PHP Interfaces and Abstract Classes

<?php
interface Drawable {
    public function draw(): string;
    public function getArea(): float;
}

interface Colorable {
    public function setColor(string $color): void;
    public function getColor(): string;
}

// Implementing multiple interfaces
class Circle implements Drawable, Colorable {
    private string $color = "black";

    public function __construct(private float $radius) {}

    public function draw(): string {
        return "Drawing circle with radius {$this->radius}";
    }

    public function getArea(): float {
        return M_PI * $this->radius ** 2;
    }

    public function setColor(string $color): void {
        $this->color = $color;
    }

    public function getColor(): string {
        return $this->color;
    }
}

$c = new Circle(5.0);
$c->setColor("red");
echo $c->draw();              // Drawing circle with radius 5
echo round($c->getArea(), 2); // 78.54
echo $c->getColor();          // red
?>

<?php
abstract class Shape {
    protected string $color;

    public function __construct(string $color = "black") {
        $this->color = $color;
    }

    // Abstract — must be implemented by child
    abstract public function area(): float;
    abstract public function perimeter(): float;

    // Concrete — shared implementation
    public function describe(): string {
        return sprintf(
            "%s: area=%.2f, perimeter=%.2f, color=%s",
            get_class($this),
            $this->area(),
            $this->perimeter(),
            $this->color
        );
    }
}

class Rectangle extends Shape {
    public function __construct(
        private float $width,
        private float $height,
        string $color = "blue"
    ) {
        parent::__construct($color);
    }

    public function area(): float      { return $this->width * $this->height; }
    public function perimeter(): float { return 2 * ($this->width + $this->height); }
}

$rect = new Rectangle(4, 6, "green");
echo $rect->describe(); // Rectangle: area=24.00, perimeter=20.00, color=green
?>

<?php
trait Timestampable {
    private ?string $createdAt = null;
    private ?string $updatedAt = null;

    public function setCreatedAt(): void {
        $this->createdAt = date("Y-m-d H:i:s");
    }

    public function setUpdatedAt(): void {
        $this->updatedAt = date("Y-m-d H:i:s");
    }

    public function getTimestamps(): array {
        return ["created" => $this->createdAt, "updated" => $this->updatedAt];
    }
}

trait SoftDeletable {
    private bool $deleted = false;

    public function softDelete(): void { $this->deleted = true; }
    public function restore(): void    { $this->deleted = false; }
    public function isDeleted(): bool  { return $this->deleted; }
}

class Post {
    use Timestampable, SoftDeletable; // use multiple traits

    public function __construct(public string $title) {
        $this->setCreatedAt();
    }
}

$post = new Post("Hello World");
$post->softDelete();
echo $post->isDeleted() ? "deleted" : "active"; // deleted
print_r($post->getTimestamps());
?>