<?php
/*
 * LinkableBehavior
 * Light-weight approach for data mining on deep relations between models. 
 * Join tables based on model relations to easily enable right to left find operations.
 * 
 * Can be used as a alternative to the ContainableBehavior:
 * - On data fetching only in right to left operations,
 * wich means that in "one to many" relations (hasMany, hasAndBelongsToMany)
 * should only be used from the "many to one" tables. i.e:
 * To fetch all Users assigneds to a Project with ProjectAssignment,
 * $Project->find('all', array('link' => 'User', 'conditions' => 'project_id = 1')) 
 *	 - Won't produce the desired result as data came from users table will be lost.
 * $User->find('all', array('link' => 'Project', 'conditions' => 'project_id = 1'))
 *   - Will fetch all users related to the specified project in one query
 * 
 * - On data mining as a much lighter approach - can reduce 300+ query find operations
 * in one single query with joins; "or your money back!" ;-)
 *
 * - Has the 'fields' param enabled to make it easy to replace Containable usage,
 * only change the 'contain' param to 'link'.
 *
 * Linkable Behavior. Taking it easy in your DB.
 * RafaelBandeira <rafaelbandeira3(at)gmail(dot)com>
 *
 * Licensed under The MIT License
 * Redistributions of files must retain the above copyright notice.
 *  
 * @version 1.0; 
 */
 
class LinkableBehavior extends ModelBehavior {
	
	protected $_key = 'link';
	
	protected $_options = array(
		'type' => true, 'table' => true, 'alias' => true,
		'conditions' => true, 'fields' => true, 'reference' => true,
		'class' => true, 'defaults' => true
	);

	protected $_defaults = array('type' => 'LEFT');
	
	public function beforeFind(&$Model, $query) {
		if (isset($query[$this->_key])) {
			$optionsDefaults = $this->_defaults + array('reference' => $Model->alias, $this->_key => array());
			$optionsKeys = $this->_options + array($this->_key => true);
			$query = am(array('joins' => array()), $query, array('recursive' => -1));
			$iterators[] = $query[$this->_key];
			$cont = 0;
			do {
				$iterator = $iterators[$cont];
				$defaults = $optionsDefaults;
				if (isset($iterator['defaults'])) {
					$defaults = array_merge($defaults, $iterator['defaults']);
					unset($iterator['defaults']);
				}
				$iterations = Set::normalize($iterator);
				foreach ($iterations as $alias => $options) {
					if (is_null($options)) {
						$options = array();
					}
					$options = am($defaults, compact('alias'), $options);
					if (empty($options['alias'])) {
						throw new InvalidArgumentException(sprintf('%s::%s must receive aliased links', get_class($this), __FUNCTION__));
					}

					if (empty($options['table']) && empty($options['class'])) {
						$options['class'] = $options['alias'];
					} elseif (!empty($options['table']) && empty($options['class'])) {
						$options['class'] = Inflector::classify($options['table']);
					}
					$_Model =& ClassRegistry::init($options['class']);			// the incoming model to be linked in query
					$Reference =& ClassRegistry::init($options['reference']); 	// the already in query model that links to $_Model
					$db =& $_Model->getDataSource();
					$associations = $_Model->getAssociated();
					if (isset($associations[$Reference->alias])) {
						$type = $associations[$Reference->alias];
						$association = $_Model->{$type}[$Reference->alias];
					} else {
						$_Model->bind($Reference->alias);
						$type = 'belongsTo';
						$association = $_Model->{$type}[$Reference->alias];
						$_Model->unbindModel(array('belongsTo' => array($Reference->alias)));
					}

					if (empty($options['conditions'])) {
						if ($type === 'belongsTo') {
							$modelKey = $_Model->escapeField($association['foreignKey']);
							$referenceKey = $Reference->escapeField($Reference->primaryKey);
							$options['conditions'] = "{$referenceKey} = {$modelKey}";
						} elseif ($type === 'hasAndBelongsToMany') {
							if (isset($association['with'])) {
								$Link =& $_Model->{$association['with']};
								if (isset($Link->belongsTo[$_Model->alias])) {
									$modelLink = $Link->escapeField($Link->belongsTo[$_Model->alias]['foreignKey']);
								}
								if (isset($Link->belongsTo[$Reference->alias])) {
									$referenceLink = $Link->escapeField($Link->belongsTo[$Reference->alias]['foreignKey']);
								}								
							} else {
								$Link =& $_Model->{Inflector::classify($association['joinTable'])};
							}
							if (empty($modelLink)) {
								$modelLink = $Link->escapeField(Inflector::underscore($_Model->alias) . '_id');
							}
							if (empty($referenceLink)) {
								$referenceLink = $Link->escapeField(Inflector::underscore($Reference->alias) . '_id');
							}
							$referenceKey = $Reference->escapeField();
							$query['joins'][] = array(
								'alias' => $Link->alias,
								'table' => $Link->getDataSource()->fullTableName($Link),
								'conditions' => "{$referenceLink} = {$referenceKey}",
								'type' => 'LEFT'
							);
							$modelKey = $_Model->escapeField();
							$options['conditions'] = "{$modelLink} = {$modelKey}";
						} else {
							$referenceKey = $Reference->escapeField($association['foreignKey']);
							$modelKey = $_Model->escapeField($_Model->primaryKey);
							$options['conditions'] = "{$modelKey} = {$referenceKey}";	
						}
					}
					if (empty($options['table'])) {
						$options['table'] = $db->fullTableName($_Model, true);
					}
					if (!empty($options['fields'])) {
						if ($options['fields'] === true && !empty($association['fields'])) {
							$options['fields'] = $db->fields($_Model, null, $association['fields']);
						} elseif ($options['fields'] === true) {
							$options['fields'] = $db->fields($_Model);
						} else {
							$options['fields'] = $db->fields($_Model, null, $options['fields']);	
						}
						$query['fields'] = array_merge($query['fields'], $options['fields']);
					}

					$options[$this->_key] = am($options[$this->_key], array_diff_key($options, $optionsKeys));
					$options = array_intersect_key($options, $optionsKeys);
					if (!empty($options[$this->_key])) {
						$iterators[] = $options[$this->_key] + array('defaults' => array_merge($defaults, array('reference' => $options['class'])));
					}
					$query['joins'][] = array_intersect_key($options, array('type' => true, 'alias' => true, 'table' => true, 'conditions' => true));
				}
				++$cont;
				$notDone = isset($iterators[$cont]);
			} while ($notDone);
		}
		return $query;
	}
}