ) ) {
			$params[ 'term_id' ] = $term;
			$query = 'SELECT * FROM {terms} WHERE vocabulary_id = :vocab_id AND id = ABS(:term_id)';
		}
		return DB::get_row( $query, $params, $term_class );
	}

	/**
	 * Gets the Term objects associated to that type of object with that id in this vocabulary
	 * For example, return all terms in this vocabulary that are associated with a particular post
	 *
	 * @param String the name of the object type
	 * @param integer The id of the object for which you want the terms
	 * @return Array The Term objects requested
	 **/
	public function get_object_terms( $object_type, $id )
	{
		$query = Query::create('{terms}')->select('id', 'term', 'term_display', 'vocabulary_id', 'mptt_left', 'mptt_right');
		$query->join('JOIN {object_terms} ON {terms}.id = {object_terms}.term_id', array(), 'object_terms');
		$query->where()->in('{terms}.vocabulary_id', $this->id);
		$query->where()->in('{object_terms}.object_type_id', self::object_type_id( $object_type ));
		$query->where()->in('{object_terms}.object_id', $id);
		return new Terms($query->results('Term'));
	}

	/**
	 * Sets the Term objects associated to that type of object with that id in this vocabulary
	 *
	 * @param String $object_type the name of the object type
	 * @param Integer $id The id of the object for which you want the terms
	 * @param Array $terms The names of the terms to associate
	 *
	 * @return boolean. Whether the associations were successful or not
	 **/
	public function set_object_terms( $object_type, $id, $terms = array() )
	{

		// Make sure we have an array
		$terms = new Terms( $terms );
		$new_terms = array();

		// Make sure we have terms and they're in the database.
		// Key the terms to their id while we're at it.
		foreach ( $terms as $term ) {
			$new_term = $this->get_term( $term );
			if ( ! $new_term instanceof Term ) {
				$new_term = $this->add_term( $term );
			}
			if ( ( $new_term != false ) && ( ! array_key_exists( $new_term->id, $new_terms ) ) ) {
				$new_terms[$new_term->id] = $new_term;
			}
		}

		// Get the current terms
		$old_terms = $this->get_object_terms( $object_type, $id );
		$keys = array_keys( $new_terms );
		foreach ( $old_terms as $term ) {
			// If the old term isn't in the new terms, dissociate it from the object
			if ( ! in_array( $term->id, $keys ) ) {
				$term->dissociate( $object_type, $id );
			}
		}

		// Associate the new terms
		foreach ( $new_terms as $term ) {
			$term->associate( $object_type, $id );
		}

		return true;
	}

	/**
	 * Remove the term from the vocabulary.  Convenience method to ->get_term('foo')->delete().
	 *
	 **/
	public function delete_term( $term )
	{
		if ( ! is_object( $term ) ) {
			$term = $this->get_term( $term );
		}

		// TODO How should we handle deletion of a term with descendants?
		// Perhaps a $keep_children flag to move descendants to be descendants of
		// the deleted term's parent? Terms should not change the left and right
		// values of other terms, and thus their deletion should only occur through
		// the vocabulary to which they belong. Is it feasible to restrict this?
		// For the moment, just delete the descendants
		$params = array( $this->id, $term->mptt_left, $term->mptt_right );
		DB::query( 'DELETE from {terms} WHERE vocabulary_id=? AND mptt_left>? AND mptt_right<?', $params );

		// Fix mptt_left and mptt_right values for other nodes in the vocabulary
		$offset = $term->mptt_right - $term->mptt_left + 1;
		$ref = $this->mptt_left;
		$params = array( $offset, $this->id, $term->mptt_left );

		// Delete the term
		$term->delete();

		// Renumber left and right values of other nodes appropriately
		DB::query( 'UPDATE {terms} SET mptt_right=mptt_right-? WHERE vocabulary_id=? AND mptt_right>?', $params );
		DB::query( 'UPDATE {terms} SET mptt_left=mptt_left-? WHERE vocabulary_id=? AND mptt_left>?', $params );

	}

	/**
	 * Check if this vocabulary is empty.
	 *
	 **/
	public function is_empty()
	{
		$query = Query::create('{terms}')->select('count(id)');
		$query->where()->in('vocabulary_id', $this->id);
		return ((int) $query->value()) == 0;
	}


