<?php

/**
 * EventHandler for simple event handling
 * @author Julius Beckmann
 * @url http://juliusbeckmann.de/
 */
class EventHandler {
    
    /**
     * Container for events
     * @type array
     */
    static $events = array();
    
    /**
     * Register a listener on a specific event
     * @param $event    Name of event
     * @param $obj      Object to be used
     * @param $method   Method to be called
     * @param $params   List of params to be used
     * @param $catch    Should Exceptions be catched
     * @return boolean
     */
    static function register($event, $obj, $method='__shutdown', $params=array(), $catch=true) {
        // Check for object
        if(!$obj || !is_object($obj)) {
            return false;
        }
        // Check for method
        if(!is_callable(array($obj, $method))) {
            return false;
        }
        // Register
        self::$events[$event][] = array(
                                    'obj'       => $obj, 
                                    'method'    => $method, 
                                    'params'    => $params,
                                    'catch'     => $catch
                                    );
        return true;
    }
    
    /**
     * Call a specific event
     * @param $event Name of event
     * @return boolean
     */
    static function call($event) {
        // Check for event list
        if(!isset(self::$events[$event])) {
            return false;
        }
        // For each registered object
        foreach(self::$events[$event] as $call) {
            $obj    = $call['obj'];
            $method = $call['method'];
            $params = $call['params'];
            $catch  = $call['catch'];
            // Check if object still exists
            if($obj && is_object($obj)) {
                // Call event
                try {
                  $obj->$method($params);  
                }
                catch(Exception $e) {
                    if(!$catch) {
                        // Raise exception
                        throw $e;
                    }
                }
            }
        }
        return true;
    }
    
}

// Code for testing / demonstration
/*

class Object1 {
    function __construct() {
        EventHandler::register('shutdown', $this, 'my_shutdown', 'Custom Shutdown Param');
    }
    function my_shutdown($param='Default Shutdown Param') {
        echo "Object1::my_shutdown() - Called with: '$param'\n";
    }
}

class Error1 {
    function __construct() {
        // Not existing method
        EventHandler::register('shutdown', $this, 'not_exists');
        
        // Private Method
        EventHandler::register('shutdown', $this, 'my_shutdown');
    }
    private function my_shutdown() {
        echo 'SHOULD NOT BE CALLED!';
    }
}

class Moribundus {
    function __destruct() {
        // Call shutdown event
        EventHandler::call('shutdown');
    }
}

$morb = new Moribundus;
$obj1 = new Object1;
$err1 = new Error1;
unset($morb);

*/