<?php 
/** 
 * The SubclassBehavior allows a model to act as a subclass of another model and
 * allows the implementation of 'ISA' relationships in Entity-Relationship database models.   
 * Parameters are passed to this behavior class to define the parent model of the subclass
 * This class was based on and inspired by Matthew Harris's ExtendableBehavior class
 * which can be found at http://bakery.cakephp.org/articles/view/extendablebehavior 
 * 
 * @author 		Eldon Bite <eldonbite@gmail.com> 
 * @license   http://www.opensource.org/licenses/mit-license.php The MIT License 
 */ 
class SubclassBehavior extends ModelBehavior { 
    /** 
     * The parent model being extended by the current model 
     * 
     * @var Object 
     */ 
    var $parentClass;
     
    /** 
     * The name of the type column, default 'type' 
     * 
     * @var string 
     */ 
    var $typeField;
    
    /** 
     * Alias for the subclass/type model 
     * 
     * @var string 
     */ 
    var $typeAlias;
     
    /** 
     * Set up the behavior. 
     * Finds parent model and determines type field settings. 
     */ 
    function setup(&$model, $config = array()) {
        $this->settings  = am(array('typeField' => 'type', 'typeAlias' => $model->alias), $config);
        $this->parentClass = $this->__getparentClass($this->settings['parentClass']);
        $this->typeField = $this->settings['typeField'];
        $this->typeAlias = $this->settings['typeAlias'];
        // Bind model associations on the fly
        foreach ($model->__associations as $assoc) {
                foreach ($this->parentClass->$assoc as $key => $value) {
		        $model->bindModel(array($assoc => array($key)));
                }
        }
    }
     
    /** 
     * Filter query conditions with the correct `type' field condition. 
     */ 
    function beforeFind(&$model, $queryData) 
    {
        if (array_key_exists($this->typeField, $model->_schema) && $model->alias != $this->parentClass->alias) {
            if (!isset($queryData['conditions'])) {
                $queryData['conditions'] = array();
            }
            if (is_string($queryData['conditions'])) {
                if (strlen(trim($queryData['conditions']))) {
                    $queryData['conditions'] = "({$queryData['conditions']}) AND ";
                }
                $queryData['conditions'] .= $model->alias.'.'.$this->typeField.' = '.$this->typeAlias;
            }
            elseif (is_array($queryData['conditions'])) { 
                if (!isset($queryData['conditions'][$model->alias.'.'.$this->typeField])) {
                    $queryData['conditions'][$model->alias.'.'.$this->typeField] = array(); 
                }
                $queryData['conditions'][$model->alias.'.'.$this->typeField] = $this->typeAlias;
            }
             
        }
        return $queryData;
    }
    
    /** 
     * Set the `type' field before saving the record. 
     */ 
    function beforeSave(&$model) 
    { 
        if (array_key_exists($this->typeField, $model->_schema) && $model->alias != $this->parentClass) { 
            if (!isset($model->data[$model->alias])) { 
                $model->data[$model->alias] = array(); 
            } 
            $model->data[$model->alias][$this->typeField] = $model->alias; 
        } 
        return true;
    }
     
    /** 
     * Get the parent model of the subclass.  
     * 
     * @param		string Parent model name
     * @return	object Parent model 
     */ 
    function __getparentClass($parentClass) 
    {
        App::import('model', $parentClass);
        return new $parentClass;
    } 
} 
?>