<?php

/**
 * SearchIndex is the base index class. Each connector will provide a subclass of this that
 * provides search engine specific behavior.
 *
 * This class is responsible for:
 *
 * - Taking index calls adding classes and fields, and resolving those to value sources and types
 *
 * - Determining which records in this index need updating when a DataObject is changed
 *
 * - Providing utilities to the connector indexes
 *
 * The connector indexes are responsible for
 *
 * - Mapping types to index configuration
 *
 * - Adding and removing items to index
 *
 * - Parsing and converting SearchQueries into a form the engine will understand, and executing those queries
 *
 * The user indexes are responsible for
 *
 * - Specifying which classes and fields this index contains
 *
 * - Specifying update rules that are not extractable from metadata (because the values come from functions for instance)
 * 
 */
abstract class SearchIndex extends ViewableData {

	function __construct() {
		$this->init();

		foreach ($this->getClasses() as $class => $options) {
			SearchVariant::with($class, $options['include_children'])->call('alterDefinition', $class, $this);
		}

		$this->buildDependancyList();
	}

	function __toString() {
		return 'Search Index ' . get_class($this);
	}

	/**
	 * Examines the classes this index is built on to try and find defined fields in the class hierarchy for those classes.
	 * Looks for db and viewable-data fields, although can't nessecarily find type for viewable-data fields.
	 */
	function fieldData($field, $forceType = null) {
		$fullfield = str_replace(".", "_", $field);
		$sources = $this->getClasses();

		foreach ($sources as $source => $options) {
			$sources[$source]['base'] = $source;
			$sources[$source]['lookup_chain'] = array();
		}

		$found = array();

		if (strpos($field, '.') !== false) {
			$lookups = explode(".", $field);
			$field = array_pop($lookups);

			foreach ($lookups as $lookup) {
				$next = array();

				foreach ($sources as $source => $options) {
					$class = null;

					foreach (SearchIntrospection::hierarchy($source, $options['include_children']) as $dataclass) {
						$singleton = singleton($dataclass);

						if ($hasOne = $singleton->has_one($lookup)) {
							$class = $hasOne;
							$options['lookup_chain'][] = array(
								'call' => 'method', 'method' => $lookup,
								'through' => 'has_one', 'class' => $dataclass, 'otherclass' => $class, 'foreignkey' => "{$lookup}ID"
							);
						}
						else if ($hasMany = $singleton->has_many($lookup)) {
							$class = $hasMany;
							$options['multi_valued'] = true;
							$options['lookup_chain'][] = array(
								'call' => 'method', 'method' => $lookup,
								'through' => 'has_many', 'class' => $dataclass, 'otherclass' => $class, 'foreignkey' => $singleton->getRemoteJoinField($lookup, 'has_many')
							);
						}
						else if ($manyMany = $singleton->many_many($lookup)) {
							$class = $manyMany[0];
							$options['multi_valued'] = true;
							$options['lookup_chain'][] = array(
								'call' => 'method', 'method' => $lookup,
								'through' => 'many_many', 'class' => $dataclass, 'otherclass' => $class, 'details' => $manyMany
							);
						}

						if ($class) {
							if (!isset($options['origin'])) $options['origin'] = $dataclass;
							$next[$class] = $options;
							continue 2;
						}
					}
				}

				if (!$next) return $next; // Early out to avoid excessive empty looping
				$sources = $next;
			}
		}

		foreach ($sources as $class => $options) {
			$dataclasses = SearchIntrospection::hierarchy($class, $options['include_children']);

			while (count($dataclasses)) {
				$dataclass = array_shift($dataclasses);
				$type = null; $fieldoptions = $options;

				$fields = DataObject::database_fields($dataclass);

				if (isset($fields[$field])) {
					$type = $fields[$field];
					$fieldoptions['lookup_chain'][] = array('call' => 'property', 'property' => $field);
				}
				else {
					$singleton = singleton($dataclass);

					if ($singleton->hasMethod("get$field") || $singleton->hasField($field)) {
						$type = $singleton->castingClass($field);
						if (!$type) $type = 'String';

						if ($singleton->hasMethod("get$field")) $fieldoptions['lookup_chain'][] = array('call' => 'method', 'method' => "get$field");
						else $fieldoptions['lookup_chain'][] = array('call' => 'property', 'property' => $field);
					}
				}

				if ($type) {
					// Don't search through child classes of a class we matched on. TODO: Should we?
					$dataclasses = array_diff($dataclasses, array_values(ClassInfo::subclassesFor($dataclass)));
					// Trim arguments off the type string
					if (preg_match('/^(\w+)\(/', $type, $match)) $type = $match[1];
					// Get the origin
					$origin = isset($fieldoptions['origin']) ? $fieldoptions['origin'] : $dataclass;

