<?php
/* -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
# ***** BEGIN LICENSE BLOCK *****
# This file is part of Plume Framework, a simple PHP Application Framework.
# Copyright (C) 2001-2007 Loic d'Anterroches and contributors.
#
# Plume Framework is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
#
# Plume Framework is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#
# ***** END LICENSE BLOCK ***** */

/**
 * Class to process a Pluf_Queue.
 *
 * This class is very simple as basically this is just a signal
 * handler. It goes throught the queue, get a free item, lock it,
 * process it by sending a signal then mark it as done.
 * 
 */
class Pluf_Queue_Processor
{
    /**
     * Get an item to process.
     *
     * @return mixed False if no item to proceed.
     */
    public static function getItem()
    {
        $item = false;
        $db = Pluf::db();
        $db->begin();
        // In a transaction to not process the same item at
        // the same time from to processes.
        $gqueue = new Pluf_Queue();
        $items = $gqueue->getList(array('filter' => $db->qn('lock').'=0',
                                         'order' => 'creation_dtime ASC'));
        if ($items->count() > 0) {
            $item = $items[0];
            $item->lock = 1;
            $item->update();
        }
        $db->commit();
        if ($item === false) return false;
        // try to get the corresponding object
        $obj = Pluf::factory($item->model_class, $item->model_id);
        if ($obj->id != $item->model_id) $obj = null;
        return array('queue' => $item, 'item' => $obj);
    }

    public static function process()
    {
        while (false !== ($q = self::getItem())) {
            /**
             * [signal]
             *
             * Pluf_Queue_Processor::process
             *
             * [sender]
             *
             * Pluf_Queue_Processor
             *
             * [description]
             *
             * This signal allows an application to perform an action on a
             * queue item. The item is set to null if none existing.
             *
             * You must not modify the 'queue' object.
             *
             * [parameters]
             *
             * array('item' => $item, 'queue' => $queue);
             *
             *
             */
            Pluf_Signal::send('Pluf_Queue_Processor::process', 
                              'Pluf_Queue_Process', $q);
            $q['queue']->lock = 2;
            $q['queue']->update();            
        }
    }
}