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package se.l4.commons.serialization.standard;

import java.io.IOException;
import java.util.Optional;

import se.l4.commons.serialization.Serializer;
import se.l4.commons.serialization.SerializerFormatDefinition;
import se.l4.commons.serialization.format.StreamingInput;
import se.l4.commons.serialization.format.StreamingOutput;
import se.l4.commons.serialization.format.Token;

/**
 * Serializer for {@link Optional} values. Will treat null as an empty
 * optional.
 */
public class OptionalSerializer
	implements Serializer>, Serializer.NullHandling
{
	private final Serializer itemSerializer;
	private final SerializerFormatDefinition formatDefinition;

	public OptionalSerializer(Serializer itemSerializer)
	{
		this.itemSerializer = itemSerializer;

		formatDefinition = itemSerializer.getFormatDefinition();
	}

	@Override
	public Optional read(StreamingInput in)
		throws IOException
	{
		if(in.peek() == Token.NULL)
		{
			// Consume the null value
			in.next();
			return Optional.empty();
		}

		T item = itemSerializer.read(in);
		return Optional.of(item);
	}

	@Override
	public void write(Optional object, String name, StreamingOutput stream)
		throws IOException
	{
		if(object != null && object.isPresent())
		{
			// Use the item serializer to serialize if there is an object present
			itemSerializer.write(object.get(), name, stream);
		}
		else
		{
			// If there is no object, write a null value
			stream.writeNull(name);
		}
	}

	@Override
	public SerializerFormatDefinition getFormatDefinition()
	{
		return formatDefinition;
	}
}