<?php
/**
 * Event_Queue
 *
 *
 * $Id$
 *
 * @author gERD Schaufelberger <gerd@php-tools.net>
 * @license PHP License
 * @package WB
 * @subpackage base
 */

WBClass::load('WBEvent');

/**
 * Event_Queue
 *
 *
 *
 * @version 0.2.1
 * @package WB
 * @subpackage base
 */
class WBEvent_Queue extends WBStdClass
{
    /**
     * singleton instance
     * @var WBEvent_Queue
     */
    protected static $instance = null;

    /**
     * table onject to access event queue
     * @var WBDatasource_Table_EventQueue
     */
    protected $table;

    /**
     * list of known matches and actions
     * @var array
     */
    protected $actions;

    /**
     * config loader
     * @var WEConfig
     */
    protected $config;

    /**
     * logger
     * @var WBLog
     */
    protected $log;

    /**
     * current event processing position
     * @var int
     */
    protected $procPos      =   0;

    /**
     * numer of events to process
     * @var int
     */
    protected $procCount    =   0;

    /**
     * get singleton instance
     *
     * @return WBEvent_Queue
     */
    public static function create()
    {
        if (self::$instance) {
            return self::$instance;
        }

        self::$instance =   new WBEvent_Queue();
        return self::$instance;
    }

    /**
     * constructor
     *
     * init table access and verify event.xml
     */
    private function __construct()
    {
        WBClass::load('WBLog'
                , 'WBClock');

        $this->log      =   WBLog::start(__CLASS__);

        $this->table    =   WBClass::create('WBDatasource_Table_EventQueue');
        $this->config   =   WBClass::create('WBConfig');
        $this->config->load('event');
        $this->actions  =   $this->config->get('actions', array());
        if (!is_array($this->actions)) {
            $this->actions  =   array();
            return;
        }

        // mormalize list of actions
        foreach ($this->actions as &$a) {
            if (!isset($a['match']) || !isset($a['chains'])) {
                $e  =   array(
                                'msg'   =>  'Error in event.xml - check "match" and "chains"',
                                'code'  =>  1,
                                'class' => __CLASS__
                            );
                throw WBClass::create('WBException_Config', $e);
            }

        }
    }

    /**
     * deny cloning object
     *
     */
    private function __clone()
    {
    }

    /**
     * add event to queue
     *
     * store event information in queue
     *
     * @param string $name
     * @param string $msg
     * @param array $data
     * @param string $timestamp in ISO format
     */
    public function add($name, $msg, $data, $timestamp)
    {
        $actions    =   $this->getActions($name);
        if (empty($actions)) {
            return null;
        }

        // log add event
        $log    =   array(
                            'action'    =>  'add',
                            'namespace' =>  '',
                            'name'      =>  $name,
                            'chain'     =>  ''
                            );
        foreach ($actions as $a) {

            // normalize "now", "async" and "namespace"
            if (isset($a['now'])) {
                $a['now']   =   true;
            } else {
                $a['now']   =   false;
            }
            if (isset($a['async'])) {
                $a['async'] =   true;
            } else {
                $a['async'] =   false;
            }
            if (!isset($a['namespace']) || empty($a['namespace'])) {
                $a['namespace'] =   '';
            }

            $save   =   array(
                        'name'      =>  $name,
                        'action'    =>  $a['action'],
                        'namespace' =>  $a['namespace'],
                        'message'   =>  $msg,
                        'data'      =>  serialize($data),
                        'created'   =>  $timestamp
                    );
            $id =   $this->table->save('eventqueue', '__new', $save);

            $log['namespace']   =   $a['namespace'];
            $log['chain']       =   $a['action'];
            $this->log->debug($log);

            // process immediatly
            if ($a['now']) {
                $this->process($id);
                continue;
            }

            // process immediatly but assynchroniously
            if ($a['async']) {
                $this->processAsync($id);
                continue;
            }
        }
    }

    /**
     * Create Event Object
     *
     * @param array action data
     * @return WBEvent
     */
    public function action2Event($action)
    {
        if (empty($action['name']) || empty($action['data']) || empty($action['message']) || empty($action['created'])) {
            $e  =   array(
                            'msg'   =>  'Event action data insufficient',
                            'code'  =>  2,
                            'class' => __CLASS__
                        );
            throw WBClass::create('WBException_Argument', $e);
        }

        // event data
        $data   =   unserialize($action['data']);

        // create event onject
        WBClass::load('WBEvent');
        return  WBEvent::create($action['name'], $action['message'], $data, $action['created']);
    }

