Virus.php

<?php

class Virus {
    public array $children = [];

    public function __construct(
        public float $weight,
        public int $age,
        public string $name,
        public string $type
    ) {}

    public function addChild(Virus $virus): void {
        $this->children[] = $virus;
    }
    public function __clone() {
        foreach ($this->children as $key => $child) {
            $this->children[$key] = clone $child;
        }
    }
    public function getTreeHtml(int $level = 0): string {
        $indent = str_repeat("&nbsp;&nbsp;&nbsp;&nbsp;", $level);
        $html = "{$indent}🦠 <strong>{$this->name}</strong> [Вид: {$this->type}, Вага: {$this->weight} мг, Вік: {$this->age} год]<br>";

        foreach ($this->children as $child) {
            $html .= $child->getTreeHtml($level + 1);
        }
        return $html;
    }
}