					$found["{$origin}_{$fullfield}"] = array(
						'name' => "{$origin}_{$fullfield}",
						'field' => $field,
						'fullfield' => $fullfield,
						'base' => $fieldoptions['base'],
						'origin' => $origin,
						'class' => $dataclass,
						'lookup_chain' => $fieldoptions['lookup_chain'],
						'type' => $forceType ? $forceType : $type,
						'multi_valued' => isset($fieldoptions['multi_valued']) ? true : false
					);
				}
			}
		}

		return $found;
	}

	/** Public, but should only be altered by variants */

	protected $classes = array();

	protected $fulltextFields = array();

	public $filterFields = array();

	protected $sortFields = array();

	/**
	 * Add a DataObject subclass whose instances should be included in this index
	 *
	 * Can only be called when addFulltextField, addFilterField, addSortField and addAllFulltextFields have not
	 * yet been called for this index instance
	 *
	 * @throws Exception
	 * @param String $class - The class to include
	 * @param array $options - TODO: Remove
	 */
	public function addClass($class, $options = array()) {
		if ($this->fulltextFields || $this->filterFields || $this->sortFields) {
			throw new Exception('Can\'t add class to Index after fields have already been added');
		}

 		$options = array_merge(array(
			'include_children' => true
		), $options);

		$this->classes[$class] = $options;
	}

	/**
	 * Get the classes added by addClass
	 */
	public function getClasses() { return $this->classes; }

	/**
	 * Add a field that should be fulltext searchable
	 * @param String $field - The field to add
	 * @param String $forceType - The type to force this field as (required in some cases, when not detectable from metadata)
	 */
	public function addFulltextField($field, $forceType = null) {
		$this->fulltextFields = array_merge($this->fulltextFields, $this->fieldData($field, $forceType));
	}

	public function getFulltextFields() { return $this->fulltextFields; }

	/**
	 * Add a field that should be filterable
	 * @param String $field - The field to add
	 * @param String $forceType - The type to force this field as (required in some cases, when not detectable from metadata)
	 */
	public function addFilterField($field, $forceType = null) {
		$this->filterFields = array_merge($this->filterFields, $this->fieldData($field, $forceType));
	}

	public function getFilterFields() { return $this->filterFields; }

	/**
	 * Add a field that should be sortable
	 * @param String $field - The field to add
	 * @param String $forceType - The type to force this field as (required in some cases, when not detectable from metadata)
	 */
	public function addSortField($field, $forceType = null) {
		$this->sortFields = array_merge($this->sortFields, $this->fieldData($field, $forceType));
	}

	public function getSortFields() { return $this->sortFields; }

	/**
	 * Add all database-backed text fields as fulltext searchable fields.
	 *
	 * For every class included in the index, examines those classes and all subclasses looking for "Text" database
	 * fields (Varchar, Text, HTMLText, etc) and adds them all as fulltext searchable fields.
	 */
	public function addAllFulltextFields($includeSubclasses = true) {
		foreach ($this->getClasses() as $class => $options) {
			foreach (SearchIntrospection::hierarchy($class, $includeSubclasses, true) as $dataclass) {
				$fields = DataObject::database_fields($dataclass);

				foreach ($fields as $field => $type) {
					if (preg_match('/^(\w+)\(/', $type, $match)) $type = $match[1];
					if (ClassInfo::is_subclass_of($type, 'StringField')) $this->addFulltextField($field);
				}
			}
		}
	}