    /**
     * process single event action chain
     *
     * load chain from queue. Create event object and call all
     * event handler.
     *
     * The chain will be marked as failed when exception was caught.
     *
     * Handlers will processed in same order they appear in chain config.
     * Process chain as long as handlers return "true", break on "false"
     *
     * @param string $id
     */
    public function process($id)
    {
        if (empty($id)) {
            return;
        }
        $now    =   WBClock::now();

        // load action
        $action =   $this->table->get('eventqueue', $id);
        $action =   $action[0];

        $log    =   array(
                        'action'    =>  'processid',
                        'namespace' =>  $action['namespace'],
                        'id'        =>  $id,
                        'chain'     =>  $action['action'],
                        'actions'   =>  0,
                        'elapsed'   =>  '0ms',
                        'msg'       =>  'OK'
                        );
        // load chain
        if (!$this->config->load('event/' . $action['action'], true)) {
            $log['msg']     =   sprintf('Could not load action chain from "%s"', $action['action']);
            $log['elapsed'] =   WBClock::stop($now, 1000, 1) . 'ms';
            $this->log->err($log);

            $save   =   array('failed' => 1);
            $this->table->save('eventqueue', $id, $save);
            return;
        }

        $chain  =   $this->config->get('chain', array());
        if (!is_array($chain)) {
            $chain  =   array();
        }
        $log['actions'] =   count($chain);
        $this->log->info($log);

        $event  =   $this->action2Event($action);

        // process chain
        foreach ($chain as $c) {

            if (!isset($c['handler'])) {
                continue;
            }

            if (!isset($c['params']) || !is_array($c['params'])) {
                $c['params']    =   array();
            }

            // start handler
            try{
                $h  =   WBClass::create('WBEvent_Handler_' . $c['handler']);
                $h->setConfig($c['params']);
            } catch(Exception $e) {
                $log['msg']     =   sprintf('Failed to instantiate event handler "%s"', $c['handler']);
                $log['elapsed'] =   WBClock::stop($now, 1000, 1) . 'ms';
                $this->log->err($log);

                $save   =   array('failed' => 1);
                $this->table->save('eventqueue', $id, $save);
                return;
            }

            // process event and see whether to break
            try{
                $eLog   =   array(
                            'action'    =>  'process',
                            'handler'   =>  $c['handler'],
                            'result'    =>  intval($h->process($event))
                        );
                $this->log->info($eLog);
                if (1 > $eLog['result']) {
                    break;
                }

            } catch(Exception $e) {
                // get processing time
                $log['elapsed'] =   WBClock::stop($now, 1000, 1) . 'ms';

                // if error is recoverable retry next time
                if ($h->isRecoverable()) {
                    $log['msg']     =   sprintf('Caught recoverable exception while processing "%s"', $c['handler']);
                    $this->log->err($log);
                    return;
                }

                $log['msg']     =   sprintf('Caught exception while processing "%s"', $c['handler']);
                $this->log->err($log);

                $eLog   =   array(
                            'action'    =>  'exception',
                            'handler'   =>  $c['handler'],
                            'code'      =>  $e->getCode(),
                            'msg'       =>  $e->getMessage()
                        );
                $this->log->notice($eLog);

                $save   =   array('failed' => 1);
                $this->table->save('eventqueue', $id, $save);
                return;
            }
        }

        // delete action on success
        $log['elapsed'] =   WBClock::stop($now, 1000, 1) . 'ms';
        $this->log->warn($log);
        $this->table->delete('eventqueue', $id);
    }

    /**
     * Process Event Asynchroniously
     *
     * Execute event queue processor to
     *
     * @param string $id
     */
    public function processAsync($id)
    {
        $base   =   WBParam::get('wb/dir/base');
        $cmd    =   '%s/bin/eqp.php -q run "%s" >>/dev/null 2>/dev/null </dev/null &';
        $cmd    =   sprintf($cmd, $base, $id);

        exec($cmd, $out, $ret);
    }

    /**
     * Find first actions for event name
     *
     * Find machting actions and return list of it
     *
     * @param string $name
     * @return array
     */
    public function getActions($name)
    {
        foreach($this->actions as $a) {
            if (preg_match($a['match'], $name)) {
                if (!isset($a['chains']) || empty($a['chains'])) {
                    return array();
                }

                if (!isset($a['chains'][0])) {
                    $a['chains']    =   array($a['chains']);
                }

                return $a['chains'];
                break;
            }
        }

        return array();
    }
}