<?php

class event implements SplSubject {

        private $pre_storage, $post_storage;

        const PRE_EVENT = 1;
        const POST_EVENT = 2;

        public function __construct() {
                $this->pre_storage = new SplObjectStorage();
                $this->post_storage = new SplObjectStorage();
        }

        public function init()
        {
                // Notify all the observers of a change
                $this->notify( );
        }

        /*
         *
         * @access      public
         * @param       SplObserver     $observer
         * @param       integer         $event_condition
         *
         */
        public function attach( SplObserver $observer, $event_condition=2 )
        {
                switch ( $event_condition )
                {
                        case 1:
                                $this->pre_storage->attach( $observer );
                                break;

                        case 2:
                                $this->post_storage->attach( $observer );
                                break;

                        default:
                                throw new Exception("Storage type not available");
                }
        }


        public function detach( SplObserver $observer ) {
                $this->storage->detach( $observer );
        }

        public function notify()
        {
                foreach ( $this->pre_storage as $observer )
                {
                        $observer->update( $this );
                }
                foreach ( $this->post_storage as $observer )
                {
                        $observer->update( $this );
                }
        }
} // end events class


class signupEmailer implements splObserver{

        public function update( SplSubject $SplSubject )
        {
                $status = $SplSubject->getStatus();
                switch ( $status[0] ) {

                        case signup::USERNAME_TAKEN:
                                echo __CLASS__ . ": Username taken!.\n";
                                break;

                        case signup::USERNAME_TOO_LONG:
                                echo __CLASS__ . ": Username too long.\n";
                                break;

                        case signup::USERNAME_TOO_SHORT:
                                echo __CLASS__ . ": Username is too short.\n";
                                break;

                        case signup::ALLOW:
                                echo  __CLASS__ . ": Username is good, Emailing admin success\n";
                                break;

                        default: throw new Exception( "Invalid status\n" );
                }
        }
} // end of mailer class


        class logger implements splObserver{

                public function update( SplSubject $SplSubject )
                {
                        echo __CLASS__." : Logged an event\n";
                }
        }

        class checkUser implements splObserver{

                public function update( SplSubject $SplSubject )
                {
                        echo __CLASS__.": This happens before the event\n";
                }
        } // end checkUser class


        class signup extends event{

                const USERNAME_TAKEN = 1;
                const USERNAME_TOO_SHORT = 2;
                const USERNAME_TOO_LONG = 3;
                const ALLOW = 4;

                public $status = array();
                public $username, $password, $ip_address;

                function init()
                {

                        // Let's simulate different signin conditions
                        $this->setStatus( rand( 1, 4 ) );

                        // Notify all the observers of a change
                        $this->notify();

                        if ( $this->status[0] == self::ALLOW ) {
                                return true;
                        }
                        return false;
                }

                private function setStatus( $status ) {
                        $this->status = array( $status, $this->username, $this->password, $this->ip_address );
                }

                function getStatus() {
                        return $this->status;
                }

        }

        // the new login class implements splSubject
        $signup = new signup();
        $signup->username = 'freddy';
        $signup->password = 'queen';
        $signup->ip_address = '127.0.0.1';

        // Attach classes to observer/listen for a login event
        $signup->attach( new signupEmailer() );
        $signup->attach( new logger() );
        $signup->attach( new checkUser, 1 );

        if( $signup->init() !== false )
        {
                echo "Signup success\n";
        }
        else
        {
                echo print_r( $signup->status );
        }