Category: Design Pattern

<?php
// --- Subsystems --- //

class InventoryService {
    public function checkStock(string $productId): bool {
        echo "Checking stock for product: $productId\n";
        // Simulated logic
        return true;
    }

    public function reserveItem(string $productId): void {
        echo "Reserving item: $productId\n";
    }
}

class PaymentService {
    public function processPayment(float $amount, string $method): bool {
        echo "Processing payment of $$amount via $method\n";
        // Simulated logic
        return true;
    }
}

class ShippingService {
    public function ship(string $productId, string $address): void {
        echo "Shipping product '$productId' to $address\n";
    }
}

class NotificationService {
    public function sendConfirmation(string $email, string $message): void {
        echo "Sending confirmation email to $email: $message\n";
    }
}

// --- Facade --- //

class OrderFacade {
    private InventoryService $inventory;
    private PaymentService $payment;
    private ShippingService $shipping;
    private NotificationService $notification;

    public function __construct() {
        $this->inventory = new InventoryService();
        $this->payment = new PaymentService();
        $this->shipping = new ShippingService();
        $this->notification = new NotificationService();
    }

    /**
     * Simplified order process using the Facade
     */
    public function placeOrder(string $productId, float $amount, string $paymentMethod, string $address, string $customerEmail): void {
        echo "Starting order process...\n";

        if (!$this->inventory->checkStock($productId)) {
            echo "Product not available in stock.\n";
            return;
        }

        $this->inventory->reserveItem($productId);

        if (!$this->payment->processPayment($amount, $paymentMethod)) {
            echo "Payment failed. Order canceled.\n";
            return;
        }

        $this->shipping->ship($productId, $address);
        $this->notification->sendConfirmation($customerEmail, "Your order for '$productId' has been successfully processed!");

        echo "Order completed successfully.\n";
    }
}

// --- Client Code --- //
$orderFacade = new OrderFacade();
$orderFacade->placeOrder(
    productId: 'SKU12345',
    amount: 199.99,
    paymentMethod: 'Credit Card',
    address: '123 Business Street, Cityville',
    customerEmail: 'customer@example.com'
);

<?php
// --- Interfaces --- //

interface InventoryInterface {
    public function checkStock(string $productId): bool;
    public function reserveItem(string $productId): void;
}

interface PaymentInterface {
    public function processPayment(float $amount, string $method): bool;
}

interface ShippingInterface {
    public function ship(string $productId, string $address): void;
}

interface NotificationInterface {
    public function sendConfirmation(string $email, string $message): void;
}

// --- Concrete Implementations --- //

class InventoryService implements InventoryInterface {
    public function checkStock(string $productId): bool {
        echo "Checking stock for product: $productId\n";
        return true;
    }

    public function reserveItem(string $productId): void {
        echo "Reserving item: $productId\n";
    }
}

/**
 * Stripe payment service
 */
class StripePaymentService implements PaymentInterface {
    public function processPayment(float $amount, string $method): bool {
        echo "Processing payment of $$amount via $method\n";
        return true;
    }
}

/**
 * PayPal payment service
 */
class PaypalPaymentService implements PaymentInterface {
    public function processPayment(float $amount, string $method): bool {
        echo "Processing PayPal payment of $$amount using $method\n";
        return true;
    }
}

class ShippingService implements ShippingInterface {
    public function ship(string $productId, string $address): void {
        echo "Shipping product '$productId' to $address\n";
    }
}

class NotificationService implements NotificationInterface {
    public function sendConfirmation(string $email, string $message): void {
        echo "Sending confirmation email to $email: $message\n";
    }
}

// --- Facade --- //

class OrderFacade {
    public function __construct(
        private InventoryInterface $inventory,
        private PaymentInterface $payment,
        private ShippingInterface $shipping,
        private NotificationInterface $notification
    ) {}

    /**
     * High-level method hiding all subsystem complexity
     */
    public function placeOrder(
        string $productId,
        float $amount,
        string $paymentMethod,
        string $address,
        string $customerEmail
    ): void {
        echo "Starting order process...\n";

        if (!$this->inventory->checkStock($productId)) {
            echo "Product not available in stock.\n";
            return;
        }

        $this->inventory->reserveItem($productId);

        if (!$this->payment->processPayment($amount, $paymentMethod)) {
            echo "Payment failed. Order canceled.\n";
            return;
        }

        $this->shipping->ship($productId, $address);
        $this->notification->sendConfirmation(
            $customerEmail,
            "Your order for '$productId' has been successfully processed!"
        );

        echo "Order completed successfully.\n";
    }
}

// --- Client Code --- //
$inventory = new InventoryService();
$payment = new PaypalPaymentService();
$shipping = new ShippingService();
$notification = new NotificationService();

$orderFacade = new OrderFacade($inventory, $payment, $shipping, $notification);

$orderFacade->placeOrder(
    productId: 'SKU12345',
    amount: 199.99,
    paymentMethod: 'PayPal',
    address: '123 Business Street, Cityville',
    customerEmail: 'customer@example.com'
);