	/**
	 * Retrieve the vocabulary
	 * @return Terms The Term objects in the vocabulary, in tree order
	 **/
	public function get_tree( $orderby = 'mptt_left ASC' )
	{
		$query = Query::create('{terms}')->select('{terms}.*');
		$query->where()->in('vocabulary_id', $this->id);
		// If the vocabulary is unique, save the extra mess of queries and fetch the object data, too
		if(in_array('unique', $this->features)) {
			$query->join('LEFT JOIN {object_terms} on {object_terms}.term_id = {terms}.id', array(), 'object_terms');
			$query->join('LEFT JOIN {object_types} on {object_types}.id = {object_terms}.object_type_id', array(), 'object_types');
			$query->select('{object_terms}.object_id');
			$query->select('{object_types}.name AS type');
		}
		$query->orderby($orderby);
		return new Terms($query->results('Term'));
	}

	/**
	 * Retrieve the terms in the vocabulary that match the specified criteria
	 * @param string $search The string to search for
	 * @return Terms The Term objects that match the search term
	 */
	public function get_search( $search, $orderby = 'mptt_left ASC' )
	{
		$search = '%' . $search . '%';
		return new Terms( DB::get_results( "SELECT * FROM {terms} WHERE vocabulary_id = :vid and LOWER(term_display) LIKE LOWER(:crit) ORDER BY {$orderby}", array( 'vid' => $this->id, 'crit' => $search ), 'Term' ) );
	}

	/**
	 * Retrieve the vocabulary as an associative array suitable for FormUI select controls
	 * @return Array The Term objects in the vocabulary, in tree order
	 **/
	public function get_options()
	{
		$tree = $this->get_tree( 'mptt_left ASC' );
		$output = array();
		if ( $firstnode = reset( $tree ) ) {
			$lastright = $lastleft = reset( $tree )->mptt_left;
			$indent = 0;
			$stack = array();
			foreach ( $tree as $term ) {
				while ( count( $stack ) > 0 && end( $stack )->mptt_right < $term->mptt_left ) {
					array_pop( $stack );
				}
				$output[$term->id] = str_repeat( '- ', count( $stack ) ) . $term->term_display;
				$stack[] = $term;
			}
		}

		return $output;
	}

	/**
	 * Get all root elements in this vocabulary
	 * @return Array The root Term objects in the vocabulary
	 */
	public function get_root_terms()
	{
		/**
		 * If we INNER JOIN the terms table with itself on ALL the descendants,
		 * then descendants one level down are listed once, two levels down are listed twice,
		 * etc. If we return only those terms which appear once, we get root elements.
		 * ORDER BY NULL to avoid the MySQL filesort.
		 */
		$query = <<<SQL
SELECT child.term as term,
	child.term_display as term_display,
	child.mptt_left as mptt_left,
	child.mptt_right as mptt_right,
	child.vocabulary_id as vocabulary_id,
	child.id as id
FROM {terms} as parent
INNER JOIN {terms} as child
	ON child.mptt_left BETWEEN parent.mptt_left AND parent.mptt_right
	AND child.vocabulary_id = parent.vocabulary_id
WHERE parent.vocabulary_id = ?
GROUP BY child.term
HAVING COUNT(child.term)=1
ORDER BY mptt_left ASC
SQL;
		return new Terms(DB::get_results( $query, array( $this->id ), 'Term' ));
	}

	/**
	 * inserts a new object type into the database, if it doesn't exist
	 * @param string The name of the new post type
	 * @param bool Whether the new post type is active or not
	 * @return none
	**/
	public static function add_object_type( $type )
	{
		$params = array( 'name' => $type );
		if ( ! DB::exists( "{object_types}", $params ) ) {
			DB::insert( "{object_types}", $params );
		}
	}

	/**
	 * Return the object type id for a named object, such as a post
	 *
	 * @param string $name The type of object
	 * @return integer The id of the object type
	*/
	public static function object_type_id( $type )
	{
		$id = (int)DB::get_value( "SELECT id FROM {object_types} WHERE name = ?", array( $type ) );
		return $id;

