made some refactoring

src/Pattern/SOLID/OpenClosed/Figures/AreaCalculator.php

@@ -0,0 +1,33 @@
+<?php
+
+/**
+ * @package: patterns
+ * @author: Yevhen Odynets
+ * @date: 2025-07-07
+ * @time: 05:28
+ */
+
+declare(strict_types = 1);
+
+namespace Pattern\SOLID\OpenClosed\Figures;
+
+class AreaCalculator
+{
+    /**
+     * @param  array  $shapes
+     *
+     * @return int|float
+     */
+    public function calculate(array $shapes, int $round_precision = 2): int|float
+    {
+        $area = [];
+
+        foreach ($shapes as $shape) {
+            $area[] = $shape->area();
+        }
+
+        $result = array_sum($area);
+
+        return is_int($result) ? $result : round($result, $round_precision, PHP_ROUND_HALF_UP);
+    }
+}

src/Pattern/SOLID/OpenClosed/Figures/Circle.php

@@ -0,0 +1,25 @@
+<?php
+
+/**
+ * @package: patterns
+ * @author: Yevhen Odynets
+ * @date: 2025-07-07
+ * @time: 05:32
+ */
+
+declare(strict_types = 1);
+
+namespace Pattern\SOLID\OpenClosed\Figures;
+
+class Circle implements ShapeInterface
+{
+    public function __construct(public int|float $radius) {}
+
+    /**
+     * @return int|float
+     */
+    public function area(): int|float
+    {
+        return M_PI * ($this->radius ** 2);
+    }
+}

src/Pattern/SOLID/OpenClosed/Figures/ShapeInterface.php

@@ -0,0 +1,17 @@
+<?php
+
+/**
+ * @package: patterns
+ * @author: Yevhen Odynets
+ * @date: 2025-07-07
+ * @time: 05:55
+ */
+
+declare(strict_types = 1);
+
+namespace Pattern\SOLID\OpenClosed\Figures;
+
+interface ShapeInterface
+{
+    public function area(): int|float;
+}

src/Pattern/SOLID/OpenClosed/Figures/Square.php

@@ -0,0 +1,25 @@
+<?php
+
+/**
+ * @package: patterns
+ * @author: Yevhen Odynets
+ * @date: 2025-07-07
+ * @time: 05:27
+ */
+
+declare(strict_types = 1);
+
+namespace Pattern\SOLID\OpenClosed\Figures;
+
+class Square implements ShapeInterface
+{
+    public function __construct(public int|float $width, public int|float $height) {}
+
+    /**
+     * @return int|float
+     */
+    public function area(): int|float
+    {
+        return $this->width * $this->height;
+    }
+}

src/Pattern/SOLID/OpenClosed/Payments/CashPaymentMethod.php

@@ -0,0 +1,20 @@
+<?php
+
+/**
+ * @package: patterns
+ * @author: Yevhen Odynets
+ * @date: 2025-07-07
+ * @time: 06:20
+ */
+
+declare(strict_types = 1);
+
+namespace Pattern\SOLID\OpenClosed\Payments;
+
+class CashPaymentMethod implements PaymentMethodInterface
+{
+    public function acceptPayment($receipt)
+    {
+        // TODO: Implement acceptPayment() method.
+    }
+}

src/Pattern/SOLID/OpenClosed/Payments/Checkout.php

@@ -0,0 +1,20 @@
+<?php
+
+/**
+ * @package: patterns
+ * @author: Yevhen Odynets
+ * @date: 2025-07-07
+ * @time: 06:19
+ */
+
+declare(strict_types = 1);
+
+namespace Pattern\SOLID\OpenClosed\Payments;
+
+class Checkout
+{
+    public function begin(Receipt $receipt, PaymentMethodInterface $payment): void
+    {
+        $payment->acceptPayment($receipt);
+    }
+}

src/Pattern/SOLID/OpenClosed/Payments/PaymentMethodInterface.php

@@ -0,0 +1,17 @@
+<?php
+
+/**
+ * @package: patterns
+ * @author: Yevhen Odynets
+ * @date: 2025-07-07
+ * @time: 06:20
+ */
+
+declare(strict_types = 1);
+
+namespace Pattern\SOLID\OpenClosed\Payments;
+
+interface PaymentMethodInterface
+{
+    public function acceptPayment($receipt);
+}

src/Pattern/SOLID/OpenClosed/Payments/Receipt.php

@@ -0,0 +1,14 @@
+<?php
+
+/**
+ * @package: patterns
+ * @author: Yevhen Odynets
+ * @date: 2025-07-07
+ * @time: 06:24
+ */
+
+declare(strict_types = 1);
+
+namespace Pattern\SOLID\OpenClosed\Payments;
+
+class Receipt {}