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

import jp.ac.u_ryukyu.ie.cr.jungle.data.list.List;
import jp.ac.u_ryukyu.ie.cr.jungle.persistent.ChangeList;
import jp.ac.u_ryukyu.ie.cr.jungle.persistent.ChangeListWriter;
import jp.ac.u_ryukyu.ie.cr.jungle.query.traverser.DifferentialInterfaceTraverser;
import jp.ac.u_ryukyu.ie.cr.jungle.query.traverser.InterfaceTraverser;
import jp.ac.u_ryukyu.ie.cr.jungle.store.TreeContext;
import jp.ac.u_ryukyu.ie.cr.jungle.store.index.Index;
import jp.ac.u_ryukyu.ie.cr.jungle.store.index.ParentIndex;
import jp.ac.u_ryukyu.ie.cr.jungle.store.logger.TreeOperationLog;
import jp.ac.u_ryukyu.ie.cr.jungle.store.operations.TreeOperation;
import jp.ac.u_ryukyu.ie.cr.jungle.transaction.context.DifferenceTreeContext;
import jp.ac.u_ryukyu.ie.cr.jungle.transaction.node.TreeNode;
import jp.ac.u_ryukyu.ie.cr.jungle.transaction.node.TreeNodeChildren;
import jp.ac.u_ryukyu.ie.cr.jungle.tree.TreeType;
import jp.ac.u_ryukyu.ie.cr.jungle.util.DefaultEither;
import jp.ac.u_ryukyu.ie.cr.jungle.util.Either;
import jp.ac.u_ryukyu.ie.cr.jungle.util.jungleError.Error;

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

import static jp.ac.u_ryukyu.ie.cr.jungle.util.jungleError.TransactionError.APPEND_FAILD;
import static jp.ac.u_ryukyu.ie.cr.jungle.util.jungleError.TreeEditorError.CAS_MISS;

public class DifferenceTransactionManager implements TransactionManager {
    private final AtomicReference<TreeContext> repository;
    private final TreeContext tip;
    private final ChangeListWriter writer;
    private final String uuid;

    public DifferenceTransactionManager(ChangeListWriter _writer, TreeContext _tip, AtomicReference<TreeContext> _repository, String _uuid) {
        repository = _repository;
        tip = _tip;
        writer = _writer;
        uuid = _uuid;
    }

    /**
     * DifferentialTreeではIndexの更新時
     * delete処理を行う必要が無いので
     * editNodeListは使用しない
     * commitの第三引数のeditNodeListは使用しない
     * しかし、末尾のノード情報をrepositoryに入れる必要があるため
     * editNodeListを使ってここに持って来ている
     * 昔はJungleTreeEditorで後からsetしていたが、
     * DifferentialInterfaceTraverserに末尾ノードを入れる必要が出てきたので
     * この実装になった
     */
    @Override
    public Either<Error, TransactionManager> commit(TreeNode subTreeRoot, TreeOperationLog log,List<TreeNode> editNodeList) {
        long currentRevision = tip.revision();
        long nextRevision = currentRevision + 1;

        final String _treeName = tip.getTreeName();
        ChangeList list = new ChangeList() {
            @Override
            public Iterator<TreeOperation> iterator() {
                return log.iterator();
            }

            @Override
            public String getTreeName() {
                return _treeName;
            }

            @Override
            public int getTreeType() {
                return TreeType.DIFFERENCE;
            }

            @Override
            public TreeOperationLog getLog() {
                return log;
            }

            @Override
            public String uuid() {
                return uuid;

            }
        };

        TreeNode root = tip.getRoot();
        Index index = tip.getIndex();
        ParentIndex parentIndex = tip.getParentIndex();
        TreeNode endNode = editNodeList.get(0);
        InterfaceTraverser traverser = new DifferentialInterfaceTraverser(root,endNode ,index, parentIndex, true);
        TreeContext newTreeContext = new DifferenceTreeContext(root, endNode, tip, list, uuid, _treeName, nextRevision, traverser);
        if (repository.compareAndSet(newTreeContext.prev(), newTreeContext)) {
            Either<Error, TreeNode> either = appendSubTree(subTreeRoot);
            if (either.isA())
                return DefaultEither.newA(either.a());
            traverser.updateIndex(tip.getEndNode());
            TransactionManager txManager = new DifferenceTransactionManager(writer, newTreeContext, repository, uuid);
            return DefaultEither.newB(txManager);
        }

        return DefaultEither.newA(CAS_MISS);
    }

    private Either<Error, TreeNode> appendSubTree(TreeNode subTreeRoot) {
        TreeNode appendedNode = tip.getEndNode();
        TreeNodeChildren children = appendedNode.getChildren();
        if (children.size() != 0)
            return DefaultEither.newA(APPEND_FAILD); //append Nodeが１つ以上子を持つ場合過去の木であるため、変更させない。そうすることで整合性を保証する
        return children.addNewChildAt(0, subTreeRoot);
    }


    @Override
    public Either<Error, TransactionManager> flashCommit(TreeNode _newRoot, TreeOperationLog _log) {
        return null;//commit(_newRoot, _log);
    }

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

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

}