/*
 * 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.impl.schema.tree;

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

import java.util.Optional;
import org.eclipse.jdt.annotation.NonNull;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidateTip;
import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeModification;
import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeTip;
import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
import org.opendaylight.yangtools.yang.data.api.schema.tree.spi.TreeNode;

abstract class AbstractDataTreeTip implements DataTreeTip {
    /**
     * Return the current root node of this tip.
     *
     * @return Current tip root node, may not be null.
     */
    protected abstract @NonNull TreeNode getTipRoot();

    abstract @NonNull YangInstanceIdentifier getRootPath();

    @Override
    public final void validate(final DataTreeModification modification) throws DataValidationFailedException {
        final InMemoryDataTreeModification m = checkedCast(modification);
        checkArgument(m.isSealed(), "Attempted to verify unsealed modification %s", m);

        m.getStrategy().checkApplicable(new ModificationPath(getRootPath()), m.getRootModification(),
            Optional.of(getTipRoot()), m.getVersion());
    }

    @Override
    public final DataTreeCandidateTip prepare(final DataTreeModification modification) {
        final InMemoryDataTreeModification m = checkedCast(modification);
        checkArgument(m.isSealed(), "Attempted to prepare unsealed modification %s", m);

        final ModifiedNode root = m.getRootModification();

        final TreeNode currentRoot = getTipRoot();
        if (root.getOperation() == LogicalOperation.NONE) {
            return new NoopDataTreeCandidate(YangInstanceIdentifier.empty(), root, currentRoot);
        }

        final Optional<? extends TreeNode> newRoot = m.getStrategy().apply(m.getRootModification(),
            Optional.of(currentRoot), m.getVersion());
        checkState(newRoot.isPresent(), "Apply strategy failed to produce root node for modification %s", modification);
        return new InMemoryDataTreeCandidate(YangInstanceIdentifier.empty(), root, currentRoot, newRoot.get());
    }

    private static InMemoryDataTreeModification checkedCast(final DataTreeModification mod) {
        checkArgument(mod instanceof InMemoryDataTreeModification, "Invalid modification class %s", mod.getClass());
        return (InMemoryDataTreeModification)mod;
    }
}