/*
 * Copyright (c) 2016 Brocade Communications Systems, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.controller.cluster.datastore.util;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.base.Verify.verifyNotNull;

import com.google.common.annotations.Beta;
import java.util.Optional;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
import org.opendaylight.yangtools.yang.data.tree.api.DataTreeModificationCursor;

/**
 * Abstract {@link DataTreeModificationCursor} which tracks the current path. Subclasses can get the current path
 * via {@link #current()}. This class is NOT thread-safe.
 *
 * @author Thomas Pantelis
 */
@Beta
public abstract class AbstractDataTreeModificationCursor implements DataTreeModificationCursor {
    private YangInstanceIdentifier current = YangInstanceIdentifier.empty();

    protected final YangInstanceIdentifier current() {
        return current;
    }

    @Override
    public final void enter(final PathArgument child) {
        current = current.node(child);
    }

    @Override
    public final void enter(final PathArgument... path) {
        for (PathArgument arg : path) {
            enter(arg);
        }
    }

    @Override
    public final void enter(final Iterable<PathArgument> path) {
        for (PathArgument arg : path) {
            enter(arg);
        }
    }

    @Override
    public final void exit() {
        checkState(!current.isEmpty());
        current = verifyNotNull(current.getParent());
    }

    @Override
    public final void exit(final int depth) {
        checkArgument(depth >= 0);

        YangInstanceIdentifier next = current;
        for (int i = 0; i < depth; ++i) {
            next = next.getParent();
            checkState(next != null);
        }

        current = next;
    }

    @Override
    public final Optional<NormalizedNode> readNode(final PathArgument child) {
        throw new UnsupportedOperationException("Not implemented");
    }

    @Override
    public void close() {
        // No-op
    }
}