	}

	/**
	 * Moves a term within the vocabulary. Returns a Term object. null parameters append the term to the end of any hierarchies.
	 *
	 * The MPTT operations can seem complex, but they're actually pretty simple:
	 * 		1: Find our insertion point:
	 * 			Either at the very end of the vocabulary, or before / after the given term
	 * 		2: Create a gap at that point:
	 * 			We'll bump everything at that point or after up enough to fit in the term we're moving
	 * 		3: Move the term:
	 * 			We know the offset between the old point and the new point, so move the range up that number of spaces.
	 * 		4: Close the original gap:
	 * 			Now we've got all our terms moved, but we need to bump everything back down to close the gap it left, similar to #2.
	 *
	 * @param Term $term The term to move.
	 * @param Term|null $target_term The term to move $term before or after, or null to move it to the very end of the vocabulary.
	 * @param bool $before True to move $term BEFORE $target_term, false (the default) to move $term AFTER $target_term.
	 * @return Term The Term object moved
	 **/
	public function move_term( $term, $target_term = null, $before = false )
	{
		// We assume that the arguments passed are valid terms. Check them before calling this.

		// If there are terms in the vocabulary, work out the reference point
		if ( !$this->is_empty() ) {

			$source_left = $term->mptt_left;
			$source_right = $term->mptt_right;
			$range = $source_right - $source_left + 1;

			DB::begin_transaction();


			// Determine the insertion point mptt_target
			if ( $target_term == null ) {
				// if no target is specified, put the new term after the last term
				$mptt_target = DB::get_value( 'SELECT MAX(mptt_right) FROM {terms} WHERE vocabulary_id = :id', array( ':id' => $this->id ) );
				$mptt_target = $mptt_target + 1;	// the left is one greater than the highest right
			}
			else {

				// if we're putting it before
				if ( $before ) {
					$mptt_target = $target_term->mptt_left;		// we're actually taking the place of the target term's left
				}
				else {
					$mptt_target = $target_term->mptt_right + 1;	// we just need to start at the next number
				}

			}

			// Create space in the tree for the insertion
			$params = array( 'vocab_id' => $this->id, 'range' => $range, 'mptt_target' => $mptt_target );
			$res = DB::query( 'UPDATE {terms} SET mptt_left = mptt_left + :range WHERE vocabulary_id = :vocab_id AND mptt_left >= :mptt_target', $params );
			if ( ! $res ) {
				DB::rollback();
				return false;
			}

			$res = DB::query( 'UPDATE {terms} SET mptt_right = mptt_right + :range WHERE vocabulary_id = :vocab_id AND mptt_right >= :mptt_target', $params );
			if ( ! $res ) {
				DB::rollback();
				return false;
			}

			// if we're moving it "down" ("forward"?) in the vocabulary, we just created a gap that changed our term's left and right values
			if ( $mptt_target < $source_left ) {
				$source_left = $source_left + $range;
				$source_right = $source_right + $range;
			}

			// figure out how far our nodes are moving
			$offset = $mptt_target - $source_left;

			// move our lucky nodes into the space we just created
			$params = array( ':offset' => $offset, ':vocab_id' => $this->id, ':source_left' => $source_left, ':source_right' => $source_right );
			$res = DB::query( '
				UPDATE {terms}
				SET
					mptt_left = mptt_left + :offset,
					mptt_right = mptt_right + :offset
				WHERE
					vocabulary_id = :vocab_id AND
					mptt_left >= :source_left AND
					mptt_right <= :source_right
				',
				$params
			);

			// Close the gap in the tree created by moving those nodes out
			$params = array( 'range' => $range, 'vocab_id' => $this->id, 'source_left' => $source_left );
			$res = DB::query( 'UPDATE {terms} SET mptt_left = mptt_left - :range WHERE vocabulary_id = :vocab_id AND mptt_left > :source_left', $params );
			if ( ! $res ) {
				DB::rollback();
				return false;
			}

			$params = array( 'range' => $range, 'vocab_id' => $this->id, 'source_right' => $source_right );
			$res = DB::query( 'UPDATE {terms} SET mptt_right = mptt_right - :range WHERE vocabulary_id = :vocab_id AND mptt_right > :source_right', $params );
			if ( ! $res ) {
				DB::rollback();
				return false;
			}


			// Success!
			DB::commit();

			return $this->get_term( $term->id );
		}
		return false;
	}


	/**
	 * Returns the number of tags in the database.
	 *
	 * @return int The number of tags in the database.
	 **/
	public  function count_total()
	{
		return count( $this->get_tree() );
	}

