package it.cavallium.dbengine.database.collections;

import it.cavallium.dbengine.client.CompositeSnapshot;
import it.cavallium.dbengine.database.serialization.Serializer;
import java.util.function.Function;
import org.jetbrains.annotations.Nullable;
import reactor.core.publisher.Mono;

@SuppressWarnings("unused")
public class DatabaseSingleMapped<A, B> implements DatabaseStageEntry<A> {

	private final DatabaseStageEntry<B> serializedSingle;
	private final Serializer<A, B> serializer;

	public DatabaseSingleMapped(DatabaseStageEntry<B> serializedSingle, Serializer<A, B> serializer) {
		this.serializedSingle = serializedSingle;
		this.serializer = serializer;
	}

	@Override
	public Mono<A> get(@Nullable CompositeSnapshot snapshot, boolean existsAlmostCertainly) {
		return serializedSingle.get(snapshot, existsAlmostCertainly).map(this::deserialize);
	}

	@Override
	public Mono<A> getOrDefault(@Nullable CompositeSnapshot snapshot, Mono<A> defaultValue) {
		return serializedSingle.get(snapshot).map(this::deserialize).switchIfEmpty(defaultValue);
	}

	@Override
	public Mono<Void> set(A value) {
		return serializedSingle.set(serialize(value));
	}

	@Override
	public Mono<A> setAndGetPrevious(A value) {
		return serializedSingle.setAndGetPrevious(serialize(value)).map(this::deserialize);
	}

	@Override
	public Mono<Boolean> setAndGetChanged(A value) {
		return serializedSingle.setAndGetChanged(serialize(value)).single();
	}

	@Override
	public Mono<Boolean> update(Function<@Nullable A, @Nullable A> updater, boolean existsAlmostCertainly) {
		return serializedSingle.update(oldValue -> {
			var result = updater.apply(oldValue == null ? null : this.deserialize(oldValue));
			if (result == null) {
				return null;
			} else {
				return this.serialize(result);
			}
		}, existsAlmostCertainly);
	}

	@Override
	public Mono<Void> clear() {
		return serializedSingle.clear();
	}

	@Override
	public Mono<A> clearAndGetPrevious() {
		return serializedSingle.clearAndGetPrevious().map(this::deserialize);
	}

	@Override
	public Mono<Boolean> clearAndGetStatus() {
		return serializedSingle.clearAndGetStatus();
	}

	@Override
	public Mono<Void> close() {
		return serializedSingle.close();
	}

	@Override
	public Mono<Long> leavesCount(@Nullable CompositeSnapshot snapshot, boolean fast) {
		return serializedSingle.leavesCount(snapshot, fast);
	}

	@Override
	public Mono<Boolean> isEmpty(@Nullable CompositeSnapshot snapshot) {
		return serializedSingle.isEmpty(snapshot);
	}

	@Override
	public DatabaseStageEntry<A> entry() {
		return this;
	}

	@Override
	public void release() {
		serializedSingle.release();
	}

	//todo: temporary wrapper. convert the whole class to buffers
	private A deserialize(B bytes) {
		return serializer.deserialize(bytes);
	}

	//todo: temporary wrapper. convert the whole class to buffers
	private B serialize(A bytes) {
		return serializer.serialize(bytes);
	}
}