/*
 * Copyright (c) 2015 Cisco 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.persisted;

import static java.util.Objects.requireNonNull;

import java.util.Collection;
import org.eclipse.jdt.annotation.NonNull;
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.DataTreeCandidateNode;
import org.opendaylight.yangtools.yang.data.tree.api.ModificationType;

/**
 * Abstract base class for our internal implementation of {@link DataTreeCandidateNode}, which we instantiate from a
 * serialized stream. We do not retain the before-image and do not implement {@link #modifiedChild(PathArgument)}, as
 * that method is only useful for end users. Instances based on this class should never be leaked outside of this
 * component.
 */
abstract class AbstractDataTreeCandidateNode implements DataTreeCandidateNode {
    private final @NonNull ModificationType type;

    protected AbstractDataTreeCandidateNode(final ModificationType type) {
        this.type = requireNonNull(type);
    }

    @Override
    public final DataTreeCandidateNode modifiedChild(final PathArgument identifier) {
        throw new UnsupportedOperationException("Not implemented");
    }

    @Override
    public final ModificationType modificationType() {
        return type;
    }

    @Override
    public final NormalizedNode dataBefore() {
        throw new UnsupportedOperationException("Before-image not available after serialization");
    }

    static DataTreeCandidateNode createUnmodified() {
        return new AbstractDataTreeCandidateNode(ModificationType.UNMODIFIED) {
            @Override
            public PathArgument name() {
                throw new UnsupportedOperationException("Root node does not have an identifier");
            }

            @Override
            public NormalizedNode dataAfter() {
                throw new UnsupportedOperationException("After-image not available after serialization");
            }

            @Override
            public Collection<DataTreeCandidateNode> childNodes() {
                throw new UnsupportedOperationException("Children not available after serialization");
            }
        };
    }
}