<?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, 'joins' => true,
		'conditions' => true, 'fields' => true, 'reference' => true,
		'class' => true, 'defaults' => true
	);

	protected $_defaults = array('type' => 'LEFT');
	
	public function beforeFind(&$Model, $query) {
/* 	  pr("Linkable::beforeFind() begin"); pr($query); */
		if (isset($query[$this->_key])) {
			$optionsDefaults = $this->_defaults + array('reference' => $Model->alias, $this->_key => array());
			$optionsKeys = $this->_options + array($this->_key => true);
			if (!isset($query['fields']) || $query['fields'] === true) {
			  //$query['fields'] = array_keys($Model->_schema);
			  $query['fields'] = $Model->getDataSource()->fields($Model);
			} elseif (!is_array($query['fields'])) {
			  $query['fields'] = array($query['fields']);
			}
			$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
/* 					pr("_Model: $options[class] : $_Model->name ($_Model->alias)"); */
/* 					pr("Reference: $options[reference] : $Reference->name ($Reference->alias)"); */
					$db =& $_Model->getDataSource();

					$associatedThroughReference = 0;
					$association = null;

					// Figure out how these two models are related, creating
					// a relationship if one doesn't otherwise already exists.
				        if (($associations = $Reference->getAssociated()) &&
					    isset($associations[$_Model->alias])) {
/* 						pr("Reference defines association to _Model"); */
						$associatedThroughReference = 1;
						$type = $associations[$_Model->alias];
						$association = $Reference->{$type}[$_Model->alias];
					}
					elseif (($associations = $_Model->getAssociated()) &&
					    isset($associations[$Reference->alias])) {
/* 						pr("_Model defines association to Reference"); */
						$type = $associations[$Reference->alias];
						$association = $_Model->{$type}[$Reference->alias];
					}
					else {
						// No relationship... make our best effort to create one.
/* 						pr("No assocation between _Model and Reference"); */
						$type = 'belongsTo';
						$_Model->bind($Reference->alias);
						// Grab the association now, since we'll unbind in a moment.
						$association = $_Model->{$type}[$Reference->alias];
						$_Model->unbindModel(array('belongsTo' => array($Reference->alias)));
					}

					// Determine which model holds the foreign key
					if (($type === 'hasMany' || $type === 'hasOne') ^ $associatedThroughReference) {
						$primaryModel = $Reference;
						$foreignModel = $_Model;
					} else {
						$primaryModel = $_Model;
						$foreignModel = $Reference;
					}

/* 					pr("primaryModel: $primaryModel->name ($primaryModel->alias)"); */
/* 					pr("foreignModel: $foreignModel->name ($foreignModel->alias)"); */
/* 					pr($type); */
/* 					pr($association); */

					if (empty($options['conditions'])) {
						if ($type === 'hasAndBelongsToMany') {
							if (isset($association['with']))
								$Link =& $_Model->{$association['with']};
							else
								$Link =& $_Model->{Inflector::classify($association['joinTable'])};

							$linkAlias = $Link->alias;
							//$linkAlias = $Link->alias . $options['alias'];

							// Get the foreign key fields (for the link table) directly from
							// the defined model associations, if they exists.  This is the
							// users direct specification, and therefore definitive if present.
							$modelLink = $Link->escapeField($association['foreignKey'], $linkAlias);
							$referenceLink = $Link->escapeField($association['associationForeignKey'], $linkAlias);

							// If we haven't figured out the foreign keys, see if there is a
							// model for the link table, and if it has the appropriate
							// associations with the two tables we're trying to join.
							if (empty($modelLink) && isset($Link->belongsTo[$_Model->alias]))
								$modelLink = $Link->escapeField($Link->belongsTo[$_Model->alias]['foreignKey'], $linkAlias);
							if (empty($referenceLink) && isset($Link->belongsTo[$Reference->alias]))
								$referenceLink = $Link->escapeField($Link->belongsTo[$Reference->alias]['foreignKey'], $linkAlias);

							// We're running quite thin here.  None of the models spell
							// out the appropriate linkages.  We'll have to SWAG it.
							if (empty($modelLink))
								$modelLink = $Link->escapeField(Inflector::underscore($_Model->alias) . '_id', $linkAlias);
							if (empty($referenceLink))
								$referenceLink = $Link->escapeField(Inflector::underscore($Reference->alias) . '_id', $linkAlias);

							// Get the primary key from the tables we're joining.
							$referenceKey = $Reference->escapeField();
							$modelKey = $_Model->escapeField();
								
							// Join the linkage table to our model.  We'll use an inner join,
							// as the whole purpose of the linkage table is to make this
							// connection.  As we are embedding this join, the INNER will not
							// cause any problem with the overall query, should the user not
							// be concerned with whether or not the join has any results.
							// They control that with the 'type' parameter which will be at
							// the top level join.
							$options['joins'][] = array('type'  => 'INNER',
																					'alias' => $options['alias'],
																					'conditions' => "{$modelKey} = {$modelLink}",
																					'table' => $db->fullTableName($_Model, true));

							// Now for the top level join.  This will be added into the list
							// of joins down below, outside of the HABTM specific code.
							$options['alias'] = $linkAlias;
							$options['table'] = $Link->getDataSource()->fullTableName($Link);
							$options['conditions'][] = "{$referenceLink} = {$referenceKey}";
						}
						elseif (isset($association['foreignKey']) && $association['foreignKey']) {
							$foreignKey = $primaryModel->escapeField($association['foreignKey']);
							$primaryKey = $foreignModel->escapeField($foreignModel->primaryKey);

							// Only differentiating to help show the logical flow.
							// Either way works and this test can be tossed out
							if (($type === 'hasMany' || $type === 'hasOne') ^ $associatedThroughReference)
								$options['conditions'][] = "{$primaryKey} = {$foreignKey}";
							else
								$options['conditions'][] = "{$foreignKey} = {$primaryKey}";
						}
						else {
							// No Foreign Key... nothing we can do.
							$options['conditions'] = array();
						}

						// The user may have specified conditions directly in the model
						// for this join.  Make sure to adhere to those conditions.
						if (isset($association['conditions']) && is_array($association['conditions']))
							$options['conditions'] = array_merge($options['conditions'], $association['conditions']);
						elseif (!empty($association['conditions']))
							$options['conditions'][] = $association['conditions'];

/* 						pr(array("Link ", $options['conditions'])); */
						//pr($modelKey);
						//pr($referenceKey);

					}
					if (empty($options['table'])) {
						$options['table'] = $db->fullTableName($_Model, true);
					}

					if (!isset($options['fields']) || !is_array($options['fields']))
					  $options['fields'] = $db->fields($_Model);
					elseif (!empty($options['fields']))
					  $options['fields'] = $db->fields($_Model, null, $options['fields']);
					    
					$query['fields'] = array_merge($query['fields'], $options['fields'],
								       (empty($association['fields']) 
									? array() : $db->fields($_Model, null, $association['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, 'joins' => true, 'conditions' => true));
				}
				++$cont;
				$notDone = isset($iterators[$cont]);
			} while ($notDone);
		}
/* 		pr("Linkable::beforeFind() end"); pr($query); */
		return $query;
	}
}