<?php

// 中介者接口
interface Mediator {
    public function sendMessage($message, Colleague $colleague);
}

// 具体中介者类
class ConcreteMediator implements Mediator {
    private $colleague1;
    private $colleague2;

    public function setColleague1(Colleague $colleague1) {
        $this->colleague1 = $colleague1;
    }

    public function setColleague2(Colleague $colleague2) {
        $this->colleague2 = $colleague2;
    }

    public function sendMessage($message, Colleague $colleague) {
        if ($colleague == $this->colleague1) {
            $this->colleague2->receiveMessage($message);
        } elseif ($colleague == $this->colleague2) {
            $this->colleague1->receiveMessage($message);
        }
    }
}

// 同事类
abstract class Colleague {
    protected $mediator;

    public function __construct(Mediator $mediator) {
        $this->mediator = $mediator;
    }

    abstract public function send($message);
    abstract public function receiveMessage($message);
}

// 具体同事类
class ConcreteColleague1 extends Colleague {
    public function send($message) {
        echo "Colleague1 sends message: $message\n";
        $this->mediator->sendMessage($message, $this);
    }

    public function receiveMessage($message) {
        echo "Colleague1 receives message: $message\n";
    }
}

// 具体同事类
class ConcreteColleague2 extends Colleague {
    public function send($message) {
        echo "Colleague2 sends message: $message\n";
        $this->mediator->sendMessage($message, $this);
    }

    public function receiveMessage($message) {
        echo "Colleague2 receives message: $message\n";
    }
}

// 客户端代码
$mediator = new ConcreteMediator();

$colleague1 = new ConcreteColleague1($mediator);
$colleague2 = new ConcreteColleague2($mediator);

$mediator->setColleague1($colleague1);
$mediator->setColleague2($colleague2);

$colleague1->send("Hello from Colleague1");
$colleague2->send("Hi from Colleague2");