/*
 * 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.yangtools.yang.data.api.schema;

import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.Map;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;

final class DuplicateFinder {
    private final Map<NormalizedNode<?, ?>, DuplicateEntry> identities = new IdentityHashMap<>();
    private final Map<NormalizedNode<?, ?>, DuplicateEntry> duplicates = new HashMap<>();

    private DuplicateFinder() {
        // Hidden on purpose
    }

    private void findDuplicates(final YangInstanceIdentifier path, final NormalizedNode<?, ?> node) {
        final DuplicateEntry i = identities.get(node);
        if (i == null) {
            final DuplicateEntry d = duplicates.get(node);
            if (d == null) {
                final DuplicateEntry n = new DuplicateEntry(path);
                identities.put(node, n);
                duplicates.put(node, n);
            } else {
                d.addDuplicate(path);
            }

            if (node instanceof NormalizedNodeContainer<?, ?, ?>) {
                final NormalizedNodeContainer<?, ?, ?> container = (NormalizedNodeContainer<?, ?, ?>) node;

                for (NormalizedNode<?, ?> c : container.getValue()) {
                    findDuplicates(path.node(c.getIdentifier()), c);
                }
            }
        } else {
            i.addHardLink(path);
        }
    }

    /**
     * Recursively scan a {@link NormalizedNode} instance and its children and
     * produce a collection of {@link DuplicateEntry} objects. Each holds the
     * original definition path and a list of hard/softlinks.
     *
     * @param node Root node, may not be null.
     * @return List of entries
     */
    static Map<NormalizedNode<?, ?>, DuplicateEntry> findDuplicates(final NormalizedNode<?, ?> node) {
        final DuplicateFinder finder = new DuplicateFinder();
        finder.findDuplicates(YangInstanceIdentifier.EMPTY, node);
        return finder.identities;
    }
}