package net.minecraft.world.level.chunk;

import java.util.List;
import java.util.function.Predicate;
import net.minecraft.core.IdMap;
import net.minecraft.network.FriendlyByteBuf;
import net.minecraft.network.VarInt;
import org.apache.commons.lang3.Validate;
import org.jspecify.annotations.Nullable;

public class SingleValuePalette<T> implements Palette<T> {
	@Nullable
	private T value;

	public SingleValuePalette(final List<T> paletteEntries) {
		if (!paletteEntries.isEmpty()) {
			Validate.isTrue(paletteEntries.size() <= 1, "Can't initialize SingleValuePalette with %d values.", (long)paletteEntries.size());
			this.value = (T)paletteEntries.getFirst();
		}
	}

	public static <A> Palette<A> create(final int bits, final List<A> paletteEntries) {
		return new SingleValuePalette((List<T>)paletteEntries);
	}

	@Override
	public int idFor(final T value, final PaletteResize<T> resizeHandler) {
		if (this.value != null && this.value != value) {
			return resizeHandler.onResize(1, value);
		} else {
			this.value = value;
			return 0;
		}
	}

	@Override
	public boolean maybeHas(final Predicate<T> predicate) {
		if (this.value == null) {
			throw new IllegalStateException("Use of an uninitialized palette");
		} else {
			return predicate.test(this.value);
		}
	}

	@Override
	public T valueFor(final int index) {
		if (this.value != null && index == 0) {
			return this.value;
		} else {
			throw new IllegalStateException("Missing Palette entry for id " + index + ".");
		}
	}

	@Override
	public void read(final FriendlyByteBuf buffer, final IdMap<T> globalMap) {
		this.value = globalMap.byIdOrThrow(buffer.readVarInt());
	}

	@Override
	public void write(final FriendlyByteBuf buffer, final IdMap<T> globalMap) {
		if (this.value == null) {
			throw new IllegalStateException("Use of an uninitialized palette");
		} else {
			buffer.writeVarInt(globalMap.getId(this.value));
		}
	}

	@Override
	public int getSerializedSize(final IdMap<T> globalMap) {
		if (this.value == null) {
			throw new IllegalStateException("Use of an uninitialized palette");
		} else {
			return VarInt.getByteSize(globalMap.getId(this.value));
		}
	}

	@Override
	public int getSize() {
		return 1;
	}

	@Override
	public Palette<T> copy() {
		if (this.value == null) {
			throw new IllegalStateException("Use of an uninitialized palette");
		} else {
			return this;
		}
	}
}