<?php
/* Please see the README and LICENSE files. */

/**
 * Facade or API for the caching stuff
 */
class Cache_Subsystem implements System_Subsystem{
    
    protected static $default_controller = self::CONTROLLER_FILE;
    /* 
     * Bitflags used for automagically deciding cache controller for an object
     */
    const EXPENSE_COMPUTATION = 1;
    const EXPENSE_IO_REMOTE = 2;
    const EXPENSE_IO_DB = 4;
    const EXPENSE_IO_FILE = 8;
    
    /*
     * Flags representing controllers
     */
    const CONTROLLER_MEMCACHE = 1;
    const CONTROLLER_FILE = 2;
    const CONTROLLER_DB = 3;
    
    public static function cache($name,$object,$age,$controller){
        $controller = self::controller_factory($controller);
        $controller->set($name, $object, $age);
        return true;
    }
    
    public static function cache_get($name,$controller){
        $controller = self::controller_factory($controller);
        return $controller->get($name);
    }
    
    protected static function controller_factory($controller){
        switch($controller){
            case self::CONTROLLER_MEMCACHE:
                return new Cache_Controller_Memcache();                
                break;
            default:
            case self::CONTROLLER_FILE:
                return new Cache_Controller_File();
                break;
            case self::CONTROLLER_DB:
                return new Cache_Controller_Db();
                break;
        }
    }
    
    
    
    
    
    /**
     * Pick a controller based on the the fags, and save an object
     * 
     * @param String $name The unique name
     * @param Mixed $object The object
     * @param int $age The age in seconds
     * @param int $flags The bitflags for controller determination
     */
    public static function auto_cache($name,$object,$age,$flags=0){
        $controller = $flag>0 ? self::pick_controller($flags):self::$default_controller;
        self::cache($name,$object,$age,$controller);
    }
    
    public static function pick_controller($flags){
        # TODO
        #
        # Use the bitflag consts to pick a correct controller
        # Ex, things that are db or file expenses could be memcache candidates 
        # whereas computation and remote expenses could be file candidates
    }
    
    
}

?>