	/**
	 * Returns the number of times the most used tag is used.
	 *
	 * @return int The number of times the most used tag is used.
	 **/
	public function max_count()
	{
		return DB::get_value( 'SELECT count( t2.object_id ) AS max FROM {terms} t, {object_terms} t2 WHERE t2.term_id = t.id AND t.vocabulary_id = ? GROUP BY t.id ORDER BY max DESC LIMIT 1', array( $this->id ) );
	}

	/**
	 * Renames terms.
	 * If the master term exists, the terms will be merged with it.
	 * If not, it will be created first.
	 *
	 * @param mixed $master The Term to which they should be renamed, or the slug, text or id of it
	 * @param Array $tags The tag text, slugs or ids to be renamed
	 **/
	public function merge( $master, $tags, $object_type = 'post' )
	{
		$type_id = Vocabulary::object_type_id( $object_type );

		$post_ids = array();
		$tag_names = array();

		// get the master term
		$master_term = $this->get_term( $master );

		if ( !isset( $master_term->term ) ) {
			// it didn't exist, so we assume it's tag text and create it
			$master_term = $this->add_term( $master );

			if( !$master_term ) {
				return;
			}

			$master_ids = array();
		}
		else {
			// get the posts the tag is already on so we don't duplicate them
			$master_ids = $master_term->objects( $object_type );

		}

		// get array of existing tags first to make sure we don't conflict with a new master tag
		foreach ( $tags as $tag ) {

			// if this is the master tag, there's nothing to do
			if ( $tag == $master ) {
				continue;
			}

			$term = $this->get_term( $tag );

			// get all the post ID's tagged with this tag
			$posts = $term->objects( $object_type );

			$ok_to_delete = true;

			// if there actually are posts, let's link those up with the new tag now
			if ( count( $posts ) > 0 ) {
				// only try and add the master tag to posts it's not already on
				$post_ids = array_diff( $posts, $master_ids );

				foreach ( $post_ids as $post_id ) {
					$r = $master_term->associate( $object_type, $post_id );

					// if we failed linking this post, we can keep trying others, but don't delete this tag when finished
					if ( $r == false ) {
						$ok_to_delete = false;
					}
					else {
						// otherwise, we did in fact merge a tag - make sure the tag is in the list of ones we merged
						$tag_names[ $tag ] = $tag;

						// and disassociate this post from the existing tag
						$term->dissociate( $object_type, $post_id );
					}

				}
			}

			// if it's still ok to delete the tag entirely, do so
			if ( $ok_to_delete ) {
				$this->delete_term( $term->id );
			}
			else {
				// otherwise, log a special message that we didn't delete it
				EventLog::log( _t( 'Not all posts tagged "%1$s" could be reassigned to "%2$s". They have been left alone.', array( $tag, $master ) ), 'err', 'vocabulary', 'habari' );
			}

		}

		EventLog::log( sprintf(
			_n( 'Term %1$s in the %2$s vocabulary has been renamed to %3$s.',
				'Terms %1$s in the %2$s vocabulary have been renamed to %3$s.',
				count( $tags )
			), implode( ', ', $tag_names ), $this->name, $master ), 'info', 'vocabulary', 'habari'
		);

	}


	/**
	 * Get the tags associated with this object
	 *
	 * @param Integer $object_id. The id of the tagged object
	 * @param String $object_type. The name of the type of the object being tagged. Defaults to post
	 *
	 * @return Terms The terms associated with this object
	 */
	public function get_associations( $object_id, $object_type = 'post' )
	{
		$terms = $this->get_object_terms( $object_type, $object_id );
		if ( $terms ) {
			$terms = new Terms( $terms );
		}

		return $terms;
	}


	/**
	 * Returns the count of times a tag is used.
	 *
	 * @param mixed $term The tag to count usage.
	 * @return int The number of times a tag is used.
	 **/
	public function post_count( $term, $object_type = 'post' )
	{
		$term = $this->get_term( $term );
		return $term->count( $object_type );
	}

	/**
	 * Moves all of the terms into a temporary area so that they can be moved
	 *
	 * @static
	 * @param  Terms $terms An array of Term objects
	 */
	public static function prep_update( $terms )
	{
		$index = -1;
		foreach($terms as $term) {
			DB::query( 'UPDATE {terms} SET mptt_left=:left, mptt_right=:right WHERE id=:id', array('id' => $term->id, 'left' => $index, 'right' => $index -1 ) );
			$index -=2;
		}
	}

}

?>
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