package jp.ac.u_ryukyu.ie.cr.shoshi.jungle.transaction;

import java.util.Iterator;
import java.util.concurrent.atomic.AtomicReference;

import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.JungleTree;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.persistent.ChangeList;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.persistent.ChangeListWriter;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.persistent.Result;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.store.ChangeSet;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.store.impl.DefaultNode;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.store.impl.logger.DefaultLogger;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.store.impl.logger.Logger;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.store.operations.Operation;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.transaction.AtomicReservableReference.Reservation;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.util.DefaultEither;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.util.DefaultError;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.util.Either;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.util.Error;

public class DefaultTransactionManager implements TransactionManager
{
	private final AtomicReservableReference<DefaultChangeSet> repository;
	private final DefaultChangeSet tip;
	private final ChangeListWriter writer;
	private final String uuid;
	
	public DefaultTransactionManager(ChangeListWriter _writer,DefaultChangeSet _changeSet,
			AtomicReservableReference<DefaultChangeSet> _repository,String _uuid)
	{
		repository = _repository;
		tip = _changeSet;
		writer = _writer;
		uuid = _uuid;
	}
	
	@Override
	public Either<Error,TransactionManager> commit(DefaultNode _newRoot,final Logger _log)
	{
		long currentRevision = tip.revision();
		long nextRevision = currentRevision + 1;
		
		ChangeList list = new ChangeList(){
			@Override
			public Iterator<Operation> iterator(){
				return _log.iterator();
			}
		};
		
		DefaultChangeSet changeSet = new DefaultChangeSet(_newRoot,tip,list,uuid,nextRevision);
		Reservation reservation = repository.makeReservation(tip,changeSet);
		if(reservation == null){
			return DefaultEither.newA((Error)new DefaultError());
		}
		Result r = writer.write(list);
		if(r == Result.SUCCESS){
			reservation.confirm();
			TransactionManager txManager = new DefaultTransactionManager(writer,changeSet,repository,uuid);
			return DefaultEither.newB(txManager);
		}
		
		return DefaultEither.newA((Error)new DefaultError());
	}

	@Override
	public String getUUID()
	{
		return uuid;
	}

	@Override
	public long getRevision()
	{
		return tip.revision();
	}
}