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

import java.util.Iterator;
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.TreeNode;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.store.impl.logger.TreeOperationLog;
import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.store.operations.TreeOperation;
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<T extends TreeNode> implements TransactionManager<T>
{
	private final AtomicReservableReference<TreeContext<T>> repository;
	private final TreeContext<T> tip;
	private final ChangeListWriter writer;
	private final String uuid;
	
	public DefaultTransactionManager(ChangeListWriter _writer,TreeContext<T> _tip,
			AtomicReservableReference<TreeContext<T>> _repository,String _uuid)
	{
		repository = _repository;
		tip = _tip;
		writer = _writer;
		uuid = _uuid;
	}
	
	@Override
	public Either<Error,TransactionManager<T>> commit(TreeNode _newRoot,final TreeOperationLog _log)
	{
		ChangeSet cs = tip.getChangeSet();
		long currentRevision = cs.revision();
		long nextRevision = currentRevision + 1;
		
		final String _treeName = cs.getTreeName();
		ChangeList list = new ChangeList(){
			@Override
			public Iterator<TreeOperation> iterator(){
				return _log.iterator();
			}
			@Override
			public String getTreeName(){
				return _treeName;
			}
			@Override
			public String uuid(){
				return uuid;
			}
		};
		
		DefaultChangeSet newCs = new DefaultChangeSet(_newRoot,cs,list,uuid, _treeName, nextRevision);
		DefaultTreeContext<T> newContext = new DefaultTreeContext<T>(_newRoot,newCs);
		
		@SuppressWarnings("rawtypes")
		Reservation reservation = repository.makeReservation(tip,newContext);
		if(reservation == null){
			return DefaultEither.newA((Error)new DefaultError());
		}
		Result r = writer.write(list);
		if(r == Result.SUCCESS){
			reservation.confirm();
			TransactionManager<T> txManager = new DefaultTransactionManager<T>(writer,newContext,repository,uuid);
			return DefaultEither.newB(txManager);
		}
		return DefaultEither.newA((Error)new DefaultError());
	}

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

	@Override
	public long getRevision()
	{
		ChangeSet cs = tip.getChangeSet();
		return cs.revision();
	}
}