package rocks.inspectit.shared.cs.storage.nio.write;

import java.nio.channels.CompletionHandler;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import rocks.inspectit.shared.cs.storage.nio.WriteReadAttachment;
import rocks.inspectit.shared.cs.storage.nio.WriteReadCompletionRunnable;

/**
 * Completion handler for asynchronous writing.
 *
 * @author Ivan Senic
 *
 */
public class WritingCompletionHandler implements CompletionHandler<Integer, WriteReadAttachment> {

	/**
	 * The log of this class. Can not be assigned via spring because this is not a component.
	 */
	private static final Logger LOG = LoggerFactory.getLogger(WritingCompletionHandler.class);

	/**
	 * {@inheritDoc}
	 * <p>
	 * On writing completion the check if the whole content of the buffer has been written is done.
	 * If not, a new write with updated position and size is performed. If yes, the completion
	 * handler is invoke if it is not null.
	 */
	@Override
	public void completed(Integer result, WriteReadAttachment attachment) {
		long bytesToWriteMore = attachment.getSize() - result.longValue();
		if (bytesToWriteMore > 0) {
			long writingSize = bytesToWriteMore;
			long writingPosition = attachment.getPosition() + result.longValue();

			attachment.setPosition(writingPosition);
			attachment.setSize(writingSize);

			attachment.getFileChannel().write(attachment.getByteBuffer(), writingPosition, attachment, this);
		} else {
			WriteReadCompletionRunnable.RunnableFuture completionRunnableFuture = attachment.getCompletionRunnableFuture();
			if (null != completionRunnableFuture) {
				completionRunnableFuture.getWriteReadCompletionRunnable().markSuccess();
				if (completionRunnableFuture.getWriteReadCompletionRunnable().isFinished()) {
					completionRunnableFuture.run();
				}
			}
		}
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public void failed(Throwable exc, WriteReadAttachment attachment) {
		LOG.error("Write to the disk failed.", exc);
		WriteReadCompletionRunnable.RunnableFuture completionRunnableFuture = attachment.getCompletionRunnableFuture();
		if (null != completionRunnableFuture) {
			completionRunnableFuture.getWriteReadCompletionRunnable().markFailed();
			if (completionRunnableFuture.getWriteReadCompletionRunnable().isFinished()) {
				completionRunnableFuture.run();
			}
		}
	}

}