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.jetbrains.annotations.Nullable;

public class SingleValuePalette<T> implements Palette<T> {
	private final IdMap<T> registry;
	@Nullable
	private T value;
	private final PaletteResize<T> resizeHandler;

	public SingleValuePalette(IdMap<T> registry, PaletteResize<T> resizeHandler, List<T> value) {
		this.registry = registry;
		this.resizeHandler = resizeHandler;
		if (value.size() > 0) {
			Validate.isTrue(value.size() <= 1, "Can't initialize SingleValuePalette with %d values.", (long)value.size());
			this.value = (T)value.get(0);
		}
	}

	public static <A> Palette<A> create(int bits, IdMap<A> registry, PaletteResize<A> resizeHandler, List<A> value) {
		return new SingleValuePalette<>(registry, resizeHandler, value);
	}

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

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

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

	@Override
	public void read(FriendlyByteBuf buffer) {
		this.value = this.registry.byIdOrThrow(buffer.readVarInt());
	}

	@Override
	public void write(FriendlyByteBuf buffer) {
		if (this.value == null) {
			throw new IllegalStateException("Use of an uninitialized palette");
		} else {
			buffer.writeVarInt(this.registry.getId(this.value));
		}
	}

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

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

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