poison.cs

public class Poison : DamageOverTime
{ 
    private Damage DamagePerTick;
    private static float DEFAULT_DURATION = 10f;
    private static float DEFAULT_PERIOD = 1f;
    private static HashSet<DamageType> damageTypes = new HashSet<DamageType> { DamageType.DAMAGE_OVER_TIME, DamageType.POISON };

    public Poison(float damageAmountPerTick) : base(new Damage(damageTypes, damageAmountPerTick * (DEFAULT_DURATION / DEFAULT_PERIOD)), DEFAULT_PERIOD, DEFAULT_DURATION)
    {
        DamagePerTick = new Damage(damageTypes, damageAmountPerTick * (DEFAULT_DURATION / DEFAULT_PERIOD));
    }

    public Poison(float damageAmountPerTick, float timeRemaining) : this(damageAmountPerTick)
    {
        this.timeRemaining = timeRemaining;
        damageRemaining = DamagePerTick * TicksRemaining();
        elapsedTime = duration - timeRemaining;
    }

    public override Damage TickDamage => DamagePerTick;

    public override DamageOverTime Add(DamageOverTime otherDot)
    {
        if(!Matches(otherDot)) {
            return this;
        }
        if(otherDot.TickDamage.Amount > TickDamage.Amount)
        {
            return otherDot;
        }

        return this;
    }

    public override List<Attribute> GetAttributes()
    {
        return new List<Attribute> { };
    }

    public override bool Matches(DamageOverTime otherDot)
    {
        return otherDot is Poison;
    }

    public override DamageOverTime Multiply(float damageScalar)
    {
        return new Poison(DamagePerTick.Amount * damageScalar, timeRemaining);
    }

    public override Pair<Damage, DamageOverTime> Tick()
    {
        float newTimeRemaining = timeRemaining - period;
        if (newTimeRemaining <= 0)
        {
            return new Pair<Damage, DamageOverTime>(Damage.zero(), Expired);
        }
        return Pair<Damage, DamageOverTime>.Of(DamagePerTick, new Poison(DamagePerTick.Amount, newTimeRemaining));
    }
}