package net.minecraft.util.random;

import com.google.common.collect.ImmutableList;
import com.mojang.serialization.Codec;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import net.minecraft.util.RandomSource;
import org.jetbrains.annotations.Nullable;

public class WeightedRandomList<E extends WeightedEntry> {
	private final int totalWeight;
	private final ImmutableList<E> items;

	WeightedRandomList(List<? extends E> items) {
		this.items = ImmutableList.copyOf(items);
		this.totalWeight = WeightedRandom.getTotalWeight(items);
	}

	public static <E extends WeightedEntry> WeightedRandomList<E> create() {
		return new WeightedRandomList<>(ImmutableList.of());
	}

	@SafeVarargs
	public static <E extends WeightedEntry> WeightedRandomList<E> create(E... items) {
		return new WeightedRandomList<>(ImmutableList.copyOf(items));
	}

	public static <E extends WeightedEntry> WeightedRandomList<E> create(List<E> items) {
		return new WeightedRandomList<>(items);
	}

	public boolean isEmpty() {
		return this.items.isEmpty();
	}

	public Optional<E> getRandom(RandomSource random) {
		if (this.totalWeight == 0) {
			return Optional.empty();
		} else {
			int i = random.nextInt(this.totalWeight);
			return WeightedRandom.getWeightedItem(this.items, i);
		}
	}

	public List<E> unwrap() {
		return this.items;
	}

	public static <E extends WeightedEntry> Codec<WeightedRandomList<E>> codec(Codec<E> elementCodec) {
		return elementCodec.listOf().xmap(WeightedRandomList::create, WeightedRandomList::unwrap);
	}

	public boolean equals(@Nullable Object object) {
		if (this == object) {
			return true;
		} else if (object != null && this.getClass() == object.getClass()) {
			WeightedRandomList<?> weightedRandomList = (WeightedRandomList<?>)object;
			return this.totalWeight == weightedRandomList.totalWeight && Objects.equals(this.items, weightedRandomList.items);
		} else {
			return false;
		}
	}

	public int hashCode() {
		return Objects.hash(new Object[]{this.totalWeight, this.items});
	}
}