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<?php

namespace WPGMZA;

/**
 * The Factory class is a base class which can be used to make any classes
 * externally extensible. A filter is added for wpgmza_create_{class} which
 * is called by createInstance. If this filter returns a subclass of Factory,
 * that filter will override the default class and will be used.
 *
 * IMPORTANT: Any objects which subclass Factory MUST be created by calling
 * createInstance on the subclass. Calling new on the constructor directly will
 * not cause this filter to fire, and the extended class will not be used.
 */
class Factory
{
    /**
     * Creates an instance of the desired subclass, this will return the default instance if no filter is used to override the process, or will return the extended class if a filter has been bound
     * @throws \Exception
     */
    public static function createInstance()
    {
        $class = get_called_class();
        $args = func_get_args();
        $count = count($args);
        $filter = "wpgmza_create_$class";

        if($class == 'WPGMZA\Factory')
            throw new \Exception('Factory createInstance would return abstract Factory');
        
        if(empty($args))
            $filter_args = array($filter, null);
        else
            $filter_args = array_merge(array($filter), $args);
        
        $override = call_user_func_array('apply_filters', $filter_args);
        
        if($override instanceof \WPGMZA\Factory)
            return $override;
        
        $reflect = new \ReflectionClass($class);
        $instance = $reflect->newInstanceArgs($args);
        
        return $instance;
    }
}