State pattern in PHP

state-pattern.php

<?php

// Interface for states
interface DeploymentState
{
    public function handle(DeploymentManager $manager);
}

// Concrete state class
class PendingState implements DeploymentState
{
    public function handle(DeploymentManager $manager)
    {
        echo "Deployment is pending.\n";
        // Transition to next state
        $manager->setState(new DeployingState());
    }
}

// Concrete state class
class DeployingState implements DeploymentState
{
    public function handle(DeploymentManager $manager)
    {
        echo "Deploying...\n";
        sleep(5);
        $manager->setState(new DeployedState());
    }
}

// Concrete state class
class DeployedState implements DeploymentState
{
    public function handle(DeploymentManager $manager)
    {
        echo "Deployment is successful.\n";
    }
}

// The context class
class DeploymentManager
{
    private $state;

    public function __construct()
    {
        $this->setState(new PendingState());
    }

    public function setState(DeploymentState $state)
    {
        $this->state = $state;
    }

    public function deploy()
    {
        $this->state->handle($this);
    }
}

// Example
$manager = new DeploymentManager();
$manager->deploy(); // Output: Deployment is pending.
$manager->deploy(); // Output: Deploying...
$manager->deploy(); // Output: Deployment is successful.