	/**
	 * Returns an interator that will let you interate through all added fields, regardless of whether they
	 * were added as fulltext, filter or sort fields.
	 *
	 * @return MultipleArrayIterator
	 */
	public function getFieldsIterator() {
		return new MultipleArrayIterator($this->fulltextFields, $this->filterFields, $this->sortFields);
	}

	public $dependancyList = array();

	function buildDependancyList() {
		$this->dependancyList = array_keys($this->getClasses());

		foreach ($this->getFieldsIterator() as $name => $field) {
			if (!isset($field['class'])) continue;
			SearchIntrospection::add_unique_by_ancestor($this->dependancyList, $field['class']);
		}
	}

	public $derivedFields = null;

	/**
	 * Returns an array where each member is all the fields and the classes that are at the end of some
	 * specific lookup chain from one of the base classes 
	 */
	function getDerivedFields() {
		if ($this->derivedFields === null) {
			$this->derivedFields = array();

			foreach ($this->getFieldsIterator() as $name => $field) {
				if (count($field['lookup_chain']) < 2) continue;

				$key = sha1($field['base'].serialize($field['lookup_chain']));
				$fieldname = "{$field['class']}:{$field['field']}";

				if (isset($this->derivedFields[$key])) {
					$this->derivedFields[$key]['fields'][$fieldname] = $fieldname;
					SearchIntrospection::add_unique_by_ancestor($this->derivedFields['classes'], $field['class']);
				}
				else {
					$chain = array_reverse($field['lookup_chain']);
					array_shift($chain);

					$this->derivedFields[$key] = array(
						'base' => $field['base'],
						'fields' => array($fieldname => $fieldname),
						'classes' => array($field['class']),
						'chain' => $chain
					);
				}
			}
		}

		return $this->derivedFields;
	}

	/**
	 * Get the "document ID" (a database & variant unique id) given some "Base" class, DataObject ID and state array
	 * 
	 * @param String $base - The base class of the object
	 * @param Integer $id - The ID of the object
	 * @param Array $state - The variant state of the object
	 * @return string - The document ID as a string
	 */
	function getDocumentIDForState($base, $id, $state) {
		ksort($state);
		$parts = array('id' => $id, 'base' => $base, 'state' => json_encode($state));
		return implode('-', array_values($parts));
	}

	/**
	 * Get the "document ID" (a database & variant unique id) given some "Base" class and DataObject
	 *
	 * @param DataObject $object - The object
	 * @param String $base - The base class of the object
	 * @param Boolean $includesubs - TODO: Probably going away
	 * @return string - The document ID as a string
	 */
	function getDocumentID($object, $base, $includesubs) {
		return $this->getDocumentIDForState($base, $object->ID, SearchVariant::current_state($base, $includesubs));
	}

	/**
	 * Given an object and a field definition (as returned by fieldData) get the current value of that field on that object
	 *
	 * @param DataObject $object - The object to get the value from
	 * @param Array $field - The field definition to use
	 * @return Mixed - The value of the field, or null if we couldn't look it up for some reason
	 */
	protected function _getFieldValue($object, $field) {
		set_error_handler(create_function('$no, $str', 'throw new Exception("HTML Parse Error: ".$str);'), E_ALL);

		try {
			foreach ($field['lookup_chain'] as $step) {
				// Just fail if we've fallen off the end of the chain
				if (!$object) return null;

				// If we're looking up this step on an array or DataObjectSet, do the step on every item, merge result
				if (is_array($object) || $object instanceof DataObjectSet) {
					$next = array();

					foreach ($object as $item) {
						if ($step['call'] == 'method') {
							$method = $step['method'];
							$item = $item->$method();
						}
						else {
							$property = $step['property'];
							$item = $item->$property;
						}

						if ($item instanceof DataObjectSet) $next = array_merge($next, $item->toArray());
						elseif (is_array($item)) $next = array_merge($next, $item);
						else $next[] = $item;
					}

					$object = $next;
				}
				// Otherwise, just call
				else {
					if ($step['call'] == 'method') {
						$method = $step['method'];
						$object = $object->$method();
					}
					elseif ($step['call'] == 'variant') {
						$variants = SearchVariant::variants($field['base'], true);
						$variant = $variants[$step['variant']]; $method = $step['method'];
						$object = $variant->$method($object);
					}
					else {
						$property = $step['property'];
						$object = $object->$property;
					}
				}
			}
		}
		catch (Exception $e) {
			$object = null;
		}

		restore_error_handler();
		return $object;
	}

	/**
	 * Given a class, object id, set of stateful ids and a list of changed fields (in a special format),
	 * return what statefulids need updating in this index
	 *
	 * Internal function used by SearchUpdater.
	 *
	 * @param  $class
	 * @param  $id
	 * @param  $statefulids
	 * @param  $fields
	 * @return array
	 */
	function getDirtyIDs($class, $id, $statefulids, $fields) {
		$dirty = array();

