Weapon v3

class Weapon
{
    private readonly int _damage;
    private int _bullets;

    public Weapon() { }

    public Weapon(int damage, int bullets)
    {
        if (damage < 0)
            throw new ArgumentOutOfRangeException();

        if (bullets < 0)
            throw new ArgumentOutOfRangeException();

        _damage = damage;
        _bullets = bullets;
    }

    public bool CanFire => _bullets > 0;

    public void Fire(IDamagable target)
    {
        if (target == null)
            throw new ArgumentNullException("target");

        if (CanFire)
        {
            target.TakeDamage(_damage);
            _bullets--;
        }
    }
}

class Player : IDamagable
{
    private int _health;

    public Player() { }

    public Player(int health)
    {
        if (health < 0)
            throw new ArgumentOutOfRangeException();

        _health = health;
    }

    public bool IsAlive => _health > 0;

    public void TakeDamage(int damage)
    {
        if (damage < 0)
            throw new ArgumentOutOfRangeException();

        if (IsAlive)
            _health = Math.Max(_health - damage, 0);
    }
}

class Bot
{
    private Weapon _weapon;

    public Bot() { }

    public Bot(Weapon weapon)
    {
        if (_weapon == null)
            throw new ArgumentNullException();

        _weapon = weapon;
    }

    public void OnSeePlayer(Player player)
    {
        if (player == null)
            throw new ArgumentNullException();

        if (player.IsAlive && _weapon.CanFire)
            _weapon.Fire(player);
    }
}

interface IDamagable
{
    public void TakeDamage(int damage) { }
}