package net.minecraft.util.random;

import java.util.List;
import java.util.Optional;
import net.minecraft.Util;
import net.minecraft.util.RandomSource;

public class WeightedRandom {
	private WeightedRandom() {
	}

	public static int getTotalWeight(List<? extends WeightedEntry> entries) {
		long l = 0L;

		for (WeightedEntry weightedEntry : entries) {
			l += weightedEntry.getWeight().asInt();
		}

		if (l > 2147483647L) {
			throw new IllegalArgumentException("Sum of weights must be <= 2147483647");
		} else {
			return (int)l;
		}
	}

	public static <T extends WeightedEntry> Optional<T> getRandomItem(RandomSource random, List<T> entries, int totalWeight) {
		if (totalWeight < 0) {
			throw (IllegalArgumentException)Util.pauseInIde((T)(new IllegalArgumentException("Negative total weight in getRandomItem")));
		} else if (totalWeight == 0) {
			return Optional.empty();
		} else {
			int i = random.nextInt(totalWeight);
			return getWeightedItem(entries, i);
		}
	}

	public static <T extends WeightedEntry> Optional<T> getWeightedItem(List<T> entries, int weightedIndex) {
		for (T weightedEntry : entries) {
			weightedIndex -= weightedEntry.getWeight().asInt();
			if (weightedIndex < 0) {
				return Optional.of(weightedEntry);
			}
		}

		return Optional.empty();
	}

	public static <T extends WeightedEntry> Optional<T> getRandomItem(RandomSource random, List<T> entries) {
		return getRandomItem(random, entries, getTotalWeight(entries));
	}
}