		// First, if this object is directly contained in the index, add it
		foreach ($this->classes as $searchclass => $options) {
			if ($searchclass == $class || ($options['include_children'] && ClassInfo::is_subclass_of($class, $searchclass))) {

				$dirty[$searchclass] = array();
				foreach ($statefulids as $statefulid) {
					$key = serialize($statefulid);
					$dirty[$searchclass][$key] = $statefulid;
				}
			}
		}

		$current = SearchVariant::current_state();


		// Then, for every derived field
		foreach ($this->getDerivedFields() as $derivation) {
			// If the this object is a subclass of any of the classes we want a field from
			if (!SearchIntrospection::is_subclass_of($class, $derivation['classes'])) continue;
			if (!array_intersect_key($fields, $derivation['fields'])) continue;

			foreach (SearchVariant::reindex_states($class, false) as $state) {
				SearchVariant::activate_state($state);

				$ids = array($id);

				foreach ($derivation['chain'] as $step) {
					if ($step['through'] == 'has_one') {
						$sql = new SQLQuery('ID', $step['class'], $step['foreignkey'].' IN ('.implode(',', $ids).')');
						singleton($step['class'])->extend('augmentSQL', $sql);

						$ids = $sql->execute()->column();
					}
					else if ($step['through'] == 'has_many') {
						$sql = new SQLQuery('"'.$step['class'].'"."ID"', $step['class'], '"'.$step['otherclass'].'"."ID" IN ('.implode(',', $ids).')');
						$sql->innerJoin($step['otherclass'], '"'.$step['class'].'"."ID" = "'.$step['otherclass'].'"."'.$step['foreignkey'].'"');
						singleton($step['class'])->extend('augmentSQL', $sql);

						$ids = $sql->execute()->column();
					}
				}

				SearchVariant::activate_state($current);

				if ($ids) {
					$base = $derivation['base'];
					if (!isset($dirty[$base])) $dirty[$base] = array();

					foreach ($ids as $id) {
						$statefulid = array('id' => $id, 'state' => $state);
						$key = serialize($statefulid);
						$dirty[$base][$key] = $statefulid;
					}
				}
			}
		}

		return $dirty;
	}

	/** !! These should be implemented by the full text search engine */

	abstract function add($object) ;
	abstract function delete($base, $id, $state) ;

	abstract function commit();

	/** !! These should be implemented by the specific index */

	/**
	 * Called during construction, this is the method that builds the structure.
	 * Used instead of overriding __construct as we have specific execution order - code that has
	 * to be run before _and/or_ after this.
	 */
	abstract function init();
}

/**
 * A search index that does nothing. Useful for testing
 */
abstract class SearchIndex_Null extends SearchIndex {

	function add($object) { }

	function delete($base, $id, $state) { }

	function commit() { }

}

/**
 * A search index that just records actions. Useful for testing
 */
abstract class SearchIndex_Recording extends SearchIndex {

	public $added = array();
	public $deleted = array();

	function reset() {
		$this->added = array();
		$this->deleted = array();
	}

	function add($object) {
		$res = array();

		$res['ID'] = $object->ID;
		
		foreach ($this->getFieldsIterator() as $name => $field) {
			$val = $this->_getFieldValue($object, $field);
			$res[$name] = $val;
		}

		$this->added[] = $res;
	}

	function getAdded($fields = array()) {
		$res = array();

		foreach ($this->added as $added) {
			$filtered = array();
			foreach ($fields as $field) {
				if (isset($added[$field])) $filtered[$field] = $added[$field];
			}
			$res[] = $filtered;
		}

		return $res;
	}

	function delete($base, $id, $state) {
		$this->deleted[] = array('base' => $base, 'id' => $id, 'state' => $state);
	}

	function commit() { }
	
}