CavalliumDBEngine/src/main/java/it/cavallium/dbengine/database/collections/DatabaseLong.java

package it.cavallium.dbengine.database.collections;

import com.google.common.primitives.Ints;
import com.google.common.primitives.Longs;
import it.cavallium.dbengine.database.LLKeyValueDatabaseStructure;
import it.cavallium.dbengine.database.LLSingleton;
import it.cavallium.dbengine.database.LLSnapshot;
import it.cavallium.dbengine.database.UpdateReturnMode;
import it.cavallium.dbengine.database.serialization.SerializationException;
import it.cavallium.dbengine.database.serialization.SerializerFixedBinaryLength;
import org.jetbrains.annotations.Nullable;
import reactor.core.publisher.Mono;

public class DatabaseLong implements LLKeyValueDatabaseStructure {

	private final LLSingleton singleton;
	private final SerializerFixedBinaryLength<Long> serializer;
	private final SerializerFixedBinaryLength<Integer> bugSerializer;

	public DatabaseLong(LLSingleton singleton) {
		this.singleton = singleton;
		this.serializer = SerializerFixedBinaryLength.longSerializer(singleton.getAllocator());
		this.bugSerializer = SerializerFixedBinaryLength.intSerializer(singleton.getAllocator());
	}

	public Mono<Long> get(@Nullable LLSnapshot snapshot) {
		return singleton.get(snapshot).handle((dataSend, sink) -> {
			try (var data = dataSend.receive()) {
				if (data.readableBytes() == 4) {
					sink.next((long) (int) bugSerializer.deserialize(data));
				} else {
					sink.next(serializer.deserialize(data));
				}
			} catch (SerializationException e) {
				sink.error(e);
			}
		});
	}

	public Mono<Long> incrementAndGet() {
		return addAnd(1, UpdateReturnMode.GET_NEW_VALUE);
	}

	public Mono<Long> getAndIncrement() {
		return addAnd(1, UpdateReturnMode.GET_OLD_VALUE);
	}

	public Mono<Long> decrementAndGet() {
		return addAnd(-1, UpdateReturnMode.GET_NEW_VALUE);
	}

	public Mono<Long> getAndDecrement() {
		return addAnd(-1, UpdateReturnMode.GET_OLD_VALUE);
	}

	public Mono<Long> addAndGet(long count) {
		return addAnd(count, UpdateReturnMode.GET_NEW_VALUE);
	}

	public Mono<Long> getAndAdd(long count) {
		return addAnd(count, UpdateReturnMode.GET_OLD_VALUE);
	}

	private Mono<Long> addAnd(long count, UpdateReturnMode updateReturnMode) {
		return singleton.update(prev -> {
			if (prev != null) {
				var prevLong = prev.readLong();
				var alloc = singleton.getAllocator();
				var buf = alloc.allocate(Long.BYTES);
				buf.writeLong(prevLong + count);
				return buf;
			} else {
				var alloc = singleton.getAllocator();
				var buf = alloc.allocate(Long.BYTES);
				buf.writeLong(count);
				return buf;
			}
		}, updateReturnMode).map(send -> {
			try (var buf = send.receive()) {
				return buf.readLong();
			}
		}).single();
	}

	public Mono<Void> set(long value) {
		return singleton.set(Mono.fromCallable(() -> {
			try (var buf = singleton.getAllocator().allocate(Long.BYTES)) {
				serializer.serialize(value, buf);
				return buf.send();
			}
		}));
	}

	@Override
	public String getDatabaseName() {
		return singleton.getDatabaseName();
	}
}