A single method util for getting the resulting potion from a potion brew

PotionResults.java

@EventHandler
public void brew(BrewEvent e) {
	ItemStack[] contents = e.getContents().getContents();
	for (int i = 2; i >= 0; i--) {
		PotionType type = result(contents[i], contents[3]);
		if (type == null) continue;
	}
}

private static PotionType result(ItemStack potion, ItemStack ing) {
	if (potion == null) return null;
	Material type = ing.getType();
	if (potion.getDurability() == 0) {
		if (type == Material.FERMENTED_SPIDER_EYE)
			return PotionType.WEAKNESS;
		return PotionType.WATER;
	}
	Potion pot = Potion.fromItemStack(potion);
	if (pot.getType() == null) pot.setType(PotionType.WATER);
	switch (pot.getType()) {
	case FIRE_RESISTANCE:
		if (type == Material.FERMENTED_SPIDER_EYE)
			return PotionType.SLOWNESS;
		return pot.getType();
	case INSTANT_DAMAGE:
		return pot.getType();
	case INSTANT_HEAL:
		if (type == Material.FERMENTED_SPIDER_EYE)
			return PotionType.INSTANT_DAMAGE;
		return pot.getType();
	case INVISIBILITY:
		return pot.getType();
	case NIGHT_VISION:
		if (type == Material.FERMENTED_SPIDER_EYE)
			return PotionType.INVISIBILITY;
		return pot.getType();
	case POISON:
		if (type == Material.FERMENTED_SPIDER_EYE)
			return PotionType.INSTANT_DAMAGE;
		return pot.getType();
	case REGEN:
		return pot.getType();
	case SLOWNESS:
		return pot.getType();
	case SPEED:
		if (type == Material.FERMENTED_SPIDER_EYE)
			return PotionType.SLOWNESS;
		return pot.getType();
	case STRENGTH:
		return pot.getType();
	case WATER:
		if (potion.getDurability() == 16)
			if (type == Material.GOLDEN_CARROT)
				return PotionType.NIGHT_VISION;
			if (type == Material.MAGMA_CREAM)
				return PotionType.FIRE_RESISTANCE;
			if (type == Material.SUGAR)
				return PotionType.SPEED;
			if (type == Material.RAW_FISH && ing.getDurability() == 3)
				return PotionType.WATER_BREATHING;
			if (type == Material.SPECKLED_MELON)
				return PotionType.INSTANT_HEAL;
			if (type == Material.SPIDER_EYE)
				return PotionType.POISON;
			if (type == Material.GHAST_TEAR)
				return PotionType.REGEN;
			if (type == Material.BLAZE_POWDER)
				return PotionType.STRENGTH;
		return PotionType.WATER;
	case WATER_BREATHING:
		if (type == Material.FERMENTED_SPIDER_EYE)
			return PotionType.INSTANT_DAMAGE;
		return pot.getType();
	case WEAKNESS:
		return pot.getType();
	default: return pot.getType();
	}
}